Sinorhizobium melilotiSymbiosisNitrogen FixationSinorhizobiumMedicago sativaSinorhizobium frediiMedicago truncatulaMedicagoPlant Root NodulationBacterial ProteinsRoot Nodules, PlantGene Expression Regulation, BacterialRhizobiumRhizobiaceaeGenes, BacterialPlant RootsPolysaccharides, BacterialMolecular Sequence DataFabaceaeRhizobium leguminosarumDNA, BacterialMelilotusSequence Analysis, DNAPhylogenyGenome, BacterialLuteolinAphidsMutagenesis, Insertional