Query: NC_009485:8138314 Bradyrhizobium sp. BTAi1 chromosome, complete genome
Lineage: Bradyrhizobium; Bradyrhizobium; Bradyrhizobiaceae; Rhizobiales; Proteobacteria; Bacteria
General Information: This organism is a photosynthetic rhizobium that is also capable of nitrogen-fixation, the first such example of such an organism. It can form nodules on the legume Aeschynomene indica and was isolated from this plant at the Boyce Thompson Institute for Plant Research in Ithaca, NY. It can form stem and root nodules. The photosynthetic reaction centers are similar to those found in purple photosynthetic bacteria and this microbe aids the plant in carbon metabolism and nitrogen metabolism.
Subject: NC_008380:855246 Rhizobium leguminosarum bv. viciae 3841, complete genome
Lineage: Rhizobium leguminosarum; Rhizobium; Rhizobiaceae; Rhizobiales; Proteobacteria; Bacteria
General Information: This biovar nodulates legumes in the Tribe Viciae (Vicia, Pisum, Lathyrus, Lens). This strain is a spontaneous streptomycin-resistant mutant of strain 300. Nitrogen-fixing plant symbiont. This organism, like other Rhizobia, establishes a symbiotic relationship with a legume plant, providing nitrogen in exchange for a protected environment. The legume roots secrete flavonoids and isoflavonoids which the bacteria recognize and use to turn on genes involved in root nodulation. Many of the root nodulation genes are involved in synthesis and secretion of a nodule inducing signal, a lipochito-oligosaccharide molecule, which the plant recognizes, triggering nodule formation. The bacterium is endocytosed and exists inside a membrane bound organelle, the symbiosome, and fixes nitrogen for the plant cell while the host cell provides carbon compounds for the bacterium to grow on. The nitrogen fixation is important as it obviates the need for expensive and environmentally damaging fertilizer use.