Skip to Main content Skip to Navigation
Theses

Étude du mécanisme d'action d'un peptide antifongique de la famille des héliomicines pour contrôler le champignon phytopathogène Botrytis cinerea

Abstract : Phytopathogenic fungi are the main cause of crop diseases. Botrytis cinerea is a necrotrophic fungus, responsible for the gray mold, targeting many plants of agronomic interest (tomato, grapevine, strawberry). The extensive control of this disease integrates research for new antifungal solutions derived from natural molecules such as antimicrobial peptides (AMPs). The peptide ETD151 is an exclusively antifungal AMP optimized from heliomicin, an insect defensin from the butterfly Heliothis virescens. This small cationic, cysteine-rich and non-cytotoxic peptide demonstrates a promising in vitro activity on phytopathogenic fungi including B. cinerea. Using multidisciplinary approaches (proteomics, sphingolipidomics, confocal microscopy), this thesis focused on a better understanding of the mechanism of action of ETD151, with the eventual goal of developing a new crop protection strategy. As a first step, bottom-up proteomic studies were conducted on B. cinerea mycelium in the presence or absence of the peptide. Differential analysis of the results allowed us to identify proteins and metabolic pathways, such as the respiratory chain, impacted by ETD151. Thereafter and based on its strong homology with heliomicin, we have demonstrated the prominent role of membrane lipids called glucosylceramides in the activity of ETD151. Two forms Bc-GlcCer-2 and Bc-GlcCer-3 have been characterized by mass spectrometry in B. cinerea and explain the sensitivity of the fungus to the antifungal peptide. These results contributed to the current protein-lipid interaction studies in NMR. Finally, we have been able to define ETD151 as a morphogenic defensin in B. cinerea, as a few insects and plants antifungal defensins. Indeed, the peptide inhibits spore germination and hyphal elongation while at the same time altering the morphology of the fungus. It also disrupts the membrane integrity and leads to the release of intracellular content, non-mechanically and without acting directly on the high-osmolarity glycerol pathway. By combination with BODIPY fluorophore, we have revealed a particular affinity of ETD151 for the cell envelope and its internalization.
Complete list of metadatas

Cited literature [294 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02969903
Contributor : Abes Star :  Contact
Submitted on : Saturday, October 17, 2020 - 1:02:11 AM
Last modification on : Saturday, October 17, 2020 - 3:25:40 AM

File

AUMER_2019_archivage.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02969903, version 1

Collections

Citation

Thomas Aumer. Étude du mécanisme d'action d'un peptide antifongique de la famille des héliomicines pour contrôler le champignon phytopathogène Botrytis cinerea. Chimie-Physique [physics.chem-ph]. Université Grenoble Alpes, 2019. Français. ⟨NNT : 2019GREAV038⟩. ⟨tel-02969903⟩

Share

Metrics

Record views

63

Files downloads

5