title: Genetic Analysis Reveals the Essential Role of Nitrogen Phosphotransferase System Components in Sinorhizobium fredii CCBAU 45436 Symbioses with Soybean and Pigeonpea Plants.
abstract: The nitrogen phosphotransferase system (PTS(Ntr)) consists of EI(Ntr), NPr, and EIIA(Ntr). The active phosphate moiety derived from phosphoenolpyruvate is transferred through EI(Ntr) and NPr to EIIA(Ntr). Sinorhizobium fredii can establish a nitrogen-fixing symbiosis with the legume crops soybean (as determinate nodules) and pigeonpea (as indeterminate nodules). In this study, S. fredii strains with mutations in ptsP and ptsO (encoding EI(Ntr) and NPr, respectively) formed ineffective nodules on soybeans, while a strain with a ptsN mutation (encoding EIIA(Ntr)) was not defective in symbiosis with soybeans. Notable reductions in the numbers of bacteroids within each symbiosome and of poly-β-hydroxybutyrate granules in bacteroids were observed in nodules infected by the ptsP or ptsO mutant strains but not in those infected with the ptsN mutant strain. However, these defects of the ptsP and ptsO mutant strains were recovered in ptsP ptsN and ptsO ptsN double-mutant strains, implying a negative role of unphosphorylated EIIA(Ntr) in symbiosis. Moreover, the symbiotic defect of the ptsP mutant was also recovered by expressing EI(Ntr) with or without the GAF domain, indicating that the putative glutamine-sensing domain GAF is dispensable in symbiotic interactions. The critical role of PTS(Ntr) in symbiosis was also observed when related PTS(Ntr) mutant strains of S. fredii were inoculated on pigeonpea plants. Furthermore, nodule occupancy and carbon utilization tests suggested that multiple outputs could be derived from components of PTS(Ntr) in addition to the negative role of unphosphorylated EIIA(Ntr).
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison.
authors.forename: Yue Zhen
authors.initials: YZ
authors.lastname: Li
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison.
authors.forename: Xue Ying
authors.initials: XY
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison.
authors.forename: Jian
authors.initials: J
authors.lastname: Jiao
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison.
authors.forename: Wen Xin
authors.initials: WX
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, and Rhizobium Research Center, China Agricultural University, Beijing, ChinaUniversity of Wisconsin-Madison cftian@cau.edu.cn.
authors.forename: Chang Fu
authors.initials: CF
authors.lastname: Tian
mesh_terms: D036561:Cajanus / Q000382:microbiology* / Q000502:physiology; D017353:Gene Deletion; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation; D010710:Phosphates / Q000378:metabolism; D010728:Phosphoenolpyruvate / Q000378:metabolism; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D053204:Root Nodules, Plant / Q000382:microbiology; D042181:Sinorhizobium fredii / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D013025:Glycine max / Q000382:microbiology* / Q000502:physiology; D013559:Symbiosis
chemical_list: D010710:Phosphates; D010728:Phosphoenolpyruvate; D010770:Phosphotransferases; D009584:Nitrogen