茶叶芳香族香气苯乙醛生物合成的光响应机制及其生理学功能研究

The volatile phenylpropanoids/benzenoids aroma (mainly including phenylacetaldehyde and phenylethyl alcohol) is an important aroma component in tea, and it is the main contributor to the rose-like aroma in tea. In recent years, studies on the metabolism of phenylacetaldehyde and phenylethanol mainly in model plant flowers and fruit tissues. However, few studies on aromatic aroma synthesis and abiotic stress regulation mechanisms in plant green tissues, especially in horticultural crops. Our previous study found that the content of phenylacetaldehyde in tea can be inhibited by visible light, and identified the key genes for the synthesis of phenylacetaldehyde. At the same time, we selected the candidate members of the PIF family, which are synergistically expressed with phenylacetaldehyde. However, how the light signaling pathways regulate the metabolism of phenylacetaldehyde in tea and the physiological function of phenylacetaldehyde have not been clarified. Therefore, this project intends to use aromatic tea-rich tea as research material, revealing the mechanism and the physiological function of tea phenylacetaldehyde biosynthesis respond to light stress by using the physiological and biochemical, transcriptomics and related molecular techniques. The present project will study the synergistic expression and interaction of PIF family gene members and structural genes, and identify the key PIF members involved in the regulation of tea phenylacetaldehyde synthesis and their target structural genes, and clarify the physiological functions of phenylacetaldehyde under light stress. The aims of the project are to show how the light signal pathway regulates the metabolism of phenylacetaldehyde in tea and the biological functions of phenylacetaldehyde.

芳香族香气（包括苯乙醛和苯乙醇）是茶叶中重要的一类香气成分。近年来，在模式植物花和果实组织中苯乙醛和苯乙醇代谢研究已成为热点，但芳香族香气合成及非生物胁迫调控机制研究在植物绿色组织尤其是园艺作物中鲜见报道。我们前期研究发现茶叶苯乙醛含量可被可见光抑制，并鉴定了苯乙醛合成关键基因，同时筛选出了与苯乙醛含量协同表达的候选转录因子PIF家族成员，但光信号通路是如何具体调控茶叶苯乙醛代谢及苯乙醛的生理学功能还未明晰。因此，本项目拟以富含芳香族香气的茶叶为研究材料，围绕茶叶苯乙醛生物合成的光响应机制及其生理学功能这一科学问题，采用生理生化、转录组学及相关分子技术手段，一方面研究PIF家族基因成员与结构基因协同表达和互作关系，鉴定参与茶叶苯乙醛合成调控的关键PIF成员及其靶标结构基因；另一方面，明晰苯乙醛在光胁迫下的生理学功能。本项目研究结果以期解析苯乙醛代谢的光响应机制及其发挥的生物学功能。

芳香族香气（包括苯乙醛和苯乙醇）是茶叶中重要的一类香气成分，本研究主要围绕茶叶苯乙醛生物合成的光响应机制及其生理学功能这一科学问题展开。本研究发现苯乙醛的生物合成在长期黑暗中被激活而在红光和蓝光下被抑制，并结合同位素示踪技术和合成路径基因表达水平，确定了茶叶中苯乙醛受光所调控的主要合成路径及关键基因CsAAAT1。同时解析了黑暗下CsAAAT1的调控机制，我们通过基因同源比对，在茶中鉴定到了7个CsPIFs基因，分别为CsPIF1，CsPIF3-1，CsPIF3-2，CsPIF7-1，CsPIF7-2，CsPIF8-1和CsPIF8-2。进一步通过基因表达和转录激活及EMSA实验，确定了CsPIF3-2可以直接与CsAAAT1基因启动子上的G-box-like结合。上述实验结果表明黑暗处理可通过诱导CsPIF3-2的表达水平促进CsAAAT1基因的表达，促进了茶叶中苯乙醛的蓄积。我们对苯乙醛在茶叶中的生理功能进行了研究，通过外源添加苯乙醛研究其对叶绿体的作用，发现苯乙醛会增强氮蓝四唑的还原速率，说明苯乙醛可能参与促进暗适应叶绿体中叶绿素的激发。本项目研究结果解析了苯乙醛代谢在茶叶组织中的光响应机制及其在暗适应叶绿体中发挥的生物学功能。