Disruption of nifA Gene Influences Multiple Cellular Processes in Sinorhizobium meliloti  

苜蓿中华根瘤菌nifA基因突变影响多种细胞学过程(英文)

作　　者：巩子英[1,2] 朱家璧[1] 俞冠翘[1] 邹华松[1] 

机构地区：[1]中国科学院上海生命科学研究院,上海植物生理生态研究所植物分子遗传国家重点实验室,上海200032 [2]中国科学院研究生院

出　　处：《Journal of Genetics and Genomics》2007年第9期783-789,共7页遗传学报（英文版）

基　　金：This work was supported by the National Grand Fundamental Research 973 Project (No. 2001CB108901);National Science Foundation of China (No. 30400267).

摘　　要：Sinorhizobium meliloti nifA is important in fixing nitrogen during symbiosis. A nifA null mutant induces small white invalid nodules in the roots of host plant. The additional phenotypic alterations associated with the disruption of the nifA gene are reported in this study. Under a free-living state, S. meliloti nifA mutant reduces its ability to swarm on a half-solid plate. Interestingly, the AHL （Acylhomoserine lactones） contents in the nifA mutant are lower than that of the wild type during the lag phase, whereas it is reversed in the logarithmic and stationary phases. Quantitative spectrophotometric assays reveal that the total amount of extracellular proteins of the nifA mutant are lower than that of the wild type. In addition, the mutant abolishes its nodulation competitive ability during symbiosis. These findings indicate that NifA plays a regulatory role in multiple cellular processes in S. meliloti.苜蓿中华根瘤菌nifA基因在共生固氮过程中担负着调控功能,nifA突变株Rm1354在宿主植物的根部诱导白色无效根瘤。本文报道Rm1354在自生状态下的表型变化。nifA的突变导致根瘤菌在半固体培养基上泳动变慢,胞外蛋白含量降低。有趣的是,Rm1354在延宕期间高丝氨酸内酯含量比野生型低,在指数期和静止期却比野生型高。另外,突变株Rm1354的竞争结瘤能力也大大减弱。这些结果揭示了苜蓿中华根瘤菌nifA基因对许多细胞学过程都有调控作用。

关 键 词：Sinorhizobium meliloti NIFA AHLs extracelluar protein SWARM 

分 类 号：S154.3[农业科学—土壤学]