Rhizobium sp BR816 produces a complex mixture of known and novel lipochitooligosaccharide molecules

Rhizobial lipochitooligosaccharide (LCO) signal molecules induce various pl ant responses, leading to nodule development. We report here the LCO struct ures of the broad-host range strain Rhizobium sp. BR816. The LCOs produced are all pentamers, carrying common C-18:1 or C-18:0 fatty acyl chains, N-me thylated and C-6 carbamoylated on the nonreducing terminal N-acetylglucosam ine and sulfated on the reducing/terminal residue. A second acetyl group ca n be present on the penultimate N-acetylglucosamine from the nonreducing te rminus. Two novel characteristics were observed: the reducing/terminal resi due can be a glucosaminitol (open structure) and the degree of acetylation of this glucosaminitol or of the reducing residue can vary.