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Clathrin is essential for virulence factors delivery in the necrotrophic fungus Botrytis cinerea

Nathalie Poussereau: University Lyon 1

<div>Fungi are important plant pathogens on agricultural and horticultural crops. Study of these microorganisms remains essential to understand pathogenic process and control plant diseases. In this context, a random insertional mutagenesis strategy, based on the <em>Agrobacterium tumefaciens</em>-mediated transformation (ATMT), was used to create a mutant library of the grey mould fungus <em>Botrytis cinerea.</em> A nonpathogenic mutant altered in the expression of a gene encoding clathrin heavy chain was selected. Clathrin heavy chain is well conserved from yeast to human and is described to be mainly involved in intracellular coat vesicles formation for endocytosis and post-Golgi trafficking of proteins. The characterization of the mutant was performed to precise the role of this protein in the infectious process of this typical necrotrophic fungus. A secretion defect of numerous proteins including known virulence factors, as Plant Cell Wall Degrading Enzymes and elicitors was observed. A clathrin-coated vesicle enriched fraction was isolated from the wild type and mutant strains. Using a proteomic approach, we analyzed and compared the proteomic composition of these clathrin-coated vesicles and present here the results. This study demonstrated for the first time the essential role of clathrin in the infectious process of a fungal pathogen and its importance in virulence factors secretion.</div>