野油菜黄单胞菌的XopR基因功能  

The Functional Study of a Type Ⅲ Effector Protein XopR in Xanthomonas campestris pv. campestris

作　　者：张巧玲[1] 戎伟[1] 李慧萍[1] 林道哲[1] 何朝族[1] 

机构地区：[1]海南大学海南省热带生物资源可持续利用重点实验室,海南海口570228

出　　处：《热带生物学报》2015年第3期261-268,共8页Journal of Tropical Biology

基　　金：海南大学青年基金资助项目(qnjj1204);海南省自然科学基金资助项目(314043)

摘　　要：野油菜黄单胞菌野油菜致病变种(Xanthomonas campestris pv.campestris,Xcc)是一种能够引起十字花科植物产生黑腐病的重要病原菌。笔者以野油菜黄单胞菌Xcc8004菌株XopR基因为研究对象,通过qRTPCR发现,XopR基因的表达受Ⅲ型调控基因hrpG和hrpX的调控,并且XopR蛋白的分泌依赖于Ⅲ型分泌系统结构基因hrcV,这表明XopR是Xcc8004的一个Ⅲ型分泌效应蛋白。利用同源重组的方法,笔者获得了XopR基因的缺失突变体ΔXopR。将野生型Xcc8004和ΔXopR突变体分别接种甘蓝品种中甘15、中甘21和大白菜品种中白83,发现ΔXopR突变体菌株致病性下降,表明XopR对于Xcc8004在甘蓝上的完整毒性是必须的。GFP融合蛋白分析发现XopR定位于拟南芥原生质体的细胞膜上,可以在拟南芥原生质体中抑制细菌鞭毛蛋白诱导的FRK1基因表达。Xanthomonas campestris pathovar campestris（ Xcc） is the causal agent of black rot disease on cruciferous plants. Xcc deliver many effector proteins into host plant cells via the type Ⅲ secretion system to help its infection and multiplication. In this study,the expression and regulation of XopR gene were analyzed through qRTPCR. The results showed that the XopR gene transcription was regulated by the type Ⅲ regulator of HrpG and HrpX,and the XopR protein secretion was type Ⅲ secretion system dependent,indicating that XopR was a typeⅢ effector protein of Xcc8004. In addition,a XopR gene deletion mutant（ Xcc8004,ΔXopR） was generated,and the disease symptoms caused by ΔXopR strain were decreased on Zhonggan15,Zhonggan21,Zhongbai83 in contrast with WT Xcc8004,suggesting that XopR was required for the full virulence of Xcc8004 on Cabbage host plants. Furthermore,XopR was proved to located in plant plasma membrane in Arabidopsis protoplasts cells by XopR-GFP fusion assay. The expression of PTI marker gene FRK1∷LUC was inhibited by XopR protein,which was consistent with the XopR function in Xoo strains.

关 键 词：Xcc8004 Ⅲ型分泌系统 XopR 

分 类 号：S432.42[农业科学—植物病理学]