水稻白叶枯病菌双组分调控系统应答调节子基因gacAxoo的功能鉴定  

Functional characterization of gacAxoo,the gene encoding a response regulator of two-component regulatory system in Xanthomonas oryzae pv.oryzae

作　　者：许景升[1] 吴茂森[1] 何晨阳[1] 

机构地区：[1]中国农业科学院植物保护研究所,植物病虫害生物学国家重点实验室,北京100193

出　　处：《植物病理学报》2010年第3期282-289,共8页Acta Phytopathologica Sinica

基　　金：国家自然科学基金项目(30671353);中央财政国家重点实验室自主研究课题专项(SKL2009SR03)

摘　　要：为了阐明水稻白叶枯病菌(Xanthomonas oryzaepv.oryzae,Xoo)双组分系统(TCS)的调控作用,本研究通过基因克隆、序列分析、缺失突变和互补、表型测定,对TCS应答调节子基因gacAxoo的功能进行了鉴定。克隆的gacAxoo基因编码蛋白GacAxoo与其它病原黄单胞菌的同源序列高度保守。GacAxoo是LuxR蛋白家族成员之一,具有磷酸受体结构域(REC)和DNA结合保守结构域(HTH)。用基因标记交换法,构建了△gacAxoo基因缺失突变体。与PXO99A相比,△gac-Axoo的致病性、致敏性、胞外降解酶类活性和嗜铁素产生能力无显著变化,但运动性明显减弱,基因互补可以使之恢复。因此,gacAxoo基因可能参与了Xoo运动性的调控。To demonstrate the novel regulatory pathways mediated in bacterial virulence and motility in Xanthomonas oryzae pv.oryzae（Xoo）,the casual agent of rice bacterial blight,molecular identification and functional characterization of GacAxoo,a response regulator of two-component regulatory system（GacSxoo/GacAxoo） in Xoo,were performed through gene cloning,sequencing and deletion analysis.GacAxoo was found to be highly conserved in plant-pathogenic Xanthomonas spp.and was one of LuxR-like protein family members,which was structurally featured in N-terminal receiver domain and C-terminal DNA-binding domain with a helix-turn-helix motif.△gacAxoo,a gacA deletion mutant,was constructed through the marker exchange.The mutant was further characterized by no significant changes in pathogenicity on rice,induction of hypersensitive response（HR） on tobacco,and activities of xylanase and cellulase compared to PXO99A.However,△gacAxoo was attenuated for motility on the semi-solid medium,which could be restored through complementation of the △gacAxoo mutant by introduction of gacAxoo.Thus,the involvement of GacAxoo in the regulation of bacterial motility of Xoo was proposed.

关 键 词：水稻白叶枯病菌 gacAxoo 双组分调控系统 致病性 运动性 

分 类 号：S435.111.47[农业科学—农业昆虫与害虫防治]