Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China.
Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Shijingshan District, Beijing 100049, China.
Food Res Int. 2021 Apr;142:110183. doi: 10.1016/j.foodres.2021.110183. Epub 2021 Feb 1.
The manufacturing process of tea (Camellia sinensis), especially oolong tea, involves multiple postharvest stresses. These stresses can induce the formation and accumulation of many important aroma compounds, such as indole-a key floral aroma contributor of oolong tea. However, little is known about the regulation mechanisms of aroma compound formation, especially epigenetic regulation. DNA methylation is an important epigenetic modification. Changes in the DNA methylation levels of promoter sequences can regulate gene expression under stress conditions. In this study, the differences in DNA methylation levels and histone 3 lysine 9 dimethylation levels of indole key biosynthetic gene (tryptophan synthase β-subunit 2, CsTSB2) were detected between untreated and continuous wounding treatment tea leaves. The results show that the DNA methylation levels affect the ability of the basic helix-loop-helix family transcription factor CsMYC2a to bind to the promoter of CsTSB2. Analyses of the transcript levels of DNA methyltransferases during oolong tea processing screened out candidate genes involved in the regulation of secondary metabolite product biosynthesis/accumulation. The results suggest that the domains rearranged methyltransferase 3, a DNA methyltransferase, is involved in the DNA methylation regulation of indole formation during the oolong tea manufacturing process. This is the first report on the involvement of DNA methylation in the regulation of aroma compound formation in tea leaves exposed to postharvest stresses.
茶叶（Camellia sinensis），尤其是乌龙茶的制作过程涉及到多个采后应激。这些应激可以诱导许多重要香气化合物的形成和积累，如吲哚——乌龙茶花香的关键贡献者。然而，对于香气化合物形成的调控机制，特别是表观遗传调控，人们知之甚少。DNA 甲基化是一种重要的表观遗传修饰。启动子序列中 DNA 甲基化水平的变化可以在应激条件下调节基因表达。在这项研究中，检测了未经处理和连续创伤处理的茶叶中吲哚关键生物合成基因（色氨酸合酶β亚基 2，CsTSB2）的 DNA 甲基化水平和组蛋白 3 赖氨酸 9 二甲基化水平的差异。结果表明，DNA 甲基化水平影响基本螺旋-环-螺旋家族转录因子 CsMYC2a 与 CsTSB2 启动子结合的能力。在乌龙茶加工过程中分析 DNA 甲基转移酶的转录水平，筛选出参与次生代谢产物生物合成/积累调控的候选基因。结果表明，域重排甲基转移酶 3（一种 DNA 甲基转移酶）参与了乌龙茶制作过程中吲哚形成的 DNA 甲基化调控。这是首次报道 DNA 甲基化参与了采后应激下茶叶香气化合物形成的调控。
