Extracellular polysaccharides and polysaccharide-containing biopolymers from Azospirillum species: properties and the possible role in interaction with plant roots.

This paper reviews the results obtained in studies of the extracellular polysaccharides, lipopolysaccharide-protein complexes, polysaccharide-lipid complexes, lipopolysaccharides, and O-specific polysaccharides from bacteria of the genus Azospirillum. On the basis of present knowledge, the possible roles of the extracellular polysaccharides and polysaccharide-containing complexes of azospirilla in interaction with the roots of plants are discussed. Some pieces of evidence are considered in light of the lectin hypothesis originally proposed for the legume-Rhizobium symbiosis. In the context of these views of Azospirillumcereal associative pairs, a key process at the early stages of the interaction is the specific reaction of cereal root lectins with the extracellular polysaccharide components, containing N-acetyl-D-glucosamine as part of their structure.