聚合态儿茶素-铝络合物在促进茶树根系生长中的作用

It have been verifed that aluminum is an important element to promote the growth of tea roots. However, beacuse there is few available aluminum in the slightly acidic or alkaline soil (such as the tea garden in the north of Yangtze river region), the growth of tea plants in these region are poorly. It has been found that the polymeric catechins (PA) from tea roots can form complexes with aluminum. The complexes PA-Al is not toxic and could promote the growth of arabidopsis roots, which is sensitive to aluminum. However, whether the PA-Al complexes are growth-promoting of tea roots? And what is the mechanism of it? In this proposal, firstly, the factors (for example pH) influence complexation and depolymerization of PA-Al will be researched in vitro; then in tea plant, research the factors effect accumulation and subcellular localization of PA-Al in vivo; utilizing reverse genetics, overexpression or knockout key transcription factors CsMYB5 that regulation PA biosynthesis in tea plant, to clarify the role of PA in promoting the growth of tea roots; finally, using the transcriptome analyses, explore the major metabolic pathways and signaling pathways, that related to PA-Al promoting the growth of tea roots. This work aims to illuminate the relationship of PA-Al complexes and growth of tea roots. The research will provide scientific basis for preparation of metal microfertilizer and management of cultivation and fertilization of tea garden in the north of Yangtze river region.

许多实验表明，铝是促进茶树根系生长的重要元素，但是由于弱酸偏碱土壤（如江北茶区）可利用态铝很少，使得茶树的生长种植受到影响。本项目前期研究发现，茶树根中聚合态儿茶素可以与铝形成络合物PA-Al，并且外源的PA-Al对拟南芥根系生长有一定促进作用。那么，PA-Al能否促进茶树根系生长及其作用机理是本项目关注的科学问题。本项目拟首先研究影响PA-Al体外络合和解聚的pH等因子；研究影响茶树体内PA-Al组织器官亚细胞定位及积累的pH等环境因子；再利用反向遗传学手段，过表达或敲除调控茶树PA合成的关键转录因子CsMYB5，明确PA在铝促进茶树根系生长中的作用；最后利用转录组学手段，通过检测PA-Al促进茶树根系生长的转录图谱，挖掘PA-Al促进根系生长的主要代谢途径及信号通路。本项目研究，通过揭示PA-Al络合物与茶树根系生长的关系，为今后金属微肥制备、江北茶区茶树栽培施肥管理提供重要科学依据。

与许多作物不同，铝是促进茶树根系生长的有益元素，然而其调控机理并不清晰。本课题研究发现，茶树体内的酚类物质在茶树喜铝耐铝的过程中发挥着重要作用。本项目研究，揭示了PA-Al的络合特性以及络合物与茶树根系生长的关系，为茶树喜铝耐铝机理的研究奠定基础，为金属微肥制备、北方地区茶树栽培施肥管理提供重要的科学依据。. 主要研究进展包括（1）茶树体内的酚类物质可以与铝络合，并且这种络合能力与溶液的pH、多酚类型和铝离子浓度显著相关。（2）利用27Al核磁技术，发现络合物EGCG-Al信号和rPA-Al信号在体外实验和茶树体内都可以检测到，在茶树体内，分别存在老叶和根中,且以结合态为主。（3）通过研究发现添加PA能缓解铝对拟南芥的毒害，说明PA-Al络合物对拟南芥的生长有益。同时，也进行了酚类物质对茶苗的处理，发现PA以及EGCG，对于铝环境下茶树的生长有重要的调节作用。（4）用不同浓度铝处理茶苗后，转录分析发现，类黄酮代谢途径以及生长素信号通路，都显著地响应铝信号。（5）铝是促进茶树根系生长的重要元素，我们研究还发现铝处理可以促使茶树根系耐铝促生菌的丰度增加，从而促进茶树根系的生长。. 发表了相关论文7篇，申请了发明专利1项；参加了4次国际学术会议并做1次大会报告；培养了5名研究生。