title: A new clade of Mesorhizobium nodulating Alhagi sparsifolia.
abstract: We isolated 33 nodule bacteria from the legume Alhagi sparsifolia growing in the desert of northwest China. They fell into three groups by restriction analysis of their rrs (small subunit ribosomal RNA) genes, and these, together with dnaK and dnaJ genes, were sequenced from representative isolates to assess their taxonomic position by phylogenetic analysis. The bacteria in each group belonged to different lineages that might represent three different new Mesorhizobium species, two of which form a novel clade very distinct from other species in the genus. Most A. sparsifolia symbionts harboured closely related nodA and nodC genes forming new lineages. The presence of these closely related symbiosis genes in various genomic backgrounds and the incongruence observed between the different gene phylogenies indicate a history of horizontal gene transfer of symbiosis genes between the A. sparsifolia symbionts.
authors.affiliation: College of Life Sciences, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Northwest A & F University, Yangling Shaanxi 712100, China.
authors.forename: Gehong
authors.initials: G
authors.lastname: Wei
authors.forename: Weimin
authors.initials: W
authors.lastname: Chen
authors.forename: J Peter W
authors.initials: JP
authors.lastname: Young
authors.forename: Cyril
authors.initials: C
authors.lastname: Bontemps
mesh_terms: D000217:Acyltransferases / Q000235:genetics; D020561:Alphaproteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D002681:China; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D007887:Fabaceae / Q000145:classification / Q000382:microbiology*; D022761:Gene Transfer, Horizontal; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics; D009586:Nitrogen Fixation / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013559:Symbiosis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D000217:Acyltransferases; C060770:NodA protein, Rhizobiales; D017351:N-Acetylglucosaminyltransferases; C060771:NodC protein, Rhizobiales