A Study on the Prevalence of Bacteria that Occupy Nodules

JORGE ANGELINI, FERNANDO IBÁÑEZ, TANIA TAURIAN, MARÍA LAURA TONELLI, LUCIO VALETTI, ADRIANA FABRA.

CURRENT MICROBIOLOGY

SPRINGER

Año: 2011 vol. 62 p. 1752 - 1759

0343-8651

Abstract In this study, bacteria hosted in root nodules of single plants of legume Arachis hypogaea L. (peanut) cv Tegua Runner growing at field were isolated. The collection of nodule isolates included both fast and slow growing strains. Their genetic diversity was assessed in order to 15 identify the more frequently rhizobial strain associated to nodules from single plants. Molecular fingerprinting of nodular isolates indicated heterogeneity, absence of a dominant genotype and, therefore, of a unique strains highly competitive. Efficient nitrogen-fixing isolates were identified as Bradyrhizobium sp. by phylogenetic analysis of the sequences of their 16S rRNA genes. The genetic diversity of 68 peanut nodulating isolates from all the collected plants was also analyzed. Considering their ERIC-PCR profiles, they were grouped in eighteen different OTUs for 60% similarity cut-off. Results obtained in this study indicate that the genetic diversity of rhizobia 26 occupying nodules from single plant is very high, without the presence of a dominant strain. Therefore, the identification of useful peanut rhizobia for agricultural purposes requires strongly the selection, among the diverse population, of a very competitive genotype in combination with a high-symbiotic performance.