Characterization of symbiotic genes and plasmid profiles of peanut rhizobia from Cordoba soils, Argentina

IBAÑEZ, F., TAURIAN, T., FABRA, A.

Villa Giardino, Córdoba

Jornada; XV Jornadas Científicas de la Sociedad de Biología de Córdoba; 2005

Sociedad de Biología de Córdoba

Abstract Arachis hypogaea L. (peanut) is an important crop all over the world that provides several food products. Ninety four percent of the national peanut production is concentrated in the center-south region of Cordoba province. With the purpose of analyzing the diversity of native rhizobia that nodulate this legume, a representative collection of peanut symbionts of this region was obtained. Previous studies that included the determination of the partial 16S rRNA gene sequence demonstrated that the population of native peanut symbionts of Cordoba soils is highly heterogeneous and includes slow and fast-growing rhizobia. In order to advance in the characterization of the available collection of fast growing peanut rhizobia, we determine the nodC gene sequence and the plasmid profiles of two of these isolates. Nodulation nodC gene of NET30 and NCHA22 isolates was amplified by using specific primers (Laguerre et al, 2001) and sequenced. Sequence analysis and phylogenetic trees were performed by using the BLASTN algorithm and the CLUSTALX software. Plasmid profiles were determined by Eckhardt type gels (Eckhardt, 1978; Wheatcroft et al., 1990). The phylogenetic relations established for these isolates by nodC gene sequencing was not consistent with the data obtained from the 16S rRNA gene sequencing. The analysis of plasmid profiles revealed that both isolates share a plasmid of similar electrophoretic mobility. The results obtained suggest us that native peanut rhizobia constitute a heterogeneous group that gained the ability to nodulate this legume by horizontal transference of genes.