Phosphatidylcholine (PC) is an important membrane component of the eukaryotic cell. In yeast fungi, two phospholipid methyltransferases catalyze consecutive steps of methylation in the formation of phosphatidylcholine from phosphatidylethanolamine. However, roles of phospholipid methyltransferases in filamentous fungi remains less investigated. We report here the characterization of two genes, choA and choC, that putatively encoded phospholipid methyltransferases in the taxol-producing fungus Pestalotiopsis microspora. Deletion of choC resulted in defects in PC production, vegetative growth and development of asexual structure. The mutant strains exhibited multiple morphological abnormalities, e.g. swollen hyphal tips and enhanced hyphal branching, and even mycelial autolysis. Some novel roles for the genes were also revealed, for instance, the deletion of either choC or choA impaired the development of pycnidia and conidia, the cell wall integrity. The mutant strains displayed a hypersensitivity to stress conditions, e.g. osmotic stress, cold and metal ions. The osmotic hypersensitivity indicates a crosstalk of PC pathways to other signaling pathways, such as the HOG pathway. Still more, choA, but not choC, was required for the production of secondary metabolites, e.g. pestalotiollide B, suggesting distinct roles of the two genes. This work would contribute to better understanding the function of phospholipid methyltransferases in fungi.

磷脂酰胆碱（PC）是真核细胞的重要膜成分。在酵母真菌中，两种磷脂甲基转移酶催化从磷脂酰乙醇胺形成磷脂酰胆碱的甲基化连续步骤。但是，磷脂甲基转移酶在丝状真菌中的作用仍需研究。我们在这里报告了两个基因choA和choC的表征，这两个基因在紫杉醇生产真菌Pestalotiopsis microspora中可能编码了磷脂甲基转移酶。删除choC会导致PC生产，营养生长和无性结构发育的缺陷。突变菌株表现出多种形态异常，例如菌丝尖端肿胀，菌丝分支增强，甚至菌丝自溶。还揭示了该基因的一些新作用，例如，choC或choA的缺失削弱了pycnidia和分生孢子的发展，细胞壁的完整性。突变菌株对胁迫条件，例如渗透胁迫，冷离子和金属离子表现出超敏性。渗透性超敏反应表明PC通路与其他信号通路（如HOG通路）发生串扰。再者，生产次级代谢产物（例如）需要choA而不是choC。。杀虫卵B，表明这两个基因的不同作用。这项工作将有助于更好地了解真菌中磷脂甲基转移酶的功能。