| Summary: | The necrotrophic fungus <i>Botrytis cinerea</i>, is considered a major cause of postharvest losses in a wide range of crops. The common fungal extracellular membrane protein (CFEM), containing a conserved eight-cysteine pattern, was found exclusively in fungi. Previous studies in phytopathogenic fungi have demonstrated the role of membrane-bound and secreted CFEM-containing proteins in different aspects of fungal virulence. However, non-G protein-coupled receptor (non-GPCR) membrane CFEM proteins have not been studied yet in phytopathogenic fungi. In the present study, we have identified a non-GPCR membrane-bound CFEM-containing protein, Bcin07g03260, in the <i>B. cinerea</i> genome, and generated deletion mutants, ΔCFEM-<i>Bcin07g03260</i>, to study its potential role in physiology and virulence. Three independent ΔCFEM-<i>Bcin07g03260</i> mutants showed significantly reduced progression of a necrotic lesion on tomato (<i>Solanum lycopersicum</i>) leaves. Further analysis of the mutants revealed significant reduction (approximately 20–30%) in conidial germination and consequent germ tube elongation compared with the WT. Our data complements a previous study of secreted Δ<i>CFEM1</i> mutants of <i>B. cinerea</i> that showed reduced progression of necrotic lesions on leaves, without effect on germination. Considering various functions identified for CFEM proteins in fungal virulence, our work illustrates a potential new role for a non-GPCR membrane CFEM in pathogenic fungi to control virulence in the fungus <i>B. cinerea</i>.
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