Novel insights into the unique characterization of N6-methyladenosine RNA modification and regulating cold tolerance in winter Brassica rapa.

N6-methyladenosine (m6A) is an mRNA modification considered essential in plants, and is a key player in gene regulation at the transcriptional and translational levels. In present study, we mapped Brassica rapa's whole transcriptome m6A profile under low-temperature stress in different cold tolerant varieties to elucidate the m6A methylation pattern. The distribution of m6A modifications changed significantly under low temperature stress. More 5'UTR m6A was deposited in strong cold-resistant varieties and responded positively to cold resistance by regulating mRNA expression abundance. The increase in m6A abundance was correlated with the increase in mRNA abundance after low temperature stress. ZAT12 might positively regulate its mRNA expression through m6A methylation. MYBC1 might be a negative regulator to cope with low-temperature stress. The hypothetical protein was involved in starch and sucrose metabolic pathways, and that the Low-quality protein was involved in the regulation of DNA binding, DNA-binding, transcription factor activity, and proline biosynthetic processes and leaf senescence pathways. In addition, a number of m6A methyltransferases and m6A demethylases play crucial roles in response to cold stress. These results revealed the critical role of m6A -modified genes under cold stress and provide new insights into the study of cold resistance in winter Brassica rapa.