茶树R2R3-MYB转录因子CsTT2表达分析及功能初步鉴定

Expression Analysis and Functional Identification of CsTT2 R2R3-MYB Transcription Factor in Tea Plants

儿茶素是茶树中特色的次生代谢产物之一,是影响茶叶的品质与风味的主要组分,具有抗氧化、抗病毒、降脂减肥等药理功效。通过系统发育进化树分析、基因表达模式分析和分子生物学试验对茶树儿茶素生物合成相关调控因子CsTT2的功能进行初步鉴定。结果显示,CsTT2是R2R3-MYB转录因子,与拟南芥中调控次生代谢产物的MYB转录因子同在一个分支。在茶树品种顶芽组织中总儿茶素含量较高,CsTT2和儿茶素生物合成相关基因的表达水平也较高。亚细胞定位、酵母试验和双荧光素酶报告系统试验结果表明,CsTT2定位在细胞核中,其编码的蛋白是具有转录激活能力的调控因子,可以结合儿茶素生物合成关键基因ANR的启动子激活其表达。

Catechin is one of the most characteristic secondary metabolites in tea plants and the main component affecting tea quality and flavor. It possesses rich pharmacological effects, such as anti-oxidation, anti-virus, lipid lowering and weight loss, etc. In this study, the function of a catechin biosynthetic regulator CsTT2 was preliminarily identified using phylogenetic analysis, gene expression pattern analysis and molecular biology experiments. The results show that CsTT2 was a R2R3-MYB transcription factor that shares a branch withthe MYB transcription factor in Arabidopsis thaliana that regulates secondary metabolites. The expression levels of CsTT2 and catechin biosynthesis genes were relatively high in the apical bud tissue of tea plants with higher total catechin content. The results of subcellular localization, yeast assay and dual luciferase reporting system further reveal that CsTT2 was located into the nucleus and the protein it encodes possessed transcriptional activation capacity. CsTT2could bind to the promoter of a key catechin biosynthetic gene ANR to activate its expression.