PMT family mannosyltransferase-mediated protein O-mannosylation is required for the development and pathogenicity of Colletotrichum graminicola

Abstract Protein O-mannosylation in the endoplasmic reticulum (ER) plays a crucial regulatory role in the development and virulence of many phytopathogenic fungi. However, the corresponding biological function and underlying regulatory mechanism mediated by this process in Colletotrichum graminicola , causing the anthracnose disease of maize ( Zea mays ), is unclear. The protein O-mannosyltransferase (PMT) family-mediated protein O-mannosylation is absent in plants, which may provide good targets for developing safe antifungal agents. In the present study, we identified three PMT family mannosyltransferases: CgPMT1, CgPMT2, and CgPMT4 in C. graminicola. The subcellular localization analyses proved that these proteins were located in the ER as previously reported. qRT-PCR results showed that the expression levels of all the three genes were highest in the conidia compared with other developmental stages. Gene knockout analysis demonstrated that the PMT-mediated protein O-mannosylation was essential for the vegetative growth, conidiation, appressorium formation, and pathogenicity of C. graminicola . Immunoprecipitation-Mass Spectrometry (IP-MS) analysis showed that the potential interaction proteins of these CgPMTs were mainly enriched in the pathways of sphingolipid metabolism, autophagy, glycosylphosphatidylinositol (GPI)-anchor modification, and endocytosis. These findings enhanced our understanding of the functions of protein O-mannosylation and provide effective molecular targets for maize disease prevention and control.