# V International APOMIXIS 2025 Conference : book of abstracts

Olivier Leblanc, Daphné Autran, Maïa Lejbowicz

► To cite this version:

Olivier Leblanc, Daphné Autran, Maïa Lejbowicz. V International APOMIXIS 2025 Conference : book of abstracts. International APOMIXIS 2025 Conference, Sep 2025, Montpellier, France. IRD; DIADE, 95 p., 2025. hal-05499824

HAL Id: hal-05499824

https://hal.science/hal-05499824v1

Submitted on 23 Feb 2026

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Distributed under a Creative Commons CC BY 4.0 - Attribution - International License
V International Conference on
APOMIXIS
2025

Montpellier, France | 16-19 SEPT.

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## BOOK OF ABSTRACTS

Program - Abstracts

List of posters

List of participants

Conference venue:
MERCURE
Montpellier Centre Comédie

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Funded by
the European Union

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MECHANISMS OF APOMICTIC DEVELOPMENT

polyploid

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These experiments have received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreements No 872417 and No 10000428.

<figure><img src="image_7.png" /></figure>

Deploying research
Sharing science
Transforming the future

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PÔLE AGRICULTURE
ENVIRONNEMENT
BIODIVERSITÉ
UNIVERSITÉ DE MONTPELLIER

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Montpellier
Méditerranée
Métropole
V International Conference on
# APOMIXIS 2025
Montpellier, France | 16-19 SEPT.

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Conference venue:
**MERCURE**
Montpellier
Centre Comédie

## WELCOME

Dear friends and colleagues,

The V International APOMIXIS 2025 Conference in Montpellier, France, from 16 to 19 September 2025, will cover most aspects of plant reproductive biology devoted to the elucidation and the use of apomixis in plant breeding and agriculture. With this fifth International Conference on Apomixis, we hope to initiate a cycle of biannual events starting with the last conference in Rosario, Argentina, in December 2023.

The conference will include two Opening Plenary lectures, 8 sessions featuring presentations by invited scientists and selected abstracts, and two forums devoted to a wide range of topics giving an overview of the latest results and trends in the field, as follows:

**Opening Plenary lecture** by Amanda GRUSZ - Univ. Minnesota Duluth, USA

**Opening Plenary lecture** by Pr. Venkatesan SUNDARESAN - UC Davis, USA

**SESSION 1** - Evolution of apomixis

**SESSION 2** - (Epi)genomics of apomixis

**SESSION 3** - Reproductive developmental plasticity

**SESSION 4** - Apomeiosis I

**SESSION 5** - Apomeiosis II

**SESSION 6** - Triggering embryogenesis

**FORUM 1** - Missing tools for harnessing apomixis in plant breeding?

**FORUM 2** - Apomixis, a plant breeding innovation?

**SESSION 7** - Seed development

**SESSION 8** - Asexual reproduction in animals

The organisers are committed to implementing measures to make the conference environmentally more sustainable and more inclusive.

Yours sincerely,

Organizing Committee

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V International Conference on
# APOMIXIS 2025
Montpellier, France | 16-19 SEPT.

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Conference venue:
**MERCURE**
Montpellier
Centre Comédie

## COMMITTEES

### ORGANIZING COMMITTEE

Institut de Recherche pour le Développement
(IRD), France

**Daphné AUTRAN**

**Olivier LEBLANC**

**Maïa LEJBOWICZ**

### SCIENTIFIC COMMITTEE

**Daphné AUTRAN** - IRD, France

**Lucia COLOMBO** - University of Milan, Italy

**Thomas DRESSELHAUS** - University of Regensburg, Germany

**Laurine GILLES** - CIRAD, France

**Stewart GILLMOR** - CINVESTAV, Mexico

**Elvira HÖRANDL** - Georg-August-Universität Göttingen, Germany

**Olivier LEBLANC** - IRD, France

**Juan Pablo ORTIZ** - IICAR, University of Rosario-CONICET, Argentina

**Nada ŠURBANOVSKI** - NIAB, UK

## ADMINISTRATIVE SECRETARIAT

Registration, accommodation - Sponsorship

Alpha Visa Congrès / APOMIXIS 2025
624 rue des Grèzes
34070 Montpellier - France

Tel: +33 4 67 03 03 00

E-mail: apomixis@alphavisa.com

Web: www.alphavisa.com/apomixis/2025
We greatly acknowledge our sponsors below:

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Funded by
the European Union

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MECHANISMS OF APOMICTIC DEVELOPMENT

* **MAD**
  Mechanisms of Apomictic Developments
  https://apomixis.eu/

polyploid

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These projects have received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreements No 872417 and No 101007438.

* **POLYPLOID**
  The polyploidy paradigm and its role in plant breeding
  https://polyploid.eu/

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Deploying research
Sharing science
Transforming the future

* **IRD**
  French National Research Institute for Sustainable Development
  https://en.ird.fr/

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* **DIADE**
  Diversity - Adaptation - Development of plants
  http://diade.ird.fr/

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PÔLE AGRICULTURE
ENVIRONNEMENT
BIODIVERSITÉ

UNIVERSITÉ DE MONTPELLIER

* **AEB**
  Agriculture-Environment-Biodiversity Division
  https://www.umontpellier.fr/en/

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montpellier
méditerranée
Métropole

* **MONTPELLIER 3M**
  Montpellier Méditerranée Métropole
  https://www.montpellier3m.fr/ - https://www.montpellier.fr/en
V International Conference on
# APOMIXIS 2025
Montpellier, France | 16-19 SEPT.

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## PLANNING AT A GLANCE

TUESDAY 16 SEPTEMBER

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WEDNESDAY 17 SEPTEMBER

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THURSDAY 18 SEPTEMBER

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FRIDAY 19 SEPTEMBER

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KEYNOTE & INVITED SPEAKERS

Opening Plenary lectures

<figure><img src="image_28.png" /><figcaption>**Amanda GRUSZ**
*Univ. of Minnesota Duluth, USA*
Evaluating a drought-driven hypothesis for the origin of obligate apomixis</figcaption></figure>

<figure><img src="image_29.png" /><figcaption>**Pr. Venkatesan SUNDARESAN**
*UC Davis, USA*
Genomics of embryo initiation and application to synthetic apomixis in rice</figcaption></figure>

SESSION 1: Evolution of apomixis

<figure><img src="image_30.png" /><figcaption>**Elvira HÖRAND**
*Univ. Göttingen, Germany*
The origin of apomixis in natural plant populations
[Link](#)</figcaption></figure>

<figure><img src="image_31.png" /><figcaption>**Petra ŠARHANOVÁ**
*Masaryk University, Department of Botany and Zoology, Plant Biosystematics Group, Czech Republic*
Clonal or sexual? The evolutionary dance of blackberries</figcaption></figure>

<figure><img src="image_32.png" /><figcaption>**Koen JF VERHOEVEN**
*Neederlands Institute of Ecology, Neederlands*
Rapid adaptation to local environments in diverse apomictic dandelion populations</figcaption></figure>

SESSION 2: (Epi)Genomics of apomixis

<figure><img src="image_33.png" /><figcaption>**Duarte Dionisio FIGUEIREDO**
*Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany*
Molecular mechanisms initiating endosperm development in flowering plants
[Link](#)</figcaption></figure>

<figure><img src="image_34.png" /><figcaption>**Juan Manuel VEGA**
*IICAR, Univ. Nac Rosario-CONICET, Argentina*
Insights into the structure and gene content of the Apomixis Controlling Locus (ACL) of *Paspalum notatum*
[Link](#)</figcaption></figure>

<figure><img src="image_35.png" /><figcaption>**Bianca BACCILI ZANOTTO VIGNA**
*EMBRAPA Southeastern Livestock, Brazil*
Apomixis and associated molecular markers development in tropical forages
[Link](#)</figcaption></figure>
## SESSION 3: Reproductive developmental plasticity

<figure><img src="image_36.png" /><figcaption>**Matthew TUCKER**
*Univ. Adelaiade, Australia*</figcaption></figure>

Distinct nucellar cell types nurture the female gametophyte in cereal ovules

Link

<figure><img src="image_37.png" /><figcaption>**Luciana DELGADO**
*IICAR, Univ. Nac Rosario-CONICET, Argentina*</figcaption></figure>

Are apomictic and sexual development related to the plasticity of ovule morphogenesis? A 3D approach in *Paspalum rufum*

Link

<figure><img src="image_38.png" /><figcaption>**Emmanuel GUIDERDONI**
*CIRAD, UMR AGAP Institute, Montpellier, France*</figcaption></figure>

Imaging of female gametophytes reveals the cause of reduced seed setting in apomictic rice

Link 1 - Link 2

## SESSION 4: Apomeiosis I

<figure><img src="image_39.png" /><figcaption>**Tim SHARBEL**
*Univ. Saskatchewan, Canada*</figcaption></figure>

The evolution of apomixis in *Boechera*, a tool for Brassica crops

Link

<figure><img src="image_40.png" /><figcaption>**Adrián GONZALO SANCHEZ**
*ETH Zürich, Switzerland*</figcaption></figure>

Genetics of meiotic and non-meiotic instability in polyploids

<figure><img src="image_41.png" /><figcaption>**Viviana ECHENIQUE**
*CERZOS-Univ. Nac del Sur-CONICET, Argentina*</figcaption></figure>

Structural characterization, gene content and gene expression of the region controlling apomeiosis in *Eragrostis curvula*

## SESSION 5: Apomeiosis II

<figure><img src="image_42.png" /><figcaption>**Üeli GROSSNIKLAUS**
*Department of Plant and Microbial Biology & Zürich-Basel Plant Science Center, Univ. of Zürich, Switzerland*</figcaption></figure>

Towards the Engineering of Synthetic Apomixis in Maize

<figure><img src="image_43.png" /><figcaption>**Lorena SIENA**
*IICAR, Univ. Nac Rosario-CONICET, Argentina*</figcaption></figure>

QUI-GON JINN, a member of the YODA family, plays a critical role during female reproduction in *Arabidopsis thaliana*

<figure><img src="image_44.png" /><figcaption>**Marta MENDES**
*Univ. Milan, Italy*
Disruption of miR160-mediated ARF10 silencing triggers aposporous phenotypes in *Arabidopsis* ovules</figcaption></figure>
## SESSION 6: Triggering embryogenesis

<figure><img src="image_45.png" /><figcaption>**Charles J. UNDERWOOD**</figcaption></figure>

Radboud University, Netherlands

Eternally hybrid: natural and engineered propagation of hybrid genomes through seeds

<figure><img src="image_46.png" /><figcaption>**Thomas WIDIEZ**</figcaption></figure>

RDP-ENS Lyon, France

On the Road to Apomixis in
Maize: A Win for Embryo-
genesis, a Wait for Apomeiosis

Link

<figure><img src="image_47.png" /><figcaption>**Kenny BOGAERT**</figcaption></figure>

Max Planck Institute of Biology,
Germany

Apomixis in the Sea?

Parthenogenesis and Maternal
Cues in Seaweeds

Link

## FORUM 1 - Missing tools for harnessing apomixis in plant breeding?

<figure><img src="image_48.png" /><figcaption>**Silvina PESSINO**</figcaption></figure>

IICAR, Univ. Nac Rosario-CONICET, Argentina

Missing tools for harnessing apomixis in plant breeding?

Link

<figure><img src="image_49.png" /><figcaption>**Emmanuel GUIDERDONI**</figcaption></figure>

CIRAD, UMR AGAP Institute,
Montpellier, France

Link 1 - Link 2

<figure><img src="image_50.png" /><figcaption>**Emidio ALBERTINI**</figcaption></figure>

University of Perugia, Italy

Link

<figure><img src="image_51.png" /><figcaption>**Peggy OZIAS-AKINS**</figcaption></figure>

Univ. Tifton, USA

Link
## FORUM 2 - Apomixis, a plant breeding innovation?

<figure><img src="image_52.png" /><figcaption>**Liana JANK**
EMBRAPA, breeder, Brazil</figcaption></figure>

Apomixis, a plant breeding innovation?

Link

<figure><img src="image_53.png" /><figcaption>**Stéphane LEMARIÉ**
INRAe, GAEL Grenoble, France</figcaption></figure>

<figure><img src="image_54.png" /><figcaption>**Marc ALBERTSEN**
Albertsen Crop Genetics for Humanity, Johnston, USA</figcaption></figure>

<figure><img src="image_55.png" /><figcaption>**Viviana ECHENIQUE**
CERZOS-Univ. Nac del Sur-CONICET, Argentina</figcaption></figure>

Link

<figure><img src="image_56.png" /><figcaption>**Üeli GROSSNIKLAUS**
University of Zürich, Zürich, Switzerland</figcaption></figure>

## SESSION 7: Seed development

<figure><img src="image_57.png" /><figcaption>**Benoit LANDREIN**
RDP-ENS Lyon, France</figcaption></figure>

Mechanical control of seed morphogenesis

Link

<figure><img src="image_58.png" /><figcaption>**Gerardo Del TORO-De LEÓN**
Max Planck Institute of Molecular Plant Physiology, Germany</figcaption></figure>

Maternal control of RNA decay safeguards embryo development

Link

<figure><img src="image_59.png" /><figcaption>**Anja SCHMIDT**
Univ. Heidelberg, Germany</figcaption></figure>

RNA helicases in shaping plasticity during sexual and apomictic reproduction through seeds

Link

## SESSION 8: Asexual reproduction in animals

<figure><img src="image_60.png" /><figcaption>**Thomas LENORMAND**
CEFE, CNRS, Montpellier, France</figcaption></figure>

Parthenogenesis and the evolution of clonality in animals

<figure><img src="image_61.png" /><figcaption>**Micaela MÜLLER**
CERZOS-Univ. Nac del Sur-CONICET, Argentina</figcaption></figure>

Beyond plants: how reproductive strategies could shape invasiveness and disease spread in freshwater snails

Link
TABLE OF CONTENTS

click to go to page

PROGRAM

<table><tr><td>■ Planning at a glance</td><td>5</td></tr><tr><td>■ Tuesday 16 September</td><td>12</td></tr><tr><td>■ Wednesday 17 September</td><td>13</td></tr><tr><td>■ Thursday 18 September</td><td>14</td></tr><tr><td>■ Friday 19 September</td><td>16</td></tr></table>

ABSTRACTS TUESDAY 16 SEPTEMBER

Opening Plenary Lectures

<table><tr><td>Keynote Speakers: Amanda GRUSZ</td><td>18</td></tr><tr><td>Venkatesan SUNDARESAN</td><td>19</td></tr></table>

SESSION 1 - Evolution of apomixis

<table><tr><td>Keynote Speaker: Elvira HÖRANDL</td><td>20</td></tr><tr><td>Invited Speakers</td><td>21</td></tr><tr><td>Oral presentations</td><td>23</td></tr></table>

ABSTRACTS WEDNESDAY 17 SEPTEMBER

SESSION 2 - (Epi)Genomics of apomixis

<table><tr><td>Keynote Speaker: Duarte Dionisio FIGUEIREDO</td><td>27</td></tr><tr><td>Invited Speakers</td><td>28</td></tr><tr><td>Oral presentations</td><td>30</td></tr></table>

SESSION 3 - Reproductive developmental plasticity

<table><tr><td>Keynote Speaker: Matthew TUCKER</td><td>33</td></tr><tr><td>Invited Speakers</td><td>34</td></tr><tr><td>Oral presentations</td><td>36</td></tr></table>

SESSION 4 - Apomeiosis I

<table><tr><td>Keynote Speaker: Tim SHARBEL</td><td>38</td></tr><tr><td>Invited Speakers</td><td>39</td></tr><tr><td>Oral presentations</td><td>41</td></tr></table>

ABSTRACTS THURSDAY 18 SEPTEMBER

SESSION 5 - Apomeiosis II

<table><tr><td>Keynote Speaker: Üeli GROSSNIKLAUS</td><td>45</td></tr><tr><td>Invited Speakers</td><td>46</td></tr><tr><td>Oral presentations</td><td>48</td></tr></table>

SESSION 6 - Triggering embryogenesis

<table><tr><td>Keynote Speaker: Charles J. UNDERWOOD</td><td>51</td></tr><tr><td>Invited Speakers</td><td>52</td></tr><tr><td>Oral presentations</td><td>54</td></tr></table>
click to go to page

ABSTRACTS FRIDAY 19 SEPTEMBER

SESSION 7 - Seed development

<table><tr><td>Keynote Speaker: Benoit LANDREIN</td><td>57</td></tr><tr><td>Invited Speakers</td><td>58</td></tr><tr><td>Oral presentations</td><td>60</td></tr></table>

SESSION 8 - Asexual reproduction in animals

<table><tr><td>Keynote Speaker: Thomas LENORMAND</td><td>62</td></tr><tr><td>Invited Speaker</td><td>63</td></tr></table>

ABSTRACTS POSTERS

<table><tr><td>S1 - Evolution of apomixis</td><td>65</td></tr><tr><td>S2 - (Epi)Genomics of apomixis</td><td>70</td></tr><tr><td>S3 - Reproductive developmental plasticity</td><td>76</td></tr><tr><td>S4 - Apomeiosis</td><td>79</td></tr><tr><td>S6 - Triggering embryogenesis</td><td>85</td></tr><tr><td>S7 - Seed development</td><td>87</td></tr><tr><td>List of posters</td><td>89</td></tr><tr><td>List of participants</td><td>92</td></tr></table>
TUESDAY 16 SEPTEMBER

From 10:00 **Conference registration**

14:00-14:10 **Welcome**

• Olivier LEBLANC - IRD, France

14:10-15:30 **Opening Plenary Lectures**

Chair: Daphné AUTRAN

14:10-14:50 • **Keynote - Evaluating a drought-driven hypothesis for the origin of obligate apomixis**
Amanda GRUSZ - *Univ. of Minnesota Duluth, USA*

14:50-15:30 • **Keynote - Genomics of embryo initiation and application to synthetic apomixis in rice**
Venkatesan SUNDARESAN - *UC Davis, USA*

15:30-16:00 **Coffee break - Posters**

16:00-17:50 **SESSION 1 - Evolution of apomixis**

Chair: Juan Pablo ORTIZ

• **KN-S1 - The origin of apomixis in natural plant populations**
Elvira HÖRANDL - *Univ. Göttingen, Germany*

• **S1-01 - Clonal or sexual? The evolutionary dance of blackberries**
Petra ŠARHANOVÁ - *Masaryk University, Department of Botany and Zoology, Plant Biosystematics Group, Czech Republic*

• **S1-02 - Rapid adaptation to local environments in diverse apomictic dandelion populations**
Koen JF VERHOEVEN - *Nederlands Institute of Ecology, Nederlands*

Selected oral presentations

• **S1-O.1 - Unraveling the Evolutionary History of the Apomictic *Dryopteris affinis* Complex (Dryopteridaceae)**
**Using Target Enrichment Sequencing**
Evelin KROL - *Systematic and Evolutionary Botany, University of Zürich, Zürich, Switzerland*

• **S2-O.2 - Comparative Genomics Narrows the Genetic Basis of Apomixis in Apple (Malus, Rosaceae)**
Charity GOECKERITZ - *HudsonAlpha Institute for Biotechnology, Huntsville, AL, United States*

• **S1-O.3 - Comparative Genomics of the Apospory-Specific Genomic Region: Insights from *Cenchrus* and Related Grasses**
Joann CONNER - *Horticulture & IPBGG, University of Georgia - Tifton, Tifton, Georgia, United States*
WEDNESDAY 17 SEPTEMBER

08:30-10:20

SESSION 2 - (Epi)Genomics of apomixis

Chair: Elvira HÖRANDL

* KN-S2 - Molecular mechanisms initiating endosperm development in flowering plants
Duarte Dionisio FIGUEIREDO - Max Planck Institute of Molecular Plant Physiology, Germany

* S2-01 - Apomixis and associated molecular markers development in tropical forages
Bianca BACCILI ZANOTTO VIGNA - EMBRAPA Southeastern Livestock, Brazil

* S2-02 - Insights into the structure and gene content of the Apomixis Controlling Locus (ACL) of *Paspalum notatum*
Juan Manuel VEGA - IICAR, Univ. Nac Rosario-CONICET, Argentina

Selected oral presentations

* S2-O.1 - Role of DNA methylation in asexual endosperm formation
Dilsher Singh KULAAR - Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

* S2-O.2 - Exploring the epigenetic landscape of sexual and apomictic *Paspalum notatum* using Oxford Nanopore Sequencing
Maricel PODIO - DREP, IICAR-UNR, Zavalla, Santa Fe, Argentina

* S2-O.3 - A Reproductive and Vegetative Atlas Database To Assess Gene Expression In *Eragrostis curvula*
Through Long Read Iso-Seq Transcriptome Sequencing
Jose CARBALLO - CERZOS-CONICET, Bahía Blanca, Buenos Aires, Argentina

10:20-11:00

Coffee break - Posters

11:00-12:50

SESSION 3 - Reproductive developmental plasticity

Chair: Thomas DRESSELHAUS

* KN-S3 - Distinct nucellar cell types nurture the female gametophyte in cereal ovules
Matthew TUCKER - Univ. Adelaide, Australia

* S3-01 - Are apomictic and sexual development related to the plasticity of ovule morphogenesis? A 3D approach in *Paspalum rufum*
Luciana DELGADO - IICAR, Univ. Nac Rosario-CONICET, Argentina

* S3-02 - Imaging of female gametophytes reveals the cause of reduced seed setting in apomictic rice
Emmanuel GUIDERDONI - CIRAD, UMR AGAP Institute, Montpellier, France

Selected oral presentations

* S3-O.1 - Early apomixis formation in nature is associated with developmental and reproductive perturbations
Patrik MRÁZ - Herbarium collections & Department of Botany, Charles University, Prague, Czechia

* S3-O.2 - Environmental Plasticity of Sexual and Asexual Seed Traits in Brassicaceae
Sinah Tabea EHLERT - Max-Planck-Institute of Molecular Plant Physiology, Potsdam, Germany

12:50-14:00

Lunch & Coffee - Posters
14:00-15:50

## SESSION 4 - Apomeiosis I

Chair: Lucia COLOMBO

* **KN-S4** - The evolution of apomixis in *Boechera*, a tool for Brassica crops
  Tim SHARBEL - *Univ. Saskatchewan, Canada*

* **S4-01** - Structural characterization, gene content and gene expression of the region controlling apomeiosis in *Eragrostis curvula*
  Viviana ECHENIQUE - *CERZOS-Univ. Nac del Sur, Argentina*

* **S4-02** - Genetics of meiotic and non-meiotic instability in polyploids
  Adrián GONZALO SANCHEZ - *ETH Zürich, Switzerland*

