小麦蓝矮植原体激发子SWP11调控寄主防御反应的分子机理研究

The wheat blue dwarf (WBD), caused by phytoplasma invasion, is one of the most important diseases affecting wheat production in northwest China. However, due to lack of stable transformation system and difficult to be cultivated in vitro, study on pathogenic mechanism of WBD still belongs to the start stage so far. Particularly, study on phytoplasma elicitor regulate of host immune responses have not been reported. Based on the previous completion of genomic sequencing of WBD phytoplasma, the effector proteins which stimulate the defence response of the host plant were screened, and finally an effector protein SWP11 was obtained for the first time on phytoplasma. we will try to study the function of SWP11 in the wheat-phytoplasma interaction by gene over-expression and gene silence. Y2H, Co-IP and BiFC technologies will be applied to identify the interacting proteins of SWP11, and VIGS will be used to study the function of the interacting proteins in plant defence response. In addition, proteomic profiling of SWP11-induced wheat plants will be analyzed to study the signal transduction pathway during the process of cell necrosis. And finally, the molecular mechanism of wheat defense response to SWP11 could be revealed. This research has important implications for studying on the interaction mechanism between SWP11 phytoplasma and the wheat, and is expected to provide a new approach for the prevention and control of WBD disease in production.

由植原体侵染引起的小麦蓝矮病是影响我国西北麦区小麦生产的重要病害。然而，植原体缺乏稳定的遗传转化体系且难以体外培养，迄今该病害致病机制的研究尚属起步阶段，特别是植原体激发子调控小麦防御反应方面至今未见相关的研究报道。本实验室前期完成了WBD植原体的基因组，并首次在植原体上筛选获得了激发小麦防御反应的激发子SWP11。本项目拟利用基因沉默和过表达技术研究SWP11在植原体-小麦互作中的功能；利用Y2H、Co-IP和BiFC等技术鉴定SWP11的互作靶标，并利用VIGS技术研究靶标蛋白在小麦防御反应中的功能，明确SWP11与小麦靶标蛋白互作的功能域和可能的信号传递作用；测定SWP11激发小麦防御反应的蛋白质组，解析小麦细胞坏死的信号传导通路，揭示SWP11激发小麦防御反应的分子机理。本研究对阐明WBD植原体与小麦互作的机制具有重要意义，有望为生产中WBD病害的防治提供新途径。

由植原体侵染引起的小麦蓝矮病是影响我国西北麦区小麦生产的重要病害。然而，植原体缺乏稳定的遗传转化体系且难以体外培养，迄今该病害致病机制的研究尚属起步阶段，特别是植原体激发子调控小麦防御反应方面至今未见相关的研究报道。本实验室前期完成了WBD植原体的基因组，并首次在植原体上筛选获得了激发小麦防御反应的激发子SWP11。本项目研究了SWP11在模式寄主植物长春花中的表达特征，在长春花感染WBD植原体后第30天，SWP11基因表达量达到最高，研究了SWP11在不同长春花组织中的表达量，发现SWP11在根中表达量最高；研究了SWP11的亚细胞定位，结果表明SWP11在烟草细胞的细胞膜、细胞质和细胞核均有定位；研究了SWP11的活性功能域，发现SWP11 N端的12到44位氨基酸是其发挥功能的关键活性功能域；利用基因沉默和过表达技术研究了SWP11在植原体-小麦互作中的功能，明确了SWP11在植原体-小麦互作中起负调控的作用；利用Y2H、AP-SWATH和BiFC等技术鉴定SWP11的互作靶标，明确了SWP11 通过与寄主植物的过氧化物酶（Prx3和prx63）互作，从而抑制了寄主植物过氧化物酶的功能，导致过氧化物酶分解过氧化氢的量减少，造成过氧化氢积累，引起寄主植物细胞过敏性坏死。测定了SWP11激发小麦防御反应的蛋白质组和转录组，数据均表明SWP11激发了寄主植物的防御反应。本研究对阐明WBD植原体与小麦互作的机制具有重要意义。