The transcription factor UvCreA regulates ustilaginoidin synthesis and pathogenicity in Ustilaginoidea virens

Ustilaginoidea virens produces several types of mycotoxins, including ustilaginoidins, during infection. The transcription factor CreA plays a central role in carbon catabolite repression, coordinating carbon source utilization during fungal growth, development, and host infection. However, knowledge is limited regarding the specific functions and molecular mechanisms by which CreA regulates mycotoxin biosynthesis and pathogenicity. In this study, we found that the wild-type U. virens strain exhibited significantly different ustilaginoidin-producing capacities under distinct carbon sources. The UvCreA gene knockout mutants exhibited slower mycelial growth, reduced pathogenicity and ustilaginoidin production, but produced significantly more conidiospores than the wild type. Consistently, expression of ustilaginoidin biosynthetic genes was significantly downregulated in the UvCreA mutant. Moreover, yeast one-hybrid and electrophoretic mobility shift assays confirmed that UvCreA binds to the promoters of the polyketide synthase gene UvPKS1 and the methyltransferase gene UgsJ . ChIP-qPCR showed significant enrichment in promoter regions of UvPKS1 and UgsJ . These findings indicate that UvCreA not only controls ustilaginoidin biosynthesis through directly binding the Ugs gene promoters, but also positively regulates mycelial growth and pathogenicity in U. virens . Therefore, this study provides theoretical insights into the regulatory mechanism of mycotoxin biosynthesis in phytopathogenic fungi.