Studies On The Positive Regulation Of H3K27me3 In Plant Gene Transcription

H3K27me3,It's a conditional inhibitory modification.Many researches show that H3K27me3 plays an important role in regulating gene silencing in the euchromatin region.It can serve as a dynamic epigenetic signal for a large number of development-related genes.Studies of animals and plants have found common results,H3K27me3 functioning as a repressive mark in regulating gene expression for inducible gene.Unexpectedly,H3K27me3 has been reported to be associated with active transcription of a subset of highly expressed genes in mammals.However,active roles of H3K27me3 in plant gene are still elusive.in this study,Leaf and root of maize B73,rice and leaf of Arabidopsis thaliana were used as research materials?Mainly through ChIP-seq,RNA-seq and Bisulfite sequencing(bs-seq)and other Omics related technologies,the distribution of H3K27me3 in whole genome and its relationship with gene expression were systematically analyzed.The relevant research results are helpful to better understand the regulation function at the whole genome level of H3K27me3 in plant genome.The main research results as follows:1)With the reported similar results,genes that are not expressed or expressed at low levels tended to have the highest levels of H3K27me3.But according to the findings of this study,Only the most highly expressed genes exhibited substantial enrichment for H3K27me3.This suggests that the modification may also be associated with highly expressed genes.2)Mesophyll cell and Bundle Sheath cell related ChIP-seq and RNA-seq data analysis results show that 242 and 93 highly expressed genes with high enrichment of H3K27me3 in Bundle Sheath cell and Mesophyll cell,respectively.Among them,134 genes are not affected by cell type,which are genes with high expression and H3K27me3 modification.3)In addition,in the maize root,rice leaf and root and arabidopsis leaf,the high expression was also found at the same time with high H3K27me3 enrichment gene,suggesting that the phenomenon is widespread in the plant gene.4)To confirm the activation regulation function of H3K27me3 to some high expressed genes,We further analyzed the relationship between H3K27me3 and gene expression in Mez mutant(mez2-m1,mez3 m4 and mez2/3).We focus on the analysis of genes in the three mutants that have the same variation trend of expression level and H3K27me3 enrichment,Compared with the wild type,The results showed that 11,2,19 gene both the enrichment of H3K27me3 and expression level was decreased in the three mutants,respectively,further indicating that H3K27me3 had a positive regulatory effect on the expression of these genes.In addition,compared with wild type,The H3K27me3 modification level of the total differentially expressed gene in mez2-ml and mez2/3 mutants was significantly decreased,but the H3K27me3 modification level of the up-regulated gene and down-regulated gene in mez3-m4 mutants was increased.This indicates that the regulating transcription mechanism of H3K27me3 modification in different mutant genes is different.5)To preliminarily elucidate the possible mechanism of positive regulation of H3K27me3 of genes expression,we analyzed H3K27me3 and DNA methylation and histone modification other correlation.The results show that H3K27me3 modification coexist with several activated histone modifications on some highly expressed genes of maize.At the same time,we found that H3K27me3 modification was negatively correlated with DNA methylation.In this way,the modification and DNA methylation or other chromatin marks synergistic effect,actively regulate gene expression.However,there is also evidence that H3K27me3 alone regulates the transcriptional activity of highly expressed genes in maize.In summary,this study preliminarily reported the unexpected association with the positive regulatory effect of H3K27me3 and expression with high expression levels in some plants,and analyzed the possible mechanism of regulatory,thus enriching the regulatory functions of H3K27me3 in plants.