### Selected oral presentations

* **S4-O.1** - Assembling haplotype-resolved genomes to explore clonal seed production in apomictic species
  Elias PRIMETIS - *Department of Plant and Animal Biology, Radboud University, Nijmegen, Netherlands*

* **S4-O.2** - Mining candidate genes of apospory in *Paspalum simplex*
  Davide PERRONE - *CNR-IBBR, Perugia, Italy*

* **S4-O.3** - Unveil the molecular mechanisms regulating diplospory
  Alex CAVALLERI - *Biosciences, University of Milan, Milano, Italy*

15:50-16:20

## Coffee break - Posters

16:20-19:00

## POSTER SESSION

* Coffee & beverages

## THURSDAY 18 SEPTEMBER

08:30-10:20

## SESSION 5 - Apomeiosis II

Chair: Nada ŠURBANOVSKI

* **KN-S5** - Towards the Engineering of Synthetic Apomixis in Maize
  Üeli GROSSNIKLAUS - *Department of Plant and Microbial Biology & Zürich-Basel Plant Science Center, Univ. of Zürich, Switzerland*

* **S5-01** - Disruption of miR160-mediated ARF10 silencing triggers aposporous phenotypes in *Arabidopsis* ovules
  Marta MENDES - *Univ. Milan, Italy*

* **S5-02** - QUI-GON JINN, a member of the YODA family, plays a critical role during female reproduction in *Arabidopsis thaliana*
  Lorena SIENA - *IICAR, Univ. Nac Rosario-CONICET, Argentina*

### Selected oral presentations

* **S5-O.1** - Evidence of pseudogamous aposporous apomixis in tetraploid sunflower
  Silvina Claudia PESSINO - *Facultad de Ciencias Agrarias, Universidad Nacional de Rosario (FCA-UNR), Santa Fe, Argentina*

* **S5-O.2** - The *BUD13* Splicing Regulator: Expression of Its Isoforms in Ovules of Sexual and Apomictic *Paspalum notatum*
  Samela DRAGA - *University of Padova, Padova, Italy*

* **S5-O.3** - Arabidopsis mutants defective in the Auxin Response Repressor IAA16 exhibit developmental alterations during female reproduction
  Maria Sol VEGA - *Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR) CONICET-UNR, Zavalla, Argentina*

10:20-11:00

## Coffee break - Posters
11:00-12:50

## SESSION 6 - Triggering embryogenesis

Chair: Laurine GILLES

* KN-S6 - Eternally hybrid: natural and engineered propagation of hybrid genomes through seeds
  Charles J. UNDERWOOD - Radboud University, Netherlands

* S6-01 - On the Road to Apomixis in Maize: A Win for Embryogenesis, a Wait for Apomeiosis
  Thomas WIDIEZ - RDP-ENS Lyon, France

* S6-02 - Apomixis in the Sea? Parthenogenesis and Maternal Cues in Seaweeds
  Kenny BOGAERT - Max Planck Institute for Biology, Germany

### Selected oral presentations

* S6-O.1 - Polyembryony by induced parthenogenesis: models and implications for synthetic apomixis
  Hannah PEHA - Sundaresan Lab, Plant Biology Dept., University of California Davis, Davis, CA, United States

* S6-O.2 - Unveiling Molecular Regulators of Synergid Cell Death Through Cell-Specific Transcriptomics
  Manuel BUENDIA MONREAL - Department of Biosciences, University of Milan, Milan, Italy

* S6-O.3 - Understanding the Molecular Mechanism underlying Parthenogenesis in Cereals
  Xixi ZHENG - Cell Biology and Plant Biochemistry, University of Regensburg, Regensburg, Germany

12:50-14:00

## Lunch & Coffee - Posters

14:00-15:30

## FORUM Table 1 - Missing tools for harnessing apomixis in plant breeding?

Chair: Silvina PESSINO - IICAR, Univ. Nac Rosario-CONICET, Argentina

* Emmanuel GUIDERDONI - CIRAD, France

* Peggy OZIAS-AKINS - Univ. Tifton, USA

* Emidio ALBERTINI - University of Perugia, Italy

15:30-16:00

## Coffee break - Posters

16:00-18:00

## FORUM Table 2 - Apomixis, a plant breeding innovation?

Chair: Liana JANK - EMBRAPA, Breeder, Brazil

* Stéphane LEMARIÉ - INRAe, France

* Viviana ECHENIQUE - CERZOS-Univ. Nac del Sur-CONICET, Argentina

* Marc ALBERTSEN - Albertsen Crop Genetics for Humanity, Johnston, USA

* Üeli GROSSNIKLAUS - University of Zürich, Zürich, Switzerland

19:30-23:00

## Conference Dinner

Restaurant L'Arbre Blanc - Montpellier
FRIDAY 19 SEPTEMBER

09:00-10:50

SESSION 7 - Seed development

Chair: Stewart GILLMOR

* KN-S7 - Mechanical control of seed morphogenesis
  Benoit LANDREIN - RDP-ENS Lyon, France

* S7-01 - Maternal control of RNA decay safeguards embryo development
  Gerardo Del TORO-De LEÓN - Max Planck Institute of Molecular Plant Physiology, Germany

* S7-02 - RNA helicases in shaping plasticity during sexual and apomictic reproduction through seeds
  Anja SCHMIDT - Univ. Heidelberg, Germany

Selected oral presentations

* S7-O.1 - Genetic determinants of autonomous endosperm formation in Arabidopsis
  Camille SALAÜN - Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

* S7-O.2 - BRI1-mediated removal of seed coat H3K27me3 marks is a brassinosteroid-independent process
  Rishabh PANKAJ - Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

10:50-11:10

Coffee break - Posters

11:10-12:15

SESSION 8 - Asexual reproduction in animals

Chair: Olivier LEBLANC

* KN-S8 - Parthenogenesis and the evolution of clonality in animals
  Thomas LENORMAND - CEFE, CNRS, Montpellier, France

* S8-01 - Beyond plants: how reproductive strategies could shape invasiveness and disease spread in freshwater snails
  Micaela MÜLLER - CERZOS-Univ. Nac del Sur-CONICET, Argentina

12:15-12:30

Closing

* Prize Awards

* Final remarks & Next Meeting announcement
V International Conference on
APOMIXIS
2025
Montpellier, France | 16-19 SEPT.

<figure><img src="image_62.png" /></figure>

<figure><img src="image_63.png" /></figure>

Conference venue:
MERCURE
Montpellier
Centre Comédie

ABSTRACTS TUESDAY 16 SEPTEMBER

<figure><img src="image_64.png" /></figure>
Evaluating a drought-driven hypothesis for the origin of obligate apomixis

Amanda GRUSZ (algrusz@d.umn.edu)

Department of Biology, University of Minnesota Duluth, Duluth, MN, United States

Apomixis is expressed in myriad ways across the tree of life, but most research in this arena is focused on flowering plants. The V International Conference on Apomixis expands upon these efforts by delivering critical updates regarding apomixis in angiosperms, while also elevating studies of reproductive mode in understudied organisms—such as ferns. In this keynote address, I emphasize ferns as a case study for exploring apomixis in non-model systems. In many organisms, xeric environments impose major constraints on life histories, and the fern life cycle is especially vulnerable. To overcome such limitations, many fern lineages in drought-prone areas have evolved an apomictic life cycle. Here, I summarize an evidence-based model for the establishment and evolution of apomixis in ferns, focusing on genetic and environmental factors that are associated with its two defining traits: diplospory and apogamy. Preliminary findings, and future directions, are shared from research in my lab that aims to evaluate the drought-driven hypothesis for the origin and evolution of obligate apomixis, offering insights for similar studies in non-model systems.

KN-1
# Genomics of embryo initiation and application to synthetic apomixis in rice

Venkatesan SUNDARESAN (sundar@ucdavis.edu)

Plant Biology, University of California, Davis, Davis, CA, US

The initiation of embryo development in sexual plants requires the fusion of male and female gametes to form a zygote. Over the past decade, characterization of the expression profiles of rice gametes and zygotes has provided molecular insights into the regulation of this key step in plant reproduction. The egg and sperm exhibit distinctive expression profiles for both mRNAs and small RNAs that are unlike any somatic cells, indicative of widespread re-programming of the genome and epigenome during gamete formation. Activation of the zygotic genome occurs before the first embryonic division, with extensive changes to the mRNA transcriptome, and re-setting of the epigenome manifested by the appearance of new small RNA profiles similar to somatic cells. Transcription factors expressed from the paternal genome appear to promote the initiation of embryogenesis by the fertilized egg cell. Manipulation of these transcription factor genes to express in unfertilized egg cells results in bypassing fertilization, and the formation of parthenogenetic embryos and haploid plants. When combined with editing of genes required for meiosis, rice plants that reproduce as genetic clones can be generated, effectively introducing apomixis into rice. Through this approach of synthetic apomixis, hybrid rice propagated as seeds can maintain uniform hybrid vigour in subsequent generations. These findings could be utilized for low-cost production of high-yielding hybrid seeds in rice and potentially in other crops, with conceivably significant impacts on agriculture.
## The origin of apomixis in natural plant populations

Elvira HÖRANDL (ehoeran@gwdg.de)

*Systematics, Biodiversity, Evolution of Plants, University of Göttingen, Göttingen, Germany*

Apomixis, the asexual reproduction via seed, is taxonomically widespread in angiosperms and occurs in many abundant and biodiverse taxa. There are two major developmental pathways: gametophytic apomixis involves a bypass or alteration of female meiosis to produce an unreduced embryo sac, and the egg cell develops parthenogenetically into an embryo. Sporophytic apomixis involves the development of an embryo out of a somatic cell of the ovule. Pollen is in most apomicts functional and reduced and needed for the fertilization of polar nuclei (pseudogamy). The origin of apomixis in natural populations, and the evolutionary and genetic background of this shift in mode of reproduction is still not well understood. There are three principle modes of origin: (1) Hybridization of sexual species, in connection with polyploidy; (2) secondary origins via fertilization of sexual species with pollen from apomictic taxa; and (3) spontaneous origins via (epi)mutations in key developmental genes. Hybridization of sexual taxa is the most common and best documented pathway. Experimental work and large-scale screenings in natural apomicts have confirmed that hybridity between sexual species is a primary trigger, probably by combining previously isolated mutations/epimutations in developmental genes, that were inherited from parental species. Polyploidy is mostly a secondary enhancer of establishing apomixis in natural populations by providing by overcoming minority cytotype exclusion, by better stress response, and breakdown of self-compatibility systems. Secondary origins occur mostly in pseudogamous plants, because the maintenance of the pollen function allows for introgression of apomixis control factors into sexual species. Spontaneous origins are the least documented case, and might be mostly expected in sporophytic apomixis where genetic control appears to be less complex. It is still an open question whether genetic or genomic predispositions favour shifts to apomixis, or whether natural occurrences are mostly a matter of chance and opportunity.
S1-01

# Clonal or sexual? The evolutionary dance of blackberries

Petra ŠARHANOVÁ (sarhanova@gmail.com), František ZEDEK, Klára PANDA, Jan POSPÍŠIL, Jakub ŠMERDA, Lucie HOROVÁ

Masaryk University, Brno, Czechia

## Introduction and Objectives:

Apomixis—the asexual formation of seeds—allows blackberries (*Rubus* subgenus *Rubus*) to reproduce clonally, preserving successful genotypes. However, this strategy has limitations, including reduced potential to generate variability and developmental issues such as smaller seeds caused by unbalanced parental genome dosage in the endosperm. Our study explores how different *Rubus* species mitigate these constraints.

## Materials and Methods:

We compare diploid and tetraploid species with varying capacities for sexual and apomictic reproduction. Through controlled crosses, flow cytometric analysis and genotyping of the seeds, we assess seed development, endosperm ploidy, and germination success in relation to reproductive mode and parental dosage.

## Results:

Diploid *R. moschus* shows a surprising ability to produce seeds via both selfing and heteroploid hybridization, exhibiting several unique reproductive traits. Tetraploid species display species-specific and variable levels of apomixis. Regardless of the reproductive mode, seeds with balanced maternal-to-paternal endosperm ratios (2m:1p) are consistently larger and germinate earlier, underscoring the advantage of increased seed size. Notably, apomictic *Rubus* can restore this balance by fertilizing the central cell with either one unreduced or two reduced sperm cells, thereby elevating endosperm ploidy and compensating for maternal excess. We also observed rare phenomena such as polytubey, triparental endosperms, and automixis among the tetraploid species.

## Conclusion:

The coexistence of clonal and sexual reproduction within and among *Rubus* species reflects a dynamic equilibrium between genetic stability and variability—an essential factor in the long-term evolutionary success of the genus. In apomicts, the ability to balance maternal and paternal genome dosage in the endosperm may enhance reproductive success and help overcome the developmental constraints typically associated with unbalanced parental contributions.
## Rapid adaptation to local environments in diverse apomictic dandelion populations

Koen VERHOEVEN (k.verhoeven@nioo.knaw.nl)

Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands

Apomictic dandelion populations are genetically diverse clonal assemblages. This makes them convenient systems for studying rapid adaptation, as selection can act efficiently on standing clonal variation in asexual populations, enabling population-level adaptation over short timescales. I will show examples of rapid selection responses of dandelion populations to different environmental challenges. In one such study, we tested if apomictic populations have adapted to urban environments, specifically to increased temperatures that are characteristic of cities (the urban heat island effect). Using dandelion samples collected along an urban-rural transect, we performed common garden phenotyping experiments to screen for genetic differentiation in seedling growth at elevated temperatures, and in vernalization requirement for flowering ability. We show that urban dandelion accessions have a growth advantage at elevated temperatures, and a reduced vernalization requirement, compared to rural accessions. These observations suggest dandelion urban adaptation, representing one of the first demonstrations of plant adaptation to urban heat islands. Genetic characterization of the populations revealed very high clonal diversity and identified ‘urban’ and ‘rural’ clones.
S1-O.1

# Unraveling the Evolutionary History of the Apomictic *Dryopteris affinis* Complex (Dryopteridaceae) Using Target Enrichment Sequencing

Evelin KROL<fnref n="1" /> (evelin.krol@systbot.uzh.ch), Jens FREIGANG², Stefan JESSEN³, Alison J. EVANS⁴, Roger GOLDING⁵, Libor EKRT⁶, Kateřina VEJVODOVÁ⁶, Dieder DE FRENS<fnref n="1" />, Emily B. SESSA⁷, Weston TESTO⁸, Michael KESSLER<fnref n="1" />

With approximately 400 species, *Dryopteris* is the third-largest genus in Dryopteridaceae, the most species-rich fern family. Characterized by a base chromosome number of 41, *Dryopteris* frequently exhibits polyploidy and apomixis, with hybridization occurring even across distinct sections. Consequently, many species complexes remain poorly understood in terms of their reticulate evolution. Among them, the *Dryopteris affinis* complex is of particular interest, as it serves as a model organism for studying apomixis.

The *D. affinis* complex, primarily distributed in Europe, includes diploid, triploid, tetraploid, and pentaploid taxa. The diploid, apomictic *D. affinis* s. str. originated from hybridization between *D. oreades* and an unknown progenitor, commonly referred to as *D. "semiaffinis"*, which is hypothesized to be extinct. Due to its apogamous gametophyte producing viable male gametes, *D. affinis* can still hybridize with sexual species. As a result, polyploid members frequently arise through hybridization between diploid *D. affinis* s. str. and other *Dryopteris* species, forming hybrid series where polyploids undergo further hybridization. Despite taxonomic efforts based on morphology, ploidy, genome size, and a limited number of molecular markers, the evolutionary relationships within this complex remain unresolved.

To clarify these relationships, we are employing target enrichment sequencing using the GoFlag408 probe set, which targets 408 exons representing 248 nuclear genes across flagellate plant lineages. By phasing hybrid subgenomes, we are determining whether diploid *D. affinis* s. str. constitutes a single apomictic species or multiple distinct diploid species, reconstructing the hybridization history of polyploid *D. affinis* taxa, and identifying the genetic signature of the *D. "semiaffinis"* subgenome.

By elucidating the evolutionary history and hybridization patterns of the *D. affinis* complex, our research will enhance our understanding of apomictic fern evolution and provide deeper insights into *D. affinis* as a model for apomixis.

<footnote n="1">¹ Systematic and Evolutionary Botany, University of Zürich, Zürich, Switzerland ; ² Tal, Bergatreute, Germany ; ³ Arktisch-Alpiner-Garten, Walter-Meusel-Stiftung, Chemnitz, Germany ; ⁴ Bioscience Department, Edge Hill University, Ormskirk, Lancashire, England ; ⁵ Fell View, Bowness-on-Solway, Cumbria, England ; ⁶ Department of Botany, University of South Bohemia, České Budějovice, Czech Republic ; ⁷ William & Lynda Steere Herbarium, New York Botanical Garden, Bronx, New York, United States ; ⁸ Pringle Herbarium, Department of Plant Biology, University of Vermont, Burlington, Vermont, United States</footnote>
Comparative Genomics Narrows the Genetic Basis of Apomixis in Apple (*Malus*, Rosaceae)

Charity GOECKERITZ (cgoeckeritz@hudsonalpha.org), Alex HARKESS

HudsonAlpha Institute for Biotechnology, Huntsville, AL, United States

Apomixis, or asexual seed production, has evolved independently in flowering plants hundreds of times in dozens of plant families. Rosaceae is especially enriched in apomictic genera, which includes the genus *Malus* (apple) - yet almost nothing is known about the genetic basis in this family. In the following work, we describe the development of a high-throughput sequencing screen to identify apomicts in diverse germplasm. We then compare the phased chromosome-scale assemblies of five apomictic *Malus* species to several sexual genomes, providing compelling evidence that a certain haplotype may serve as the genetic source of apomixis in apple. Syteny alignments indicate major structural rearrangements and hemizygous sequence in this region relative to sexual species, which may be related to the propagation of certain long terminal repeats (LTRs). We further use gene annotations created by publicly-available transcriptomes and Viridiplantae protein datasets to narrow down the genetic basis to several candidate genes for further investigation.
S1-O.3

# Comparative Genomics of the Apospory-Specific Genomic Region: Insights from *Cenchrus* and Related Grasses

Joann CONNER (jconner@uga.edu), Peggy OZIAS-AKINS

*Horticulture & IPBGG, University of Georgia - Tifton, Tifton, Georgia, United States*

Apomixis, a form of asexual reproduction through seeds, enables progeny to remain genetically identical to the maternal parent. This process occurs through distinct developmental pathways, namely adventitious embryony, diplospory, and apospory. For agriculture, apomixis holds transformative opportunity by enabling the fixation of hybrid vigor in crops. Within the Poaceae (grass family), apomixis is commonly associated with polyploid genomes and suppressed recombination near the apomictic locus.

In the genus *Cenchrus* (Tribe: *Paniceae*, subtribe: *Cenchrinae*), apomixis is regulated by the Apospory-Specific Genomic Region (ASGR), a hemizygous, non-recombining locus that harbors genes/genetic factors responsible for apomeiosis (the production of unreduced female gametes retaining the genotype of the maternal plant) and parthenogenesis (embryo development of the egg cell without fertilization). The *ASGR-BabyBooMLike* (*ASGR-BBML*) gene, identified in apomictic *Cenchrus*, was verified as the parthenogenetic factor. The apomeiosis gene/genetic factor is still undiscovered.

*ASGR-BBML* and additional molecular markers associated with the ASGR in *Cenchrus*, are highly conserved at the apomictic locus in *Urochloa* and *Megathyrsus* (Tribe: *Paniceae*, subtribe: *Melinidinae*). With the completion of high-quality genome assemblies for apomictic *C. ciliaris*, *C. setaceus*, *U. brizantha*, and *M. maximus*, comparative genomics can be employed to identify conserved candidate genes for apomeiosis within the ASGR. Additionally, analysis of non-conserved ASGR regions and ASGR-carrier chromosomes may begin to provide further insights into the evolution of this locus.
V International Conference on
APOMIXIS
2025
Montpellier, France | 16-19 SEPT.

<figure><img src="image_65.png" /></figure>

<figure><img src="image_66.png" /></figure>

Conference venue:
MERCURE
Montpellier
Centre Comédie

ABSTRACTS WEDNESDAY 17 SEPTEMBER
## Molecular mechanisms initiating endosperm development in flowering plants

Duarte FIGUEIREDO (figueiredo@mpimp-golm.mpg.de)

Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

Seed development in Angiosperms starts with a double fertilization event, whereby two paternal sperm cells fertilize the maternal gametes, the egg cell and the central cell. This leads to the formation of two fertilization products: the embryo, which will form the next generation, and the nourishing endosperm. These two structures are surrounded by a seed coat of maternal origin. Although in the vast majority of species fertilization is necessary for seed formation, some plants can form asexual seeds. This phenomenon is called apomixis. The introduction of this mode of reproduction is highly desirable in agriculture because it would allow the fixation of hybrid vigor, and also for maintaining crop yields in situations where pollination is deficient, for example due to high temperatures of lack of pollinators. One of the components of apomictic seed development is the production of an asexual (or autonomous) endosperm. Although the mechanisms that allow apomicts to develop autonomous endosperms remain mostly undiscovered, the genetic and epigenetic manipulation of central cells of sexual species leads to the formation of apomictic-like endosperms. This means that asexual endosperm formation is possible in sexual species but is repressed in normal conditions. Importantly, this means that those mechanisms can potentially be exploited to engineer apomictic-like endosperm formation, which is the last standing barrier for the introduction of pollen-independent seed formation in crops.
## Apomixis and associated molecular markers development in tropical forages

Bianca BACCILI ZANOTTO VIGNA<fnref n="1" /> (bianca.vigna@embrapa.br), Aline DA COSTA LIMA MORAES², Marcelo MOLLINARI<fnref n="3" />, ⁴, Anete PEREIRA DE SOUZA², Sanzio CARVALHO LIMA BARRIOS⁵, Cacilda BORGES DO VALLE⁵, Antonio Augusto FRANCO GARCIA⁶, Heitor MENDONÇA⁶, André PICH BRUNES⁷, Miguel DALL'AGNOL⁷, Julia LONGHI⁷, Frederico DE PINA MATTA<fnref n="1" />, Alessandra PEREIRA FÁVERO<fnref n="1" />

Forage grasses are the primary feed source for cattle in Latin America. In Brazil, *Urochloa* species cover around 160 million hectares, supporting the country's position as the world's top beef exporter. *Urochloa humidicola* is a key forage for poorly drained soils, while native grasslands in southern South America, dominated by *Paspalum* spp., are essential for regional beef and dairy production. Among them, *Paspalum notatum* (bahiagrass) stands out for its high forage quality, low input demand, and turf use. Both *U. humidicola* and *P. notatum* reproduce by aposporic apomixis, a trait of major importance for breeding programs. Early identification of apomictic individuals is crucial for developing new cultivars, and molecular markers linked to apomixis enable marker-assisted selection (MAS), increasing breeding efficiency. In *U. humidicola*, a high-density linkage map with 4,873 SNPs and allele dosage in an F1 hexaploid population allowed the mapping of the apospory-specific genomic region (ASGR) and the trait itself to linkage group 3, syntenic to chromosome 3 of *U. ruziziensis* and chromosome 1 of *Setaria italica*. Apospory segregated as a single dominant locus, with two SNPs fully linked to the trait. KASP-SNP markers with 100% linkage to ASGR are being developed for use in breeding. In *Paspalum* species, previous reports identified only RAPD markers for apomixis, which lack reliability. Current efforts focus on identifying SNPs linked to the Apomixis Controlling Region (ACR) in *P. notatum* through genome wide association study (GWAS). The aim is to develop reliable KASP-SNP markers for MAS, reducing time and increasing the precision of cultivar development in tropical forage breeding programs.

