Differentiation of genome-wide DNA methylation between japonica and indica rice

Abstract

Rice (Oryza sativa L.) subspecies japonica and indica show distinct morphological and genetic differentiation. However, the differences in the genome-wide DNA methylation and its effects on gene expression and metabolic levels between japonica and indica rice remain unclear. In this study, we investigated the genome-wide DNA methylation, transcriptomes and metabolomes of 12 representative japonica and indica rice accessions, to reveal the differentiation between rice subspecies. We detected 83 327 differentially methylated regions (DMRs) and 14 903 DMR-associated genes between two subspecies. Indica rice showed significantly lower levels of the CG, CHG, and CHH methylation compared with japonica rice. Subsequently, we identified 5596 differentially expressed genes between the two subspecies, predominantly enriched in pathways related to carbohydrate and amino acid metabolism. By integrating DNA methylation with transcriptomic data, a significant correlation was established between methylation patterns and the expression level of key agronomic genes in rice. Furthermore, multi-omics analyses reveal that carbohydrate metabolism pathways, especially the tricarboxylic acid (TCA) cycle metabolites, are remarkable differentiation between rice subspecies. These results provide a foundation for future studies in rice domestication and genetic improvement.