Rhizobium leguminosarumRhizobiumRhizobium etliNitrogen FixationSymbiosisSinorhizobium melilotiFabaceaePeasPlants, MedicinalVicia sativaViciaGenes, BacterialTrifoliumBacterial ProteinsBacteriaRoot Nodules, PlantMolecular Sequence DataRhizobiaceaeMedicagoCosmidsDNA, BacterialGene Expression Regulation, BacterialLens PlantPlant Root NodulationRhizobium tropiciPlasmidsPlant RootsHydrogenaseLipid APolysaccharides, Bacterial