School of Life Science, Anhui Agricultural University, Hefei, Anhui, 230036, China.
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, 230036, China.
Sci Rep. 2018 Jan 9;8(1):130. doi: 10.1038/s41598-017-18133-z.
There were several high concentrations of flavonoid components in tea leaves that present health benefits. A novel purple-leaf tea variety, 'Mooma1', was obtained from the natural hybrid population of Longjing 43 variety. The buds and young leaves of 'Mooma1' were displayed in bright red. HPLC and LC-MS analysis showed that anthocyanins and O-Glycosylated flavonols were remarkably accumulated in the leaves of 'Mooma1', while the total amount of catechins in purple-leaf leaves was slightly decreased compared with the control. A R2R3-MYB transcription factor (CsMYB6A) and a novel UGT gene (CsUGT72AM1), that were highly expressed in purple leaf were isolated and identified by transcriptome sequencing. The over-expression of transgenic tobacco confirmed that CsMYB6A can activate the expression of flavonoid-related structural genes, especially CHS and 3GT, controlling the accumulation of anthocyanins in the leaf of transgenic tobacco. Enzymatic assays in vitro confirmed that CsUGT72AM1 has catalytic activity as a flavonol 3-O-glucosyltransferase, and displayed broad substrate specificity. The results were useful for further elucidating the molecular mechanisms of the flavonoid metabolic fluxes in the tea plant.
茶叶中存在几种具有健康益处的高浓度类黄酮成分。一种新型的紫叶茶品种“Mooma1”是从龙井 43 号品种的自然杂交群体中获得的。“Mooma1”的芽和嫩叶呈现鲜艳的红色。HPLC 和 LC-MS 分析表明，在“Mooma1”的叶片中显著积累了花青素和 O-糖基化类黄酮，而与对照相比，紫叶中的儿茶素总量略有减少。通过转录组测序分离并鉴定了一个 R2R3-MYB 转录因子（CsMYB6A）和一个新型的 UGT 基因（CsUGT72AM1），它们在紫叶中高度表达。转烟草的过表达证实 CsMYB6A 可以激活类黄酮相关结构基因的表达，特别是 CHS 和 3GT，从而控制转基因烟草叶片中花青素的积累。体外酶促测定证实 CsUGT72AM1 具有作为黄酮醇 3-O-葡萄糖基转移酶的催化活性，并显示出广泛的底物特异性。这些结果有助于进一步阐明茶树中类黄酮代谢通量的分子机制。
