Sulfur metabolism-mediated fungal glutathione biosynthesis is essential for oxidative stress resistance and pathogenicity in the plant pathogenic fungus Fusarium graminearum

Abstract

ABSTRACTThe oxidative stress response is required for plant pathogens to endure host-derived oxidative stress during infection. Previously, we identified the eight transcription factors (TFs) involved in the oxidative stress response in the plant pathogenic fungus Fusarium graminearum and found that of these TFs, the deletion of FgbZIP007 caused hypersensitivity to oxidative stress. However, the underlying mechanisms of Fgbzip007 are not fully understood. Based on chromatin immunoprecipitation followed by sequencing (ChIP-seq) analysis, we found the regulons of Fgbzip007, and further genetic studies demonstrated that Fgbzip007 is a key regulator for sulfur assimilation. The deletion strains of FgbZIP007 and its regulons exhibited low level of glutathione biosynthesis, which led to characterize glutathione biosynthesis. Fgbzip007-mediated sulfur assimilation is required for glutathione biosynthesis, which is essential for oxidative stress resistance and pathogenicity in F. graminearum. Although the reduced resistance of glutathione-deficient mutants against oxidative stress was restored by overexpression of FCA7, encoding a core peroxidase, but not on pathogenicity, suggesting that glutathione in pathogenesis is independent of antioxidant properties. This study characterized the function of genes of glutathione biosynthesis, provides specific insight into how Fgbzip007 regulates pathogenesis in F. graminearum, and establishes a genetic framework for the molecular dissection of a TF Fgbzip007 with the integration of pathogen responses to oxidative stress.IMPORTANCEFusarium graminearum is a destructive fungal pathogen that causes Fusarium head blight (FHB) on a wide range of cereal crops. To control fungal diseases, it is essential to comprehend the pathogenic mechanisms that enable fungi to overcome host defenses during infection. Pathogens require an oxidative stress response to overcome host-derived oxidative stress. Here, we identify the underlying mechanisms of the Fgbzip007-mediated oxidative stress response in F. graminearum. ChIP-seq and subsequent genetic analyses revealed that the role of glutathione in pathogenesis is not dependent on antioxidant functions in F. graminearum. Altogether, this study establishes a comprehensive framework for the Fgbzip007 regulon on pathogenicity and oxidative stress responses, offering a new perspective on the role of glutathione in pathogenicity.

Keywords

• oxidative stress response
• sulfur metabolism
• glutathione
• γ-glutamylcysteine
• pathogenicity