<footnote n="1">¹Embrapa Southeastern Livestock, Embrapa, São Carlos, SP, Brazil ; ²Biology Institute, University of Campinas, Campinas, SP, Brazil ;</footnote>

<footnote n="3">³Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, United States ; ⁴Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina, United States ; ⁵Embrapa Beef Cattle, Embrapa, Campo Grande, MS, Brazil ; ⁶Escola Superior de Agricultura Luiz de Queiroz, University of São Paulo, Piracicaba, SP, Brazil ; ⁷Faculdade de Agronomia, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil</footnote>
Insights into the structure and gene content of the Apomixis Controlling Locus (ACL) of *Paspalum notatum*

Juan Manuel VEGA¹ (jvega@iicar-conicet.gob.ar), Maricel PODIO¹, Julie ORJUELA², Lorena Adelina SIENA¹, Cedric MARIAC², Julien SERRET², Silvina Claudia PESSINO¹, Olivier LEBLANC², Juan Pablo Amelio ORTIZ¹

¹ DREP, IICAR (CONICET - UNR), Zavalla, Santa Fe, Argentina ; ² DIADE, University of Montpellier, IRD, CIRAD, Montpellier, France

In *P. notatum*, apomixis is expressed mainly at the polyploid (tetraploid) level. The trait is controlled by a non-recombinant, hemizygous region, known as the Apomixis Controlling Locus (ACL). Genetic analyses have estimated that the ACL spans approximately 36 Mbp and is syntenic to segments of rice chromosomes 2 and 12. Recently, we assembled the genomes of three tetraploid genotypes, the obligate apomictic Q4117, the experimentally obtained facultative apomictic (highly sexual) Q3664 and the fully sexual Q4188, using a chromosome-level assembly of a diploid sexual cytotype as a reference. The aim of this study was to resolve the ACL genomic sequence in these plants, identify possible structural variations and annotate its gene contents. To achieve this, ONT long-read sequencing was used to obtain 30x-70x genome coverage for the three genotypes. Several contigs carrying ACL-linked markers identified in the Q4117 de novo assembly were used to create a custom database for targeted coverage enrichment via ONT adaptive sampling, in which the obligate apomictic tetraploid genotype Q3775 was included. In addition, the whole assembly of Q4117 was improved using Bionano optical mapping data. Two ACL-linked scaffolds were reconstructed and aligned against the reference genome. The ACL consists of a 35-Mb insertion into the pericentromeric region of chromosome 9. Its structure comprises duplicated fragments from chromosomes 5 and 8 (homeologous to rice chromosomes 2 and 12) arranged in a mosaic pattern associated with repetitive elements, and 1648 intact and fragmented genes. Several of them are related to reproduction, growth and development. Comparative analysis showed a high degree of ACL conservation in the two obligate apomictic genotypes Q4117 and Q3775, while it is absent in Q3664 and Q4188.
S2-O.1

Role of DNA methylation in asexual endosperm formation

Dilsher Singh KULAAR (kulaar@mpimp-golm.mpg.de), Duarte Dionísio FIGUEIREDO

Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

Post-fertilisation auxin production is the molecular trigger for endosperm development in sexual plant species. If this trigger is provided to unfertilised ovules in Arabidopsis, either in the form of exogenous auxin or by lifting the silencing marks from maternal auxin biosynthesis genes, it leads to the formation of autonomous endosperm, which is one the key components of apomixis. These asexual endosperms, however, do not develop as much as sexual endosperms: they do not cellularise and eventually collapse. Interestingly, DNA hypomethylation leads to autonomous endosperms that are more proliferative and, in some cases, even cellularise. This indicates that DNA methylation regulates important determinants of these asexual endosperms. We therefore analysed various DNA methylation mutants and found that different DNA methylation contexts had varying effects on different aspects of autonomous endosperm formation. Out of these, the *drm2* mutant, which has loss of *de novo* & asymmetric DNA methylation, is impaired in autonomous endosperm formation, even though there are no noticeable defects in the sexual seeds. Through transcriptomic analyses, we found that many genes linked to abiotic stress responses are down-regulated in *drm2* ovules. It is therefore possible that some of these stress pathways have been co-opted to play roles in early stages of seed development. Hence, we are making use of such DNA methylation mutants to identify and understand the processes vital for the formation of asexual endosperms, which are normally repressed in sexually reproducing plant species.
Exploring the epigenetic landscape of sexual and apomictic *Paspalum notatum* using Oxford Nanopore Sequencing

Maricel PODIO¹ (podio@iicar-conicet.gob.ar), Juan Manuel VEGA¹, Lorena Adelina SIENA¹, Olivier LEBLANC², Silvina Claudia PESSINO¹, Juan Pablo A ORTIZ¹

¹ DREP, IICAR-UNR, Zavalla, Santa Fe, Argentina ; ² DIADE, Univ. Montpellier, IRD, CIRAD, Montpellier, France

*Paspalum notatum* is a perennial grass native to South America with variations in ploidy levels and reproductive modes. The diploid cytotype (2n=2x=20) reproduces sexually, while the tetraploid cytotype (2n=4x=40) reproduces through aposporous apomixis. In this species, apomixis is governed by a single genetic region known as the Apomixis Controlling Locus (ACL). The ACL is a complex genomic structure enriched in both coding and non-coding sequences, repetitive elements, and strong cytosine methylation. It is also characterized by a distorted segregation ratio and suppressed recombination. Emerging evidence implicates small interfering RNAs and RNA-directed DNA methylation (RdDM) in apomictic regulation, and cytosine demethylation in *Paspalum simplex* has been shown to impair parthenogenesis. To investigate epigenetic variation associated with the reproductive mode and ploidy level, we characterized DNA methylation patterns of four genotypes from Oxford Nanopore Technologies (ONT) long read sequencing data generated with the Dorado base caller and the Modkit software for base modification analysis. One diploid sexual (PnR1), one tetraploid sexual (Q4188), and two tetraploid apomictic genotypes (Q4117, obligate, and Q3664, facultative) were analyzed. Our results revealed that, in the context CG, Q4117 showed 10% less methylation (~54%) than Q4188 and Q3664 (~64%), while PnR1 displayed an intermediate level (~57%). In the CHH context, Q3664 and PnR1 had more than 10% less methylation than the other genotypes. Meanwhile, methylation levels in the CHG context were similar across genotypes, ranging from 82% to 89%. Additionally, Q4117 exhibited the fewest methylated genes in CHG context, while it presented the higher rRNA methylated in contexts CG and CHG. These findings demonstrate the usefulness of Oxford Nanopore technology in revealing variability in methylation landscapes between genotypes, representing a significant step towards identifying epigenetics associated with ploidy levels and reproductive modes.
S2-O.3

# A Reproductive and Vegetative Atlas Database To Assess Gene Expression In *Eragrostis curvula* Through Long Read Iso-Seq Transcriptome Sequencing

Jose CARBALLO<fnref n="1" /> (jcarballo@cerzos-conicet.gob.ar), Juan Pablo SELVA<fnref n="1" />, ², Emidio ALBERTINI³, Mario CACCAMO⁴

*Eragrostis curvula* is a species member of the Poaceae family that is used as a model species for diplosporous apomixis in grasses. Previously, different efforts such as short read sequencing were made to obtain a high-quality genome annotation. However, the allopolyploid nature and other complexities of the *E. curvula* genome did not allow the achievement of an appropriate gene reference for differential expression analyses or isoforms identification. Hence, taking advantage of the long read transcript sequencing, an Iso-Seq library of the apomictic allotetraploid cv. Don Walter (2n=4x=40) was constructed using different tissues to target the majority of the transcript variants expressed in this species. Parallelly, eight Illumina RNA-seq libraries were sequenced in triplicate to generate the first atlas database of *E. curvula*. The included tissues were: leaves, roots, whole spikelets, anthers in pre-meiosis and post-meiosis and pistils in pre-meiosis, post-meiosis and pre-anthesis.

The Iso-Seq reads processing resulted in a total of 230,142 potential transcripts. After filtering, based on length and coding potential, 204,330 transcripts were obtained, corresponding to 88,304 unique genes, which represents ~2.3 transcripts per gene. These genes were used as reference for quantifying short read RNA sequences. To assess the relationships between samples, a PCA was produced showing three groups, one corresponding to leaves and roots, another one with spikelets and anthers in post-meiosis, and the third group with anthers in pre-meiosis and pistils samples. The expression analysis showed that the spikelets have the highest number of expressed genes, probably, because it contains reproductive and non-reproductive tissue. The atlas database generated through different sequencing technologies in this project is an outstanding resource to study gene expression in *E. curvula* apomictic genotypes and an excellent tool for the identification of tissue-specific genes.

<footnote n="1">¹ CERZOS-CONICET, Bahía Blanca, Buenos Aires, Argentina ; ² Departamento de Agronomía, Universidad Nacional del Sur, Bahía Blanca, Argentina ; ³ Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy ; ⁴ NIAB, Park Farm, Villa Road, Histon, Cambridge CB24 9NZ, NIAB, Cambridge, United Kingdom</footnote>
Distinct nucellar cell types nurture the female gametophyte in cereal ovules

Matthew TUCKER<fnref n="1" /> (matthew.tucker@adelaide.edu.au), Xiujuan YANG², Laura WILKINSON², Ling XU², Lucia COLOMBO³, Ryan LISTER⁴, Hengbin GAO⁴

In seed plants, the ovule is a multifunctional organ that not only supports the development of the female gametophyte and its germ cells but also regulates the flow of maternal resources into the developing seed. These functions rely on the coordinated development of three key tissues: the nucellus, integuments, and funiculus. In *Arabidopsis*, the nucellus is relatively small and composed of few cells, whereas in cereal crops like barley (*Hordeum vulgare*), the female gametophyte is embedded within a large, multicellular nucellus.

Although the precise role of the nucellus remains unclear, it exhibits developmental plasticity—balancing germline differentiation with nutrient accumulation and programmed cell death. Intriguingly, in aposporous apomictic species, nucellar cells adjacent to the female germline can undergo changes in identity and initiate gametogenesis, suggesting a shift in cell fate.

Our research focuses on the nucellus to uncover the characteristics and functions of cells neighboring the germline, with the goal of identifying sexual “modifiers” that could be harnessed in reproductive strategies supporting apospory. In this presentation, I will share recent findings on the roles of cell wall components, regulatory transcription factors, and distinct nucellar cell types in female gametophyte development. These insights are advancing our understanding of nucellar function in reproduction and may reveal new targets for optimizing grain development in cereal crops.

<footnote n="1">¹ Waite Research Institute, University of Adelaide, Urrbrae, SA, Australia ; ² School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, SA, Australia ; ³ University of Milan, Milan, Italy ; ⁴ University of Western Australia, Perth, WA, Australia</footnote>
# Are apomictic and sexual development related to the plasticity of ovule morphogenesis? A 3D approach in *Paspalum rufum*

Luciana DELGADO<fnref n="1" /> (luciana.delgado@conicet.gov.ar), Constanza PAGANI<fnref n="1" />, Inès OUEDRAOGO², Célia BAROUX³, Daphné AUTRAN²

Natural species of *Paspalum* are organised in agamic complexes, in which different ploidy levels are linked to sexual or apomictic reproduction. In apomictic aposporic plants, additional enlarged cells, called Aposporous Initials (AIs), surround the sexual Megaspore Mother Cell (MMC) and produce aposporic embryo sacs. Although apomictic, polyploid plants are mostly facultative, and in addition, some sexual diploid genotypes can reproduce by apomixis. The same genotype may display significant developmental plasticity during megasporogenesis and megagametogenesis, and ovules can generate both sexual and/or apomictic pathways in different proportions depending on environmental conditions.

Furthermore, developmental plasticity is also present in ovules of sexual plants, such as Arabidopsis and Maize, where a pool of precursor cells enters the MMC differentiation trajectory up to variable steps, depending on genotypes and species. As development proceeds, mostly a single MMC *per ovule* enters meiosis. In addition, in both sexual and apomictic systems, the formation of reproductive cells is strongly linked to ovule growth and geometry.

Here, we focus on the early steps of female reproductive development and ask, at a cellular level, whether differential geometry and topology in the ovule primordium influence AI and MMC differentiation, conditioning the shift between apomixis and sexuality.

For this purpose, we generated a collection of 136 3D images of diploid/tetraploid and sexual/apomictic genotypes of *Paspalum rufum* ovules, spanning MMC differentiation. We analyse 3D morphological and topological descriptors at both cellular and organ levels. The first observations indicate a pool of candidate archesporial cells at early stages, canalised later to a single enlarged MMC, associated also with higher network centrality measures. Moreover, ovule growth and differentiation of the reproductive cells appear differentially coordinated according to ploidy levels. A comprehensive analysis of MMC and AI initiation is underway to understand the developmental plasticity associated with sexual to aposporic transitions in *Paspalum*.

<footnote n="1">¹ IICAR-CONICET, FCA-UNR, Zavalla, Santa Fe, Argentina ; ² DIADE, Université de Montpellier, IRD, CIRAD, Montpellier, France ; ³ Zürich-Basel Plant Science Center, Institute of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland</footnote>
Imaging of female gametophytes reveals the cause of reduced seed setting in apomictic rice

Laurine GILLES<fnref n="1" />, ² (laurine.gilles@cirad.fr), Matthieu DEJEAN<fnref n="1" />, ², Donaldo MEYNARD<fnref n="1" />, ², Aurore VERNET<fnref n="1" />, ², Jean-luc VERDEIL<fnref n="1" />, ², Daphné AUTRAN³, Emmanuel GUIDERDONI<fnref n="1" />, ²

Recent breakthroughs in engineering synthetic apomixis in rice open new avenues for clonal propagation of F1 seeds, offering promising prospects to reach the small farmer fields. The most efficient method to date for converting rice hybrids to apomixis combines the *Mitosis instead of Meiosis (MiMe)* triple mutation which induce apomeiosis with egg cell expression of *BABYBOOM 1* to trigger parthenogenesis. However, high frequency (95-100%) of clonal seed production remains associated with a low grain filling rate (25-40%), raising questions about the origin and fate of unfilled grains. This bottleneck still prevents further field development of the technology. To address this, we conducted a large-scale screening of ovaries collected at pre-anthesis and post-anthesis stages in fully penetrant apomictic plants of three rice hybrids. Female gametogenesis appears to occur normally in synthetic apomicts, with an embryo sac abortion rate comparable to that observed in control hybrids. Interestingly, two- to sixteen-celled parthenogenetic embryos are already observed 3-4 days before anthesis (panicles still not emerged from the flag leaf sheath), indicating that parthenogenesis from the unfertilized egg cell can start shortly after completion of female gametophyte formation. At pre-anthesis stage, 16-64 celled parthenogenetic embryos are observed in 90-95% of embryo sacs together with synergids and polar nuclei. However, 48 hours post-fertilization, consistent with the low grain filling rate, only 25-40% of the embryos are accompanied by endosperm nuclei. This suggests that the fusion between the sperm nucleus and the polar nuclei may be hampered, likely due to the early development of parthenogenetic embryos. The precise timing and underlying cause of this massive failure are currently under investigation.

<footnote n="1">¹ AGAP institute, CIRAD, Montpellier, France ; ² CIRAD-INRAE-Institut Agro-University of Montpellier, University of Montpellier, Montpellier, France ; ³ DIADE, Université de Montpellier, IRD, CIRAD, Montpellier, France</footnote>
Early apomixis formation in nature is associated with developmental and reproductive perturbations

Patrik MRÁZ<fnref n="1" /> (mrazpat@natur.cuni.cz), Begoña QUIRÓS-DE-LA-PEÑA²,³, Pavel ZDVOŘÁK<fnref n="1" />, Eliška ZÁVESKÁ³, Yann BERTRAND³, Jiřina JOSEFIOVÁ³, Zuzana SEJFOVÁ³, Barbora FREJOVÁ³, Daniel PAPEŽ², Núria BELTRÁN SANZ², Alexander BELYAYEV³, Jindřich CHRTEK²,³

Apomixis is a deviation from sexual reproduction that includes processes such as the avoidance of meiosis, the autonomous embryo development from unreduced egg cell, and either autonomous endosperm formation or pseudogamy. Because successful apomixis depends on the tight coordination of these altered developmental processes, early transitions from sexual to asexual reproduction are expected to involve increased developmental abnormalities, often resulting in reduced seed set. However, due to their low fitness, such transitional individuals or populations are likely short-lived and therefore rarely observed in nature.

We investigated a rare, reproductively unstable population of a predominantly triploid species within the *Hieracium nigrescens* group (Asteraceae, morphologically intermediate between *H. alpinum* and *H. murorum*), which likely represents a recently formed polyploid lineage. We used RADseq genomic approach and cytogenetics and found that this triploid species is closely related to the sympatric diploid sexual *Hieracium alpinum*, and likely originated via hybridization between *H. alpinum* and a co-occurring tetraploid species from the same group. Compared to other apomictic taxa in the area, individuals from this triploid population exhibit significantly reduced seed set. This reproductive instability was also reflected in atypical ploidy patterns in embryos and endosperm analysed by flow cytometric analyses of seeds. In addition to predominant apomictic and rare sexual patterns (BII and BIII hybrids), we observed seeds lacking endosperm or, more rarely, embryos; seeds with high-ploidy endosperm; instances of polyembryony; and either somatic polyploidization of unreduced embryo sac or automixis.

The persistence of this reproductively unstable population is likely supported by ongoing frequent formation through hybridization of co-occurring parental taxa, as well as enhanced below-ground clonal propagation. This may relax selective pressures for the stabilization of apomictic reproduction. To our knowledge, this is one of the first documented cases of ongoing apomixis formation in natural plant populations.

<footnote n="1">¹ Herbarium collections & Department of Botany, Charles University, Prague, Czechia ; ² Department of Botany, Charles University, Prague, Czechia ; ³ Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia</footnote>
S3-O.2

Environmental Plasticity of Sexual and Asexual Seed Traits in Brassicaceae

Sinah Tabea EHLERT (ehlert@mpimp-golm.mpg.de), Duarte D. FIGUEIREDO

Max-Planck-Institute of Molecular Plant Physiology, Potsdam, Germany

Reproduction via seeds can occur sexually or asexually (through apomixis) in angiosperms. Sexual reproduction is dependent on two sperm cells which orchestrate a double fertilization event, whereas the apomictic reproduction can occur completely independent of sperm cells. In either case, the produced seeds consist of an embryo, the nourishing endosperm and the protective seed coat. The apomictic reproduction pathway can be divided into the following steps: (1) apomeiosis, (2) parthenogenesis and (3) the formation of an endosperm either via pseudogamy or autonomous endosperm (AE) formation. The processes of apomeiosis as well as parthenogenesis are already well studied whereas the process of AE formation remains unclear. When drawing attention to the habitat of asexually reproducing species (animals as well as plants), it was observed that apomicts tend to colonize colder and more northern environments than their sexual relatives. Therefore, we are testing a possible role of environmental factors underlying apomictic phenotypes by investigating phenotypic plasticity of AE formation under different conditions. This is achieved by using a variety of geographically distinct *Arabidopsis thaliana* accessions, in which we induce asexual traits. Our initial results show clear genotype x environment (GxE) interactions when it comes to the formation of AEs. As a next step, we want to identify (epi-) genetic temperature-dependent determinants of AE formation. Additionally, we are testing the influence of temperature on the mode of reproduction on a natural apomict, *Boechera* sp., which is a close relative of *Arabidopsis thaliana*. With this, we aim to study how sexual and asexual endosperms respond to environmental changes, and whether these responses can be adaptive.
## The evolution of apomixis in *Boechera*, a tool for Brassica crops

Tim SHARBEL (Tim.Sharbel@usask.ca)

University of Saskatchewan, Saskatoon, Saskatchewan, Canada

### Introduction and Objectives:

The focus of my research group is to understand the evolution of apomixis in *Boechera*, a wild apomictic relative of Brassica crops, with the goal of applying this knowledge to the agriculture industry. Our work, which combines evolutionary comparative methods and genomics, has led to the identification of candidate genes involved in apomixis in addition to important plant phenotypes which are being used in long-term crossing projects.

### Materials and Methods:

A two-pronged approach has been taken over the last 8 years. In the first, a comparative genomics project involving multiple sexual and apomictic genotypes was performed. In a second project, an ongoing backcrossing experiment involving multiple lineages of apomictic pollen donors onto sexual mother plants was performed, followed by genome sequencing of the parents and crosses.

### Results:

We have produced one high-quality sexual genome assembly, in addition to multiple sexual and apomictic genomes to lower quality and have identified and positioned all identified apomixis polymorphisms. Combined with the data from our crossing experiment, this work has provided a plethora of information for understanding apomictic genome evolution in *Boechera*.

