RESUMO
Through the use of a single, random 15mer as a primer, between 1 and 12 DNA amplification products were obtained per strain from a selection of 84 Rhizobium and Bradyrhizobium isolates. A principal-coordinate analysis was used to analyse the resulting amplified DNA profiles and it was possible to assign isolates to specific groupings. Within the species Rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped together. Isolates of Rhizobium meliloti and Bradyrhizobium species formed their own clear, specific groups. Although it was possible to identify individual isolates on the basis of differences in their amplified DNA profiles, there was evidence that some amplified segments were conserved among individuals at the biovar and species levels.
Assuntos
DNA Bacteriano/genética , Amplificação de Genes , Polimorfismo Genético/genética , Rhizobiaceae/classificação , Rhizobium/classificação , Sequência de Bases , Dados de Sequência Molecular , Filogenia , Rhizobiaceae/genética , Rhizobiaceae/isolamento & purificação , Rhizobium/genética , Rhizobium/isolamento & purificaçãoRESUMO
The use of single random primers, selected in the absence of target sequence information, has been shown to be effective in producing DNA amplifications that provide fingerprints which are unique to individual organisms. DNA amplification by random priming was applied to the DNA from isolates of Rhizobium leguminosarum biovar trifolii. Amplification products were produced using a number of primers, and the resulting fingerprints allowed strain differentiation. However, the effectiveness of primers was dependent upon length and GC content. It was also possible to amplify DNA directly from cells in culture and in nodule tissue. Lysis of these cells was achieved simply through heat applied in the initial DNA denaturation stage of the thermal reaction. The ability to produce varied amplification patterns from different Rhizobium isolates, especially directly from nodules, gives this method potential for use in examining genetic structures and relationships in Rhizobium populations.