FgMsn2 negatively regulates general stress responses and autophagy in Fusarium graminearum

Abstract Effective adaptation to diverse stressors is essential for fungal survival and pathogenicity. The mechanisms underlying general stress responses in Fusarium graminearum , the pathogen responsible for Fusarium head blight (FHB) in cereal crops, remain unclear. In this study, we identify FgMsn2 as a negative regulator of general stress responses in F. graminearum . Deletion of FgMsn2 leads to resistance of F. graminearum to oxidative, osmotic, and cell wall stresses. Mechanically, FgMsn2 represses autophagy by inhibiting the expression of autophagy-related genes, including FgATG8 , and stress conditions trigger the cytoplasmic localization of FgMsn2. Additionally, the Δ FgMsn2 mutants show significantly reduced virulence on wheat, indicating the critical role of FgMsn2 in pathogenicity. These findings uncover a unique regulatory function of FgMsn2, which contrasts with its positive role in stress responses reported in other fungi, and provide valuable insights for developing novel strategies to manage FHB.