Rhizobium tropiciRhizobiumPhaseolusFabaceaePlants, MedicinalNitrogen FixationRhizobium leguminosarumAgricultural InoculantsSinorhizobiumRhizobiaceaeRoot Nodules, PlantRhizobium etliSymbiosisGenes, BacterialMolecular Sequence DataDNA, BacterialPlant RootsBacterial ProteinsRNA, Ribosomal, 16SSinorhizobium melilotiPlant Root NodulationPhylogenyMedicago sativaSequence Analysis, DNA