Functional Characterization Of Histone H3 Methylation Pattern In Development And Pathogenicity Of Magnaporthe Oryzae

The rice blast, a major epidemic of rice, caused by the fungus Magnaporthe oryzae, is responsible for destructive losses in rice and wheat production globally. Epigenetic inheritance is found to play more and more important roles in gene expression, however few is known about the epigenetic function on the rice blast fungus Magnaporthe oryzae. H3 methylation modifications can be dynamically regulated by two classes of enzymes, histone methyltransferases and histone demethylases. H3 methylation level on defined residue can affect the chromatin structure. In general, H3K4 hypermethylation and H3K9 hypomethylation are marks of euchromatin which is transcriptional active, whereas heterochromatin, a condensed and gene silencing structure, is usually H3K9 methylation riched and H3K4 methylation lessened.JmjC (Jumonji C) domain-containing proteins are supposed to be histone oxidative demethylases utilizing iron (II) and 2-oxoglutarate as cofactors. Here we focused on 7 putative JmjC domain-containing proteins and 6 other histone methyltransferases and histone demethylases homolog genes, and studied how H3 methylation influences fungal development and pathogenicity by gene knockout.We found that the deletion of MoLID2 (JMD5), MoRPH1 (JMD6), MoCUL4, MoCLR4, MoSETl and MoHP1B in M. oryzae led to serious defects in fungal unsexual development. The virulence of ΔMolid2, ΔMorph1, ΔMoclr4, ΔMolsd1 and ΔMoset1 on rice and barley were weakened. Western blotting results of 5 mutants (ΔMolid2, ΔMorphl,ΔMoclr4, ΔMocul4, and ΔMoset1) revealed that the deletion of MoLID2 increased H31ys4 (H3K4) and H31ys9 (H3K9) methylation level in M. oryzae. For MoRph1, the methylation of H31ys36 (H3K36) is intensified in ΔMorph1. Significantly, the dimethylation of H3K4 was blocked, and mono- and trimethylation H3K4 were also depressed in ΔMoset1. And, ΔMoclr4 and ΔMocul4 performed a lower level of H3K4 methylation and H3K9me3. Swi6 in S. pombe, as a heterochromatin protein, could interact with H3K9me2 and H3K9me3 contributing to the assembly of heterochromatin. MoHp1B was the homologue of Swi6 in M. oryzae. By observing the location of MoHp1B-GFP, we found that compared to 2-4 spots of MoHp1B-GFP distributed in the wild type, a raised number of MoHp1B-GFP spots in ΔMolid.2 was observed. More seriously, status of MoHp1B-GFP distribution in ΔMosetl was diffused, and this was extremely likely to because of spreading of heterochromation in genome wide with a negligible level of H3K4 methylation. Overall, in M. oryzae, H3 methylation patterns modified by histone methyltransferases and demethylases regulated chromatin construction having an effect on gene activity in large-scale thus affecting fungal development and pathogenicity.