Characterization and symbiotic importance of acidic extracellular polysaccharides of Rhizobium sp. strain GRH2 isolated from acacia nodules.

AUTOR(ES)

Lopez-Lara, I M

RESUMO

Rhizobium sp. wild-type strain GRH2 was originally isolated from root nodules of the leguminous tree Acacia cyanophylla and has a broad host range which includes herbaceous legumes, e.g., Trifolium spp. We examined the extracellular exopolysaccharides (EPSs) produced by strain GRH2 and found three independent glycosidic structures: a high-molecular-weight acidic heteropolysaccharide which is very similar to the acidic EPS produced by Rhizobium leguminosarum biovar trifolii ANU843, a low-molecular-weight native heterooligosaccharide resembling a dimer of the repeat unit of the high-molecular-weight EPS, and low-molecular-weight neutral beta (1,2)-glucans. A Tn5 insertion mutant derivative of GRH2 (exo-57) that fails to form acidic heteropolysaccharides was obtained. This Exo- mutant formed nitrogen-fixing nodules on Acacia plants but infected a smaller proportion of cells in the central zone of the nodules than did wild-type GRH2. In addition, the exo-57 mutant failed to nodulate several herbaceous legume hosts that are nodulated by wild-type strain GRH2.

Documentos Relacionados

• Characterization of polysaccharides of Rhizobium meliloti exo mutants that form ineffective nodules.
• Essentiality of Boron for Symbiotic Dinitrogen Fixation in Pea (Pisum sativum) Rhizobium Nodules.
• Three Replicons of Rhizobium sp. Strain NGR234 Harbor Symbiotic Gene Sequences
• Partial Chemical and Physical Characterization of Two Extracellular Polysaccharides Produced by Marine, Periphytic Pseudomonas sp. Strain NCMB 2021
• Requirement of succinate dehydrogenase activity for symbiotic bacteroid differentiation of Rhizobium meliloti in alfalfa nodules.