Changes in the epigenome and transcriptome of rice in response to Magnaporthe oryzae infection

DNA methylation participates in regulating the expression of coding and non-coding regions in plants. To investigate the association between DNA methylation and pathogen infection, we used whole-genome bisulfite sequencing to survey temporal DNA methylation changes in rice after infection with the rice blast fungus Magnaporthe oryzae. In contrast to previous findings in Arabidopsis, global DNA methylation levels in rice increased slightly after rice blast infection. We identified over 38,000 differentially methylated regions (DMRs), and hypermethylated DMRs far outnumbered hypomethylated DMRs. Most DMRs were located in transposable element regions. Using transcriptome analysis, we identified 8830 differentially expressed genes (DEGs) after 1, 3, and 5 days of infection. Over one-third of DEGs, most of which were CHH-type DMRs, were associated with DMRs. Functional analysis of the CHH DMR-DEGs indicated their involvement in many important biological processes, including cell communication and response to external stimulus. The transcription of many NBS-LRR family genes was affected by changes in DNA methylation, suggesting that DNA methylation plays essential roles in the response of rice to M. oryzae infection. More broadly, the DNA methylation analysis presented here sheds light on epigenomic involvement in plant defense against fungal pathogens.