### Discussion and Conclusion:

Understanding why and how apomixis in plants (and parthenogenesis in animals) has evolved from sexual ancestors requires an understanding of the relative benefits of both forms of reproduction, in addition to quantifications of genetic and phenotypic variability on the population level. Here, we have leveraged 25 years of apomixis research in the genus *Boechera* to design and complete two major projects whose combined goal was to identify functional genetic components of apomixis. Coupled with genomic advances, this work sheds light on functional elements of apomixis, and the processes through which they have evolved in a genome devoid of recombination.
Structural characterization, gene content and gene expression of the region controlling apomeiosis in *Eragrostis curvula*

José CARBALLO<fnref n="1" /> (jcarballo@cerzos-conicet.gob.ar), Cristian GALLO², Juan SELVA³, Giacomo BONGIORNO⁴, Nada SURBANOVSKI⁵, Diego ZAPPACOSTA⁶, Mario CÁCCAMO⁷, Emidio ALBERTINI⁸, Viviana ECHENIQUE⁹ (echeniq@cerzos-conicet.gob.ar)

The *Eragrostis curvula* complex has a basic chromosome number of × = 10 and includes cytotypes with different ploidy levels (2x – 8x). Diploid plants reproduce sexually while higher ploidy levels plants reproduce by pseudogamous diplosporous apomixis. Our results indicate that apomeiosis in this species is controlled by a single hemizygous genomic region (*APO-locus*) located in one of the two sub-genomes of the species (subgenome A) having an extension of approximately 24Mbp on linkage group 9 of the apomictic Don Walter's map, delimited by three co-segregating markers. The comparison of the region delimited by these markers between sexual and apomictic genomes of the species showed a poor level of synteny, having an extension of approximately 11 Mbp in the sexual genotype. The *Eragrostis curvula* *APO-locus* contains 485 genes that are grouped in "islands" surrounded by long arrays of tandem repeats (Satellite DNAs) associated to the centromere region. One hundred and forty-three (143) of these genes show homology with genes present in the homoeologous 9B chromosome and 81 genes are exclusively present in the *APO* locus of seven apomictic genotypes. They are expressed in different plant tissues and organs. Some of these *APO* genes were also captured by pistils transcriptomics analysis and PCR, corroborating their absence in sexual genotypes. It was also observed that some transcripts show differential splicing depending on whether the gene is located in the *Apo locus* (Chrom. 9A) or in the corresponding region on the homoeologous 9B chromosome. Many of the genes present in the region show mutations or short versions compared with the homoeologous version on 9B; many of these genes are regulatory genes and have no homology with any known gene, and other genes seem not to have any role in reproduction. A reverse genetic approach is being followed to functionally characterize these genes.

<footnote n="1">¹ CERZOS, CONICET, Bahía Blanca, Buenos Aires, Argentina ; ² CERZOS/Departamento de Ciencias de la Computación, CONICET/UNS, Bahía Blanca, Buenos Aires, Argentina ; ³ CERZOS/Departamento de Agronomía, CONICET/UNS, Bahía Blanca, Argentina ; ⁴ Department of Agricultural, Food and Env, UNIPG, Perugia, Italy ; ⁵ Crops Epigenetics, NIAB, Cambridge, United Kingdom ; ⁶ CERZOS/Departamento de Agronomía, CONICET/UNS, Bahía Blanca, Buenos Aires, Argentina ; ⁷ NIAB, Cambridge, United Kingdom ; ⁸ Dept. of Agricultural, Food and Environmental Sciences, UNIPG, Perugia, Italy ; ⁹ CERZOS/Departamento de Agronomía, CONICET/UNS, Bahía Blanca, Argentina</footnote>
# Genetics of meiotic and non-meiotic instability in polyploids

Adrián GONZALO (a.gonzalo88@gmail.com)

ETH Zürich, Zürich, Switzerland

Apomixis can enable clonal propagation of meiotically unstable genomes through seeds. This is the case for some polyploids, where multiple chromosome sets cause meiotic instability and infertility. Deciphering the genetic basis of these defects holds potential for engineering fertile and stable novel (neo-)polyploid varieties, with or without the tool of synthetic apomixis. Here we characterized some of the potential sources of instability in neo-polyploids and explored solutions to these problems. First, we re-engineered meiotic recombination to show that it is possible to artificially alleviate meiotic defects in neo-polyploid *Arabidopsis thaliana*. However, we observed no improvement in fertility due to defects in pollen tube growth. To address this problem we identified two loci associated with restored normal pollen tube growth in naturally occurring polyploids of *Arabidopsis arenosa*. Finally, we also identified genotype-specific chromosome breakage at fragile sites as a potential cause of genome instability and infertility. Altogether, our results illustrate that, apart from meiotic fidelity, other traits also compromise fertility and genome integrity.
Assembling haplotype-resolved genomes to explore clonal seed production in apomictic species

Elias PRIMETIS<fnref n="1" />, ² (elias.primetis@ru.nl), Bas HEIDEMANN<fnref n="1" />, Koen VERHOEVEN³, Bruno HUETTEL⁴, Charles UNDERWOOD<fnref n="1" />, ²

Apomixis - clonal seed production in plants - naturally occurs in less than 0.1% of plant species and it does not take place in any major crop. In contrast to its rarity, apomixis is spread across the plant tree of life and recurrently evolved to fix hybrid genotypes across generations. In agriculture, a successful application of apomixis in sexual crops would fix hybrid genomes through seed, drastically altering the global supply and accessibility of hybrid seeds. To accomplish this, we need to understand the molecular mechanisms of apomixis in natural parthenogenetic species like dandelion. This is possible by generating high-quality genome assemblies of various apomictic species, including the common triploid apomictic dandelion. Using PacBio HiFi reads, high coverage HiC and short read data we are generating high-quality polyploid dandelion genomes. So far, the first-rate data used for the genome assembly of two apomictic dandelions allows us to assemble their full triploid genome. Also, we are able to locate the *PAR* locus in those assemblies, which is responsible for the parthenogenesis in dandelion. As a result, those initial outcomes are promising for high-quality genome assemblies. In future, we plan to develop a targeted pan-genome of sexual and apomictic dandelions as well as genome assemblies of other apomictic species from the *Asteraceae* family. This will allow us to investigate genome structure and evolution of clonal reproduction in a highly diverse panel of apomictic species and closely related sexual lineages. By comparing the chromosomal organization of asexual and sexual lineages, we aim to identify structural polymorphisms associated with apomixis, such as large-scale rearrangements, lineage-specific genes and mutations. Understanding these genomic differences will provide insights into the evolution of clonal reproduction and its underlying molecular mechanisms.

<footnote n="1">¹ Department of Plant and Animal Biology, Radboud University, Nijmegen, Netherlands ; ² Department of Chromosome Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany ; ³ Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands ; ⁴ Max Planck Genome Center Cologne, Max Planck Institute for Plant Breeding Research, Cologne, Germany</footnote>
S4-O.2

Mining candidate genes of apospory in *Paspalum simplex*

Davide PERRONE<fnref n="1" /> (davideperrone@cnr.it), Andrea RUBINI<fnref n="1" />, Maria Eugenia CACERES<fnref n="1" />, Juan Pablo ORTIZ², Lorena SIENA², Juan Manuel VEGA², Maricel PODIO², Edoardo FRANCO<fnref n="1" />, Fulvio PUPILLI<fnref n="1" />

We used *Paspalum simplex*, a natural tetraploid aposporous apomictic species, as a model for mining genes for apospory i.e. the development of unreduced embryo sac starting from one or more nucellus cells (aposporous initial/s) that acquire the commitment of a functional megaspore with a somatic chromosome number. Genetic approaches have revealed that in *P. simplex* the genetic determinants of apospory are localized in the apomixis controlling locus (ACL), a single dominant allele embedded in a recombinationally blocked region of heterochromatic nature. However, the role of genes acting downstream these determinants are still unknown. Moreover, it was demonstrated that DNA methylation has a role to activate the apomixis pathways in *Paspalum*. Therefore, to better investigate the genomic structure of the ACL, the role of methylation and to mine candidate genes outside the ACL, experiments are in progress to compare the apomictic and sexual genomes of *P. simplex* at the *i*) structural, *ii*) transcriptomic and *iii*) methylome levels. Here we report preliminary information about the genome sequencing efforts to obtain a reference genome of the species by using Oxford Nanopore long reads sequencing. HMW-DNA were extracted from leaves of sexual and apomictic tetraploid genotypes of *P. simplex*. Data were processed with Dorado and gave us 66X coverage for sexual and 100X for apomictic. ONT long reads improve assembly completeness, overcoming problems as polyploidy, repetitive elements and high heterozygosity. Since, ONT reads have a certain rate of sequencing error, we used NextDenovo assembler that uses a correction and then assembly strategy, to improve assembly consistency and single-base accuracy. The results of this project are expected to contribute to the understanding of genetic control of apomixis and, in the medium/long perspective to the harnessing of apomixis in major crops.

Keywords: Apomixis, *Pasaplum simplex*, genome assembly, ONT.

<footnote n="1">¹ CNR-IBBR, Perugia, Italy ; ² Conicet - IICAR-UNR, Rosario, Santa Fe, Argentina</footnote>
Unveil the molecular mechanisms regulating diplospory

Alex CAVALLERI<fnref n="1" /> (alex.cavalleri@unimi.it), Camilla BANFI<fnref n="1" />, Letizia CORNARO<fnref n="1" />, Mara CUCINOTTA<fnref n="1" />, Peter J. VAN DIJK², Tatyana RADOEVA², Diana RIGOLA², Rik OP DEN CAMP², Lucia COLOMBO<fnref n="1" />

Apomixis is an asexual reproductive mechanism in which the embryo forms without fertilization. Clonal seed propagation allows the fixation of a given genotype through generations, making the study of the molecular mechanism underling apomixis of high importance for the design of new plant breeding strategies. In the apomictic strategy known as diplospory, the Megaspore Mother Cell sexual meiosis is substituted by the apomeiotic division, giving origin to unreduced and unrecombined megaspores. Despite this, a detailed characterisation of this process at cellular and subcellular levels has been hampered by its occurrence in the ovary. Thanks to the microscopic analysis of ovules from different *Asteraceae* species we could obtain an accurate description of the apomeiotic division. Moreover, by confronting either apomictic, sexual or loss-of-diplospory *Taraxacum officinale* lines we highlighted the main differences between sexual and apomictic reproduction, showing that apomeiosis superimposes on the canonical sexual meiotic division by acting on homologous chromosome synapsis and segregation.

<footnote n="1">¹ Biosciences, University of Milan, Milano, Italy ; ² KeyGene N.V, Wageningen, Netherlands</footnote>
V International Conference on
APOMIXIS
2025
Montpellier, France | 16-19 SEPT.

<figure><img src="image_67.png" /></figure>

<figure><img src="image_68.png" /></figure>

Conference venue:
**MERCURE**
Montpellier
Centre Comédie

ABSTRACTS THURSDAY 18 SEPTEMBER

<figure><img src="image_69.png" /></figure>
Towards the Engineering of Synthetic Apomixis in Maize

Üeli GROSSNIKLAUS (grossnik@botinst.uzh.ch), Nina CHUMAK, Frédérique PASQUER, Arco BRUNNER, Wenjing SHE, Marion GAILLARD

Department of Plant and Microbial Biology & Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland

Apomixis, the asexual reproduction through seed, plants that are genetically identical to the mother plant (clones). The engineering of apomixis in crop species has the potential to completely transform agriculture. Among others, it would allow the maintenance of complex genotypes, including those of F1 hybrids. Gametophytic apomixis deviates from sexual reproduction in three major steps: (1) meiosis is circumvented or aborted (apomeiosis), (2) embryogenesis initiates without fertilization (parthenogenesis); and (3) developmental adaptations enable the formation of functional endosperm.

Using forward genetic screens, we aim at identifying mutations that mimic the major elements of apomixis with the ultimate goal to combine these elements to engineer apomixis in crops. In a forward genetic screen in maize, we identified the *non-reduction in female4* (*nrf4*) mutant displaying apomeiosis. Homozygous *nrf4* plants produce over 95% unreduced female gametophyte containing functional gametes. Using transposon display, the *Nrf4* gene was identified and found to encode a monocot-specific pioneer protein. The effect of the *nrf4* mutation on meiosis is complex, leading to both first and second division restitution. Nonetheless, depending on the genetic background of the mother plant, up to 35% of the unreduced female gametes were derived from a mitotic division. Thus, about a third of the *nrf4* mutant meiocytes display a phenotype akin to mitotic diplospory. In another screen, we searched for mutants displaying parthenogenetic development of a viable embryo and identified the *parthenogenesis1* (*par1*) mutant, producing up to 6% parthenogenotes, corresponding to about a 100-fold increase in the spontaneous parthenogenesis rate. By combining *nrf4* with a tetraploid «haploid inducer” (THI) line that we generated to maintain endosperm balance in interploidy crosses, we recovered up to 15% clonal progeny. Our findings show that producing clonal seed is possible and demonstrates that the engineering of synthetic apomixis is within reach in maize, one of the world’s most important crops.
Disruption of miR160-mediated ARF10 silencing triggers aposporous phenotypes in *Arabidopsis* ovules

Marta A. MENDES¹ (marta.mendes@unimi.it), Silvina PESSINO², Mara CUCINOTTA³, Carolina COLONNO², Lucia COLOMBO¹, Jimena GALLARDO¹, Gregorio OROZCO ARROYO¹

¹ University of Milan, Milan, ITALY ; ² CONICET ROSARIO, ROSARIO, Argentina ; ³ University of Milan, Milan, Italia

The transition from sexual to asexual reproduction in plants is a major target for crop improvement through the engineering of apomixis. Here, we demonstrate that spatial silencing of *AUXIN RESPONSE FACTOR 10* (*ARF10*) by miR160 is essential for proper female germline specification in *Arabidopsis thaliana*. Using transgenic lines expressing a miR160-insensitive version of *ARF10* (mARF10), we show that ectopic ARF10 expression leads to the formation of multiple functional megaspores, including unreduced cells of somatic origin, which give rise to additional, misoriented gametophytes — a hallmark of apospory. Our results further demonstrate that *ARF10* misregulation causes cell identity defects within the embryo sacs and increases the frequency of gametophytic abnormalities, mimicking key features of natural apomictic species. Genetic and epigenetic analyses reveal that *ARF10* expression is tightly controlled by the transcription factor SEEDSTICK, the silencing protein ARGONAUTE1, and the RdDM pathway, which together mediate both direct transcriptional repression and miR160 abundance. Remarkably, orthologous of *ARF10* in rice exhibit conserved regulatory patterns, supporting a shared developmental framework across monocots and dicots.
QUI-GON JINN, a member of the YODA family, plays a role during female reproduction in *Arabidopsis thaliana*

Lorena A. SIENA<fnref n="1" /> (siena@iicar-conicet.gob.ar), Caroline MICHAUD², Carolina COLONO<fnref n="1" />, María SOL VEGA<fnref n="1" />, Juan Pablo A. ORTIZ<fnref n="1" />, Silvina C. PESSINO<fnref n="1" />, Olivier LEBLANC²

Paspalum notatum, a subtropical forage grass native to South America, has proven to be a fruitful model for studying apomixis in plants. Several genes associated with apomixis have been identified through genetic mapping and comparative mRNA analyses, including QUI-GON JINN (QGJ) encoding a MAPK3 protein of the YODA family. Interestingly, the downregulation of QGJ in P. notatum apomictic genotypes has been associated with a decrease in the number of unreduced (aposporous) embryo sacs. To disclose QGJ function during sexual development, we have undertaken its functional characterization in the model plant Arabidopsis thaliana using genetic and cellular approaches. The protein accumulation generated by GUS reporter lines indicated that QGJ is expressed during ovule development and accumulates in the L1 cell layer of the ovule primordium, but not in the placenta. QGJ is also expressed in degenerating megaspores, while functional megaspores completely lack signal. Finally, in developing seeds, the endosperm showed GUS accumulation, but the zygote and growing embryos were completely devoid of signal. Furthermore, qgj defective mutants led to reproductive alterations of the female development, in a manner reminiscent of apomixis. Furthermore, qgj mutants showed alterations during female meiosis, female gametophytic development and early seed development. These results indicate that QGJ is expressed during megasporogenesis and endosperm development, and suggest that its function is related with megaspore degeneration in the tetrad, gametophyte development and non-cell autonomous control of embryo development.

<footnote n="1">¹ Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR) CONICET-UNR, Zavalla, Santa Fe, Argentina ; ² DIADE, Univ. Montpellier, IRD, CIRAD, Montpellier, France</footnote>
Evidence of pseudogamous aposporous apomixis in tetraploid sunflower

Silvina Claudia PESSINO<fnref n="1" />,² (pessino@iicar-conicet.gob.ar), Lucía AMATO<fnref n="1" />,², Gloria ROMERO<fnref n="1" />,², Graciela NESTARES<fnref n="1" />,², Marta B. BIANCHI<fnref n="1" />, Carolina M. COLONO<fnref n="1" />,², Bocchini MARIKA<fnref n="3" />, Emidio ALBERTINI<fnref n="3" />, Ana C. OCHOGAVÍA<fnref n="1" />,²

Apomixis has the potential to revolutionize sunflower breeding. In previous studies, we identified two diploid (2x) sunflower lines (Rf974 and Rf975) that naturally form aposporous embryo sacs (AES), produce normal reduced pollen, and generate 15% triploid BIII progeny. This study aimed to assess the impact of colchicine-induced polyploidization and hybridization on the reproduction of these lines. Colchicine treatment produced seven Rf974-4x-C0 and twelve Rf975-4x-C0 tetraploid plants, which were characterized by flow cytometry and phenotypic analysis. COplants were bagged and self-pollinated to obtain the C1 generation. Ten seeds from one Rf974-4x-C1 and three Rf975-4x-C1plants were germinated and confirmed as tetraploids. Their reproductive behavior was analyzed using differential interference contrast (DIC) microscopy. Apospory penetrance was 100%, while expressivity (i.e., percentage of ovules with AES) reached, in average, 42.4% (95% CI: 30.5–55.1%) in Rf974-4x-C1 and 32.1% (95% CI: 23.8–42.7%) in Rf975-4x-C1. In emasculated plants, two individuals per genotype (Rf974-4x-C1-19.4, -19.8 and Rf975-4x-C1-35.5, -35.8) showed an average of 63.1% (95% CI: 46–77.7%) ovules with AES and 36.8% (95% CI: 22.3–54%) with proembryos arrested at various stages. Eight direct and reciprocal crosses Rf975-4x-C1× Rf974-4x-C1 were performed. F1 hybrids were 1) emasculated and bagged; and 2) self-pollinated to produce F2 seeds. Emasculated/bagged inflorescences of the Rf975-4x-C1-35.3 × Rf974-4x-C1-19.1 cross (plant 6) produced 85.71 % (95% CI: 72.1–93.28%) of immature seeds with cotyledonary embryos arrested at different developmental stages. Other plants of different crosses showed similar levels of embryo development after emasculation. Pollen escape was ruled out, as seeds failed to mature. Maternal genotypes are currently being assessed in the F2generation using McSEED-based progeny testing. These findings support the occurrence of pseudogamous aposporous apomixis in colchicine-induced tetraploid sunflower lines, with promising implications for breeding.

<footnote n="1">¹ Facultad de Ciencias Agrarias, Universidad Nacional de Rosario (FCA-UNR), Santa Fe, Argentina ; ² Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR) CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina ;</footnote>

<footnote n="3">³ Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università degli Studi di Perugia, Umbria, Italy</footnote>
# The *BUD13* Splicing Regulator: Expression of Its Isoforms in Ovules of Sexual and Apomictic *Paspalum notatum*

Samela DRAGA (samela.draga@unipd.it)

University of Padova, Padova, Italy

*Paspalum notatum* is capable of forming seeds through either sexual reproduction or apomixis. In this species, we identified that the ortholog of the yeast BUD SITE SELECTION PROTEIN 13 (*BUD13*), a component of the RES spliceosomal complex, is expressed in florets as a truncated isoform (SHORT) lacking the herpes simplex virus regulatory protein (ICP4) domain. Moreover, apomictic genotypes display an upregulated transcript (SHORT1) with an extended 5' untranslated region, whereas in sexual plants, the predominant transcript (SHORT2) lacks this feature. Both variants originate from the same genomic locus, located in a subtelomeric region of *P. notatum* chromosome 6, which also encodes the full-length canonical isoform. A survey of sequences from 243 plant species revealed analogous truncated transcript isoforms in 47, with a statistically significant prevalence in taxa known to reproduce asexually. From premeiosis to anthesis, *BUD13* is expressed throughout the ovule in sexual genotypes, whereas in apomictic genotypes, expression is absent from the female germline. Remarkably, expression in apomictic ovules is reactivated only in aposporous egg cells and unfertilized maternal proembryos. These findings reveal clear spatial and temporal divergence in *BUD13* expression between sexual and apomictic programs, offering insights for future studies on the molecular regulation of asexual seed formation.
**Arabidopsis** mutants defective in the Auxin Response Repressor IAA16 exhibit developmental alterations during female reproduction

Maria Sol VEGA<fnref n="1" /> (mvega@iicar-conicet.gob.ar), Olivier LEBLANC², Silvina PESSINO<fnref n="1" />, Juan Pablo ORTIZ<fnref n="1" />, Lorena SIENA<fnref n="1" />

Auxin plays an essential role in many aspects of plant development, including growth and reproduction. Recently, we found that the auxin response repressor *IAA30* of *Paspalum notatum* is down-regulated in ovules of apomictic genotypes compared to sexual genotypes at the anthesis and early embryogenesis stages. Furthermore, differences in the spatio-temporal expression between reproductive modes were revealed by *in situ* hybridization experiments. These results suggest a contrasting regulation of auxin signalling during sexual and apomictic seed formation in this species. In order to analyze the biological function of *IAA30* during plant reproduction, we decided to study *IAA16*, its predicted orthologue in *Arabidopsis thaliana*. RT-PCR experiments showed that *IAA16* is expressed in siliques, leaves, seedlings and roots. These data will be further completed using wild-type plants expressing the pIAA16:IAA16:Ruby construct. Cytoembryological analysis of two *iaa16* mutant lines revealed the formation of multiple enlarged cells around the megaspore mother cell, the functional megaspore and the developing embryo sac, an observation reminiscent of aposporous initials. After pollination, both mutant lines showed defects in embryo patterning and one of them developed twin-embryos. Seedlings with one cotyledon and seeds with double shoots (polyembryony) were also detected. To further investigate the defects, we crossed *iaa16* with auxin patterning and cell identity marker lines. Analysis of *iaa16* plants expressing the pWOX2-CENH3-GFP reporter construct confirmed abnormal symmetry patterns in the embryos. Fluorescence analysis for pDRN:GFP in *iaa16* embryos suggested an altered auxin signal distribution. The results of this work indicate an essential role for *IAA16* in the specification of female germline fate and embryogenesis in *Arabidopsis*.

