Synergistic regulation of sugar metabolism by histone acetyltransferases FgSas3 and FgRtt109 in a mycotoxin-producing fungal pathogen

Fusarium head blight (FHB), primarily caused by Fusarium graminearum, is a globally destructive fungal disease that reduces cereal crop yields and threatens food safety due to mycotoxin contamination. In this study, we systematically analyzed histone acetyltransferases in F. graminearum and identified two of them, FgSAS3 and FgRTT109, with overlapping functions. The Fgsas3 Fgrtt109 double deletion mutant showed severely impaired vegetative growth, conidiation, sexual development, pathogenicity, and mycotoxin production. Transcriptome and metabolome analyses revealed that the double mutant had major alterations in carbohydrate metabolism, particularly in the conversion of disaccharides to monosaccharides. This was demonstrated by decreased disaccharide concentrations, increased monosaccharide levels, and enhanced growth of the double mutant on media supplemented with disaccharides. Taken together, our findings demonstrate that FgSAS3 and FgRTT109 synergistically regulate carbohydrate metabolism, which in turn modulates fungal development, infection, and mycotoxin biosynthesis.