假眼小绿叶蝉取食与产卵诱导的茶树防御反应及机理

Both herbivore feeding and oviposition can induce plants to systemically produce defense responses. However, currently, most researches only focus on feeding- or oviposition-induced plant defenses, especially on feeding-induced defenses in a specific plant-herbivore system; few studies explored defense responses of plants induced by both herbivore feeding and oviposition. In this project, tea plant (Camellia sinensis), tea leafhopper (Empoasca vitis) and its egg parasitod (Stethynium empoascae) will be used as a research system. By combining molecular biology, chemistry, metabonomics, transcriptome and entomology, the influence of tea plants infested by E. vitis gravid females (feeding plus oviposition), preoviposition females (feeding) or both gravid and preoviposition females simultaneously and successively on the population fitness and/or searching behavior of the subsequent E. vitis and its egg parasitoid S. empoascae will be investigated. Moreover, the differences in levels of defense-related signal molecules, expression levels of defense-related genes and profiles of defense-related chemicals in tea plants when attacked by E. vitis gravid females, preoviposition females or both gravid and preoviposition females simultaneously and successively will be compared. Furthermore, we will identify the main defensive compounds that resist E. vitis. Finally, the role of different signaling pathways in the E. vitis feeding- and oviposition-induced tea plant defense responses will be dissected. This comprehensive analysis will completely elucidate the differences, at molecular, chemical and ecological levels, in defense responses of tea plants elicited by E. vitis feeding and oviposition, respectively, and their interactions, as well as clarify the mechanisms underlying these differences. The study will not only provide new insights into mechanisms of plant-insect interactions and herbivore induced plant defenses, but also lay the foundation for controlling insect pests by exploiting induced plant defenses-based techniques.

植食性昆虫取食或产卵均可诱导植物产生系统性的抗虫防御反应。然而，目前对某一特定植物-植食性昆虫研究系统，大多只研究单一的取食或产卵诱导的植物防御反应，而很少有开展在植食性昆虫取食与产卵联合为害下植物的整体防御反应的研究。本项目以茶树—假眼小绿叶蝉—三棒缨小蜂为研究对象，利用分子生物学、化学、代谢组学、转录组学以及昆虫学等研究技术与方法，通过系统剖析叶蝉产卵雌成虫为害、产卵前期雌成虫为害，以及二者同时或先后为害时对后续叶蝉及三棒缨小蜂种群适合度、行为，以及茶树信号分子与防御化合物含量等的影响，分析相关信号转导途径、防御化合物等在其中的作用，全面揭示假眼小绿叶蝉取食和产卵各自及联合为害时所诱导的茶树防御反应在分子、化学与生态水平上的异同，以及产生这些差异的机理。研究的实施，不仅在理论上可加深对昆虫与植物互作关系的认识，而且在实践上也可为利用植物诱导抗虫性防治害虫提供重要的理论与技术指导。

植食性昆虫取食或产卵均可诱导植物产生系统性的抗虫防御反应。然而，目前对某一特定植物-植食性昆虫研究系统，大多只研究单一的取食或产卵诱导的植物防御反应，而很少有开展在植食性昆虫取食与产卵联合为害下植物的整体防御反应。本项目利用分子生物学、化学、代谢组学、转录组学以及昆虫学等研究技术与方法，通过系统剖析叶蝉产卵雌成虫为害、产卵前期雌成虫为害，以及二者同时或先后为害时对后续叶蝉种群适合度和行为以及茶树信号分子与防御化合物含量等的影响，分析相关信号转导途径、防御化合物等在其中的作用。研究结果表明，茶小绿叶蝉取食和产卵均能显著上调CsPAL2、CsPR5和CsCHIb等防御相关基因的转录表达，提高儿茶素类、多胺类和黄酮类化合物含量的显著积累，以及显著增强茶树组织的木质化程度，从而影响后续若虫的生长发育速率与存活率；进而，我们发现叶蝉产卵能在一定程度上抑制取食所诱导的防御反应，起抑制作用的活性成分存在于叶蝉的产卵液中，具体化学结构有待进一步鉴定。研究结果证实茶树茉莉酸、水杨酸和脱落酸信号途径协同调控茶小绿叶蝉为害所诱导的茶树防御反应；其中，茉莉酸信号途径在调控茶树抵御叶蝉为害的过程中发挥主导作用。根据试验结果，我们推测先期叶蝉为害（无论产卵还是取食）利用水杨酸和脱落酸与茉莉酸信号转导途径之间的拮抗作用对后期叶蝉为害诱导的茶树防御反应产生抑制作用，从而有利于叶蝉的生长、发育和繁衍。本研究较为深入地揭示了茶小绿叶蝉取食和产卵各自及联合为害时所诱导的茶树防御反应的异同以及产生这些差异的机理。研究结果在理论上可加深对昆虫与植物互作关系的认识，而且在实践上也可为利用植物诱导抗虫性防治害虫提供重要的理论与技术指导。