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

Abstract

The hemibiotrophic ascomycete fungus Colletotrichum gloeosporioides 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 C. gloeosporioides 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 CgEnd3 resulted in severe defects in endocytosis. C. gloeosporioides infects its host through a specialized structure called appressorium, and ΔCgEnd3 showed deficient appressorium formation, melanization, turgor pressure accumulation, penetration ability of appressorium, cellophane membrane penetration, and pathogenicity. CgEnd3 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 CgEnd3 changed the responses to cell-wall integrity agents and fungicide fludioxonil. However, CgEnd3 regulated appressorium formation and endocytosis in a calcium signaling-independent manner. Taken together, these results demonstrate that CgEnd3 plays pleiotropic roles in endocytosis, calcium signaling, cell-wall integrity, appressorium formation, penetration, and pathogenicity in C. gloeosporioides, and it suggests that CgEnd3 or endocytosis-related genes function as promising antifungal targets.

Mucin Msb2 cooperates with the transmembrane protein Sho1 in various plant surface signal sensing and pathogenic processes in the poplar anthracnose fungus Colletotrichum gloeosporioides

“…In the Δ CgMsb2Sho1 double mutant, very few appressoria formed, and those that did form showed defects in both appressorium penetration and invasive growth (Figure 2a–d ). Reactive oxygen species ( ROS) play an essential role in plant defence responses, and we previously revealed that the small G protein CgCdc42 and the endocytosis‐related protein CgEnd3 are also required for invasive growth, while exogenous treatment with the ROS inhibitor diphenyleneiodonium chloride (DPI) restored the defect efficiently (Wang et al, 2021a ; Wang et al, 2018 ). Therefore, DPI was added during conidial germination at a final concentration of 5 µM.…”

NADPH Oxidases Play a Role in Pathogenicity via the Regulation of F-Actin Organization in Colletotrichum gloeosporioides

“…The results indicated the change in the cell wall composition of Δ CgnoxB , Δ CgnoxR , and Δ CgnoxAnoxB . Chitin synthases participate in the biosynthesis of chitin and are involved in the cell wall integrity of filamentous fungi ( Yang and Zhang, 2019 ; Wang et al., 2021 ). Therefore, the expression changes of chitin synthases in the mutants were investigated.…”

“…Therefore, the expression changes of chitin synthases in the mutants were investigated. There were seven chitin synthases ( CgCHS ) identified in C. gloeosporioides ( Wang et al., 2021 ). The qRT-PCR assay ( Figure 8C ) showed that in Δ CgnoxA , the relative expression levels of CgCHS2 , CgCHS3 , CgCHS4 , CgCHS6 , and CgCHS7 increased over twofold; meanwhile, all seven genes were upregulated in Δ CgnoxB .…”

Cyclocarya paliurus Reprograms the Flavonoid Biosynthesis Pathway Against Colletotrichum fructicola

“…Appressorium development is essential to penetrate the host. To explore the underlying mode of action of CPF’s effect on appressorium formation, we tested four genes reported to participate in the regulation of appressorium formation in Colletotrichum species ( Miyara et al, 2010 ; Lin et al, 2012 ; Dubey et al, 2016 ; Wang et al, 2021 ). The expression of these appressorium formation-related genes was significantly suppressed by CPF treatment ( Figure 7H ).…”