Tolerance to salinity and alkalinity of rhizobia isolates from the Salado River Basin: a sustainable alternative to improve the quality of the inoculants for Lotus tenuis in this region

BERGOTTINI VM; CASTAGNO LN; PAZ RC; RUIZ OA; ESTRELLA MJ

Lotus Newsletter

INIA La Estanzuela

Lugar: Colonia; Año: 2008 vol. 38 p. 51 - 52

1510-7809

The Salado river Basin (SRB) is the most important area for cattle ranch production in Argentina. This activity is based on the use of natural pastures because the edaphic and climatic conditions restrict the implantation and persistence of”traditional legumes”in saline-alkaline lowlands (30% of the total area). L. tenuis is an exotic legume well adapted to these conditions, but in spite of its successful naturalization, the survival of this species during the seedling stage is limited and is a critical step for further implantation (Miñón et al., 1990). With the aim to improve seedling survival and forage quality of this legume, the genetic diversity of native rizobia that stablish symbiosis with L. tenuis was evaluated, for further selection of isolates with a better symbiotic efficiency than commercial inoculants in saline soils. A high genetic diversity was found among the rizobia of the SRB (Estrella et al., 2007). The symbiotic performance of one native isolate was superior to that strains recommended for commercial formulations of inoculants tested under control and salt stress conditions. RFLP analysis of 16S rDNA genes of native isolates with better symbiotic performance revealed that the taxonomy of Lotus tenuis symbionts in not only restricted to Mesorhizobium loti species, the type specie to L. tenuis and L. corniculatus (Saeki and Kouchi. 2000), and can involve others species and genus. It can be concluded that populations of rizobia in soils of the SRB are a source of genetic and symbiotic variability that can be used to obtain high quality inoculants for L. tenuis.ReferencesMIÑÓN D.P., SEVILLA G.H., MONTES L. and FERNANDEZ O. 1990. Lotus tenuis: Leguminosa forrajera para la Pampa Deprimida. [Lotus tenuis: forage legume for Pampa Deprimida.] Boletín Técnico Estación Experimental Agropecuaria Balcarce, Nº 98, 8. [In Spanish]ESTRELLA M.J., CASTAGNO L.N., MUÑOZ S., CASSAN P., RUIZ O.A., OLIVARES J., SOTO M.J. and SANJUAN J. 2007. Taxonomic, symbiotic and physiological evaluation of symbionts from L. tenuis to perform inoculants of high quality in the Salado River Basin. RELAR, XXIII Reunión Latinoamericana de Rizobiología. Los Cocos, Argentina. 2007. (Abstracts)SAEKI, K. and KOUCHI H. 2000. The Lotus Symbiont, Mesorhizobium loti: Molecular Genetic Techniques and Application. Journal of Plant Research, 113, 457-465.AcknowledgementsThis work was supported by UE-FP6-517617 (LOTASSA).1Estrella, MJ is a Researcher of the CIC (Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Argentina).