RESUMO

Fifteen isolates from several nodulated tropical legumes from Puerto Rico (USA) were characterised by their phenotypic, molecular and symbiotic features. The identification of isolates was based on a polyphasic approach, including phenotypic characteristics, 16S rRNA sequencing, Low molecular weight (LMW) RNA profiles, Two Primers-RAPD patterns, and restriction patterns from 16S rDNA molecules. Despite of the variety of hosts included in this study the 15 isolates were separated into only two groups that corresponded to Rhizobium gallicum and Rhizobium tropici. This work shows that R. gallicum and R. tropici nodulate legume plants, such as Sesbania, Caliandra, Poitea, Piptadenia, Neptunia and Mimosa species, that were not previously considered as hosts for these rhizobia. Moreover, some of these host plants can be nodulated by both species. The results confirm the great promiscuity of R. tropici and also support the hypothesis that the species R. gallicum may be native from America or cosmopolitan and worldwide spread.

Assuntos

Fabaceae/microbiologia , Fixação de Nitrogênio , Rhizobium tropici/classificação , Rhizobium/classificação , Clima Tropical , Proteínas de Bactérias , DNA Ribossômico/análise , Dados de Sequência Molecular , N-Acetilglucosaminiltransferases/genética , Fenótipo , Polimorfismo de Fragmento de Restrição , Porto Rico , RNA Ribossômico 16S/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Rhizobium/genética , Rhizobium/crescimento & desenvolvimento , Rhizobium tropici/genética , Rhizobium tropici/crescimento & desenvolvimento , Análise de Sequência de DNA , Simbiose