Role of SET domain proteins in histone modification and pathogenicity in F. graminearum. (A) Colony morphologies of wild-type PH-1 and seven individual SET domain deletion mutants grown on complete medium (CM) for 3 days. (B) Colony diameters of strains in A. Data are mean ± standard deviation (s.d.) (n = 3). Different letters indicate statistically significant differences (ANOVA, Tukey's multiple comparisons test, P < 0.05). (C) Western blot analysis of PH-1 and deletion mutants using antibodies against H3K4me3, H3K9me3, H3K27me3, H3K36me3, and H4K20me3. Anti-H3 served as a loading control. (D) Relative histone methylation levels, normalized to H3, quantified by ImageJ software. PH-1 band intensity was set to 1. (E) Symptoms on flowering wheat heads inoculated with conidial suspensions of the indicated strains, photographed at 15 days postinoculation (dpi). (F) Symptoms on wheat seedling stems inoculated with mycelial plugs from the indicated strains, photographed at 5 dpi.