THE STRUCTURES AND BIOLOGICAL-ACTIVITIES OF THE LIPO-OLIGOSACCHARIDE NODULATION SIGNALS PRODUCED BY TYPE-I AND TYPE-2 STRAINS OF BRADYRHIZOBIUM-JAPONICUM

Bradyrhizobium japonicum produces lipo-oligosaccharide signal molecule s that induce deformation of root hairs and meristematic activity on s oybeans. R japonicum USDA135 (a Type I strain) produces modified chiti n pentasaccharide molecules with either a terminal N-C-16:0- or N-C18: 1-glucosamine with and without an O-acetyl group at C-6 and with 2-O-m ethylfucose linked to C-6 of the reducing N-acetylglucosamine. An addi tional molecule has N-C-16:1-glucosamine and no O-acetyl group. All of these molecules cause root hair deformation on Vicia sativa and Glyci ne soja. The C18:1-containing molecules were tested and found to induc e meristem formation on G. soja. USDA61 (a Type II strain) produces ei ght additional molecules. Five have a carbamoyl group on the terminal N-acylglucosamine. Six have chitin tetrasaccharide backbones. Three ha ve a terminal N-acyl-N-methylglucosaminosyl residue. In four molecules , the reducing-end N-acetylglucosamine is glycosidically linked to gly cerol and has a branching fucosyl, rather than a 2-O-methylfucosyl, re sidue. One molecule has a terminal N-acylglucosamine that has both ace tyl and carbamoyl groups (one each).