Autophagy is a conserved degradation process that maintains intracellular homeostasis to ensure normal cell differentiation and development in eukaryotes. is one of the key molecular components of the autophagy pathway. In this study, we identified and characterized, a homologue of (yeast) in the necrotrophic plant pathogen Yeast complementation experiments demonstrated that can functionally complement the defects of the yeast null mutant. Direct physical interaction between BcAtg8 and BcAtg4 was detected in the yeast two-hybrid system. Subcellular localization assays showed that green fluorescent protein-tagged BcAtg8 (GFP-BcAtg8) localized in the cytoplasm as preautophagosomal structures (PAS) under general conditions but mainly accumulated in the lumen of vacuoles in the case of autophagy induction. Deletion of (Δ mutant) blocked autophagy and significantly impaired mycelial growth, conidiation, sclerotial formation, and virulence. In addition, the conidia of the Δ mutant contained fewer lipid droplets (LDs), and quantitative real-time PCR (qRT-PCR) assays revealed that the basal expression levels of the LD metabolism-related genes in the mutant were significantly different from those in the wild-type (WT) strain. All of these phenotypic defects were restored by gene complementation. These results indicate that is essential for autophagy to regulate fungal development, pathogenesis, and lipid metabolism in The gray mold fungus is an economically important plant pathogen with a broad host range. Although there are fungicides for its control, many classes of fungicides have failed due to its genetic plasticity. Exploring the fundamental biology of can provide the theoretical basis for sustainable and long-term disease management. Autophagy is an intracellular process for degradation and recycling of cytosolic materials in eukaryotes and is now known to be vital for fungal life. Here, we report studies of the biological role of the autophagy gene in The results suggest that autophagy plays a crucial role in vegetative differentiation and virulence of .

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In eukaryotes, the ubiquitin-like (UBL) protein-activating enzymes play a crucial role in autophagy process, however, it is poorly characterized in filamentous fungi. Here, we investigated the functions of two UBL activating enzymes, BcAtg3 (E2) and BcAtg7 (E1) in the plant pathogenic fungus Botrytis cinerea. The physical interaction of BcAtg3 with BcAtg7 was demonstrated by yeast two-hybrid system. Subcellular localization assays showed that BcAtg3 diffused in cytoplasm, and BcAtg7 localized in cytoplasm as pre-autophagosomal structures (PAS). Target gene deletion experiments revealed that both BcATG3 and BcATG7 are essential for autophagy pathway. Notably, the single deletion mutant of BcATG3 and BcATG7 displayed similar biological phenotypes, including the defects in mycelial growth, conidiation and sclerotial formation. Infection tests showed that both BcATG3 and BcATG7 were required for full virulence of B. cinerea. All of these defective phenotypes were rescued by gene complementation. These results indicate that BcATG3 and BcATG7 are necessary for autophagy to regulate fungal development and pathogenesis in B. cinerea.

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