CgEnd3 Regulates Endocytosis, Appressorium Formation, and Virulence in the Poplar Anthracnose Fungus .

The hemibiotrophic ascomycete fungus is the causal agent of anthracnose on numerous plants, and it causes considerable economic losses worldwide. Endocytosis is an essential cellular process in eukaryotic cells, but its roles in remain unknown. In our study, we identified an endocytosis-related protein, CgEnd3, and knocked it out via polyethylene glycol (PEG)-mediated protoplast transformation. The lack of resulted in severe defects in endocytosis. infects its host through a specialized structure called appressorium, and Δ showed deficient appressorium formation, melanization, turgor pressure accumulation, penetration ability of appressorium, cellophane membrane penetration, and pathogenicity. also affected oxidant adaptation and the expression of core effectors during the early stage of infection. CgEnd3 contains one EF hand domain and four calcium ion-binding sites, and it is involved in calcium signaling. A lack of changed the responses to cell-wall integrity agents and fungicide fludioxonil. However, regulated appressorium formation and endocytosis in a calcium signaling-independent manner. Taken together, these results demonstrate that plays pleiotropic roles in endocytosis, calcium signaling, cell-wall integrity, appressorium formation, penetration, and pathogenicity in , and it suggests that or endocytosis-related genes function as promising antifungal targets.