<span style="mso-bidi-language:HI">Rhizobial lipopolysaccharide as the receptor in lectin<i>-Rhizobium </i>interaction </span>

Abstract

<span style="mso-bidi-language:HI">Rhizobial specificity was examined on the basis of interaction between legume lectins (peanut, pea and soybean) and different rhizobial species (various bradyrhizobia specific for peanut, P 14-93 and SB16). Legume lectins showed higher affinity towards host-specific <i>Rhizobium </i>and lipopolysaccharides (LPS) isolated from those particular rhizobia. Two LPS mutants of peanut-specific <i>Bradyrhizobium </i>sp. (<i>Arachis</i>)<i> </i>strain GN17 were isolated by Tn5 mutagenesis. These mutants (GN17MI and GNI7M2) were characterized by their higher hydrophobicity with respect to the parent cells. The hexose content in exopolysaccharides. (EPS) and LPS of the mutants was found reduced significantly, whereas 2-keto-3-deoxyoctulosonic acid (Kdo) and uronic acid in LPS were less by 20-times and thrice, respectively in the mutants. Glucose was the major sugar in LPS from all the strains. However, glucosamine appeared only in the mutants. Spectrofluorimetric analysis showed that LPS from GN17Ml mutant interacted most significantly with peanut root agglutinin or lectin (PRA II). The results indicate that LPS on the surface of rhizobial cells is the possible receptor for lectin.

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