α-d-Mannopyranosyl-(1→4)-α-d-glucuronopyranosyl-(1→2)-myo-inositol, a new and unusual oligosaccharide from cultured rose cells

Abstract

Abstract Cell-suspension cultures of rose (Rosa sp.) accumulated approximately micromolar concentrations of a novel, extracellular, non-reducing trisaccharide, characterised here as α- d -mannopyranosyl-(1→4)-α- d -glucuronopyranosyl-(1→2)-myo-inositol (MGI). Acid hydrolysis of [glucuronic acid-14C]MGI, isolated after incubation of the cells with d -[6-14C]glucuronic acid, readily yielded [14C]glucuronic acid-inositol, which was relatively resistant to further hydrolysis, as revealed by chromatography and electrophoresis. The complete structure and stereochemistry of MGI was elucidated using one and two dimensional NMR spectroscopic techniques. The structure of MGI suggests a biosynthetic origin from a membrane-bound glycophosphosphingolipid (GPS). We propose that GPSs represent a hitherto unrecognised source of oligosaccharin signalling molecules in plants.