College of Tea and Food Sciences, Wuyi University, Tea Engineering Research Center of Fujian Higher Education, Tea Science Research Institute of Wuyi University, Wuyishan 354300, China; Key Laboratory of Tea Science, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350007, China.
Key Laboratory of Tea Science, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350007, China.
Food Res Int. 2024 Oct;194:114939. doi: 10.1016/j.foodres.2024.114939. Epub 2024 Aug 18.
Understanding the epigenetic responses to mechanical wounding stress during the postharvest processing of oolong tea provides insight into the reprogramming of the tea genome and its impact on tea quality. Here, we characterized the 5mC DNA methylation and chromatin accessibility landscapes of tea leaves subjected to mechanical wounding stress during the postharvest processing of oolong tea. Analysis of the differentially methylated regions and preferentially accessible promoters revealed many overrepresented TF-binding motifs, highlighting sets of TFs that are likely important for the quality of oolong tea. Within these sets, we constructed a chromatin accessibility-mediated gene regulatory network specific to mechanical wounding stress. In combination with the results of the TF-centred yeast one-hybrid assay, we identified potential binding sites of CsMYC2 and constructed a gene regulatory network centred on CsMYC2, clarifying the potential regulatory role of CsMYC2 in the postharvest processing of oolong tea. Interestingly, highly accessible chromatin and hypomethylated cytosine were found to coexist in the promoter region of the indole biosynthesis gene (tryptophan synthase β-subunit, CsTSB) under wounding stress, which indicates that these two important epigenetic regulatory mechanisms are jointly involved in regulating the synthesis of indole during the postharvest processing of oolong tea. These findings improve our understanding of the epigenetic regulatory mechanisms involved in quality formation during the postharvest processing of oolong tea.
理解乌龙茶采后加工过程中机械损伤应激的表观遗传反应，可为茶树基因组的重编程及其对茶叶品质的影响提供深入了解。在这里，我们对乌龙茶采后加工过程中受到机械损伤应激的茶叶进行了 5mC DNA 甲基化和染色质可及性图谱分析。差异甲基化区域和优先可及启动子的分析揭示了许多高丰度的 TF 结合基序，突出了一组可能对乌龙茶品质很重要的 TF。在这些集合中，我们构建了一个专门针对机械损伤应激的染色质可及性介导的基因调控网络。结合以 TF 为中心的酵母单杂交测定的结果，我们鉴定了 CsMYC2 的潜在结合位点，并构建了以 CsMYC2 为中心的基因调控网络，阐明了 CsMYC2 在乌龙茶采后加工中的潜在调控作用。有趣的是，在创伤应激下吲哚生物合成基因（色氨酸合酶β亚基，CsTSB）的启动子区域中发现了高可及染色质和低甲基化胞嘧啶的共存，这表明这两种重要的表观遗传调控机制共同参与调控吲哚在乌龙茶采后加工过程中的合成。这些发现提高了我们对乌龙茶采后加工过程中品质形成涉及的表观遗传调控机制的理解。
