ABSTRACT

The S-adenosyl-L-homocysteine hydrolase (Sah1) plays a crucial role in methylation and lipid metabolism in yeast and mammals, yet its function remains elusive in filamentous fungi. In this study, we characterized Sah1 in the phytopathogenic fungus F. graminearum by generating knockout and knockout-complemented strains of FgSAH1. We found that the FgSah1-GFP fusion protein was localized to the cytoplasm, and that deletion of FgSAH1 resulted in defects in vegetative growth, asexual and sexual reproduction, stress responses, virulence, lipid metabolism, and tolerance against fungicides. Moreover, the accumulations of S-adenosyl-L-homocysteine (AdoHcy) and S-adenosyl-L-methionine (AdoMet) (the methyl group donor in most methyl transfer reactions) in ΔFgSah1 were seven- and ninefold higher than those in the wild-type strain, respectively. All of these defective phenotypes in ΔFgSah1 mutants were rescued by target gene complementation. Taken together, these results demonstrate that FgSah1 plays essential roles in methylation metabolism, fungal development, full virulence, multiple stress responses, lipid metabolism, and fungicide sensitivity in F. graminearum. To our knowledge, this is the first report on the systematic functional characterization of Sah1 in F. graminearum.

摘要

S-腺苷-L-同型半胱氨酸水解酶（Sah1）在酵母和哺乳动物的甲基化和脂质代谢中起着至关重要的作用，但其功能在丝状真菌中仍然难以捉摸。在这项研究中，我们通过产生 FgSAH1 的敲除和敲除互补菌株来表征植物病原真菌禾谷镰刀菌中的Sah1。我们发现 FgSah1-GFP 融合蛋白定位于细胞质，而FgSAH1的缺失导致营养生长、无性和有性生殖、应激反应、毒力、脂质代谢和对杀菌剂耐受性的缺陷。此外，在 ΔFgSah1分别比野生型菌株高 7 倍和 9 倍。ΔFgSah1突变体中的所有这些缺陷表型都通过靶基因互补来挽救。总之，这些结果表明FgSah1在禾谷镰刀菌的甲基化代谢、真菌发育、全毒力、多重应激反应、脂质代谢和杀菌剂敏感性中起重要作用。据我们所知，这是关于禾谷镰刀菌 Sah1 系统功能表征的第一份报告。