<footnote n="1">¹ Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR) CONICET-UNR, Zavalla, Argentina ; ² DIADE, Univ. Montpellier, IRD, CIRAD, Montpellier, France</footnote>
Eternally hybrid: natural and engineered propagation of hybrid genomes through seeds

Charles UNDERWOOD (charles.underwood@ru.nl)

Radboud University, Nijmegen, The Netherlands

Most plant species reproduce via sex and the segregation of genetic information takes place in recombinant offspring. A minority of plant species have evolved reproductive systems, including apomixis and allopolyploidy, that allow the fixation and propagation of hybrid genotypes – and heterosis – though seeds. The propagation of heterosis over generations can reduce the cost of hybrid seed production, facilitate new types of hybrid breeding, and make it possible to harness hybrid vigor in crops that are not presently cultivated as hybrids. Here, a new class of engineered hybrids that propagate heterosis through seeds will be presented and a blueprint for their application in crop improvement will be outlined.
On the Road to Apomixis in Maize: A Win for Embryogenesis, a Wait for Apomeiosis

Thomas WIDIEZ (thomas.widiez@ens-lyon.fr), Peter ROGOWSKY

Reproduction et Développement des Plantes, INRAE at ENS LYON, Lyon, France

Apomixis is a form of asexual reproduction through seeds that gives rise to clonal offspring genetically identical to the mother plant. In sexually reproducing plants such as *Arabidopsis thaliana* and rice, engineering of reproduction has led to synthetic apomixis. To achieve synthetic apomixis, two key components are required: (1) the Mitosis instead of Meiosis (MiMe) system, which generates unreduced and unrecombined chromosomes, and (2) the induction of embryo formation directly from diploid MiMe egg cells, without contribution from the paternal genome.

In maize, the “haploid inducer line” fulfils this second component of apomixis, as its pollen triggers a special form of parthenogenesis known as gynogenesis. This process leads to the development of seeds containing embryos that carry only the maternal genetic information. The identification of key molecular players allows us to decipher the molecular and cellular events underlying gynogenesis in maize, highlighting the pivotal role of the peri-germ cell membrane that surrounds the two sperm cells. As for the conversion of meiosis into mitosis -*MiMe system*-, mutations in three meiosis genes have been shown to be sufficient to induce this phenotype in *A. thaliana* and rice. In maize, we have identified orthologous genes as potential targets for mutation to recreate the MiMe phenotype. Preliminary work indicates impairment of fertility when mutating some of these genes, that would necessitate alternative strategies to successfully establish the MiMe system in maize. In summary, by combining targeted mutations to induce the MiMe system and gynogenesis via the haploid inducer line, we are aiming to establish synthetic apomixis in maize.
Apomixis in the Sea? Parthenogenesis and Maternal Cues in Seaweeds

Kenny A. BOGAERT<fnref n="1" />, ² (kenny.bogaert@tuebingen.mpg.de), Eloise DRIES², ³, Yannick MEYERS², Daniel LIESNER<fnref n="1" />, Anagha KERUR<fnref n="1" />, Floriele M. GONZAGA², Jakob F. M. JAKOB F. M.², Eliane E. ZAKKA², Tom BEECKMAN⁴, ⁵, Susana M. COELHO<fnref n="1" />, Olivier DE CLERCK²

Kelps are ecologically and economically significant brown seaweeds cultivated for food, animal feed, agricultural
biostimulants, pharmacologically active compounds, alginate extraction, and renewable biomaterials.
Understanding their embryogenesis and life cycle is key to improving breeding practices. While kelp zygotes
develop largely externally from the maternal gametophyte, their early development involves a physical connection
to the oogonial wall of the gametophyte. Detachment of fertilized or unfertilized eggs from the maternal oogonial
cell wall in *Undaria pinnatifida* (Wakame) disrupts normal embryonic polarity and, in the case of eggs, leads to
a strong increase in parthenogenetic development. While a round morphology and a tendency to detach are
used as phenotypic markers to identify parthenotes, our observations indicate that these traits are not exclusive
to parthenogenetic embryos and are correlated with detachment itself. Parthenotes are often – but not always
- morphologically recognisable by delayed growth and therefore can become indistinguishable without genetic
markers. Notably, when part of the maternal oogonial cell wall remains attached, normal patterning is restored,
underscoring the critical role of maternal extracellular cues in directing basal cell fate. Furthermore, the absence
of contact with maternal tissue increases parthenogenesis, highlighting the critical role of maternal signals in
the initial stages of development. These results show a key role for the connection to the maternal oogonial cell
wall in apical-basal patterning in kelps. This observation is reminiscent of another brown alga, *Fucus*, where the
cell wall directs cell fate by localised secretion of sulphated F2 fucans from the maternal cell wall. Together with
emerging evidence of reproductive plasticity in kelps, these findings underscore the potential importance and
breeding potential of apomixis in kelps.

<footnote n="1">¹ Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany ; ² Phycology Research Group, Ghent University, Ghent, Belgium ; ³ Laboratory of Cell and Developmental Biology, Laboratory of Cell and Developmental Biology, Wageningen University & Research, Wageningen, Netherlands ; ⁴ VIB Center for Plant Systems Biology, Ghent, Belgium ; ⁵ Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium</footnote>
S6-O.1

# Polyembryony by induced parthenogenesis: models and implications for synthetic apomixis

Hannah PEHA (hpeha@ucdavis.edu), Hui REN, Debra SKINNER, Venkatesan SUNDARESAN

Sundaresan Lab, Plant Biology Dept., University of California Davis, Davis, CA, United States

**Introduction and Objectives:**

Parthenogenesis—the formation of embryos from unfertilized egg cells—is a key step in synthetic apomixis. Induction of parthenogenesis has primarily been achieved through ectopic expression of pluripotency factors, namely from the *Baby Boom* family of transcription factors. A frequently associated phenomenon is polyembryony, especially twinning, observed in several crop and model plant species. The commercial viability of synthetic apomixis as a breeding tool will depend on reducing polyembryony when implementing it in crops like maize, where twinning is undesirable.

**Materials and Methods:**

We briefly describe the phenomenon of twinning and present molecular and phenotypic evidence from parthenogenetic lines developed in our lab and reported by others.

**Results:**

Evaluation of the available evidence supports two distinct models for twin production: (1) **dizygotic twins**, which arise from separate egg cells, and (2) **monozygotic twins**, which originate from a single egg cell that splits during zygotic development. These independent mechanisms can act in combination, together explaining the range of twin and triplet phenotypes that we and others have observed.

**Discussion and Conclusion:**

The twin formation models proposed here offer future directions for basic research and suggest potential strategies to reduce polyembryony in synthetic apomictic breeding systems.

*This work was supported by awards IOS-2505324 and IOS-2343681 to V.S. from the National Science Foundation, USA.*

**References:**

1. Peha, H., Ren, H., Skinner, D., & Sundaresan, V. (2025). Twin embryo formation by induced parthenogenesis. *Plant Reproduction, 38*(1), 3. https://doi.org/10.1007/s00497-024-00512-y
S6-O.2

# Unveiling Molecular Regulators of Synergid Cell Death Through Cell-Specific Transcriptomics

Manuel BUENDIA MONREAL¹ (manuel.buendia@unimi.it), Maria FLORES TORNERO², Marta Adelina MENDES¹

¹ Department of Biosciences, University of Milan, Milan, Italy ; ² University of Valencia, Valencia, Spain

In plants, female gametophyte development begins with a single megaspore mother cell undergoing meiosis, producing four haploid cells, with one developing into the functional megaspore. After subsequent cell divisions, most flowering plants form a seven-celled gametophyte composed of the central cell, three antipodal cells, two synergid cells and one egg cell. Synergid cells play a key role in fertilization by secreting signals that attract pollen tubes. Upon contact, the receptive synergid (rsyn) degenerates, allowing the pollen tube to release two sperm cells that fertilize the egg and central cell, forming the zygote and endosperm. The remaining persisting synergid (psyn) must also degenerate to prevent attraction of additional pollen tubes. In Arabidopsis, the transcription factor VERDANDI (VDD) is essential for rsyn degeneration. In *verdandi*(*vdd*) mutants, rsyn fails to degenerate, blocking pollen tube entry and resulting in fertilization failure. These mutants provide a model for comparing degenerating (wild-type) and non-degenerating (*vdd*) synergids.

This project aims to identify molecular regulators of synergid cell death by comparing cell-specific transcriptomes in wild-type and *vdd* ovules before and after pollination. We use pMYB98-GFP lines, which express GFP specifically in synergids, as wild-type background. Flowers are emasculated to control pollination timing. Subsequently, pre-pollination samples are collected from pistils at the pollen-receptive stage, while post-pollination samples are collected 16-20 hours after manual pollination. Ovules are enzymatically treated to release GFP-labeled synergids, which are isolated via microcapillary collection and used for RNA-seq. Pre-pollination samples have been collected; their RNA-seq analyses and the collection of post-pollination samples are ongoing.

Comparative transcriptomic analysis will reveal differentially expressed genes associated with synergid identity, pollination-induced changes, and regulators of synergid cell death. Moreover, this cell-specific transcriptomic approach could be used for studying diverse aspects of development in other gametophytic cells, including other species.
S6-O.3

Understanding the Molecular Mechanism underlying Parthenogenesis in Cereals

Xixi ZHENG¹ (xixi.zheng@ur.de), Maria TORNERO¹, Uwe SCHWARTZ², Thomas DRESSELHAUS¹

¹Cell Biology and Plant Biochemistry, University of Regensburg, Regensburg, Germany ; ²Computational Core Unit, University of Regensburg, Regensburg, Germany

Parthenogenesis, describes spontaneous embryogenesis from an unfertilized egg cell and thereby generates offspring genetically identical to the mother plant, and is a key component of apomixis (asexual reproduction through seeds). The underlying mechanisms of parthenogenesis remain poorly understood. Apomixis is rare in cultivated crops but commonly found in many wild species. Here, we use the apomictic grass *Tripsacum dactyloides* to address these questions. As the closest wild relative of maize, Tripsacum is sexually reproducing as a diploid, but all polyploids display apomixis via parthenogenesis. We collected egg cells from diploid and tetraploid Tripsacum lines to compare their gene expression. We observed that parthenogenetic eggs possess relatively specific cell cycle gene expression pattern that confers division potentials. Transcriptional reprogramming plays a significant role through both gene activation and repression; notably, *BBMs* are highly expressed in parthenogenetic eggs but completely silenced in sexual eggs. We are currently characterizing the function(s) of candidate genes via creation of ectopic sexual egg cell-expression lines and knock-outs in maize. We found that both ectopic expression and knockout of *ZmBBM1* can induce twin embryo formation. Higher-order *Zmbbms* mutants can even lead to embryo abortion.
Mechanical control of seed morphogenesis

Benoit LANDREIN (benoit.landrein@ens-lyon.fr)

*Laboratory of Plant Development and Reproduction, CNRS, Lyon, France*

Plant organ growth relies on mechanical interactions between cells and tissues. These interactions generate forces that influence key cellular processes involved in growth and differentiation. However, the extent to which mechanical signals, alongside biochemical cues, regulate plant organ morphogenesis remains poorly understood. In this talk, I will present recent work from my team demonstrating how mechanical interactions between two genetically and physically distinct compartments: the endosperm and the seed coat, govern the growth of the *Arabidopsis* seed, ultimately determining its final size and shape. This work highlights the crucial role of mechanical signals in coordinating tissue behavior during organ morphogenesis.
Maternal control of RNA decay safeguards embryo development

Gerardo DEL TORO DE LEON (deltoro@mpimp-golm.mpg.de), M. Sofia TRENTI, Varsha VASUDEVAN, Ursula KRAUSE, Claudia KÖHLER

Plant Reproductive Biology and Epigenetics, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

In angiosperms, the seed consists of three genetically distinct components: the embryo, the endosperm, and the maternal integuments. Double fertilization results in the formation of a diploid embryo and a triploid endosperm, both of which develop within maternal sporophytic integuments. Although a direct influence of thematernal sporophytic tissues on embryo development has been proposed, supporting molecular evidence remains scarce. Here, we show that secondary siRNAs generated by the impairment of the exosome complex cause embryo abortion through a maternal sporophytic effect. Mutations in the exosome subunits cause embryo arrest associated with ectopic post-transcriptional gene silencing (PTGS). Complementation of the exosome using seed coat promoter-specific expression rescues this defect, demonstrating maternal control of embryogenesis via an RNA decay safety pathway. Our results suggest that siRNA overloading of AGO1 disrupts miRNA function, leading to embryo arrest. This study provides direct evidence for maternal regulation of embryonic development likely mediated by small RNA transfer from the integuments with unchecked RNA decay.

S7-01
RNA helicases in shaping plasticity during sexual and apomictic reproduction through seeds

Anja SCHMIDT (anja.schmidt@alumni.uni-heidelberg.de)

University of Hohenheim, Hohenheim, Germany

Reproduction and seed formation are not only crucial steps in the life cycle of higher plants, but plant seeds are major sources of energy for human and animal nutrition. Nowadays, the production of sufficient food for the increasing world population is a major challenge faced, in particular as more and more often yield loss results from changing climate and extreme weather conditions. A precise understanding of the gene regulatory control of plant reproduction and changes in response to environmental stress is therefore of great relevance.

Increasing evidence suggests importance of members of the ancient gene family of RNA helicases in regulation of plant sexual reproduction and apomixis. Interestingly, we recently showed that *A. thaliana* plants carrying mutant alleles of a single RNA helicase, *RH17* show phenotypes closely resembling elements of apomixis. Like in aposporous apomicts, a two germline lineages frequently initiate development in a single ovule, occasionally leading to formation of a two embryos in the same seed. Moreover, in the absence of fertilization, seed coat development is observed at certain frequencies and evidence suggests occasional initiation of autonomous endosperm formation. While the molecular role of RH17 is to date not well understood, first evidence suggests functions in ribosomal processes and splicing control, thereby potentially controlling genes involved in germline development. Strikingly, RH17 is not only involved in regulation of reproductive development, but also appears to alter resilience to abiotic stress, designating it an interesting candidate gene for regulation of aspects of reproductive mode and stress response.

S7-02
Genetic determinants of autonomous endosperm formation in Arabidopsis

Camille SALAÜN (salaun@mpimp-golm.mpg.de), Duarte D. FIGUEIREDO

Seed Development and Apomixis, Plant Reproductive Biology and Epigenetics, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

In Angiosperms, seed development starts with the double fertilization of the maternal gametes by two sperm cells. This leads to the formation of two distinct structures, the embryo and the endosperm, surrounded by a maternal seed coat. Some species called apomicts can produce clonal seeds without fertilization. However, this highly desirable agronomical trait is not present in crops. The apomixis process involves three steps: bypassing meiosis, embryo parthenogenesis and autonomous endosperm formation. This project aims at deciphering the molecular mechanisms involved in autonomous endosperm formation. Hormonal treatments with auxin or mutations in components of the Polycomb Repressive Complex 2 (PRC2) induce the first step of autonomous endosperm formation, but its growth and cellularization are still a limiting factor. Among PRC2 mutants, *fie* leads to the formation of big autonomous seeds, whereas *fis2* produces small autonomous seeds. A genetic suppressor screen led to the identification of ARID2, an AT-rich interaction domain containing protein, as a genetic determinant of large autonomous endosperm in *fie* mutants. This protein has been shown to take part in multiple protein complexes named PEAT. Further functional studies conducted on ARID2 and different members of these PEAT complexes revealed a possible role for this complex in the genetic repression of seed development prior to fertilization in addition or in parallel with that of PRC2. These results shed light on the repression of autonomous seed development in non-apomict species and provide new keys for the engineering of autonomous seeds in crops.

S7-O.1
S7-O.2

BRI1-mediated removal of seed coat H3K27me3 marks is a brassinosteroid-independent process

Rishabh PANKAJ<fnref n="1" /> (pankaj@mpimp-golm.mpg.de), Rita B. LIMA², Guan-Yu LUO<fnref n="1" />, Sinah EHLERT<fnref n="1" />, Gerardo DEL TORO-DE LEÓN<fnref n="1" />, Heinrich BENTE<fnref n="1" />, Pascal FINGER<fnref n="1" />, ³, Hikaru SATO⁴, Duarte D. FIGUEIREDO<fnref n="1" />

Seed development in angiosperms starts with double fertilization, where two paternal sperm cells fertilize the maternal gametes. This leads to the formation of the embryo and of the endosperm. These fertilization products are enveloped by the maternally-derived seed coat, the development of which is inhibited prior to fertilization by the Polycomb Repressive Complex 2 (PRC2). This complex deposits the repressive histone mark H3K27me3, whose removal is necessary for seed coat formation. Our results show that JUMONJI-type (JMJ) histone demethylases are expressed in the seed coats of *Arabidopsis thaliana* (Arabidopsis) and are necessary for its formation. We propose that JMJ activity is coupled to Brassinosteroid (BR) function, as BR transcription factors physically recruit JMJ proteins to target loci. Consistent with this, loss of BR biosynthesis and signaling leads to seed coat defects, and that loss of the main BR receptor, BRI1, results in H3K27me3 hypermethylation. Moreover, our data suggests BRI1 mediating H3K27me3 removal independently of BRs, while a different receptor, BRL3, likely regulates seed coat formation in a BR-dependent manner. We thus propose a model where seed coat development relies on canonical and non-canonical functions of BR receptors.

<footnote n="1">¹ Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany ; ² Radboud Universiteit, Nijmegen, Netherlands ; ³ University of Potsdam, Potsdam, Germany ; ⁴ The University of Tokyo, Kashiwa, Japan</footnote>
Parthenogenesis and the evolution of clonality in animals

Thomas LENORMAND (thomas.lenormand@cefe.cnrs.fr)

Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, Montpellier, France

Since Maynard-Smith formulated the paradox of sex, theoretical results have provided a much clearer picture of the different mechanisms and circumstances that may favour the maintenance of sexual reproduction in eukaryotes. Despite this progress, however, explaining why sex is so prevalent despite its high costs (e.g. two-fold) remains difficult. One possibility is that transitions between sexual and asexual reproduction are more difficult than most models assume. This idea has long been recognized, but the potential underlying mechanisms have not been fully understood. In animals, while some asexual species may bypass meiosis altogether (e.g. through vegetative reproduction), there is strong evidence that asexuality often evolves via modifications of meiosis in parthenogens, with clonality being the end product rather than the initial state. I will explain the theory underlying these scenarios and provide examples of these transitions and secondary evolution using examples from crustaceans and other groups. I will also demonstrate how these processes can contribute to resolve the paradox of sex.
Beyond plants: how reproductive strategies could shape invasiveness and disease spread in freshwater snails

Micaela MÜLLER BAIGORRIA¹, ² (micaela.muller431@gmail.com), Elodie CHAPUIS², Nicolás BONEL¹, Pilar ALDA¹

¹ GEE, CERZOS (Universidad Nacional del Sur/CONICET), Bahía Blanca, Argentina ; ² MIVEGEC (IRD/CNRS/Université de Montpellier), Montpellier, France

Reproductive strategies profoundly influence evolutionary outcomes and ecological processes. Here, we extend key concepts from plant reproductive biology to the animal kingdom by focusing on freshwater snails—specifically lymnaeids—as a model system. We investigate how variation in mating systems, including self-fertilization and outcrossing, shapes both colonization processes and disease transmission.

Using an integrative framework that combines observational data, population genetics, and phylogenetic analysis, we examine how these reproductive modes influence both the establishment success and long-term persistence of snail populations. Self-fertilization, in particular, offers reproductive assurance in newly colonized or disturbed habitats where mates are scarce or environmental conditions are unstable. This strategy enables rapid population growth from a single founder, thereby facilitating expansion. However, a species that reproduces by self-fertilization for many generations shows a genomic degradation and a reduced genetic diversity that translates into a low adaptive potential, which is why self-fertilization is considered to be an evolutionary dead. In other words, all these detrimental genetic and genomic effects are predicted to drive selfing lineages to extinction on the long term.

However, a group of lymnaeid snails (the genus *Galba*), comprising selfing snails and dating back over 20 million years, stands as a notable exception. Its persistence challenges traditional assumptions and suggests that, under specific ecological conditions—such as amphibious lifestyles and reduced interspecific competition—long-term selfing may remain evolutionarily viable.

We also examine how reproductive strategies intersect with epidemiological dynamics. Selfing populations, characterized by low genetic variation, may facilitate parasite transmission by sustaining genetically uniform host populations. These insights underscore the broader ecological and public health implications of reproductive strategies, particularly in the context of snail-borne zoonoses. By bridging concepts across kingdoms, our work emphasizes the importance of reproductive diversity and invites a rethinking of long-held assumptions about the evolutionary fate of selfing lineages.
V International Conference on
APOMIXIS
2025
Montpellier, France | 16-19 SEPT.

<figure><img src="image_70.png" /></figure>

<figure><img src="image_71.png" /></figure>

Conference venue:
MERCURE
Montpellier
Centre Comédie

ABSTRACTS POSTERS
S1-P.1

# The Pan-genome Assembly of *Eragrostis curvula* Reveals Differences Associated with Ploidy and Reproductive mode

Emidio ALBERTINI<fnref n="1" /> (emidio.albertini@unipg.it), Giacomo BONGIORNO<fnref n="1" />, José CARBALLO², Cristian Andres GALLO², ³, Diego ZAPPACOSTA², ⁴, Viviana ECHENIQUE², ⁴

*Eragrostis curvula* (weeping lovegrass) is a perennial forage grass characterized by substantial variation in reproductive modes, ranging from strict sexuality to facultative and obligate apomixis, and a broad spectrum of ploidy levels (from 2x to 8x). Although the recently published reference genome of the diploid cultivar *Victoria* has facilitated the identification of genomic regions linked to key agronomic traits, such as forage quality, it fails to encompass the full extent of the species' genomic diversity, particularly in polyploid apomictic genotypes. In this study, we generated a comprehensive pan-genome for *E. curvula* to explore genome-wide variation, infer phylogenetic relationships among accessions, and assess the impact of ploidy on genome structure and reproductive strategy. The pan-genome was assembled through an iterative mapping and *de novo* assembly strategy: short reads from 10 genetically diverse accessions (i.e., P214208, P299920, OTA, Tanganyika USDA, Bahiense, Ermelo, Don Luis, UNST9355, Don Eduardo, and Don Pablo) were sequentially aligned to the reference genome; unmapped reads were assembled independently, annotated, and integrated into the growing pan-genomic reference. This approach enabled the identification of accession-specific genes and genomic regions not present in the diploid reference genome. The resulting pan-genome was used for short-variant calling (SNPs and InDels), presence/absence variation (PAV), and phylogenetic analysis. The Tanganyika-INTA accession was not used to construct the new pan-genome assembly and was included in short-variant and PAV analyses. The present study demonstrates the utility of a reference-guided iterative approach for pan-genome construction using short-read sequencing data. It provides a comprehensive base for understanding the genetic diversity, evolutionary processes, and reproductive mechanisms that shape *E. curvula*.

