Rhizobial polysaccharides involved in the symbiosis with Glycine max

Polysaccharides produced by the nitrogen-fixing microsymbionts of soybean r epresent a significant commitment of reduced carbon by the organism. This d oes not assure that they play some role in the symbiosis but it would be lo gical if one or more of the types of polysaccharide was important. For exop olysaccharide (EPS) - the extracellular polysaccharide produced in culture, the situation is still confusing and is complicated by the fact that many EPS-negative mutants have complex phenotypes. For "nodule polysaccharide" ( NPS) - the extracellular polysaccharide produced in nodules, the situation is also unclear; extensive studies suggest that NPS does not play a role in the nodule - where it was discovered and is easiest to document. Some role of NPS in the infection process under certain soil conditions is still a p ossibility. For the cyclic P-glucans, recent evidence indicates that these molecules are crucial for the establishment of an effective symbiosis and t his is probably true because of their ability to "disarm" plant defense mec hanisms.