The Role of Rhizobium Meliloti Surface Polysaccharides in Nodule Development

摘要: The soil bacterium Rhizobium meliloti is well known for its symbiosis with Medicago sativa (alfalfa). It induces the development of so called root nodules which are infected by microsymbiont. After colonization nodules, microsymbiont able to fix atmospheric nitrogen. Mutants R. synthesizing altered surface polysaccharides turned out be affected in nodule and, particular, recognition process between two symbiotic partners. Concerning exopolysaccharides, produces acidic exopolysaccharide EPS I necessary infection induced alfalfa (Leigh et al. 1985; Muller 1988). A large gene cluster on second megaplasmid was identified contains 19 genes involved biosynthesis (Fig. 4a). meliloti, addition, has cryptic ability produce a exopolysaccharide, designated II, characterized completely different structure (Glazebrook, Walker 1989; Her 1990). question, whether II can replace during will discussed this article. In we show that mutants deficient induce pseudonodules exhibiting plant defence reactions.