title: Following phylogenetic tracks of Astragalus cicer microsymbionts.
abstract: A multilocus phylogenetic approach was applied to elucidate the phylogeny of Astragalus cicer rhizobia derived from Poland, Ukraine, and Canada. The strains selected for the studies represented three main geographically different phenons of these bacteria. Phylogenetic analyses were performed with three chromosomal housekeeping loci (16S rRNA, atpD, glnII) and three symbiotic genes located on a plasmid (nodA, nodC, nifH). The "core" and "auxiliary" gene trees revealed that A. cicer nodule isolates were intermingled with the strains of Mesorhizobium species, which implies that they are descendents of the same ancestor as mesorhizobia and fall into the Mesorhizobium genus. The noted congruence of the housekeeping and symbiotic gene phylogenies of A. cicer microsymbionts indicates that sym loci are transferred to these bacteria through vertical transmission without a significant participation of intergeneric horizontal gene spread. All the three sym gene sequences of the Polish and Ukrainian A. cicer nodule isolates were more closely related to one another than to the corresponding sequences of the Canadian isolates. The phylogeographic patterns of the sym genes of intercontinental strains point to their relatively long, separate, evolutionary history.
authors.affiliation: Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Wdowiak-Wróbel
authors.forename: Wanda
authors.initials: W
authors.lastname: Małek
mesh_terms: D020561:Alphaproteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics; D002170:Canada; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology* / Q000502:physiology; D005843:Geography; D008969:Molecular Sequence Data; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D011044:Poland; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis; D014455:Ukraine
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S