First genomic analysis of the broad-host-range Rhizobium sp. LPU83 strain, a member of the low-genetic diversity Oregon-like Rhizobium sp. group

TORRES TEJERIZO, G.A.; DEL PAPA M. F; DRAGHI, W. O.; LOZANO M.J.; GIUSTI, M. A.; MARTINI, C.; SALAS, E.; SALTO, I.; WIBBERG, D.; SZCZEPANOWSKI, R; WEIDNER S.; SCHLÜTER, A.; LAGARES, A.; PISTORIO, M.

JOURNAL OF BIOTECHNOLOGY

ELSEVIER SCIENCE BV

Lugar: doi:10.1016/j.jbiotec.2011.01.011; Año: 2011 vol. 155 p. 3 - 10

0168-1656

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 thisplant to maximize crop production is therefore an important objective. A fundamental constraint tothis aim emerges when a moderately low soil pH hampers the establishment of an effective symbiosiswith 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 strainsare acid-tolerant, highly competitive for acidic-soil-alfalfa nodulation, but inefficient for biologicalnitrogen fixation with alfalfa. These features position the Oregon-like rhizobia as strains of potentialrisk in agricultural soils compared with the efficient symbiont E. meliloti. Moreover, the collectedgenetic information has revealed that the genomic structure of these rhizobial isolates is complex interms of sequence similarities shared with other rhizobia. Such a "patched" genetic composition hasobviously imposed severe restrictions to the classical taxonomy of these rhizobia. In this review wesummarize the accumulated knowledge about the Oregon-like rhizobia and present a phylogeneticanalysis based on genome sequence data of Rhizobium sp. LPU83 obtained by a high-througthputsequencing on the Genome Sequencer FLX Titanium platform. The accessibility of the completegenomic sequence will release up more experimental possibilities since this information will thenenable biochemical studies as well as proteomics and transcriptomics approaches.