茶树体内聚合态儿茶素合成途径和积累规律的研究

Polymeric catechins (Proanthocyanidins, PAs) are responsible for bitterness and astringency in some fruits and vegetation organs. The biosynthesis and metabolism of PAs in tea plant has not caused concern, because the content of these compounds is very low in the leaf of tea plant. Interestingly, our previous researches showed that roots of tea plants also had high activity of flavonoid biosynthes. That activity mainly induced the accumulation of polymeric catechins, conld not induce the accumulation of free-type catechins. And light treatment had postive effects on increasing the contents of PAs in tea leaves. In order to discover the melacular mechinism of the accumulation of PAs in tea plant, three area researches will be carried out in this project. Firstly, we will detect PAs accumulation in different tissues, and same tissue in different environment conditions. Secondly, the genes from tea genome, transcriptome, cDNA library, and GenBank data, will be screened by differentially expressed spectrum analysis. Finally, cloning and functional analysis of the selected genes from the data will be carried out. The project, being completed as planed, would be helpful for understanding the moleculor mechanism of polymeric catechin biosynthesis, and would provide theoretic foundation of metabolic regulation of catechins.

聚合态儿茶素(原花青素, PAs)是植物果实及营养器官中引起收敛性、苦涩味特征成分之一。由于鲜叶中PAs含量相对较低，茶树PAs生物合成及代谢并未引起广泛关注。本项目前期意外发现，茶树根系具有较高的类黄酮合成能力，但根系并未大量积累游离态儿茶素，而主要转变为聚合态儿茶素；另外，光照诱导能显著提高茶树叶片中PAs含量。本项目拟在明确聚合态儿茶素的积累规律的基础上，利用前期获得的茶树基因组、转录组、cDNA文库及GenBank数据，通过不同组织器官及环境诱导的差异表达谱分析，深入挖掘茶树儿茶素糖基转移酶、儿茶素糖苷转运蛋白以及儿茶素聚合酶等相关基因，开展茶树PAs合成相关基因的体外功能分析和转基因验证。本项研究的顺利实施，将有望揭示茶树体内儿茶素转移和氧化聚集的分子机理，为有效调控茶树类黄酮代谢奠定理论基础。

本课题在明确聚合态儿茶素的积累规律的基础上，利用前期获得的茶树基因组、转录组、cDNA文库及GenBank数据，通过不同组织器官及环境诱导的差异表达谱分析，深入挖掘了UFGT、F3'5'H以及儿茶素聚合酶等相关基因，开展了茶树PAs合成相关基因的体外功能分析和转基因验证。本课题揭示了茶树体内儿茶素转移和氧化聚集的分子机理，为有效调控茶树类黄酮代谢奠定理论基础。