小麦蓝矮植原体致病关键效应蛋白的鉴定及其致病机理研究

Wheat blue dwarf(WBD)disease is a new destructive disease, which frequently appears in the winter wheat of arid areas of Northwest China and results in significant yield losses. However, it is still unclear about the virulence factors and pathogenesis, which hinder the effective prevention of WBD disease. In previous studies, we have sequenced the complete genome of WBD phytoplasma, and four virulence factor candidates have been identified through transient expression assays in Nicotiana benthamiana plants, which provide the groundwork for identification of virulence factors to better understand the pathogenic mechanisms. So that, we will focus on the following studies: First, genetic transforming virulence factor candidates into Brachypodium distachyon; Second, functional analysis of virulence factor candidates in Brachypodium distachyon; Third, molecularcytology studies of the pathogenetic mechanism of virulence factors. Through the above study, the work will identify the virulence factors to further reveal the pathogenetic mechanisms of WBD phytoplasma, which will provide new approaches for disease control. This study is not only the important theoretical problem to be elucidated in the world, but also the key technical problem to be solved for prevention and control the serious diseases.

小麦蓝矮病（Wheat blue dwarf, WBD）是我国小麦上一种新的危险性病害，由植原体侵染引起。该病害在西北干旱地区间歇性发生，给小麦生产带来巨大损失。目前，由于对该病原的致病因子与致病机理尚不明确，限制了病害的有效防治。本实验室目前已经完成了WBD植原体全基因组序列测定，并从编码的分泌蛋白中筛选出了4个候选致病效应蛋白基因，为开展WBD植原体的致病效应蛋白基因的鉴定及其致病机理研究奠定了基础，有望为生产中病害防治提供新途径。因此，本课题拟重点开展：一、候选致病效应蛋白基因遗传转化二穗短柄草研究；二、候选致病效应蛋白基因在二穗短柄草上的致病功能鉴定；三、致病效应蛋白致病的分子细胞学机理研究。通过以上研究，最终得到小麦蓝矮植原体关键致病效应蛋白基因并揭示其致病分子机理，为植原体病害的防治探索新途径。本研究既是国内外本学科需要解析的重要理论问题，也是亟待解决的重大病害防控技术问题。

小麦蓝矮病是西北冬麦区一种重要的植原体病害，造成严重的产量损失。揭示小麦蓝矮（WBD）植原体的致病机理是生产中亟待解决的关键问题。本研究从WBD植原体基因组中预测到37个分泌蛋白，（1）并从中鉴定出4个候选效应蛋白，其中， SWP1引起本氏烟丛枝症状，SWP11激发寄主防御反应，SWP12和SWP21抑制寄主防御反应。（2）探明了SWP1引起丛枝的机理。首先，将SWP1基因遗传转化拟南芥和二穗短柄草，均得到了有明显丛枝症状的转基因植株，证实SWP1是WBD植原体编码的致病关键效应蛋白。通过在本氏烟中瞬时表达SWP1的缺失突变体，进一步明确了CC卷曲螺旋是SWP1引起丛枝的关键功能域。（3）利用酵母双杂交和BiFC的方法筛选到了拟南芥中SWP1的靶标蛋白——转录因子TCP12和TCP18。（4）探索了SWP1与TCP18的互作机理.结果表明SWP1通过蛋白酶体介导TCP18的降解，操控植物的分枝发育，导致植物丛枝发病。本研究鉴定出4个具有重要生物学功能的WBD植原体候选效应蛋白，并进一步揭示了致病因子SWP1引起植物丛枝的分子机理，为小麦蓝矮病的有效防控奠定了重要基础，也为我国报道的100余种植原体病害的致病机理研究提供新的思路。