FvMbp1-Swi6 complex regulates vegetative growth, stress tolerance, and virulence in Fusarium verticillioides

The mycotoxigenic fungus Fusarium verticillioides is a common pathogen of grain and medicine that contaminates the host with fumonisin B1 (FB1) mycotoxin, poses serious threats to human and animal health. Therefore, it is crucial to unravel the regulatory mechanisms of growth, and pathogenicity of F. verticillioides. Mbp1 is a component of the MluI cell cycle box binding factor complex and acts as an APSES-type transcription factor that regulates cell cycle progression. However, no information is available regarding its role in F. verticillioides. In this study, we demonstrate that FvMbp1 interacts with FvSwi6 that acts as the cell cycle transcription factor, to form the heteromeric transcription factor complexes in F. verticillioides. Our results show that ΔFvMbp1 and ΔFvSwi6 both cause a severe reduction of vegetative growth, conidiation, and increase tolerance to diverse environmental stresses. Moreover, ΔFvMbp1 and ΔFvSwi6 dramatically decrease the virulence of the pathogen on the stalk and ear of maize. Transcriptome profiling show that FvMbp1-Swi6 complex co-regulates the expression of genes associated with multiple stress responses. These results indicate the functional importance of the FvMbp1-Swi6 complex in the filamentous fungi F. verticillioides and reveal a potential target for the effective prevention and control of Fusarium diseases. Environmental Implication Fusarium verticillioides is a well-known fungal pathogen that causes severe disease in agriculture and medicine and contaminates the host with fumonisin B1 (FB1) mycotoxin, affects the yield and quality of grain worldwide and human health. In-depth explore of the regulatory mechanism of pathogenicity of Fusarium verticillioides is critical to our understanding of its pathobiology and developing antifungal drugs. This study shows that FvMbp1-Swi6 complex is essential for vegetative growth, conidiation and pathogenicity in Fusarium verticillioides, laying a theoretical foundation for preventively controlling mycotoxigenic fungus Fusarium verticillioides, and providing a potential target against pathogenic filamentous fungi.