Symbiotic abilities of Sinorhizobium fredii with modified expression of purL.
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.
Xie
Bo
B
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070, Wuhan, People's Republic of China.
Chen
Da-Song
DS
Zhou
Kui
K
Xie
Yu-Qun
YQ
Li
You-Guo
YG
Hu
Guo-Yuan
GY
Zhou
Jun-Chu
JC
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
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D020719:Glucuronides; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C022385:phosphoribosylformylglycinamidine synthetase