title: Genetic diversity and biogeography of rhizobia associated with Caragana species in three ecological regions of China.
abstract: Twenty-two genospecies belonging mainly to Mesorhizobium, and occasionally to Rhizobium and Bradyrhizobium, were defined among the 174 rhizobia strains isolated from Caragana species. Highly similar nodC genes were found in the sole Bradyrhizobium strain and among all the detected Mesorhizobium strains. A clear correlation between rhizobial genospecies and the eco-regions where they were isolated was found using homogeneity analysis. All these results demonstrated that Caragana species had stringently selected the rhizobia symbiotic genotype, but not the genomic background; lateral transfer of symbiotic genes from Mesorhizobium to Bradyrhizobium and among the Mesorhizobium species has happened in the Caragana rhizobia; and biogeography of Caragana rhizobia exists. Furthermore, a combined cluster analysis, based upon the patterns obtained from amplified 16S rRNA gene and 16S-23S intergenic spacer restriction analyses, BOX PCR and SDS-PAGE of proteins, was reported to be an efficient method to define the genospecies.
authors.affiliation: The State Key Laboratory for Agrobiotechnology/Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Yang Li
authors.initials: YL
authors.lastname: Lu
authors.forename: Wen Feng
authors.initials: WF
authors.lastname: Chen
authors.forename: En Tao
authors.initials: ET
authors.lastname: Wang
authors.forename: Su Hua
authors.initials: SH
authors.lastname: Guan
authors.forename: Xue Rui
authors.initials: XR
authors.lastname: Yan
authors.forename: Wen Xin
authors.initials: WX
authors.lastname: Chen
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics; D032602:Caragana / Q000382:microbiology*; D002681:China; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D022761:Gene Transfer, Horizontal; D014644:Genetic Variation; D005843:Geography; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics; D010802:Phylogeny; D020543:Proteome / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012230:Rhizobiaceae / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D020543:Proteome; D012336:RNA, Ribosomal, 16S; D017351:N-Acetylglucosaminyltransferases; C060771:NodC protein, Rhizobiales