A Novel Transcription Factor FgHOY1 Regulates OS1 Transcription to Mediate Fludioxonil Resistance in Fusarium graminearum.

Maize ear rot and stalk rot are mainly caused by Fusarium graminearum, which severely reduces maize yield. This pathogen produces DON mycotoxin to contaminate maize and threaten food safety. Fludioxonil exhibits high control efficacy against this fungus, while its regulatory mechanism remains poorly understood. This study elucidates the molecular mechanism of transcription factor FgHOY1 in response to fludioxonil. FgHOY1 regulates hyphal growth, conidiation, pathogenicity and DON biosynthesis, and ΔFgHOY1 strain shows markedly enhanced fludioxonil resistance. Fludioxonil treatment significantly downregulates the expression of FgHOY1. Meanwhile, FgHOY1 directly binds to the OS1 promoter to modulate transcription and regulates Hog1 phosphorylation. This study clarifies the FgHOY1-mediated regulatory pathway of fludioxonil resistance, providing a theoretical basis for exploring fungicide-resistance networks, disease green prevention and rational fungicide application.