<footnote n="1">¹ Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, Italy ; ² Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS), Centro Científico Tecnológico CONICET, Bahia Blanca, Argentina ; ³ Departamento de Ciencias de la Computación, Universidad Nacional del Sur, Bahia Blanca, Argentina ; ⁴ Dpto. de Agronomía, Universidad Nacional del Sur, Bahia Blanca, Argentina</footnote>
S1-P.2

Expression analysis of DORNRÖSCHEN/ENHANCER OF SHOOT REGENERATION 1 (DRN/ESR1) in reproductive tissues of sexual and apomictic *Paspalum notatum*

María Sol VEGA¹ (mvega@iicar-conicet.gob.ar), Lorena Adelina SIENA¹, Maricel PODIO¹, Juan Manuel VEGA¹, Olivier LEBLANC², Silvina Claudia PESSINO¹, Juan Pablo A. ORTIZ¹

¹Grupo DREP, IICAR (CONICET-UNR), Zavalla, Santa Fe, Argentina ; ²DIADE, Univ. Montpellier, IRD, CIRAD, Montpellier, France

Auxin plays a crucial role in various aspects of plant development and reproduction. In gametophytic apomixis, clonal embryos arise from unreduced egg cells through parthenogenesis. In *Paspalum notatum*, parthenogenetic embryos can be observed in some aposporous embryo sacs prior to anthesis, and their number increases following exogenous auxin application (auxin test). Recently, we identified a homolog of the auxin-response repressor *AtIAA16*, named *PnIAA30*, within the *P. notatum* Apomixis Controlling Locus (ACL). Expression analyses revealed that *PnIAA30* transcripts are downregulated in the ovules of apomictic genotypes compared to sexual ones at anthesis and 1-3 days post-anthesis (early embryogenesis). Moreover, *in situ* hybridization showed spatial and temporal differences in *PnIAA30* expression between sexual and apomictic ovules. In *Arabidopsis*, a known interactor of *AtIAA16* is *ARF5/MONOPTEROS (MP)*, an activator of auxin-responsive genes. *ARF5/MP* positively regulates *DORNRÖSCHEN/ENHANCER OF SHOOT REGENERATION 1 (DRN/ESR1)*, an AP2 transcription factor involved in embryonic patterning, auxin perception, and transport. The aim of this study was to analyze *DRN* expression levels in reproductive tissues of sexual and apomictic *P. notatum* genotypes to evaluate whether differences in auxin signaling responses correlate with reproductive mode. Mining the transcriptome of reproductive tissues from both genotypes revealed four *DRN* isoforms, one of which characterized by a specific deletion, was significantly overexpressed in apomicts across all developmental stages analyzed. qRT-PCR assays confirmed the overexpression of *DRN* transcripts in apomictic genotypes at the post-anthesis stage. Additionally, *DRN* expression levels increased following exogenous auxin treatment. Our findings indicate that a specific *DRN/ESR1* isoform is upregulated in the apomictic transcriptome throughout development and confirm that *DRN/ESR1* expression levels are modulated in response to auxin treatment. This evidence underscores the potential importance of investigating the functional relationship among *PnIAA30*, *MP*, and *DRN*, which may link auxin signaling to the regulation of apospory and parthenogenesis.
S1-P.3

# Revisiting Fundamental Knowledge of St. John's Wort (*Hypericum perforatum*): Insights from Two Decades of Research as Model Species for Apomixis

Fabio PALUMBO (fabio.palumbo@unipd.it), Samela DRAGA, Giovanni GABELLI, Gianni BARCACCIA

University of Padova, Legnaro (Padova), Veneto, Italy

*Hypericum perforatum* L. (St. John's Wort) is a prominent medicinal plant renowned for its wide array of bioactive compounds, and it has also emerged as a valuable model for investigating apomixis in dicots. Over the past two decades, substantial advancements have been achieved in elucidating the genetic, molecular, and cytological features of apomixis in this species. Notable discoveries include the identification of the HAPPY (*Hypericum APOSPORY*) locus and elucidation of the roles of epigenetic regulators, including *IDN2*- and *FDM*-like genes, which contribute to the differentiation between sexual and asexual reproductive pathways. Despite these advancements, the genetic mechanisms governing apomixis in *H. perforatum* remain inadequately understood. Furthermore, the majority of genomic and transcriptomic studies conducted on *H. perforatum* have focused on the biosynthesis of medicinal metabolites, rather than on reproductive biology. Nonetheless, emerging technologies such as single-cell RNA sequencing (scRNA-seq), spatial transcriptomics, and adaptive sampling offer powerful tools to investigate specific genomic targets and key molecular players involved in the apomixis mechanism of *H. perforatum*.
## Sexual and Asexual Genome Evolution in Flowering Plants

Smriti RATHEE<fnref n="1" /> (smriti.rathee@uni-goettingen.de), Pengfei YIN², Axel HIMMELBACH³, Nils STEIN³, ⁴, Argyris PAPANTONIS², Elvira HÖRANDL<fnref n="1" />

Flowering plants can reproduce via sexual outcrossing, selfing, and apomixis. Asexuality is advantageous because it avoids the twofold cost of sex and results in adaptation to environmental stability. Whereas, sexuality can be advantageous in dynamic environments for generating genetic variance, and for purging deleterious mutations. The lack of meiotic recombination and syngamy in the asexual genome leads to decreased probability of fixing advantageous mutations, accumulation of deleterious mutations and the loss of meiotic recombinational DNA repair mechanisms. All of this plays a central role in the evolutionary theory of sex. In short term, polyploidy can lead to a temporary rise in the fitness because it buffers the negative effects of the mutational load by masking recessive deleterious mutations. However, in long term, masked mutations persist longer and with higher frequencies in the population before being eliminated by selection. Plastomes and mitochondrial genomes of apomictic plants are expected to have lower mutation rates compared to sexual outcrossing plant species which facilitates hybridization and high gene flow between lineages. Here, we aim to utilize an evolutionarily young polyploid complex- *Ranunculus auricomus* species complex to study the nuclear and organelle genome evolution of sexual and asexual plants. This complex consists of more than 840 morphospecies, mainly tetraploid or hexaploid apomicts. The apomictic polyploids arose from hybridization of sexual progenitors. Transcriptome analysis has shown that facultative sexuality might counteract genome-wide mutation accumulation. We will perform PacBio Hifi and Hi-C assembly of each three samples from sexual / apomictic tetraploid species to analyse dN/dS ratios, allelic sequence divergence, transposable elements, repetitive regions, and structural differences. We will analyse plastomes and mitochondrial genome to study nuclear organelle genome co-evolution and compare mutation rates of apomictic / sexual taxa. This study will help us understand evolution of apomixis.

<footnote n="1">¹ A.v.H. Inst. for Plant Sci., Dept. of Syst., Biodiv. & Evol. of Plants, Georg-August-Universität Göttingen, Göttingen, Lower Saxony, Germany
² Institute of Pathology, University Medical Center Göttingen, Göttingen, Lower Saxony, Germany
³ Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Seeland, Saxony-Anhalt, Germany
⁴ Department of Crop Sciences, Center of integrated Breeding Research (CiBreed), Göttingen, Lower Saxony, Germany</footnote>
## Apomixis in breeding: *Paspalum notatum* hybrids with improved lipid profile and clonal reproduction

Lara MARINO<fnref n="1" /> (marino@iicar-conicet.gob.ar), Silvia ALTABE², Carolina Marta COLONO<fnref n="1" />, Maricel PODIO<fnref n="1" />, Juan Pablo Amelio ORTIZ<fnref n="1" />, David BALABAN<fnref n="1" />, Juliana STEIN<fnref n="1" />, Nicolás SPOTO<fnref n="1" />, Carlos ACUÑA³, Lorena Adelina SIENA<fnref n="1" />, José GERDE<fnref n="1" />, Emidio ALBERTINI⁴, Silvina Claudia PESSINO<fnref n="1" />

Increased linolenic acid (omega-3, 18:3) content in ruminant diets has been linked to reduced methane emissions during grazing and to the production of milk and meat with enhanced nutritional value. In previous work, we developed two *Paspalum notatum* genotypes (JS9 and JS71) with reduced omega-6:omega-3 fatty acid ratios in their leaves and obligate apomictic reproduction. This was achieved by screening a *P. notatum* germplasm collection and identifying a sexual tetraploid genotype with low expression of *SUGAR-DEPENDENT 1 (SDP1)* and *PEROXISOMAL ABC TRANSPORTER 1 (PXA1)*, two key regulators of lipid metabolism. Fatty acid methyl ester profiling by GC-MS confirmed elevated 18:3 levels in this genotype, which was used as the maternal parent in a cross with an apomictic pollen donor. From the resulting F₁ population, we selected two hybrids (JS9 and JS71) that exhibited even lower expression of *SDP1* and *PXA1*, increased 18:3 content, and obligate clonal reproduction. These hybrids showed omega-6:omega-3 ratios that were 32.5% to 50.0% lower than the control genotype, making them strong candidates for grazing trials focused on nutritional improvement. Seasonal leaf lipid quantification showed that JS9 consistently has a 25% higher lipid content, while JS71 shows a 15–20% reduction, compared to the control. Notably, JS9 also exhibit significantly enhanced germination: Q4117 (control): 34.36% (95% CI: 27.22–42.25%, n = 163); JS9: 64.05% (95% CI: 55.86–71.53%, n = 153). These findings demonstrate that JS9 is an obligate apomictic hybrid with improved germination capacity, increased total lipid content, and a favorable omega-6:omega-3 fatty acid profile in leaves. This genotype holds strong potential for deployment in sustainable livestock systems aimed at improving product quality and mitigating environmental impacts.

<footnote n="1">¹ Instituto de Investigaciones en Ciencias Agrarias de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina, Zavalla, Santa Fe, Argentina ; ² Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina, Rosario, Santa Fe, Argentina ; ³ Instituto de Botánica del Nordeste, Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina, Corrientes, Corrientes, Argentina ; ⁴ Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Perugia, Argentina</footnote>
New insights into Eragrostis curvula's sexual and apomictic reproductive development

María Cielo PASTEN<fnref n="1" /> (mcpasten@cerzos-conicet.gob.ar), José CARBALLO<fnref n="1" />, Alejandra Raquel DÍAZ<fnref n="1" />, Chiara MIZZOTTI², Mara CUCINOTTA², Lucia COLOMBO², Viviana Carmen ECHENIQUE<fnref n="1" />, Marta Adelina MENDES²

Apomixis, defined as asexual propagation by seeds, is considered of great importance for agriculture as it allows the fixation of desired traits and its propagation through generations. *Eragrostis curvula* (Schrad.) Ness, is a perennial grass that comprises a polymorphic complex including sexual and diplosporous apomictic cytotypes, where all apomicts are polyploids. In this study we present the first detailed description of female and male gametophyte development in *E. curvula* through confocal laser microscopy, contrasting three genotypes: the fully apomictic Tanganyika, the facultative apomictic Don Walter, and the sexual OTA-S. Our analysis has led to the identification of specific morphological characteristics for each genotype, mainly depicting a larger ovule in the sexual genotype's reproductive development after the meiosis stage. These results reveal potentially important features, which could be used for a simple identification of genotypes. Furthermore, we have studied the localized expression of a gene found to be differentially expressed in contrasting genotypes of *E. curvula*. The gene *SQUAMOSA PROMOTER BINDING PROTEIN-LIKE7 (SPL7)* has been previously linked with flower development and abiotic stresses in several species, thus *in situ* hybridizations were carried out in the model plant *Arabidopsis thaliana*, as well as sexual and apomictic *E. curvula* genotypes. Differential expression was detected, specifically determining an overexpression of the gene in the sexual genotype. These results demonstrated that it could be an interesting candidate to understand the mechanisms behind apomictic development.

<footnote n="1">¹ CERZOS-CONICET, Bahía Blanca, Argentina ; ² Università Degli Studi di Milano, Milano, Italy</footnote>
Transcriptomic and Integrated Network Analysis to study the genetic relationships between apomixis and ploidy in *Eragrostis curvula*

Danilo Fabrizio SANTORO<fnref n="1" /> (danilofabrizio.santoro@unipg.it), Maria Cielo PASTEN², José CARBALLO², Cristian Andrés GALLO², Emidio ALBERTINI<fnref n="1" />, Viviana ECHENIQUE² (echeniq@cerzos-conicet.gob.ar)

Polyploidization is a phenomenon that can have a beneficial impact on biomass yield and stress tolerance of plants and it could even trigger the emergence of unique reproductive modes, such as apomixis. Apomixis, defined as an asexual mode of reproduction by seeds, is considered of paramount importance for agriculture as it allows the generation of clonal offspring with desired traits. *Eragrostis curvula* (Schrad.) Ness is a model species for studying diplosporous apomixis due to its natural diversity in ploidy levels and reproductive modes. High-throughput RNA sequencing transcriptome analysis was performed to investigate the molecular relationships between apomixis and polyploidization in this species. In this way, RNA from leaves of 10 genotypes with ploidy levels ranging from 2x to 8x were collected and sequenced. Ploidy-dependent transcriptional responses were observed, particularly at higher ploidy levels. Differential expression analyses revealed functional categories uniquely modulated between ploidies. We also identified ploidy-specific differences in the patterns of transcription factor families, which may underlie the transcriptional reprogramming differences upon genome duplication. The enrichment analysis of metabolic pathways revealed the pivotal involvement of genes associated with primary and secondary metabolism, stress responses, DNA repair and replication processes. Integrated network analysis uncovered a set of switch genes associated with the transition from sexuality to apomixis, potentially acting as central regulatory nodes. A WGCNA was applied to identify highly co-expressed clusters of genes (modules) significantly associated with apomictic genotypes compared to their sexual counterparts. These findings contribute to a deeper understanding of the intricate network of transcriptional dynamics governed by either genome duplication or reproduction mode shifts in *E. curvula*. This study provides a valuable framework for future molecular breeding studies aimed at improving quality and forage yield in this agronomically important species, and to facilitate the transfer of apomixis to major crops to stabilize hybrid vigor.

<footnote n="1">¹ Department of Agricultural, Food and Environmental Sciences (DSA3), University of Perugia, Perugia, Perugia, Italy ; ² Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS), CONICET, Bahía Blanca, Buenos Aires, Argentina</footnote>
# Targeted Nanopore Adaptive Sampling Enables High-Quality, Phased Assembly of the HAPPY Locus in *Hypericum perforatum*

Giovanni GABELLI (giovanni.gabelli@unipd.it), Samela DRAGA, Damiano RIOMMI, Fabio PALUMBO, Gianni BARCACCIA

*Department of Agronomy, Food, Natural resources, Animal and Environment, University of Padova, Legnaro (PD), Italy*

Apomixis, a naturally occurring form of asexual reproduction through seeds, holds significant potential for plant breeding. However, the genetic determinants involved in the mechanisms regulating this phenomenon have yet to be identified in many species. St. John's wort (*Hypericum perforatum* L.) is considered a robust model for studying apomixis due to its relatively small genome (0.375 pg/1Cx), short generation time (up to three flowering stage/year in greenhouse conditions), and versatile reproductive strategy, which ranges from fully sexual plants to nearly obligate apomictic ones. The HAPPY locus (*Hypericum APOSPORY*) was demonstrated to be responsible for apospory, while being uncoupled from parthenogenesis.

To investigate the genetic basis of apomixis in H. perforatum, we compiled available data and identified the region containing the HAPPY locus on chromosomes 3A, 3B, 3C, and 3D of a tetraploid phased genome assembly recently released. Therefore, we developed a targeted sequencing system based on Nanopore long reads (adaptive sampling) to generate a highly contiguous and high-quality phased genome assembly of the HAPPY locus. To optimize the method, we sequenced and assembled the different haplotypes of the HAPPY locus for a tetraploid apomictic and a hexaploid sexual. The annotation of the region was conducted through an integrative approach combining in silico analyses and transcriptome-based methods, leveraging previously generated RNA-seq datasets derived from bud tissues of sexual and apomictic genotypes. By optimizing the adaptive sampling technique, we aim to enable future investigations across diverse populations displaying contrasting reproductive strategies (sexual vs. apomictic). This will facilitate, on one hand, the investigation of allelic variation at the HAPPY locus, and on the other, the precise identification of the genetic determinant responsible for apospory. Finally, the haplotype reconstruction of each genotype will enable comprehensive validation of hypotheses pertaining to the expression of apospory as a function of allele dosage effects.
# Uncovering genetic determinants of autonomous endosperm formation in natural apomictic populations of *Boechera*

Ömer ILTAS (Oemer.İltas@mpimp-golm.mpg.de), Duarte D. FIGUEIREDO

Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

In most flowering plants, seed development is tightly coupled with double fertilization, which simultaneously initiates the formation of two developmentally coordinated structures: the embryo, and the endosperm. The endosperm is one of the most essential compartments of the seed, as it nourishes and supports the developing embryo and seedling, and serves as a major source of calories for both humans and livestock. Its development is strictly blocked prior to fertilization and only activated afterward. Although rare in nature, some species can autonomously initiate endosperm formation without fertilization. This phenomenon is particularly evident in apomictic plants, where embryo development bypasses fertilization, leading to production of clonal offspring. While many apomicts still require fertilization for endosperm formation (pseudogamy), some species have evolved true autonomous endosperm development. Experimental manipulation in sexual species, including *Arabidopsis fertilization-independent seed (fis)* mutants and exogenous auxin applications, demonstrate that endosperm proliferation can be triggered without fertilization. However, the resulting endosperm often fails to complete critical developmental transitions. Despite these advances, the molecular mechanisms underlying functional autonomous endosperm development remain unclear. In this project, we aim to elucidate the molecular basis of autonomous endosperm development in natural apomictic *Boechera* populations. By combining quantitative trait locus (QTL) mapping and comparative -omics approaches, we will identify the genetic determinants that enable fertilization-independent endosperm formation. Furthermore, using reverse genetic approaches, we will functionally validate candidate genes in sexual and apomictic model species. Uncovering the genetic determinants of autonomous endosperm formation will not only reveal fundamental biological mechanisms behind but also enable engineering full apomixis in crops, paving the way for pollen-free seed and fruit production.
Assessing ploidy as a determinant of apomictic traits in dandelion T. officinale

Ana Catarina SILVA (anacatarina.silva@mpimp-golm.mpg.de), Duarte FIGUEIREDO

Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany

Engineering apomixis, the asexual reproduction via seeds, in crops would present several advantages for agriculture, such as pollen-independent seed production. This is particularly relevant since global warming will impact pollen viability and subsequently affect fruit and seed production. To obtain apomictic crops it is necessary to engineer three developmental components: (1) avoidance of meiosis, (2) fertilization-independent embryo development, and (3) autonomous endosperm (AE) formation. To date, avoidance of meiosis and fertilization-independent embryo formation have been successfully engineered in crops. However, the same is not true for AE formation. To introduce this trait, we first need to understand the molecular mechanisms underlying AE formation. In dandelion, which has been established as a model organism for the study of apomixis, apomictic populations are triploids while sexual populations are diploids. To date, no locus associated with AE was identified in dandelion, thus, it has been purported that AE formation is due to polyploidy and not to a genetic determinant. In my PhD project, I aim to identify determinants that regulate AE formation. Particularly, I am assessing whether inducing polyploidization in sexual dandelions leads to the formation of AE, or if the trait is rather linked to a dominant genetic determinant. This work will contribute to the engineering of the last required developmental component of apomixis, aiming to achieve pollen independent seed formation in crops.
Engineering apomixis in tomato: combining apomeiosis with egg-cell expressed *ToPAR*

Iris ZAHN<fnref n="1" /> (iris.zahn@ru.nl), Nicole JANSEN<fnref n="1" />, Sofia ORTEGA<fnref n="1" />, Zhihua CHENG², Roven ROMMEL FUENTES², Yazhong WANG², Charles UNDERWOOD<fnref n="1" />, ²

Most plants reproduce sexually, where the combination of meiosis (leading to genetically unique gametes) and fertilization (fusion of genetically distinct sperm and eggs) leads to genetically variable offspring. A few species, like the common dandelion, can reproduce asexually and produce clonal seeds through apomixis. The two hallmarks of apomixis are apomeiosis and parthenogenesis. In this project, we aim to engineer apomixis in tomato by combining these two components. Heterologous expression of the dandelion *PARTHENOGENESIS* gene (*ToPAR*) has been shown to induce parthenogenesis in a variety of species, including lettuce, rice and pearl millet. Here, we study *ToPAR* when expressed in tomato egg cells. Ploidy analysis of the T1 generation will be used to determine whether *ToPAR* induces maternal haploids in tomato. Concomitantly, we combined egg-cell directed *ToPAR* expression with the *Mitosis instead of Meiosis (MiMe)* system for apomeiosis. This combination could lead to clonal reproduction in hybrid tomato plants. Ultimately, engineering apomixis in tomato can contribute to the propagation of hybrid tomatoes, displaying heterosis, in perpetuity.

