title: First genomic analysis of the broad-host-range Rhizobium sp. LPU83 strain, a member of the low-genetic diversity Oregon-like Rhizobium sp. group.
abstract: Alfalfa (Medicago sativa) is the most cultivated forage legume for cattle and animal feeding, occupying about 32 million hectares over the world. Management of the N₂-fixing symbiosis of this plant to maximize crop production is therefore an important objective. A fundamental constraint to this aim emerges when a moderately low soil pH hampers the establishment of an effective symbiosis with indigenous and/or inoculated rhizobia. Besides the association of alfalfa with Ensifer (Sinorhizobium) meliloti, this legume is able to establish a symbiosis with Ensifer (Sinorhizobium) medicae and with less characterized types of rhizobia, such as the Oregon-like strains, Rhizobium sp. Or191 initially isolated in the USA, and the Rhizobium sp. LPU83 strain, from Argentina. These strains are acid-tolerant, highly competitive for acidic-soil-alfalfa nodulation, but inefficient for biological nitrogen fixation with alfalfa. These features position the Oregon-like rhizobia as strains of potential risk in agricultural soils compared with the efficient symbiont E. meliloti. Moreover, the collected genetic information has revealed that the genomic structure of these rhizobial isolates is complex in terms of sequence similarities shared with other rhizobia. Such a "patched" genetic composition has obviously imposed severe restrictions to the classical taxonomy of these rhizobia. In this work we summarize the accumulated knowledge about the Oregon-like rhizobia and present a phylogenetic analysis based on genome sequence data of Rhizobium sp. LPU83 obtained by a high-throughput sequencing on the Genome Sequencer FLX Titanium platform. The accessibility of the complete genomic sequence will release up more experimental possibilities since this information will then enable biochemical studies as well as proteomics and transcriptomics approaches.
authors.affiliation: IBBM (Instituto de Biotecnología y Biología Molecular), CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, (1900) La Plata, Argentina.
authors.forename: Gonzalo Torres
authors.initials: GT
authors.lastname: Tejerizo
authors.forename: María Florencia
authors.initials: MF
authors.lastname: Del Papa
authors.forename: Walter
authors.initials: W
authors.lastname: Draghi
authors.forename: Mauricio
authors.initials: M
authors.lastname: Lozano
authors.forename: María de Los Ángeles
authors.initials: Mde L
authors.lastname: Giusti
authors.forename: Carla
authors.initials: C
authors.lastname: Martini
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Salas
authors.forename: Ileana
authors.initials: I
authors.lastname: Salto
authors.forename: Daniel
authors.initials: D
authors.lastname: Wibberg
authors.forename: Rafael
authors.initials: R
authors.lastname: Szczepanowski
authors.forename: Stefan
authors.initials: S
authors.lastname: Weidner
authors.forename: Andreas
authors.initials: A
authors.lastname: Schlüter
authors.forename: Antonio
authors.initials: A
authors.lastname: Lagares
authors.forename: Mariano
authors.initials: M
authors.lastname: Pistorio
mesh_terms: D014644:Genetic Variation; D016680:Genome, Bacterial; D023281:Genomics / Q000379:methods*; D000455:Medicago sativa / Q000382:microbiology; D009586:Nitrogen Fixation / Q000235:genetics; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics; D012231:Rhizobium / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D020579:Sinorhizobium / Q000235:genetics; D013559:Symbiosis / Q000235:genetics