荧光假单胞菌2P24中gidA基因对PcoI/PcoR群体感应系统的影响  

Effect of the gidA gene on the PcoI/PcoR quorum-sensing system in Pseudomonas fluorescens 2P24

作　　者：张伟[1] 张博[1] 吴小刚[1] 张力群[1] 

机构地区：[1]中国农业大学植物病理系,北京100193

出　　处：《微生物学通报》2014年第2期258-266,共9页Microbiology China

基　　金：国家863计划项目(No.2011AA10A205);国家自然科学基金项目(No.31071725;31272082)

摘　　要：【目的】荧光假单胞菌(Pseudomonas fluorescens)2P24中PcoI/PcoR群体感应系统是调控生物膜形成与植物根部定殖能力的重要元件,同时该系统也受到多种上游因子的调控。利用遗传学方法研究P.fluorescens 2P24中gidA基因对群体感应系统的调控作用。【方法】将群体感应信号合成基因pcoI的转录报告质粒p970km-pcoIp转入菌株2P24和gidA基因突变体中以检测gidA对pcoI基因表达的影响,并利用报告菌Agrobacterium tumefaciens NTL4(pZLR4)测定菌株2P24及其衍生菌的信号N-乙酰高丝氨酸内酯(AHL)产量。【结果】gidA基因突变后pcoI基因的转录表达和AHL产量与野生型2P24相比显著降低。gidA基因突变体的游动能力没有受到明显的影响,但生物膜的形成显著低于野生型和互补菌株。小麦根部定殖实验表明,温室条件下gidA突变菌株在灭菌土和自然土中对小麦根尖和根围的定殖量较野生型和互补菌显著减少。此外,突变gidA基因并不影响菌株在LB培养基中的生长,但以葡萄糖、蔗糖、果糖、甘油、半乳糖、阿拉伯糖、甘露糖、木糖或山梨醇为唯一碳源时,gidA突变体的生长受到明显的抑制。【结论】GidA对假单胞菌2P24中的PcoI/PcoR群体感应系统、生物膜形成、定殖和碳源利用具有显著的正调控作用。[Objective] The PcoI/PcoR quorum-sensing （QS） system in Pseudomonas fluorescens 2P24, important for biofilm formation and plant root colonization, was influenced by multiple upstream regulatory elements. In this study, the effect of the gidA gene on QS system was studied by genetic analysis. [Methods] The transcriptional reporter of pcoI gene on plasmid p970km-pcoIp was used to monitor the pcoI expression in the wild type strain 2P24 and its gidA gene mutant. Agrobacterium tumefaciens NTL4 （pZLR4） was used as the reporter strain to detect QS signal molecule N-acyl-homoserine lactone （AHL） production. [Results] Mutation of the gidA gene in strain 2P24 did not influence its swimming capacity, but significantly decreased pcoI transcription and AHL production. Furthermore, the biofilm formation and the colonization on the wheat rhizosphere and tips in both the gnotobiotic and natural soil were remarkably reduced in the gidA gene mutant compared with the wild type and the complementary strain. Although the gidA mutation in strain 2P24 did not affect the bacterial growth in the rich medium （LB）, it significantly affected the utilization of multiple carbon sources in the minimal medium, including glucose, sucrose, fructose, glycerol, galactose, arabinose, mannose, xylose and sorbitol. [Conclusion] These results suggest that GidA function as a globle regulatory element influenced the PcoI/PcoR QS system, biofilm formation, colonization ability and carbon source utilization in P. fluorescens 2P24.

关 键 词：荧光假单胞菌 群体感应 GidA 

分 类 号：S432.4[农业科学—植物病理学] Q93[农业科学—农业昆虫与害虫防治]