Wei Jiaping, Shen Yingzi, Dong Xiaoyun, Zhu Yajing, Cui Junmei, Li Hui, Zheng Guoqiang, Tian Haiyan, Wang Ying, Liu Zigang
State Key Laboratory of Aridland Crop Science, Lanzhou, China.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China.
Front Genet. 2022 Aug 17;13:968494. doi: 10.3389/fgene.2022.968494. eCollection 2022.
Winter rapeseed is the largest source of edible oil in China and is especially sensitive to low temperature, which causes tremendous agricultural yield reduction and economic losses. It is still unclear how DNA methylation regulates the formation of freezing tolerance in winter rapeseed under freezing stress. Therefore, in this study, the whole-genome DNA methylation map and transcriptome expression profiles of freezing-resistant cultivar NTS57 (NS) under freezing stress were obtained. The genome-wide methylation assay exhibited lower levels of methylation in gene-rich regions. DNA methylation was identified in three genomic sequence contexts including CG, CHG and CHH, of which CG contexts exhibited the highest methylation levels (66.8%), followed by CHG (28.6%) and CHH (9.5%). Higher levels of the methylation were found in upstream 2 k and downstream 2 k of gene regions, whereas lowest levels were in the gene body regions. In addition, 331, 437, and 1720 unique differentially methylated genes (DMGs) were identified in three genomic sequence contexts in 17NS under freezing stress compared to the control. Function enrichment analysis suggested that most of enriched DMGs were involved in plant hormones signal transduction, phenylpropanoid biosynthesis and protein processing pathways. Changes of genes expression in signal transduction pathways for cytokinin (CK) and jasmonic acid (JA) implied their involvement in freezing stress responses. Collectively, these results suggested a critical role of DNA methylation in their transcriptional regulation in winter rapeseed under freezing stress.
冬油菜是中国食用油的最大来源，且对低温特别敏感，低温会导致农业产量大幅下降和经济损失。目前仍不清楚DNA甲基化如何在冻害胁迫下调控冬油菜抗冻性的形成。因此，在本研究中，获得了抗冻品种NTS57（NS）在冻害胁迫下的全基因组DNA甲基化图谱和转录组表达谱。全基因组甲基化分析显示，基因丰富区域的甲基化水平较低。在包括CG、CHG和CHH在内的三种基因组序列背景中鉴定到了DNA甲基化，其中CG背景的甲基化水平最高（66.8%），其次是CHG（28.6%）和CHH（9.5%）。在基因区域的上游2k和下游2k中发现较高水平的甲基化，而在基因本体区域中甲基化水平最低。此外，与对照相比，在冻害胁迫下的17NS中，在三种基因组序列背景中分别鉴定到了331、437和1720个独特的差异甲基化基因（DMG）。功能富集分析表明，大多数富集的DMG参与植物激素信号转导、苯丙烷生物合成和蛋白质加工途径。细胞分裂素（CK）和茉莉酸（JA）信号转导途径中基因表达的变化表明它们参与了冻害胁迫反应。总的来说，这些结果表明DNA甲基化在冻害胁迫下冬油菜的转录调控中起关键作用。
