茶蚜取食抑制茶树对茶尺蠖抗性的分子机理研究

Plant-mediated interactions between insects play an important role in regulating population dynamics of insects. However, the mechanisms responsible for plant-mediated interactions between insects remain largely unknown. In this project, two important tea pests with different feeding habits-tea aphid Toxoptera aurantii and tea geometrid Ectropis oblique will be selected as our study objects. Based on our previous results on herbivore-induced tea defense responses, combining molecular biology, analystic chemistry, metabonomics and transcriptome, we will investigate the influence of infestation by tea aphid on the behavior and performance of tea geometrid and its parasitoid Apanteles sp.. Moreover, we will compare the difference in the levels of defense-related signal molecules, defense-related chemical profile and the transcriptome of defense-related genes in tea plants when infested by the caterpillar alone or together with the aphid. Finally, the influence of exogenous application of signal molecules or inhibitors of different signal transduction pathways on induced tea plants defense responses and resistance will be determined. This comprehensive analysis will completely elucidate the molecular mechanism responsible for the inhibitory role of infestation by tea aphid on defense responses of tea plants by tea geometrid. The study will not only provide new insights into mechanisms of plant-insect interactions, herbivore induced plant defenses and adaptation coevolution, but also lay the foundation for forecasting of pest population densities and the exploitation of environment-friendly pest control methods, such as breeding of tea varieties resistant to herbivores.

植物介导的昆虫种间互作在调节昆虫的种群动态中发挥着重要作用。然而，目前对于昆虫种间互作机理还了解的很少。本项目选择具有不同取食习性的两种重要茶树害虫-茶蚜和茶尺蠖作为研究对象，在我们已有研究工作基础上，结合利用分子生物学、分析化学、代谢组学、转录组学以及昆虫学等研究方法，通过测定茶蚜取食对茶尺蠖及其天敌行为与种群适合度的影响、比较茶尺蠖幼虫单独取食或与茶蚜共同取食等不同处理下茶树防御化合物指纹图、防御相关基因转录组和防御相关信号分子含量等的差异，以及分析不同信号分子或信号途径抑制剂处理下茶树诱导防御反应与抗性的变化，全面揭示茶蚜取食抑制茶树对茶尺蠖抗性的分子机理。研究的实施，不仅在理论上可加深对昆虫与植物的互作关系、植物诱导防御反应机理以及植食性昆虫适应性进化等方面的认识，而且在实践上也可为害虫种群的预测预报以及治理（如抗性育种）等提供重要的理论与技术指导。

植物在受到一种植食性昆虫为害后所产生的诱导防御反应，能对当时和后续的同种或异种的害虫产生直接和间接、有利或不利的影响。茶蚜和茶尺蠖是目前茶园中常发的、可给茶叶生产带来严重影响的重要害虫，常重叠发生。我们的研究结果表明，茶蚜和茶尺蠖同时为害茶树并不影响茶尺蠖幼虫的体重变化，但蚜虫以一定密度（50头或100头）为害茶树4d或6d后会显著促进后续茶尺蠖幼虫的生长发育速率。此外，茶蚜预为害后，后续茶尺蠖幼虫寄生蜂（单白绵绒茧蜂）的茧重也显著高于对照，但复合危害茶苗的挥发物并未影响天敌的行为选择。茶蚜为害通过降低茶树叶片中JA和SA含量抑制了茶树对茶尺蠖的抗性。机理研究结果表明，茶蚜通过影响茶树初级营养物质分配和糖醇类、酚酸类等代谢物积累，干扰了茶树对茶尺蠖幼虫的抗性反应，从而促进了茶尺蠖幼虫的生长发育。