The phenol-2-monooxygenase FgPhm1 regulates DON synthesis, pathogenicity and environmental stress response in...

Fusarium graminearum is a devastating plant pathogenic fungus that produces mycotoxins and is the predominant pathogen causing Fusarium head blight. Phenol-2-monooxygenase is an oxidoreductase that is responsible for the conversion of phenol to catechol. However, the role of phenol-2-monooxygenase in filamentous fungi remains unclear. This study showed that the deletion of the phenol-2-monooxygenase gene FgPHM1 leads to defects in vegetative growth, conidia production, sexual reproduction, and plant infection. FgPhm1 is localized to the nucleoplasm and regulates DON production. In addition, FgPhm1 is required for the formation of toxisomes and regulates the expression of TRI genes. RNA-seq analysis showed that the differentially expressed genes in the mutant were enriched in secondary metabolite biosynthesis, carbon metabolism, and pyruvate metabolism. Interestingly, the FgPHM1 deletion mutant was tolerant to phenol stress, whereas it was sensitive to catechol and oxidative stress. FgPhm1 is required for reactive oxygen species production in F. graminearum, and the expression level of FgPHM1 gene is induced by H₂O₂. Moreover, FgPhm1 regulates autophagy in F. graminearum under nitrogen starvation or rapamycin treatment in F. graminearum. Taken together, this study demonstrated that FgPhm1 is essential for the development and production of DON and plays important roles in the pathogenicity and stress response of F. graminearum, and RNA-seq revealed that FgPhm1 was involved in the biosynthesis of secondary metabolites in F. graminearum.