INRAO

Elise Forgues¹
Louis Carles¹
Marie Foulongne-Oriol¹

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# Maize kernel associated Fusarium communities is affected by agronomical context

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@ExChange

## Background

Fusarium (FER) and Gibberella ear rots (GER), caused by a cortege of *Fusarium* species, are the two most devastating diseases of maize (*Zea mays* L.), reducing yield and affecting grain quality worldwide, especially by contamination with mycotoxins. The spectrum of *Fusarium spp.* that led to infections is likely to be shaped by environmental conditions such as temperature, moisture or drought stress, but also by agricultural practices, including tillage, irrigation, crop rotation or plant variety.

Ongoing climate change (CC) is already impacting the distribution and prevalence of different *Fusarium* species. This can lead to shifts in the dominant pathogens causing FER and GER under various cropping systems, potentially altering the mycotoxin profiles observed in maize grain. In this context, the use of agricultural CC mitigation practices could also be questioned in regard to population pathogens evolution. Understanding the modulation of FER and GER pathogens populations to the combined pressures of CC and evolving agricultural practices is essential for predicting the emergence and/or spread of epidemics. The aim of the present study was to describe the representativeness of *Fusarium* species on maize kernels in various agronomical contexts, including soil type, irrigation management, and geographical location, over a period of 2 years, using a metabarcoding approach targeting the specific EF1 alpha region. This description will allow for the identification of key factors driving the risk of FER and GER and associated mycotoxin contamination.

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F. graminearum

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F. culmorum

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@MycSA

F. verticilloides

## Sampling plan

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2019
* 14 Waxy
* 114 Conso
* 6 Geographical origin
* 107 Irrigated
* 21 No irrigated
* 66 Silt
* 19 Alluvium
* 21 Black earth
* 22 Sand

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2020
* 15 Waxy
* 41 Conso
* 4 Geographical origin
* 7 Irrigated
* 49 No irrigated
* 7 Clay
* 33 Silt
* 16 Black earth

## Metabarcoding approach

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Extraction

DNA

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Bioinformatic treatments

Illumina HiSeq Sequencing

(Cobo-Diaz and al 2019)

## Pipeline of analyses

Raw sequence data from
HiSeq sequencing of
EF1-alpha gene

Trimming parameters,
read filtering and
merging

Taxonomic
assignment and
correction

Final ASV table for R
analyze

DADA2 in QIIME2

BLASTn

* Estimated amplicon size : 430bp

* 300 bp for cleaning

* 20 bp for primers

Local database
FUSARIUMID_v3.0_modified

This workflow shows the different stages of pre-processing and the parameters used in the study.

## Main Fusarium species and others

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* 68% of sequences were affiliated with *Fusarium* spp.

* *F. graminearum* and *F. proliferatum* were found to be the two most abundant species

## Co-occurrence

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* *Fusarium* spp. communities were found distinct according to sample geographical origin.

* Despite location-specific trends, not overall systematic exclusion or species association was found.

* Some locations displayed a reverse pattern of co-occurrence.

## Composition of Fusarium species

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Taxon

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* The level of diversity within sample was highly variable between locations

* Although this may be due to soil type, there are also differences in species diversity depending on whether or not the soil has been irrigated. Similarly, differences can also be found within the same soil type, as in the case of silt in the communes of Montfort and Saint Aubin.

* A diversity of *Fusarium* species profile distribution was observed according to geographical origins.

* Within each location, the patterns of *Fusarium* species representativeness appeared quite similar.

* Ychoux displayed a distinct *Fusarium* species profile with a greater representativeness of *F. oxysporum* and *F. temperatum*.

* Cazères samples were also characterised by a larger abundance of *F. proliferatum* than the others sampling locations.

* The level of diversity within sample was highly variable between locations

* Although this may be due to soil type, there are also differences in species diversity depending on whether or not the soil has been irrigated. Similarly, differences can also be found within the same soil type, as in the case of silt in the communes of Montfort and Saint Aubin.

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## Conclusion and perspectives

This study provided information on the representativeness of *Fusarium* species on maize in southern France. *F. graminearum*, *F. proliferatum* and *F. verticillioides* were the most predominant species found, as commonly described in European countries as been responsible for ear and kernel rots in maize. *Fusarium* community assemblies greatly varied according to location, confirming that environmental factors play a major role in shaping their composition. The preliminary results suggest that soil type is likely to affect *Fusarium* communities present on maize kernels at harvest. This observation could be attributed to variations in the inherent conduciveness of different soil types to support fungal persistence and facilitate re-infection in subsequent cropping cycles. Irrigation practices do not seem to influence representativeness of *Fusarium* species.

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Centre
Nouvelle Aquitaine - Bordeaux

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MycSA
UR 2024
Myologie et Sécurité des aliments

INRAO

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tetrae

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MAÏSADOUR
NOTRE CULTURE. VOTRE BIEN-VIVRE

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contact :

Elise.forgues@inrae.fr

Marie.foulongne-oriol@inrae.fr

1 UR MycSA, INRAE,

71 Avenue Edouard Bourlaux CS2032,

33882 Villenave d'Ornon, Cedex

Tél. : + 33 (0)5 57 12 24 //

https://www6.bordeaux-aquitaine.inra.fr/mycsa

TETRAE - AC²TION

https://www.tetrae.fr/les-projets/ac2tion