茶树倍半萜代谢差异化响应不同虫害胁迫的分子机制

Sesquiterpene compounds play an important ecological function in induced resistance of plants. Tea plant (Camellia sinensis) is rich in secondary metabolites, including a variety of terpenoids. It has been proved that tea sesquiterpene volatiles have a function of direct defense by repelling insect pests or indirect defense by attracting natural predators. We cloned three key genes CsHMGR1, CsHMGR2 and Cstps1 which are responsible for tea sesquiterpene MVA metabolic pathways, and found that they have significantly different reactions respond to diverse herbivore damage. In order to know what kind of plant signal accepting different insect damage stimulation and regulating tea sesquiterpene metabolism to perform defense function. Based on earlier studies, we want to use transcriptomics, metabolomics and reverse genetics method to find the signal which recognizes different herbivore damage and demonstrate the molecular mechanism how this signal regulate sequiterpene metabolism response to different biotic hurts. This study will help us to understand the intrinsic evolutionary mechanisms among multi-nutrient levels in the tea plantation ecosystem, further to develop new ecological pest management strategies.

挥发性倍半萜类化合物是植物重要的次生代谢物，它们作为植保素在植物的诱导性防御过程中发挥重要功能。茶树的次生代谢产物丰富，虫害能够诱导茶树释放多种茶树倍半萜挥发物，具有驱避害虫的直接防御效应或吸引天敌的间接防御效应。申请者克隆了茶树倍半萜MVA代谢途径的关键基因CsHMGR1、CsHMGR2和Cstps1，发现它们对不同虫害胁迫的响应明显不同，这与不同虫害诱导下的茶树挥发物特征谱的研究结果吻合。目前对究竟是哪种信号识别不同虫害刺激，并合理调控茶树倍半萜类物质代谢，从而实现经济有效的针对性防御仍不清楚。本申请拟在前期的研究基础上，通过转录组学、代谢组学和反向遗传学方法，明确主导虫害损伤调控茶树倍半萜代谢的信号分子，阐明该信号识别不同虫害信号并差异化调控植株响应不同损伤的分子机制。本研究对揭示"茶树-昆虫-天敌"三级营养关系的进化机制和开辟新的害虫生态治理策略有重要意义。

获得19条典型TPS，经原核表达和酶的生化活性分析，确定各TPS功能；鉴定一批JAs 信号相关调控基因或作用元件；获得6个过表达转基因拟南芥株系或突变体回补株系。明确JAs 信号调控茶树倍半萜合成代谢，证明JAs信号在虫害损伤诱导茶树萜类代谢的过程中起主导作用。明确茶树倍半萜代谢对不同虫害方式响应不同及其分子机制，建立了转基因拟南芥与突变体回补株系并验证。首次发现茶树的两个变种间挥发性萜类物质，尤其是倍半萜代谢的显著差异，大叶种茶树（普洱茶种/阿萨姆种）花释放近30种倍半萜化合物，而中小叶种（茶种/中国种）基本无组成性倍半萜产生。