Soutenance de thèse : Glen CALVAR

Role of the clathrin adaptor AP-1 in the virulence and the biogenesis process of secretory vesicles in the plant-pathogenic fungus Botrytis cinerea

Doctorant : Glen CALVAR

Laboratoire INSA : MAP

Ecole doctorale : ED341  Évolution, Ecosystèmes, Microbiologie, Modélisation

Plant pathogenic fungi represent an increasing threat to global food security which is increased by climate change. Understanding the mechanisms of pathogenesis is therefore essential to limit the development of fungal diseases in plants. The virulence of these fungi is largely based on the secretion of various proteins capable of degrading the host plant's constituents. Before being released into the extracellular environment, these proteins pass through the endoplasmic reticulum, the Golgi apparatus and sometimes the endosome, and are transported from one cellular compartment to another in intracellular vesicles. Today, the mechanisms of secretion, and more particularly of the biogenesis of these vesicles, are very little studied in fungi, despite being essential for the comprehension of pathogenesis. To better understand these mechanisms, we have created an under-expression mutant of a gene encoding for a subunit of the clathrin adaptor AP-1 in the necrotrophic fungus Botrytis cinerea. This adaptor is involved in the biogenesis of secretory granules in Drosophila and humans. Characterization of the AP-1 mutant revealed that the complex was involved in polarized growth, fungal cell-wall synthesis, and the secretion of hydrolytic enzymes essential for fungal nutrition and virulence. To better understand the putative role of this adaptor in vesicle biogenesis, we also undertook the enrichment of intracellular vesicles, and we propose a strategy to isolate secretory vesicles. Our study shows for the first time the importance of the clathrin adaptor AP-1 in secretion mechanisms in a plant pathogenic fungus.