S-adenosyl-L-homocysteine hydrolase FgSah1 is required for fungal development and virulence in <i>Fusarium graminearum</i>

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 <i>F. graminearum</i> by generating knockout and knockout-complemented strains of <i>FgSAH1</i>. We found that the FgSah1-GFP fusion protein was localized to the cytoplasm, and that deletion of <i>FgSAH1</i> 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 Δ<i>FgSah1</i> were seven- and ninefold higher than those in the wild-type strain, respectively. All of these defective phenotypes in Δ<i>FgSah1</i> mutants were rescued by target gene complementation. Taken together, these results demonstrate that <i>FgSah1</i> plays essential roles in methylation metabolism, fungal development, full virulence, multiple stress responses, lipid metabolism, and fungicide sensitivity in <i>F. graminearum</i>. To our knowledge, this is the first report on the systematic functional characterization of Sah1 in <i>F. graminearum</i>.