DNA damage drives DNA methylation generation and evolution in plant

In mammals, it has long been hypothesized that DNA damage could induce DNA hypermethylation and contribute to carcinogenesis. However, the evidence that DNA damage is a cause of genome hypermethylation is still insufficient. Here, we demonstrated that, in plant, DNA damage can induce DNA hypermethylation in the context of symmetric CG, CHG as well as asymmetric CHH. Mechanically, DNA damage regulates the DREAM complex, to induce CG and CHG methylation. Moreover, DNA damage also utilizes the RdDM pathway to induce CHH hypermethylation. The hypermethylation sites of CG and CHG resulting from DNA damage tend to localize to gene body, and a large proportion of them are de nove generated. In contrast, the hypermethylation sites of CHH induced by DNA damage were mainly concentrated in the centromere and pre-centromere regions, and most of them are amplification of existing CHH methylation. Importantly, withdrawing the DNA damage or blocking the DNA damage response signal could fully abolish the CHH hypermethylation, partially rescue the CHG hypermethylation, but rarely recover the CG hypermethylation, indicating that DNA damage leaves symmetric DNA methylation as genetic imprinting. Collectively, our results suggest that DNA damage drives DNA methylation generation and evolution in plants. Overall design: whole genome bisulfite sequencing of seedlings total DNA from different arabidopsis thaliana samples cultured for 14 days