Xu Jianmei, Li Jingyi, Liu Yihao, Zheng Peng, Liu Shaoqun, Sun Binmei
College of Horticulture, South China Agricultural University, Guangzhou, 510642, China.
Plant Physiol Biochem. 2025 Feb;219:109401. doi: 10.1016/j.plaphy.2024.109401. Epub 2024 Dec 15.
Galloylated catechins are the dominant polyphenols in Camellia sinensis (L.) O. Kuntze. The mechanisms responsible for accumulation of these specialized metabolites in tea plants remains unclear. This paper presents an extended member of subgroup 5 of transcription factors R2R3-MYB, CsMYB34, as a critical gene specifically regulating galloylated catechin biosynthesis. CsMYB34 has a TT2-type motif [VIRTKATRCSKVFIP]. Its transcription levels were positively correlated with galloylated catechin content in 19 tea varieties, with correlation coefficients ≥0.79. Suppression of CsMYB34 expression caused a significant decrease in galloylated catechin content, as well as reduced expression levels of the key galloylated catechin biosynthesis gene CsSCPL4. Yeast one-hybrid (Y1H), electrophoretic mobile shift assay (EMSA) and dual-luciferase reporter system (DLR) showed that CsMYB34 interacts directly with the promoter region of CsSCPL4, thereby upregulating its transcription. This research indicates that the CsMYB34 transcription factor selectively modulates the biosynthetic pathway of galloylated catechins, thereby offering a plausible rationale for the observed elevated levels of these compounds in tea leaves.
没食子酰化儿茶素是茶树中主要的多酚类物质。茶树中这些特殊代谢产物积累的机制尚不清楚。本文介绍了转录因子R2R3-MYB第5亚组的一个扩展成员CsMYB34，它是特异性调控没食子酰化儿茶素生物合成的关键基因。CsMYB34具有一个TT2型基序[VIRTKATRCSKVFIP]。在19个茶树品种中，其转录水平与没食子酰化儿茶素含量呈正相关，相关系数≥0.79。抑制CsMYB34的表达导致没食子酰化儿茶素含量显著降低，同时关键的没食子酰化儿茶素生物合成基因CsSCPL4的表达水平也降低。酵母单杂交（Y1H）、电泳迁移率变动分析（EMSA）和双荧光素酶报告系统（DLR）表明，CsMYB34直接与CsSCPL4的启动子区域相互作用，从而上调其转录。该研究表明，CsMYB34转录因子选择性地调控没食子酰化儿茶素的生物合成途径，从而为茶叶中这些化合物含量升高提供了合理的解释。