<footnote n="1">¹ Department of Plant & Animal Biology, Radboud University, Nijmegen, Netherlands ; ² Department of Chromosome Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany</footnote>
S3-P.1

Ploidy-specific phenotypic traits in diploid and tetraploid aposporous sunflower

Lucía AMATO¹, ² (pessino@iicar-conicet.gob.ar), Gloria ROMERO¹, Iara KATZAROFF¹, David SANCHEZ¹, Balaban DAVID¹, ², Graciela NESTARES¹, ², Silvina Claudia PESSINO¹, ², Ana C. OCHOGAVÍA¹, ²

¹ Facultad de Ciencias Agrarias, Universidad Nacional de Rosario (FCA-UNR), Santa Fe, Argentina ; ² Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR) CONICET-UN, Facultad de Ciencias Agrarias, Santa Fe, Argentina

In previous studies, we identified two diploid (2x) sunflower lines (Rf975 and Rf974) that naturally exhibit aposporous embryo sacs (AES) and produce triploid BIII progeny. Since full expression of apomixis is typically associated with polyploidy, we used colchicine treatments to induce tetraploidy (4x) in these aposporous diploid lines. However, ploidy assessment in treated plants requires flow cytometry analysis on a large number of individuals. The objective of this study was to investigate the impact of ploidy level on phenotypic traits in sunflower, aiming to develop a simple method for ploidy pre-classification. A total of 180 seeds per genotype were sown, germinated, and treated with colchicine at three concentrations: 0.3% (v/v), 0.4% (v/v), and 0% (v/v) (control). Plants were grown under field conditions until physiological maturity. The experiment was repeated in the next growing season. Flow cytometry identified seven 4x plants derived from Rf974 (Rf974-4x-C0) and 12 from Rf975 (Rf975-4x-C0). Phenotypic traits were evaluated in the next selfing generation (C1) and showed significant differences between 4x and 2x lines: (i) reduced plant height at the early reproductive stage (R1), with a 19.2% decrease in Rf974-4x-C1 and 31.2% in Rf975-4x-C1 compared to their 2x isolines (p < 0.01); (ii) increased adaxial stomatal length (giga effect), with 36.9 µm in Rf974-4x-C1vs. 20.9 µm in Rf974-2x, and 36.8 µm in Rf975-4x-C1 vs. 21.6 µm in Rf975-2x (p < 0.001); (iii) presence of ligulate flowers and bracts in the capitulum center, observed in 40% of Rf974-4x-C1 and 29.3% of Rf975-4x-C1, but absent in the diploid lines; and (iv) increased pollen size (giga effect), with 38.9 µm in Rf974-4x-C1 vs. 30.6 µm in Rf974-2x, and 38.5 µm in Rf975-4x-C1 vs. 30.8 µm in Rf975-2x. These 4x-specific phenotypic traits may facilitate rapid pre-classification in future experiments aiming to generate polyploid sunflower plants.
# Development of a reproductive calendar in *Eragrostis curvula* to guide transcriptomic studies of apomixis

Juan Pablo SELVA<fnref n="1" />, ² (jpselva@criba.edu.ar), Diego ZAPPACOSTA<fnref n="1" />, ², Cristian GALLO<fnref n="1" />, <fnref n="3" />, Viviana ECHENIQUE<fnref n="1" />, ²

*Eragrostis curvula* (weeping lovegrass) is a model system for studying diplosporous apomixis due to its unique reproductive mode, wide range of ploidy levels and reproductive behaviors and the availability of genomic and epigenomic tools. A major limitation for transcriptomic studies in this species has been the difficulty to isolating female reproductive tissues at precise developmental stages, without other floral tissues that introduce expression noise from non-target tissues. To overcome this, we performed a detailed cytoembryological and morphometric characterization of male and female gametophyte development in seven *E. curvula* genotypes with distinct ploidies and reproductive modes (sexual, facultative apomictic, and obligate apomictic) to identify relationships between floral parameters and female reproductive developmental stages. Using differential interference contrast (DIC) microscopy and methyl salicylate clarification, we identified cytological markers that distinguish apomictic and sexual female reproductive developmental stages. These stages were then correlated with external floral parameters, such as pistil and anther length, to establish a genotype-specific reproductive calendar. Among the measured traits, pistil length showed the highest consistency with developmental stages, enabling accurate staging of ovules—particularly for early stages critical to cell fate determination. Synchrony between male and female reproductive development was also evaluated, and no consistent differences were observed across genotypes with different ploidy levels or reproductive modes. RNA extraction from pistils at selected reproductive developmental stages yielded high-quality mRNA suitable for transcriptomic analysis. Our approach enhances the resolution and accuracy of developmental stage-specific sampling, and it lays the foundation for dissecting the genetic basis of apomixis in *E. curvula*, with potential applications for engineering clonal reproduction in crop species.

<footnote n="1">¹ CERZOS-CONICET, Bahía Blanca, Argentina ; ² Departamento de Agronomía, Universidad Nacional del Sur, Bahía Blanca, Argentina ;</footnote>

<footnote n="3">³ Departamento de Ciencias e Ingeniería de la Computación, Universidad Nacional del Sur, Bahía Blanca, Argentina</footnote>
# Modes of reproduction in *Rubus* subgenus *Rubus* ser. *Glandulosi*

Jan POSPÍŠIL (pospisiljan45@gmail.com), Petra ŠARHANOVÁ

Department of Botany and Zoology, Masaryk University, Brno, Czechia

## Introduction and Objectives:

*Rubus* subgenus *Rubus* is a taxonomically complex and diverse group, comprising between 250 and 1000 species. While only a few are diploid and sexual, most polyploid taxa exhibit varying degrees of apomixis with pseudogamous endosperm development. The fruit is an aggregate of drupelets, each capable of forming sexually or apomictically. Species from ser. *Glandulosi* show high hybridization potential and reproductive variability. Our objective was to determine the predominant reproductive mode in selected tetraploid species and assess how pollen donors influence seed development.

## Materials and Methods:

We conducted controlled crosses using maternal plants from ser. *Glandulosi*, which were emasculated, selfed, or crossed with other tetraploid *Rubus* species (*R. vatavensis*, *R. bifrons*, *R. epipsilos*, and a mixed pollen donor group). Seeds were analyzed using flow cytometric seed screening (FCSS) to determine embryo and endosperm ploidy. Additionally, microsatellite genotyping by next-generation sequencing was performed to assess parental contributions.

## Results, Discussion and Conclusion:

Most seeds developed apomictically, showing embryo:endosperm ploidy levels of 4x:10x (41%), 4x:12x (42%), or 6x:10x (10%). Only about 7% of seeds were formed sexually, with a 4x:6x embryo:endosperm ratio. Genotyping revealed the presence of paternal alleles in apomictic endosperms and allowed identification of rare reproductive events such as fertilization by two reduced sperm cells or one unreduced sperm. Pollen donor identity also influenced seed size and reproductive outcome.

Our results highlight the reproductive plasticity of tetraploid *Rubus* species and the utility of combining FCSS with genotyping to distinguish reproductive modes. This dual approach offers valuable insights into the evolution and maintenance of sexual and apomictic reproduction in complex plant groups.
Apomeiosis circumvents inter-subspecific hybrid sterility in rice

Donaldo MEYNARD<fnref n="1" />, ² (donaldo.meynard@cirad.fr), Aurore VERNET², ³, Matthieu DEJEAN², ⁴, Ronan RIVALLAN², ⁵, Julien FROUIN², ⁶, Sylvie VAN COPPENOLLE², ⁶, Raphaël MERCIER⁷, Venkatesan SUNDARESAN⁸, Laurine GILLES², ⁹, Emmanuel GUIDERDONI², ⁹

F1 hybrids are known to exhibit higher yield and yield stability than pure lines, due to the phenomenon of hybrid vigor, also known as heterosis. In rice, inter-subspecific hybrids between indica and japonica varieties benefits from an even higher heterosis (ca. 30%) than intra-subspecific hybrids. However, indica/japonica hybrids generally also exhibit partial fertility currently hampering their harnessing as F1 hybrid cultivars. In this study, using CRISPR/Cas9 to induce the triple Mitosis instead of Meiosis (MiMe) mutations which trigger apomeiosis (production of unrecombined and unreduced gametes) in two indica/japonica F1 hybrids exhibiting 5.5% and 55% average grain filling, we were able to restore near-full and full fertility respectively in apomeiotic F1 plants. Next, combining apomeiosis with a low to moderate frequency of parthenogenesis in the egg cell, resulting in synthetic apomixis, we confirmed the maintenance of the high level of fertility in clonal diploid progenies of apomictic F1 hybrids. Altogether, these results open new avenues for the clonal reproduction through seeds of distant hybrids with high level heterosis in crops. Key-words: apomeiosis, F1 hybrid, indica/japonica, hybrid sterility, rice, synthetic apomixis

<footnote n="1">¹ AGAP Institute, CIRAD, Montpellier, France ; ² University of Montpellier, CIRAD-INRAE-Institut Agro, Montpellier, France ; ³ AGAP Institute/AFEG/BIOS, AGAP/First co-authors/CIRAD, Montpellier, France ; ⁴ AGAP Institute/PHIV Platform/BIOS, AGAP/co-authors/CIRAD, Montpellier, France ; ⁵ AGAP Institute/Genotyping Platform/BIOS, AGAP/co-authors/CIRAD, Montpellier, France ; ⁶ AGAP Institute/GIV/BIOS, AGAP/co-authors/CIRAD, Montpellier, France ; ⁷ Plant Breeding Research, Max Planck Institute/co-authors, Cologne, Germany ; ⁸ Dept. of Plant Sciences, Davis, CA, USA, University of California/co-authors, Davis, CA, USA ; ⁹ AGAP Institute/GIV/BIOS, AGAP/co-corresponding author/CIRAD, Montpellier, France</footnote>
Exploring the role of ARF6 in apomictic reproduction of *Paspalum notatum*

Carolina Marta COLONO<fnref n="1" /> (colono@iicar-conicet.gob.ar), Juan Pablo Amelio ORTIZ<fnref n="1" />, Maricel PODIO<fnref n="1" />, Lucia COLOMBO², Silvina Claudia PESSINO<fnref n="1" />

In previous transcriptomic analyses involving *Paspalum notatum* plants, the transcription factor AUXIN RESPONSE FACTOR 6 (PnARF6) was identified as a potential candidate involved in apomixis. PnARF6 transcripts are expressed in florets throughout reproductive development, showing consistent differential expression between sexual and apomictic plants. The objective of this study was to investigate the role of PnARF6 during *P. notatum* reproductive development. We identified two PnARF6 floral isoforms: the canonical one (Pn_ARF6_1), which encoded the typical Class-A ARF, and a second, shorter one (Pn_ARF6_2) lacking the C-terminal PB1 domain. Pn_ARF6_1 is downregulated in florets of apomictic plants at all stages, while Pn_ARF6_2 is overexpressed in florets of apomictic plants during post-meiosis. Pn_ARF6_1 transcripts map to two different loci, located in the subtelomeric regions of the short arm of chromosome 5 and the long arm of chromosome 6. In contrast, Pn_ARF6_2 transcripts map to the subtelomeric region of the short arm of chromosome 8, in an area containing many positional markers genetically linked to apomixis. Additionally, we examined the small RNA floral transcriptomes of *Paspalum notatum* and found that miR167, a key regulator of ARF6 transcription/translation, is overexpressed in apomictic ovules. miR167 stem-loop RT-qPCR experiments conducted on spikelets at the meiosis stage confirmed statistically significant upregulation in apomictic plants. We are currently initiating in situ hybridization experiments and preparing constructs for functional analysis in transformed plants.

<footnote n="1">¹ Instituto de Investigaciones en Ciencias Agrarias de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Zavalla, Santa Fe, Argentina ; ² Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy</footnote>
Reproductive alterations resembling apospory in tetraploid (4x) *Arabidopsis thaliana*

Silvina Claudia PESSINO<fnref n="1" /> (pessino@iicar-conicet.gob.ar), Carolina Marta COLONO<fnref n="1" />, Marika BOCCHINI², Gianpiero MARCONI², Emidio ALBERTINI², Marta Adelina MENDES³, Ignacio EZQUER³

*Arabidopsis thaliana* is widely regarded as a sexual species; however, most reproductive studies have focused exclusively on diploid (2x) individuals. In plants, polyploidization and hybridization often induce genome shock, leading to genetic, epigenetic, and developmental changes. The objective of this study was to examine the reproductive development of three autotetraploid (4x) *A. thaliana* ecotypes: (1) colchicine-induced 4x Landsberg erecta (4xLer); (2) colchicine-induced 4x Columbia (4xCol); and (3) the natural autotetraploid Warschau (Wa-1). Ovules were cleared with chloral hydrate and analyzed using Nomarski differential interference contrast microscopy. According to Newcombe's test for two-sided 95% confidence intervals of a single proportion, abnormal ovule frequencies were significantly higher in 4x compared to 2x genotypes: 4xLer: 0.3819 (CI: 0.3224–0.4450; n=254); 4xCol: 0.3252 (CI: 0.2627–0.3944; n=206); 4xWa-1: 0.4206 (CI: 0.3569–0.4869; n=233); vs. 2xLer: 0.1085 (CI: 0.0628–0.1784; n=129); 2xCol: 0.0872 (CI: 0.0531–0.1382; n=195). Observed abnormalities included enlarged nuclei adjacent to the megaspore mother cell, the functional megaspore, or the FG2 gametophyte, as well as additional megagametophytes or supernumerary enlarged nuclei at the FG7 stage. A progeny test was performed using a 4xLer × 4xCol cross. Leaf DNA was extracted from three individuals each of 4xLer, 4xCol, and 4xF₁ hybrids, along with 25 4xF₂ progeny. AFLP analysis revealed unexpected genetic variation among the F₁ plants. Notably, one F₂ individual exhibited a genetic profile nearly identical to the maternal F₁, suggesting maternal reproduction in ~4% of ovules (95% CI: 0.21%–22.32%). We are currently inducing genome duplication in fluorescent reproductive identity marker lines to further characterize these alterations. Our results suggest that ~38% of ovules in both colchicine-induced and natural tetraploids exhibit extra female germline development, with residual maternal reproduction observed in 4xF₁-derived progeny.

<footnote n="1">¹ Instituto de Investigaciones en Ciencias Agrarias de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Zavalla, Santa Fe, Argentina ; ² Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università degli Studi di Perugia, Perugia, Italy ; ³ Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy</footnote>
S4-P.4

Unraveling the mechanism of gametophytic apomixis in *Hieracium tenuiflorum*

Alessandro RUIU<fnref n="1" /> (alessandro.ruiu@iusspavia.it), Fabio RADI², Lucia COLOMBO², Emidio ALBERTINI<fnref n="1" />, Mara CUCINOTTA²

Apomixis, an asexual reproductive mechanism enabling clonal seed formation without fertilization, offers a powerful tool for modern agriculture. Despite its immense potential, the underlying molecular and genetic mechanisms of apomixis remain largely unknown. *Hieracium tenuiflorum* is an ideal model system for unraveling these mechanisms, as both sexual and apomictic cytotypes naturally occur within the species. *Hieracium tenuiflorum* is caractherized by gamethophytic apomixis of the Antennaria type, in which the megaspore mother cell (MMC) directly specifies into an unreduced functional megaspore (FM). Furthermore, flow cytometry studies have evaluated the ploidy of the apomictic plants against the sexual cytotypes, proving that *H. tenuiflorum* apomictic cytotypes are triploid. This project aims to elucidate the molecular factors governing apomictic reproduction in *Hieracium tenuiflorum*. To achieve this, we are also actively developing an in vitro regeneration and transformation protocol for *Hieracium tenuiflorum*, which is crucial for a deeper comprehension of the factors involved during apomixis. Moreover, we're committed to sequencing and mapping the genome of *Hieracium tenuiflorum*. This is particularly significant given the high variability within the *Hieracium* genus, where genome sizes range from approximately 3.5 Gb to 10 Gb. This effort will provide a comprehensive genomic resource, which will facilitate the identification of candidate genes and regulatory elements involved in apomixis, ultimately contributing to the potential transfer of this valuable trait to major crop species.

<footnote n="1">¹ Dipartimento di scienze Agrarie, Alimentari e Ambientali, Università degli studi di Perugia, Perugia, Italy ; ² Dipartimento di bioscienze, Università degli studi di Milano, Milano, Italy</footnote>
S4-P.5

## Apomeiosis stability in weeping lovegrass: genetic control across time and environments

Martin Raul QUEVEDO¹ (mquevedo@cerzos-conicet.gob.ar), Juan Pablo SELVA¹, ², Viviana ECHENIQUE¹, ², Diego ZAPPACOSTA¹, ²

¹ CERZOS- CONICET UNS, Bahia Blanca, Argentina ; ² Departamento Agronomía- Universidad Nacional del Sur, Bahia Blanca, Argentina

Weeping lovegrass (*Eragrostis curvula*) is a perennial grass that exhibits a specific form of embryo sac development known as *Eragrostis*-type, that is being used as a model species to investigate the genetic and epigenetic regulation of apomixis. Most apomictic plants are facultative, with sexuality typically strongly repressed or expressed at very low levels under normal conditions. Stressful situations can de-repress sexuality, increasing the occurrence of sexual processes in apomictic plants. In *E. curvula*, mapping studies have shown that apomeiosis is controlled by a single genomic region. However, the frequency of apomictic reproduction varies widely among hybrids (from 3% to 97%), suggesting that additional regulatory mechanisms may be involved.

This study aimed to evaluate the stability of apomeiosis expression in sibling plants exhibiting different frequencies of apomeiosis, assessed across multiple years and contrasting environmental conditions. Plants from a mapping population derived from a cross between the tetraploid cultivars OTA-S and Don Walter were analyzed. Panicles were collected at the onset of anthesis for phenotypic analysis based on the identification of structures characteristic of either apomictic or sexual development. Samples from plants growing in the greenhouse and also under field conditions collected during spring flowering periods (November-December) for at least three years were evaluated. Eleven plants were selected to be evaluated based on their apomeiosis frequency: low (≤ 30%), medium (30-70%), or high (≥ 70%).

Results showed that all the evaluated plants maintained consistent levels of apomeiosis expression across the years. The same situation was observed between samples grown under greenhouse or field conditions. These findings suggest that, while environmental factors may influence the expression of the trait, genetic factors play a more dominant role in regulating apomeiosis in *E. curvula*.
S4-P.6

# Transcriptomic profiling of *Eragrostis curvula* reproductive tissues reveals upregulation of DNA replication-associated pathways in apomictic genotypes

Juan Pablo SELVA<fnref n="1" />,² (jpselva@criba.edu.ar), José CARBALLO<fnref n="1" />, Nada SURBANOVSKI<fnref n="3" />, Lawrence PERCIVAL-ALWYN<fnref n="3" />, Mario CACCAMO<fnref n="3" />, Viviana ECHENIQUE<fnref n="1" />,²

Sexual reproduction in plants involves meiosis, a reductional division that halves the chromosome number during gamete formation. In contrast, the *Eragrostis*-type diplosporous apomixis is characterised by the absence of meiosis in the megaspore mother cell (MMC), which remains diploid and forms the embryo sac through two mitotic divisions. To investigate the molecular mechanisms underlying this process, we performed RNA-seq analysis of *E. curvulareproductive* tissues. Detailed cytoembryological analyses of pistils from sexual, facultative, and fully apomictic genotypes allowed us to identify developmental stages from the archesporial cell to the mature embryo sac. Correlation with pistil morphology enabled accurate staging and selection of samples for transcriptomic profiling. Transcript quantification was performed using HISAT2 with the Don Walter 4x genome as reference, and differential expression analysis was carried out with DESeq2. In Tanganyika USDA and Don Walter, both apomictic genotypes, 3,062 and 2,800 genes were upregulated, and 2,716 and 991 were downregulated, respectively, when comparing with sexual genotype (OTA-s). Among these, 1,674 and 382 genes were commonly upregulated and downregulated, in both apomictic genotypes, respectively. Annotation using the EggNOG database enabled classification into KEGG pathways. Genes upregulated in apomictic ovules were predominantly involved in DNA synthesis, mismatch repair, and excision repair pathways, all associated with DNA replication. Given that mitosis is always preceded by DNA replication, whereas meiosis includes a replication step only prior to the first division, the enrichment of replication-related transcripts in apomictic genotypes is consistent with a mitotic developmental program. This is in agreement with the diplosporous nature of embryo sac formation in *E. curvula*, where meiosis is bypassed and development proceeds through successive mitotic divisions.

<footnote n="1">¹ CERZOS-CONICET, Bahía Blanca, Argentina ; ² Departamento de Agronomía, Universidad Nacional del Sur, Bahía Blanca, Argentina ;</footnote>

<footnote n="3">³ NIAB, Histon, Cambridge, United Kingdom</footnote>
S6-P.1

Novel candidate genes for inducing parthenogenesis in Arabidopsis and soybean

Letizia CORNARO (letizia.cornaro@wur.nl), Kim BOUTILIER

*Laboratory of Biochemistry, Wageningen University & Research, Wageningen, Netherlands*

Apomixis is widely seen as a revolutionary strategy for advancing crop improvement. Indeed, this reproductive system enables the one-step fixation of valuable traits across multiple generations and the full exploitation of heterosis, simplifying the production of hybrids and cultivars. A central component of apomixis is parthenogenesis – the development of embryos directly from egg cells without fertilization. This process occurs naturally in apomictic plants, through heterochronic expression of transcription factors like PARTHENOGENESIS/DAZ3 and BABY BOOM. Similar phenotypes can also be induced in sexually reproducing plants by driving the expression of these transcription factors into the egg cell. Whereas engineering parthenogenesis at reasonably high rates has been achieved in monocots, its induction in dicots remains a challenge.

To address this, we are using a forward genetics approach to identify new candidate transcription factors and DNA-binding proteins for their potential to trigger parthenogenesis. By comparing gene expression profiles from Arabidopsis zygotes with 2-4-celled embryogenic structures – derived from in vitro microspore embryo culture – we identified a large set of candidate parthenogenesis genes. These genes will be evaluated for their ability to induce parthenogenesis in the model plant Arabidopsis thaliana, and the functions and expression patterns of promising candidates will be further characterized. Due to its importance as a food and feed crop, we will use soybean as a proof of concept to verify the possibility of introducing the parthenogenesis trait into a strictly self-pollinating dicot crop.
# Uncovering OsBBM1 Promoter Regulatory Elements for Embryo Initiation in Rice

Ashley CHRISMAN<fnref n="1" /> (amchrisman@ucdavis.edu), Venkatesan SUNDARESAN<fnref n="1" />, Yossira VAZQUEZ², Hsin Fang LEE², Debra SKINNER<fnref n="1" />

**Introduction and Objectives:**

The rice transcription factor *OsBBM1* (BABY BOOM 1) initiates embryogenesis and can induce parthenogenesis when ectopically expressed in the egg cell.<fnref n="1" /> *OsBBM1* is normally expressed in sperm cells and early zygotes, but is silenced in the egg cell.<fnref n="1" /> This project aims to identify cis-regulatory elements within the *OsBBM1* promoter that promote expression in sperm cells and zygotes, and prevent activation in the egg cell.

**Materials and Methods:**

A series of transcriptional reporter constructs containing progressive 5' deletions of the *OsBBM1* promoter were fused to fluorescent and GUS reporters and transformed into wild-type rice. Reporter expression is currently being evaluated across reproductive and vegetative tissues using fluorescence microscopy, GUS staining, and RT-qPCR. By comparing expression levels and tissue specificity across deletions, we aim to pinpoint promoter regions essential for *OsBBM1* regulation.

**Results, Discussion and Conclusion:**

Preliminary observations suggest that distinct regions of the *OsBBM1* promoter are required for proper spatial regulation. Certain deletions lead to ectopic or altered expression, consistent with the presence of both activating elements that enable sperm-specific expression and repressive elements that restrict activity in other tissues. Deletions that broaden expression domains are of particular interest, as they could provide clues to repressive elements that contribute to the silencing of *OsBBM1* in the egg cell.

*OsBBM1* expression in zygotes is initially restricted to the paternal allele after fertilization, suggesting that strong epigenetic repression prevents activation of the maternal allele in the egg cell. These experiments aim to uncover the cis-regulatory elements responsible for this expression, as well as repression of the maternal allele. Defining these elements could enable identification of upstream regulators as well as development of improved methods to induce parthenogenesis in rice.

