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

Abstract

The necrotrophic fungus Botrytis cinerea, 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 B. cinerea genome, and generated deletion mutants, ΔCFEM-Bcin07g03260, to study its potential role in physiology and virulence. Three independent ΔCFEM-Bcin07g03260 mutants showed significantly reduced progression of a necrotic lesion on tomato (Solanum lycopersicum) 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 ΔCFEM1 mutants of B. cinerea 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 B. cinerea.

Functional Characterization of the Nep1-Like Protein Effectors of the Necrotrophic Pathogen – Alternaria brassicae

“…Recent studies have revealed that necrotrophic pathogens also secrete small proteinaceous effectors that can function as pathogenicity factors. Some prominent examples of proteinaceous necrotrophic effectors that induce necrotic cell death include PtrToxA, SnToxA, BcCFEM1, BcXYG1, and the NEP-like proteins in various necrotrophs ( Ciuffetti et al, 2010 ; Dallal Bashi et al, 2010 ; Arya et al, 2020 ).…”

Bioinformatics Analysis and Functional Characterization of the CFEM Proteins of Metarhizium anisopliae

“…In B. Cinerea , the CFEM protein Bcin07g03260 contains only one transmembrane domain, which differs from the G-protein-coupled receptor. When the Bcin07g03260 gene was knockout, the fungus would significantly reduce spore germination and bud tube elongation resulting decreased infection rate on leaves [ 44 ]. In this study, three CFEM proteins from M. anisopliae have multiple transmembrane regions (CFEM82 and CFEM91 with six transmembrane regions, CFEM80 with seven transmembrane regions), and one (CFEM83) has a single transmembrane region ( Figure 2 ).…”

Bioinformatics and Transcriptome Analysis of CFEM Proteins in Fusarium graminearum

“…Disruption of this gene results in decreased virulence and increased sensitivity to osmotic and cell wall stress, indicating that BcCFEM1 is required for virulence and plays a key role in stress resistance [ 25 ]. The recent work by Arya et al [ 26 ] illustrates a potential new role for a non-GPCR membrane CFEM in pathogenic fungi to control virulence in the fungus B. cinerea .…”

“…Target deletion of BcCFEM1 in Botrytis cinerea suggested that the gene contributes to conidial production and stress tolerance, and most importantly the gene disrupt mutants resulted in decreased virulence on French bean ( Phaseolus vulgaris ) leaves, indicated that it was involved in pathogenicity [ 25 ]. Recently, the study by Arya et al indicated that Bcin07g03260 (a non-GPCR membrane-bound CFEM protein) deletion mutants of B. cinerea also showed significantly reduced progression of a necrotic lesion on tomato ( Solanum lycopersicum ) leaves [ 26 ].…”