Study On The Transcriptional Regulation Mechanism Of FvSwi4-FvSwi6 Complex Of Fusarium Verticillioides

Recent years,corn stalk rot caused by Fusarium verticillioides has become an important disease on corn,which not only effects the quality of corn but also produces polyketide my cotoxin fumonisin(FB1),which poses a serious threat onthe health of human and animals and food safety.Studies have shown that the methyltransferase FvSet2 and FvDim5 of Fusarium verticillioides are important for the fungal virulence and FB1 Biosynthesis.Here,we found that FvSet2 is responsible for catalyzing the trimethylation of lysine at position 36 of H3 histone(H3K36me3),while FvDim5 is responsible for catalyzing the trimethylation of lysine at position 9 of H3 histones(H3K9me3).Methyltransferase catalyzes the methylation modification of the corresponding histone residues,thereby regulating the growth and development of pathogens and the expression of disease-related genes,but the specific regulatory mechanism remains unknown.In eukaryotes,bHLH transcription factors have highly conserved domains and participate in many biological functions in cells,such as cell division,cell metabolism,and signal transduction.Our recent research found that bHLH transcription factors FvSwi4-FvSwi6 complex regulates the pathogenicity fungal development,and secondary metabolism of Fusarium verticillioides.In summary,we found that the FvSwi4-FvSwi6 complex interacts with FvSet2 and FvDim5 to regulate the methylation level of histones H3K36me3 and H3K9me3 respectively,thereby regulating the expression of genes related to pathogenicity,growth and lipid synthesis.The main findings are:1)Interaction between the complex FvSwi4-FvSwi6 and FvSet2 or FvDim5 were veritied via protein affinity capture,protein immunoprecipitation experiments(Co-IP),and yeast two hybridFurthermore we found that the intensity of methylated H3K36me3 and H3K9me3 in ?FvSwi4 and ?FvSwi6 were siginicantly lower compared to wild-type Fv102,indicating that the transcription factor FvSwi4-FvSwi6 complex was involved in the process of H3K36me3 and H3K9me3 modification.Combined with the previous experimental results,the pathogenicity of ?FvSwi4 and ?FvSwi6 were significantly reduced.It is proposed that FvSwi4 and FvSwi6 played an important role in the modification process of H3K36me3 and H3K9me3,thereby regulating the transcriptional expression of disease-related genes.2)FvSwi4 and FvSwi6 are a type of bHLH transcription factors,which can directly bind to the promoter of targeted genes to regulate the transcriptional expression.Through the Chromatin immunoprecipitation sequencing(ChIP-Seq)experiment,the genes directly regulated by the transcription factor FvSwi4 were studied,including cell division,lipid synthesis,secondary metabolism etc.The FvSwi4 of possible motif sequences were analyzed,and key genes were selected for EMSA experiments.The results showed that the protein FvSwi6 binds to the promoter regions of genes FvDgal,FvMcm6 and FvRad26.In conclusion,the transcription factors FvSwi4 and FvSwi6 in Fusarium verticillioides can directly regulate the transcriptional expression of genes in combination with the gene promoter region,and can also indirectly affect gene expression by regulating the methylation of histones H3K9me3 and H3K36me3.Then precisely regulate the downstream gene transcription expression.