title: Symbiotic abilities of Sinorhizobium fredii with modified expression of purL.
abstract: Previous reports showed that a transposon-induced PurL- mutant of Sinorhizobium fredii induced pseudonodules on Glycine max and the addition of 5-aminoimidazole-4-carboxamide-riboside or adenine to the plant could not restore the mutant to establish effective symbiosis. To gain a better understanding of the impact of the purL gene on symbiosis formation, we measured the effect of modified expression of this gene on the symbiotic abilities of S. fredii on soybean (G. max). A 1.98-kb in-frame deletion mutant in the purL gene of S. fredii was constructed. Transcriptional modification of the purL gene was conducted using several promoters such as those of lac, nifH, nifQ, and fixN. It was found that reduced expression of purL gene or suitable symbiotic expression of purL (such as with the promoter nifH or nifQ) can efficiently establish symbiosis of S. fredii on G. max without the exogenous supplementation of any adenine or purine precursor; at least a minimal level of expression of purL is essential for effective symbiosis with soybean.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070, Wuhan, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xie
authors.forename: Da-Song
authors.initials: DS
authors.lastname: Chen
authors.forename: Kui
authors.initials: K
authors.lastname: Zhou
authors.forename: Yu-Qun
authors.initials: YQ
authors.lastname: Xie
authors.forename: You-Guo
authors.initials: YG
authors.lastname: Li
authors.forename: Guo-Yuan
authors.initials: GY
authors.lastname: Hu
authors.forename: Jun-Chu
authors.initials: JC
authors.lastname: Zhou
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D020719:Glucuronides / Q000378:metabolism; D016254:Mutagenesis, Insertional; D009586:Nitrogen Fixation / Q000235:genetics / Q000502:physiology; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D010957:Plasmids; D016133:Polymerase Chain Reaction; D042181:Sinorhizobium fredii / Q000201:enzymology* / Q000235:genetics; D013025:Glycine max / Q000378:metabolism / Q000382:microbiology*; D013559:Symbiosis / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D020719:Glucuronides; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C022385:phosphoribosylformylglycinamidine synthetase