Identification and analysis of genomic diversity of rhizobia from Sesbania native species from Argentina.

MONTECCHIA, MARCELA S.; PUCHEU, NORMA L.; KERBER, NORMA L; GARCIA, AUGUSTO F.

Los Cocos, Córdoba, Argentina

Congreso; XXIII Reunión Latinoamericana de Rhizobiología; 2007

RELAR

Sesbania species are a group of legumes native to the tropics and subtropics, and diverse rhizobial taxa are known to nodulate Sesbania spp. In Argentina, Sesbania exasperata (Kunth) y S. virgata (Cav.) Pers. are 2 out of 4 Sesbania native species. In this work rhizobia from these species were genotypically and phenotypically characterized. The isolates were characterized by rep-PCR, ARDRA, 16S-23S rDNA IGS-RFLP, 16S rDNA sequencing, plasmid profiles, FAME, utilization of carbon sources and growth conditions (T, pH, salinity, antibiotics). rep-PCR data uncovered a remarkable genomic diversity among the isolates but including a high number of clonemates. Based on 16S rDNA sequence analysis, the microsymbionts of S. virgata can be classified as Azorhizobium doebereinerae, and those from S. exasperata as Rhizobium sp., related to R. giardinii. The Rhizobium sp. strains nodulating S. exasperata probably represents a novel rhizobial species since they show a 16S rDNA sequence similarity with the most closely related species of as low as 97%, in addition to phenotypic differences.