Genomic variations combined with epigenetic modifications rewire open chromatin in rice

Abstract

Cis-regulatory elements (CREs) fine-tune gene transcription in eukaryotes. CREs with sequence variations play vital roles in driving plant or crop domestication. However, how global sequence and structural variations (SVs) are responsible for multilevel changes between indica and japonica rice (Oryza sativa) is still not fully elucidated. To address this, we conducted multiomic studies using MNase hypersensitivity sequencing (MH-seq) in combination with RNA sequencing (RNA-seq), chromatin immunoprecipitation sequencing (ChIP-seq), and bisulfite sequencing (BS-seq) between the japonica rice variety Nipponbare (NIP) and indica rice variety 93-11. We found that differential MNase hypersensitive sites (MHSs) exhibited some distinct intrinsic genomic sequence features between NIP and 93-11. Notably, through MHS-genome-wide association studies (GWAS) integration, we found that key sequence variations may be associated with differences of agronomic traits between NIP and 93-11, which is partly achieved by MHSs harboring CREs. In addition, SV-derived differential MHSs caused by transposable element (TE) insertion, especially by noncommon TEs among rice varieties, were associated with genes with distinct functions, indicating that TE-driven gene neo- or subfunctionalization is mediated by changes of chromatin openness. This study thus provides insights into how sequence and genomic SVs control agronomic traits of NIP and 93-11; it also provides genome-editing targets for molecular breeding aiming at improving favorable agronomic properties.