基于植物防御路径间交互作用的烟粉虱反防御策略机制研究

Crosstalk between different signaling pathways was thought to equip plant with a powerful regulatory capacity to finely tune its defense responses, and consequently, enhance its fitness. However, recent studies show that some herbivores can manipulate or interfere with the crosstalk between different signaling pathways to suppress plant effective defenses, which is one of strategies employed by herbivores to disarm plant defense. Bemisia tabaci has been recently recognized as an important invasive pest in China. Previous studies show that B. tabaci has the capability of disarming plant defense. Regarding the underlying mechanisms, conclusive evidence has still been lacking. In the present study, we will employ B. tabaci and its host plant tomato as a model system to examine the changes in plant defense responses against whitefly feeding, in term of defensive gene, phytohormones, and secondary metabolites. On the other hand, we will exploit tomato mutants, targeted gene silencing techniques, and field experiments to investigate the mechanisms involved in the manipulation of JA-SA crosstalk by whitefly, and the influence of disarming plant defense by B. tabaci on its population development in field. Our expected findings will advance our understanding of the ecological and evolutionary interaction between whitefly and host plant, and uncover the underlying mechanisms involved in disarming plant defense by whitefly feeding.

植物体内不同信号路径间的交互作用，被认为是植物精确调控其防御反应，提高其适应性的重要表现。但是，最近有研究表明植食者能够利用并干扰植物体内不同信号路径间的交互作用，达到抑制植物防御反应的目的，这是植食性昆虫反防御策略之一。烟粉虱是近年来快速入侵我国的重要农业害虫。已有研究表明，烟粉虱具有反防御策略，但关于其内在机制的研究仍处于推论阶段，尚缺乏结论性试验证据。本研究以烟粉虱及其田间寄主番茄作为研究模式系统，从基因、激素、次生代谢物等多个水平，详细分析番茄应对烟粉虱取食的生理变化；同时结合转基因突变体、靶标基因沉默及田间试验等试验方法，深入了解烟粉虱调控茉莉酸-水杨酸信号互作的分子机制，以及反防御策略对烟粉虱田间种群繁衍的影响。预计所得结果不仅有助于深入了解烟粉虱与寄主植物的生态进化关系，而且可以阐明烟粉虱反防御策略的内在机制，即从另一视角深化对烟粉虱入侵机制的了解。

植物体内不同信号路径间的交互作用，被认为是植物精确调控其防御反应，提高其适应性的重要表现。但是，最近有研究表明植食者能够利用并干扰植物体内不同信号路径间的交互作用，达到抑制植物防御反应的目的，这是植食性昆虫反防御策略之一。烟粉虱是近年来快速入侵我国的重要农业害虫。已有研究表明，烟粉虱具有反防御策略，但关于其内在机制的研究仍处于推论阶段，尚缺乏结论性试验证据。本研究以烟粉虱及其田间寄主番茄作为研究模式系统，从基因、激素、次生代谢物等多个水平，详细分析番茄应对烟粉虱取食的生理变化；同时结合转基因突变体、靶标基因沉默及田间试验等试验方法，深入了解烟粉虱调控茉莉酸（JA）-水杨酸(SA)信号互作的分子机制，以及反防御策略对烟粉虱田间种群繁衍的影响。研究发现（1）在室内及半田间条件下，JA防御反应在番茄防御烟粉虱若虫发育过程中均起关键作用，但对其成虫发育无影响；（2）烟粉虱取食过程中能够将JA防御反应抑制，同时诱导SA防御反应；且SA路径的激活在烟粉虱抑制JA防御反应中发挥重要作用；（3）烟粉虱调控JA-SA信号互作的关键转录因子为WRKY4；（4）烟粉虱诱导的番茄挥发物同样能够激活邻近植株SA防御反应，并抑制JA防御反应，从而导致邻近番茄抗虫性下降。这一系列研究结果表明烟粉虱通过操控番茄体内JA-SA信号互作，实现对番茄及其邻近植株的防御反应的瓦解，从而促进其种群快速扩算、入侵。