The genome sequence of Rhizobium sp. LPU83, a peculiar rhizobia able to nodulate alfalfa, common bean and Leucaena

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

Bielefeld, Alemania

Simposio; 5th CeBiTec Symposium. New frontiers in microbial genome research.; 2010

CebiTec- Bielefeld University,

Alfalfa is the main forage used in several countries for cattle and animal feeding. Only in Argentina there are over 6 million ha cultivated with alfalfa, where the symbiosis with eficient rhizobia represents a central point to assure the entry of fixed nirogen to agricultural soils. In addition to the association of alfalfa with its N2-fixing symbionts Sinorhizobium meliloti and S. medicae (both completely sequenced), the legume is able to associate with a much less characterizad type of rhizobia represented by strains related to the Rhizobium sp. Or191 initially isolated in the USA (Eardly, et al., 1985, Eardly, et al., 1992, Eardly, et al., 1995) and Rhizobium sp. LPU83 isolated in Argentina (Del Papa et al., 1999). These rhizobia are acid tolerant, have an extended host inefficient for nitrogen-fixation in association with alfalfa. All these features point the Oregon-like rhizobia as a factor of risk in agricultural soils where they co-exist and compete with the efficient symbiont S. meliloti. Because of their peculiar phenotypic and taxonomic characteristics, these rhizobia have attracted the attention of rhizobiologists ever since their original isolation by Eardly et al. (1985). The accumulated evidence strongly supports the concept that these rhizobia are related to both tropical-legume-infecting rhizobia (i. e., the bean-nodulating R. etli) and temperate-legume-infecting rhizobia (i. e., the Medicago-nodulating Sinorhizobia). Thus, the Oregon-like isolates represent a valuable system to better understand the underlying mechanisms of rhizobial diversification and evolution.R. sp. LPU83 was sequenced to understand, at the molecular level, the parasitic character of the Oregon-like rhizobia compared to the eficient S. meliloti and S. medicae.