Characterization of the Role of a Non-GPCR Membrane-Bound CFEM Protein in the Pathogenicity and Germination of .

The necrotrophic fungus , 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 genome, and generated deletion mutants, ΔCFEM-, to study its potential role in physiology and virulence. Three independent ΔCFEM- mutants showed significantly reduced progression of a necrotic lesion on tomato () 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 mutants of 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 .