# WALNUT Project: Does cell wall pectic fraction modification influence plant nutrition and/or phytoremediation capacities ?

Jonathan Robilliard<fnref n="1" />,<fnref n="3" />, Sophie Bouton<fnref n="1" />, Karine Pageau<fnref n="1" />, Catherine Rayon<fnref n="1" />, Stéphanie Guénin<fnref n="2" />,
Laurent Gutierrez<fnref n="2" />, Pierre Delaplace<fnref n="3" />, Olivier Van Wuytswinkel<fnref n="1" />

## Abstract

The project aims to increase the knowledge of the biological function of enzymes modifying the structure of pectins (or PRE for "Pectin Remodeling Enzymes") in the primary plant cell wall. Among these enzymes, Pectin MethylEsterases (PME, EC 3.1.1.11) catalyse the hydrolysis of C6 galacturonic acid methylester group present in newly synthesized homogalacturonans [1]. Analysis of recent bibliography indicates a potential role for the pectins demethylesterification in the plant response to nutritional (nitrogen, phosphorus) [2,3,4] or heavy metal (ex: cadmium) [5,6,7] stresses, evidenced by an increase/decrease of PME activity in such conditions.

## Objective

Highlight and study the role of pectin methylesterification in the transport and apoplastic translocation of ions, both in root and aerial tissues

## Strategy

### Production of transgenic plants: Modified PME activity

**Planned constructions:**

**PME activity ↗**

- Expression of PMEi5 (inhibitor of PME)

- RNAi construction
  (→ targeting root specific PME genes)

Some RNAi lines have already shown a decrease in PME activity

PME activity of plantlets (cultivated in liquid medium for 7 days): RNAi line "Pme a 2.4" and its control Col 0

<figure><img src="image_1.png" /></figure>

p < 0,05 (*)

Error bar : standard deviation

**PME activity ↗**

- Expression of VdPME (Verticilium dahliae PME)

<figure><img src="image_2.png" /></figure>

<figure><img src="image_3.png" /></figure>

Very strong PME activity
[8]

**Using Promotors :**

- Ubiquitin

- Root specific

- Leaf specific

**GreenGate cloning method [9]:**

<figure><img src="image_4.png" /></figure>

Characterization of
parietal
modifications

### Dexamethasone induction system [10]:

→ Allows expression of a gene at the desired time

<figure><img src="image_5.png" /></figure>

### Impact of modifications on the absorption and transport of ions

**Hydroponic culture:**

<figure><img src="image_6.png" /></figure>

## Perspectives

This project is part of a national and regional strategy for the reduction of phytosanitary products allowing increased protection of cultivated soils and the environment, in particular on the preservation of soils, groundwater and biodiversity. In addition, the project will also focus on the ability of the plant wall and more particularly the remodeling of pectins by PMEs to fix heavy metals which are extremely common pollutants in the soils of industrial wastelands, particularly present in the Hauts-de-France region and could also provide new innovative solutions in soil phytoremediation strategies.

## References

[1] Sénéchal et al. (2014) J Exp Bot 65:5125. ; [2] Landi S. and Esposito S. (2017) Front. Plant Sci. 8: 1376. ; [3] Podgorska et al. (2017) Front. Plant Sci. 8: 1344. ; [4] Hoehenwarter et al. (2015) BMC Plant Biol 16: 106. ; [5] Li et al. (2017) Plant Physiology and Biochemistry 119: 265. ; [6] Corso et al. (2021) New Phytol. 230: 669. ; [7] Wu et al. (2021) Environmental Pollution doi.org/10.1016/j.envpol.2021.117218 ; [8] Safran J et al. (2021) Int J Biol Macromol. 15;176:165-176. doi: 10.1016/j.ijbiomac.2021.02.035. ; [9] Lampropoulos A et al. (2013) PLoS One. 2013 Dec 20;8(12):e83043. doi: 10.1371/journal.pone.0083043. ; [10] Schürholz AK et al. (2018) Plant Physiol. 2018 Sep;178(1):40-53. doi: 10.1104/pp.18.00463. Epub 2018 Jul 19.

<footnote n="1">¹Université de Picardie Jules Verne - UMRT INRAE 1158 BioEcoAgro - Biologie des Plantes et Innovation (BioPI)</footnote>

<footnote n="2">² Université de Picardie Jules Verne – Centre de Ressources Régionales en Biologie Moléculaire (CRRBM)</footnote>

<footnote n="3">³ Université de Liège - Gembloux Agro-Bio Tech (GxABT) - TERRA - Plant Sciences</footnote>