Forkhead Box Proteins Modulate Development, Pathogenicity, and Fungicide Sensitivity in Transcription-Dependent and -Independent Ways.

The forkhead box (FOX) proteins are a conserved family of eukaryotic transcription factors with diverse biological functions. However, the role and evolution of FOX proteins in filamentous fungi have not been fully explored. In this study, we identified and characterized four FOX transcription factors and two forkhead-associated domain (FHA) proteins in the fungal pathogen , the causative agent of head blight on cereal crops. Our results reveal that the FOX transcription factors FgHcm1 and FgFoxO4, along with the FHA domain-containing protein FgFha1, are essential for the full virulence of . These proteins regulate fungal penetration of wheat spikelets by modulating the expression of penetration-related genes. In addition, FgHcm1, FgFoxO4, and FgFha1 influence both asexual and sexual reproduction. Deletion of these genes also confers increased sensitivity to various stressors including fungicides. Notably, the gene deletion mutants Δ, Δ, and Δ exhibited heightened sensitivity to tebuconazole, and these proteins regulate the inducible expression of the gene in response to tebuconazole treatment. Furthermore, Δ mutants showed increased sensitivity to rapamycin with impaired autophagic responses. This study represents the first comprehensive analysis of FOX and FHA proteins in a filamentous fungal pathogen, highlighting their critical roles in virulence, stress tolerance, and fungicide resistance in .