Histone H3K4 methylation regulates hyphal growth, secondary metabolism and multiple stress responses in F usarium graminearum

Summary Histone H 3 lysine 4 methylation ( H3K4me ) is generally associated with actively transcribed genes in a variety of eukaryotes. The function of H3K 4me in phytopathogenic fungi remains unclear. Here, we report that F g S et1 is predominantly responsible for mono‐, di‐ and trimethylation of H3K 4 in F usarium graminearum . The FgSET 1 deletion mutant (Δ FgSet 1) was crippled in hyphal growth and virulence. H3 K 4me is required for the active transcription of genes involved in deoxynivalenol and aurofusarin biosyntheses. Unexpectedly, FgSet 1 plays an important role in the response of F . graminearum to cell wall‐damaging agents via negatively regulating phosphorylation of FgMgv 1, a core kinase in the cell wall integrity pathway. In addition, Δ FgSet 1 exhibited increased resistance to the transcription elongation inhibitor mycophenolic acid. Yeast two‐hybrid assays showed that FgSet 1 physically interacts with multiple proteins including FgBre 2, FgSpp 1 and FgSwd 2. FgBre 2 further interacts with FgSdc 1. Western blotting analyses showed that FgBre 2 and FgSdc 1 are associated with H3K4me . Both proteins are also involved in regulating deoxynivalenol biosynthesis and in responses to mycophenolic acid and cell wall‐damaging agents. Taken together, these data indicate that H 3 K 4me plays critical roles not only in regulation of fungal growth and secondary metabolism but also in multiple stress responses in F . graminearum .