Symbiotic host specificity between leguminous plants and rhizobia is determined by substituted and acylated glucosamine oligosaccharide signals.
Rhizobia are nitrogen-fixing bacteria which invade root hairs of leguminous plants and induce, in a specific manner, the formation of root nodules in which they fix nitrogen. The early steps of the symbiosis can be considered as a reciprocal molecular communication between the two partners. Initially, the plant excretes a gene inducer which stimulates the expression of bacterial nodulation genes. These nodulation genes are responsible for the synthesis of extracellular host-specific signals, called nodulation factors. The bacterial nodulation factors were isolated and structurally identified as substituted and N-acylated chitin oligosaccharides. These prokaryotic lipo-oligosaccharide signals play a key role in the symbiosis by controlling the host specificity of the bacteria. They constitute a new class of signalling molecules able to elicit nodule organogenesis in leguminous plants in the absence of bacteria.
Lerouge
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Centre Régional de Spectroscopie, URA-CNRS 464, Université de Rouen, Mont Saint Aignan, France.
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D007887:Fabaceae / Q000382:microbiology / Q000502:physiology*; D005798:Genes, Bacterial; D005944:Glucosamine / Q000378:metabolism*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D010946:Plants, Medicinal; D012230:Rhizobiaceae / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D013045:Species Specificity; D013559:Symbiosis
D009844:Oligosaccharides; D005944:Glucosamine