决定茶树EGCG含量的关键生态因子及其调控机制研究

EGCG (epigallocatechin-3-gallate) is the core of biochemical components of tea sensory quality, and it also plays a crucial role in health benefits. The aim of this project is to investigate the key ecological factors and their regulation mechanism of affecting EGCG content in tea plant based on the results of our previous studies on tea plant resources with high EGCG content and their chemical regulation mechanism, screening out key genes of EGCG biosynthesis, as well as ecological factors in tea garden and based on the discovery that the promoter of three key transcriptional factors in EGCG biosynthesis has some response elements of ecological factors. In this project, the study on response mechanism of EGCG content to ecological factors will be performed and the mathematical model would be constructed by the cultivar “1005” with high EGCG content, in order to explore the key ecological factors affecting the EGCG content in tea plants with the method of response surface. Moreover, the real-time quantitative flouorescence PCR, crossover analysis, Logistic regression and MDR analysis would be applied to ascertain the miRNA, transcriptional factors and structural genes involving in molecular and interaction mechanism regulating EGCG content in tea plant, so that the ecological effects related to EGCG biosynthesis would be revealed and the scientific foundation of improving tea quality could be provided.

表没食子儿茶素没食子酸酯（EGCG）是茶叶感官品质的核心生化成分与保健品质的关键活性成分。基于高EGCG含量的茶树资源与化学调控、EGCG生物合成关键基因筛选、茶园生态因子等三方面的前期探索，并发现茶树EGCG生物合成三个关键转录因子的启动子具有生态因子响应元件，本项目拟开展决定茶树EGCG含量的关键生态因子及其调控机制研究。以高EGCG含量的茶树新品系“1005”为实验材料，应用响应曲面法，研究茶树EGCG含量对生态因子的响应规律并构建数学模型，明确决定茶树EGCG含量的关键生态因子；应用实时荧光定量PCR技术、叉生分析、Logistic回归和MDR分析，进一步探明关键生态因子诱导miRNA、转录因子、结构基因调控茶树EGCG含量的分子机制与互作机制，旨在揭示茶树EGCG生物合成过程的生态效应，为改善茶叶品质提供科学依据。

1项目背景.EGCG（epigallocatechin-3-gallate，表没食子儿茶素没食子酸酯）是决定茶叶品质的关键成分，其含量受生态因子影响，但决定茶树EGCG含量的关键生态因子及其调控机制尚未明确，本项目致力于探明茶树EGCG含量对生态因子的响应规律及其分子机制和互作机制。.2主要研究内容.本项目以高EGCG含量茶树新品系“1005”的父本（黄旦）茶树为实验材料，应用响应曲面法Box-Behnken设计多因素互作实验，研究：茶树EGCG含量对生态因子的响应规律；关键生态因子诱导miRNA、转录因子和结构基因调控茶树EGCG含量的分子机制；决定茶树EGCG含量的关键生态因子与转录因子、miRNA、结构基因之间的互作机制。.3重要结果.（1）温度是决定茶树EGCG含量的关键生态因子。.（2）在不同环境温度、空气相对湿度、光强处理下，茶树EGCG含量分别受11、18、6个转录因子和11、14、14个关键结构基因调控，受21、6、3个miRNA的负向影响，7、5、11个miRNA的正向影响。在过高基质湿度处理下，miR5240和NovlemiR1b调控基因Cs4CL1的表达下调，进而降低了EGCG含量。.（3）茶树EGCG生物合成过程的生态效应及其互作网络：在较适生态条件下，酚酸类代谢向类黄酮代谢转化，促进茶树EGCG生物合成，主要受到5个结构基因(CsANS、CsF3H、CsCHI、CsCHS和CsaroDE)，11个miRNAs (miR164、miR396d、miR5264、miR166a、miR171d、miR529、miR396a、miR169、miR7814、miR3444b、miR5240)，7个转录因子(MYB93、NAC2、NAC6、NAC43、WRK24、bHLH30和WRK70）的综合调控。.4关键数据.（1）决定茶树EGCG含量的最优生态因子组合：在温度28℃，光合有效辐射280µmol·m-2·s-1，基质相对湿度70%，空气相对湿度90%的生态条件下，黄旦茶树EGCG含量达14.46%，比放置于室外的茶树提高了86.83%。.（2）茶树EGCG含量与生态因子变化之间的数学模型（方程见正文第1页）。.5科学意义.本研究揭示了茶树EGCG生物合成过程的生态效应，为深入理解EGCG含量与生态因子的关系提供新线索，为改善茶叶品质提供科学依据。