Zhang Yanrui, Pan Haiyan, Wu Qiong, Zha Yinong, Su Jingjing, Li Fangdong, Tong Wei, Zhang Liang, Xia Enhua
National Key Laboratory for Tea Plant Germplasm Innovation and Resource Utilization, Anhui Agricultural University, Hefei, 230036, China.
Tea Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
Plant J. 2025 Mar;121(6):e70108. doi: 10.1111/tpj.70108.
Catechins were diversely accumulated in Thea plants and were crucial for tea flavor, yet the mechanism underlying the diverse catechins distribution in Thea plants remained elusive. We herein collected a total of 19 Thea and 12 non-Thea plants to investigate their catechins distribution and the underlying mechanism. Results showed that the distribution pattern of catechins in cultivated tea plants significantly differs from that of wild relatives. (+)-Gallocatechin gallate (GCG) was detected in over 50% of wild tea plants but was almost undetectable in cultivated tea plants. Conversely, (-)-Epigallocatechin gallate (EGCG) was extensively distributed in tea cultivars but accumulated extremely low in a few wild relatives such as Camellia tetracocca and C. ptilophylla. Expression analysis found that the expression of flavonoid 3',5'-hydroxylase (F3'5'H) was highly correlated with EGCG accumulation in Thea plants. Yeast one-hybrid and luciferase assays showed that CsMYB1, a key catechins regulator, could bind to the promoter of F3'5'H and activate its expression to promote EGCG accumulation in cultivated tea plants; yet it was unable to bind to and activate the promoter of F3'5'H of C. tetracocca due to a 14-bp deletion in the promoter, leading to a low content of EGCG. Results also showed that silencing the expression of anthocyanidin synthase (ANS) enhanced the metabolic flux of catechins toward GCG but not EGCG in tea plants, consistent with the observation of high GCG content in C. ptilophylla with low ANS expression. Overall, the results illustrated the mechanism underlying catechins variation in Thea plants and would help to facilitate the utilization of wild tea plants toward future breeding.
儿茶素在茶属植物中积累情况多样，对茶叶风味至关重要，但茶属植物中儿茶素分布差异的潜在机制仍不清楚。我们在此收集了总共19种茶属植物和12种非茶属植物，以研究它们的儿茶素分布及其潜在机制。结果表明，栽培茶树中儿茶素的分布模式与野生近缘种显著不同。超过50%的野生茶树中检测到（+）-没食子儿茶素没食子酸酯（GCG），但在栽培茶树中几乎检测不到。相反，（-）-表没食子儿茶素没食子酸酯（EGCG）在茶树品种中广泛分布，但在一些野生近缘种如四球茶和毛枝茶中积累极低。表达分析发现，类黄酮3',5'-羟化酶（F3'5'H）的表达与茶属植物中EGCG的积累高度相关。酵母单杂交和荧光素酶试验表明，儿茶素关键调控因子CsMYB1可与F3'5'H的启动子结合并激活其表达，从而促进栽培茶树中EGCG的积累；然而，由于启动子中14 bp的缺失，它无法结合并激活四球茶F3'5'H的启动子，导致EGCG含量较低。结果还表明，沉默花青素合酶（ANS）的表达增强了茶树中儿茶素向GCG而非EGCG的代谢通量，这与毛枝茶中ANS表达低但GCG含量高的观察结果一致。总体而言，这些结果阐明了茶属植物中儿茶素变异的潜在机制，并将有助于促进野生茶树在未来育种中的利用。
