Análises de restrição do DNA Ribossomal Amplificado (ARDRA) em estudos de diversidade intra-específica de Azospirillum amazonense isolado de diferentes espécies de brachiaria.

ABSTRACT: The limitation of nitrogen is considered one of the most important factors for the Brazilian pastures degradation. However there are evidences that pastures formed by some species of Brachiaria could be benefited by the biological nitrogen fixation (BNF) guaranteeing a higer longevity to these pastures. Previus studies showed that the diazotrophic bacteria found inassociation with Brachiaria were mainly from the Azospirillum amazonense specie. Since associations between these microorganisms and plants are generally conditioned by the vegetation, it is possible that different Brachiaria genotypes can exercise a selective effect on the Azospirillum populations. The aim of this work was to study the intra-specific diversity of A. amazonense isolates and to establish possible influences of different Brachiaria species and edaphoclimatic conditions. The characterisation of the diversity among these isolates was conducted using restriction analysis of different portions of the rDNA. This methodology was capable to show important information regarding the diversity among the studied isolates of A. amazonense, showing possible effects of the environment and Brachiaria species