**References:**

1. Khanday et al. 2019. Nature doi.org/10.1038/s41586-018-0785-8

<footnote n="1">¹ Department of Plant Biology, University of California Davis, Davis, CA, United States ; ² College of Biological Sciences, University of California Davis, Davis, CA, United States</footnote>
S7-P.1

The double mutant *osarf8osarf18* exhibits altered reproductive development in *Oryza sativa*

Jimena GALLARDO<fnref n="1" /> (jimenagallardo@hotmail.com.ar), Gregorio OROZCO ARROYO<fnref n="1" />, Davide PERRONE<fnref n="1" />, Lucia COLOMBO<fnref n="1" />, Silvina PESSINO², Marta MENDES<fnref n="1" />

The family of AUXIN RESPONSE FACTORS (ARFs) genes plays a crucial role in many growth and development processes in plants, including the morphology of reproductive organs. Recently, our working group demonstrated that strict spatial regulation of ARF10 by miR160 is essential for the induction of a single female germline in *Arabidopsis thaliana* and, significantly, that ectopic expression of ARF10 throughout the ovule leads to the emergence of supernumerary functional megaspore (FM). The formation of these extra FM results in the development of misoriented, supernumerary, morphologically dissimilar female gametophytes, a phenotype mimicking aposporous apomixis. Phylogenetic analyses suggest that in *Oryza sativa* the orthologs of ARF10 are OsARF8/OsARF18. Using CRISPR-Cas9 technology, we produced different mutant lines for both genes that are currently under functional characterization. A preliminary analysis showed a substantial reduction in seed production in the *osarf8 osarf18* mutant lines compared to the wild type, which could be associated with irregularities in ovule and pollen development.

<footnote n="1">¹ Dip. di Bioscienze, Università degli Studi di Milano, Milano, Italy ; ² Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Conicet, Rosario, Argentina</footnote>
Reproductive, flow cytometric and cytohistological studies reveal autonomous apomixis in triploid *Limonium* species (sea lavenders, Plumbaginaceae)

Catarina GOMES DOMINGUES<fnref n="1" /> (catarinaagomes01@gmail.com), Vicelina SOUSA<fnref n="2" />, Elvira HÖRANDL³, Ana CAPERTA<fnref n="1" />

The genus *Limonium* Miller comprises species showing a polymorphic sexual system associated with flower polymorphism and linked to a sporophytic self-incompatibility system, hybridity, polyploidy, and apomixis. In some species, embryo sac development follows a tetrasporic pattern with meiotically reduced embryo sacs in sexual diploids and unreduced diplosporic embryo sacs in polyploid gametophytic apomicts, and autonomous endosperm formation. Mature seeds with at least nine weeks, from both diploid and tetraploid species, have an embryo enveloped by endosperm tissue formed exclusively by starch grains and a single aleurone layer and basal layer transfer surrounded by the seed coat.

In this study, we aimed to evaluate the reproduction modes of triploid *Limonium algarvense* and *L. daveaui*, and the morphohistological development of the embryo and endosperm using immature seeds of diploid and triploid plants through single seed flow cytometric screening and cytohistology. Flower pollen-stigma combinations were also determined, and immature inflorescences were covered with fine mesh bags before anthesis to test for autonomous apomixis.

Results revealed that plants were self-sterile and three different embryo and endosperm ploidy patterns were detected: (i) a single triploid embryo peak; (ii) two peaks corresponding to an embryo and an endosperm with a double ploidy level; and (iii) a single hexaploid endosperm peak. The first pattern was observed in mature seeds while those with a single endosperm peak were seen in immature seeds. In these latter seeds, the presence of an embryo surrounded by endosperm living cells with nuclei and few starch grains was detected.

Overall, our results support the reproduction via asexually formed seeds in the studied species as well as pollen-independent endosperm formation.

<footnote n="1">¹ Linking Landscape, Environment, Agriculture and Food (LEAF) Research Center, School of Agriculture, University of Lisbon, Lisbon, Portugal;</footnote>

<footnote n="2">² Forest Research Centre (CEF), TERRA Associate Laboratory, School of Agriculture, University of Lisbon, Lisbon, Portugal; ³ Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Göttingen, Göttingen, Germany</footnote>
V International Conference on
APOMIXIS
2025
Montpellier, France | 16-19 SEPT.

<figure><img src="image_72.png" /></figure>

<figure><img src="image_73.png" /></figure>

Conference venue:
MERCURE
Montpellier
Centre Comédie

LIST OF POSTERS

<figure><img src="image_74.png" /></figure>
## S1 - Evolution of apomixis

<table><thead><tr><td>Last name</td><td>First name</td><td>Title of poster</td><td># poster</td></tr></thead><tbody><tr><td>ALBERTINI</td><td>Emidio</td><td>The Pan-genome Assembly of Eragrostis curvula Reveals Differences Associated with Ploidy and Reproductive mode</td><td>S1-P.1</td></tr><tr><td>ORTIZ</td><td>Juan Pablo A.</td><td>Expression analysis of DORNRÖSCHEN/ENHANCER OF SHOOT REGENERATION 1 (DRN/ESR1) in reproductive tissues of sexual and apomictic Paspalum notatum</td><td>S1-P.2</td></tr><tr><td>PALUMBO</td><td>Fabio</td><td>Revisiting Fundamental Knowledge of St. John's Wort (Hypericum perforatum): Insights from Two Decades of Research as Model Species for Apomixis</td><td>S1-P.3</td></tr><tr><td>RATHEE</td><td>Smriti</td><td>Sexual and Asexual Genome Evolution in Flowering Plants</td><td>S1-P.4</td></tr><tr><td>MARINO</td><td>Lara</td><td>Apomixis in breeding: Paspalum notatum hybrids with improved lipid profile and clonal reproduction</td><td>S1-P.5</td></tr></tbody></table>

## S2 - (Epi)Genomics of apomixis

<table><thead><tr><td>Last name</td><td>First name</td><td>Title of poster</td><td># poster</td></tr></thead><tbody><tr><td>CARBALLO</td><td>José</td><td>New insights into Eragrostis curvula's sexual and apomictic reproductive development</td><td>S2-P.1</td></tr><tr><td>ECHENIQUE</td><td>Viviana</td><td>Transcriptomic and Integrated Network Analysis to study the genetic relationships between apomixis and ploidy in Eragrostis curvula</td><td>S2-P.2</td></tr><tr><td>GABELLI</td><td>Giovanni</td><td>Targeted Nanopore Adaptive Sampling Enables High-Quality, Phased Assembly of the HAPPY Locus in Hypericum perforatum</td><td>S2-P.3</td></tr><tr><td>ILTAS</td><td>Ömer</td><td>Uncovering genetic determinants of autonomous endosperm formation in natural apomictic populations of Boechera</td><td>S2-P.4</td></tr><tr><td>SILVA</td><td>Ana Catarina</td><td>Assessing ploidy as a determinant of apomictic traits in dandelion T. officinale</td><td>S2-P.5</td></tr><tr><td>ZAHN</td><td>Iris</td><td>Engineering apomixis in tomato: combining apomeiosis with egg-cell expressed ToPAR</td><td>S2-P.6</td></tr></tbody></table>

## S3 - Reproductive developmental plasticity

<table><thead><tr><td>Last name</td><td>First name</td><td>Title of poster</td><td># poster</td></tr></thead><tbody><tr><td>PESSINO</td><td>Silvina Claudia</td><td>Ploidy-specific phenotypic traits in diploid and tetraploid aposporous sunflower</td><td>S3-P.1</td></tr><tr><td>SELVA</td><td>Juan Pablo</td><td>Development of a reproductive calendar in Eragrostis curvula to guide transcriptomic studies of apomixis</td><td>S3-P.2</td></tr><tr><td>POSPÍŠIL</td><td>Jan</td><td>Modes of reproduction in Rubus subgenus Rubus ser. Glandulosi</td><td>S3-P.3</td></tr></tbody></table>

## S4 - Apomeiosis

<table><thead><tr><td>Last name</td><td>First name</td><td>Title of poster</td><td># poster</td></tr></thead><tbody><tr><td>MEYNARD</td><td>Donaldo</td><td>Apomeiosis circumvents inter-subspecific hybrid sterility in rice</td><td>S4-P.1</td></tr><tr><td rowspan="2">PESSINO</td><td rowspan="2">Silvina Claudia</td><td>Exploring the role of ARF6 in apomictic reproduction of Paspalum notatum</td><td>S4-P.2</td></tr><tr><td>Reproductive alterations resembling apospory in tetraploid (4x) Arabidopsis thaliana</td><td>S4-P.3</td></tr><tr><td>RUIU</td><td>Alessandro</td><td>Unraveling the mechanism of gametophytic apomixis in Hieracium tenuiflorum</td><td>S4-P.4</td></tr><tr><td rowspan="2">SELVA</td><td rowspan="2">Juan Pablo</td><td>Apomeiosis stability in weeping lovegrass: genetic control across time and environments</td><td>S4-P.5</td></tr><tr><td>Transcriptomic profiling of Eragrostis curvula reproductive tissues reveals upregulation of DNA replication-associated pathways in apomictic genotypes</td><td>S4-P.6</td></tr></tbody></table>
## S6 - Triggering embryogenesis

<table><thead><tr><td>Last name</td><td>First name</td><td>Title of poster</td><td># poster</td></tr></thead><tbody><tr><td>CORNARO</td><td>Letizia</td><td>Novel candidate genes for inducing parthenogenesis in Arabidopsis and soybean</td><td>S6-P.1</td></tr><tr><td>CHRISMAN</td><td>Ashley</td><td>Uncovering OsBBM1 Promoter Regulatory Elements for Embryo Initiation in Rice</td><td>S6-P.2</td></tr></tbody></table>

## S7 - Seed development

<table><thead><tr><td>Last name</td><td>First name</td><td>Title of poster</td><td># poster</td></tr></thead><tbody><tr><td>GALLARDO</td><td>jimena</td><td>The double mutant osarf8osarf18 exhibits altered reproductive development in Oryza sativa</td><td>S7-P.1</td></tr><tr><td>GOMES DOMINGUES</td><td>Catarina</td><td>Reproductive, flow cytometric and cytohistological studies reveal autonomous apomixis in triploid Limonium species (sea lavenders, Plumbaginaceae)</td><td>S7-P.2</td></tr></tbody></table>
V International Conference on
APOMIXIS
2025
Montpellier, France | 16-19 SEPT.

<figure><img src="image_75.png" /></figure>

<figure><img src="image_76.png" /></figure>

Conference venue:
MERCURE
Montpellier
Centre Comédie

LIST OF PARTICIPANTS
**ALBERTINI Emidio**

Agricultural, Food and
Environmental Sciences
Università degli Studi di Perugia
PERUGIA - ITALY
emidio.albertini@unipg.it

**ALBERTSEN Marc**

Albertsen Crop Genetics for Humanity
JOHNSTON - IO - UNITED STATES
marcca67@gmail.com

**AUTRAN Daphné**

DIADE
IRD
MONTPELLIER - FRANCE
daphne.autran@ird.fr

**BACCILI ZANOTTO VIGNA Bianca**

Southeastern Livestock
Embrapa
SÃO CARLOS, SP - BRAZIL
bianca.vigna@embrapa.br

**BARCACCIA Gianni**

DAFNAE
University of Padova
LEGNARO - PD - ITALY
gianni.barcaccia@unipd.it

**BEMER Marian**

Biosystematics
Wageningen University & Research
WAGENINGEN - NETHERLANDS
marian.bemer@wur.nl

**BOGAERT Kenny**

Department of Algal Development
and Evolution
Max Planck Institute of Molecular
Plant Physiology
TÜBINGEN - GERMANY
kenny.bogaert@tuebingen.mpg.de

**BREJO DE ALMEIDA E SILVA Ana**
**Catarina**

Research Group: Figueiredo
Max Planck Institute of Molecular
Plant Physiology
POTSDAM - BB - GERMANY
anacatarina.silva@mpimp-golm.mpg.de

**BUENDIA MONREAL Manuel**

Biosciences
University of Milan
MILAN - ITALY
manuel.buendia@unimi.it

**CARBALLO José**

CERZOS
CONICET
BAHÍA BLANCA - ARGENTINA
jcarballo@cerzos-conicet.gob.ar

**CAVALLERI Alex**

Biosciences
University of Milan
MILAN - ITALY
alex.cavalleri@unimi.it

**CHRISMAN Ashley**

Plant Biology - Sundaresan Lab
University of California Davis
DAVIS - CA - UNITED STATES
amchrisman@ucdavis.edu

**COLOMBO Lucia**

Bioscienze
Università degli Studi di Milano
MILAN - MI - ITALY
lucia.colombo@unimi.it

**CONNER Joann**

Horticulture & IPBGG
University of Georgia
TIFTON - GA - UNITED STATES
jconner@uga.edu

**CORNARO Letizia**

Laboratory of Biochemistry
Wageningen University & Research
WAGENINGEN - NETHERLANDS
letizia.cornaro@wur.nl

**DEL TORO DE LEON Gerardo**

Plant Reproductive Biology and
Epigenetics
Max Planck Institute of Molecular
Plant Physiology
POTSDAM - GERMANY
deltoro@mpimp-golm.mpg.de

**DELGADO Luciana**

IICAR - DREP
CONICET
ZAVALLA - SF - ARGENTINA
luciana.delgado@conicet.gov.ar

**DRAGA Samela**

University of Padova
PADOVA - ITALY
samela.draga@unipd.it

**DRESSELHAUS Thomas**

Plant Cell Biology, Biochemistry
and Biotechnology
University of Regensburg
REGENSBURG - BV - GERMANY
thomas.dresselhaus@ur.de

**ECHENIQUE Viviana**

CERZOS
CONICET
BAHÍA BLANCA - BA - ARGENTINA
echeniq@criba.edu.ar

**EHLERT Sinah Tabea**

AG Figueiredo
Max Planck Institute of Molecular
Plant Physiology
POTSDAM - BB - GERMANY
ehlert@mpimp-golm.mpg.de

**FIGUEIREDO Duarte**

Max Planck Institute of Molecular
Plant Physiology
POTSDAM - GERMANY
figueiredo@mpimp-golm.mpg.de

**GABELLI Giovanni**

DAFNAE
University of Padova
LEGNARO - PD - ITALY
giovanni.gabelli@unipd.it

**GALLARDO Jimena**

Bioscienze
Università degli Studi di Milano
MILAN - ITALY
jimenagallardo@hotmail.com.ar

**GILLES Laurine**

BIOS UMR - AGAP institut
Cirad
MONTPELLIER - FRANCE
laurine.gilles@cirad.fr

**GILLMOR Stewart**

Unidad de Genómica Avanzada
Cinvestav
IRAPUATO - GTO - MEXICO
stewart.gillmor@cinvestav.mx

**GOECKERITZ Charity**

HudsonAlpha Institute for Biotechnology
HUNTSVILLE - AL - UNITED STATES
cgoeckeritz@hudsonalpha.org

**GOMES DOMINGUES Catarina**

Instituto Superior de Agronomia
University of Lisbon
LISBOA - PORTUGAL
catarinaagomes01@gmail.com

**GONZALO Adrian**

ETH Zürich
ZÜRICH - ZH - SWITZERLAND
adrian.gonzalo@biol.ethz.ch
**GROSSNIKLAUS Ueli**

Department of Plant and Microbial Biology
University of Zürich
ZÜRICH – ZH – SWITZERLAND
grossnik@botinst.uzh.ch

**GRUSZ Amanda**

Biology
University of Minnesota Duluth
DULUTH – MN – UNITED STATES
algrusz@d.umn.edu

**GUIDERDONI Emmanuel**

AGAP institut
Cirad
MONTPELLIER – FRANCE
guiderdoni@cirad.fr

**HEIDEMANN Bas**

Plant & Animal Biology - Underwood Lab
Radboud University
NIJMEGEN – NETHERLANDS
bas.heidemann@ru.nl

**HÖRANDL Elvira**

Systematics, Biodiversity, Evolution
of Plants
University of Göttingen
GÖTTINGEN – GERMANY
ehoeran@gwdg.de

**ILTAS Omer**

Plant Reproductive Biology and
Epigenetics
Max Planck Institute of Molecular
Plant Physiology
POTSDAM – GERMANY
oemer.iltas@mpimp-golm.mpg.de

**JANK Liana**

Beef Cattle
Embrapa
CAMPO GRANDE – MS – BRAZIL
liana.jank@embrapa.br

**JURANIC Martina**

Plant breeding
Wageningen University & Research
WAGENINGEN – NETHERLANDS
martina.juranic@wur.nl

**KROL Evelin**

Systematic and Evolutionary Botany
University of Zürich
ZÜRICH – SWITZERLAND
evelin.krol@systbot.uzh.ch

**KULAAR Dilsher Singh**

Max Planck Institute of Molecular
Plant Physiology
POTSDAM – GERMANY
kulaar@mpimp-golm.mpg.de

**LANDREIN Benoit**

Laboratory of Plant Development and
Reproduction
CNRS
LYON – FRANCE
benoit.landrein@ens-lyon.fr

**LEBLANC Olivier**

DIADE
IRD
MONTPELLIER – FRANCE
olivier.leblanc@ird.fr

**LEJBOWICZ Mała**

DIADE
IRD
MONTPELLIER – FRANCE
maia.lejbowicz@ird.fr

**LEMARIÉ Stéphane**

EcoSocio / GAEL
INRAE
GRENOBLE – FRANCE
stephane.lemarie@inrae.fr

**LENORMAND Thomas**

CNRS
MONTPELLIER – FRANCE
thomas.lenormand@cefe.cnrs.fr

**LIMA Rita**

Plant & Animal Biology - Underwood Lab
Radboud University
NIJMEGEN – NETHERLANDS
rita.bastoslima@ru.nl

**LING MENG Lm**

Gateway Research Center
KWS
ST LOUIS – MO – UNITED STATES
ling.meng@kws.com

**MENDES Marta**

Biosciences
University of Milan
MILAN – ITALY
marta.mendes@unimi.it

**MEYNARD Donaldo**

BIOS UMR - AGAP institut
Cirad
MONTPELLIER – FRANCE
donaldo.meynard@cirad.fr

**MICHAUD Caroline**

DIADE
IRD
MONTPELLIER – FRANCE
caroline.michaud@ird.fr

**MRÁZ Patrik**

Herbarium collections & Department of
Botany
Charles University
PRAHA – CZECH REPUBLIC
mrazpat@natur.cuni.cz

**MÜLLER Micaela**

CERZOS - Grupo de Genética y
Ecología Evolutiva
CONICET
BAHÍA BLANCA – BA – ARGENTINA
micaela.muller431@gmail.com

**ORTIZ Juan Pablo Amelio**

IICAR - DREP
CONICET
ZAVALLA – SF – ARGENTINA
ortiz@iicar-conicet.gob.ar

**OZIAS-AKINS Peggy**

University of Georgia
TIFTON – GA – UNITED STATES
pozias@uga.edu

**PALUMBO Fabio**

DAFNAE
University of Padova
LEGNARO – PD – ITALY
fabio.palumbo@unipd.it

**PANKAJ Rishabh**

AG Figueiredo
Max Planck Institute of Molecular
Plant Physiology
POTSDAM – GERMANY
pankaj@mpimp-golm.mpg.de

**PEHA Hannah**

Plant Biology - Sundaresan Lab
University of California Davis
DAVIS – CA – UNITED STATES
hpeha@ucdavis.edu

**PERRONE Davide**

Istituto Bioscienze e Biorisorse
Consiglio Nazionale delle Ricerche
PERUGIA – ITALY
davideperrone@cnr.it

**PESSINO Silvina Claudia**

IICAR
CONICET
ZAVALLA – SF – ARGENTINA
pessino@iicar-conicet.gob.ar
**POSPÍŠIL Jan**

Botany and Zoology
Masaryk University
BRNO - CZECH REPUBLIC
pospisiljan45@gmail.com

**PRIMETIS Elias**

Plant Genome Engineering
Radboud University
NIJMEGEN - NETHERLANDS
elias.primetis@ru.nl

**RADOEVA Tanya**

Innovation for Crops
KeyGene
WAGENINGEN - NETHERLANDS
tanya.radoeva@keygene.com

**RATHEE Smriti**

Systematics, Biodiversity and Evolution
of Plants
George August University of Goettingen
GÖTTINGEN - NI - GERMANY
smriti.rathee@uni-goettingen.de

**RUIU Alessandro**

Genetica Agraria
Università degli Studi di Perugia
PERUGIA - PG - ITALY
alessandro.ruiu@iusspavia.it

**SALAÜN Camille**

Seed Development and Apomixis
Max Planck Institute of Molecular
Plant Physiology
POTSDAM - GERMANY
salaun@mpimp-golm.mpg.de

**ŠARHANOVÁ Petra**

Botany and Zoology
Masaryk University
BRNO - CZECH REPUBLIC
sarhanova@gmail.com

**SCHMIDT Anja**

University of Hohenheim
STUTTGART - GERMANY
anja.schmidt@alumni.uni-heidelberg.de

**SELVA Juan Pablo**

CERZOS - Plant Biotechnology Lab
CONICET
BAHÍA BLANCA - BA - ARGENTINA
jpselva@criba.edu.ar

**SHARBEL Tim**

University of Saskatchewan
SASKATOON - SK - CANADA
tim.sharbel@usask.ca

**SIENA Lorena**

IICAR - DREP
CONICET
ZAVALLA - SF - ARGENTINA
siena@iicar-conicet.gob.ar

**SUNDARESAN Venkatesan**

Plant Biology - Sundaresan Lab
University of California Davis
DAVIS - CA - UNITED STATES
sundar@ucdavis.edu

**SURBANOVSKI Nada**

Plant Genetics
National Institute of Agricultural Botany
EAST MALLING - KE - UNITED KINGDOM
nada.surbanovski@niab.com

**TUCKER Matthew**

Waite Research Institute
University of Adelaide
URRBRAE - SA - AUSTRALIA
matthew.tucker@adelaide.edu.au

**UNDERWOOD Charles**

Plant & Animal Biology - Underwood Lab
Radboud University
NIJMEGEN - NETHERLANDS
charles.underwood@ru.nl

**VAN DIJK Peter**

KeyGene
WAGENINGEN - NETHERLANDS
peter.van-dijk@keygene.com

**VEGA Juan Manuel**

IICAR - DREP
Laboratorio de Biología Molecular
CONICET
ZAVALLA - SF - ARGENTINA
jvega@iicar-conicet.gob.ar

**VEGA Maria Sol**

IICAR
CONICET
ZAVALLA - SF - ARGENTINA
mvega@iicar-conicet.gob.ar

**VERHOEVEN Koen**

Terrestrial Ecology
Netherlands Institute of Ecology
NIJMEGEN - NETHERLANDS
k.verhoeven@nioo.knaw.nl

**WIDIEZ Thomas**

INRAE
LYON - FRANCE
thomas.widiez@ens-lyon.fr

**ZAHN Iris**

Radboud University
NIJMEGEN - NETHERLANDS
iris.zahn@ru.nl

**ZHENG Xixi**

University of Regensburg
REGENSBURG - GERMANY
xixi.zheng@ur.de