Structure of the Primary Cell Walls of Suspension-Cultured Rosa glauca Cells

Abstract

Cell walls of suspension-cultured cells of R. glauca were fractionated by 2 different extraction procedures. The 1st involved a stepwise fractionation scheme based on alkaline extraction. The 2nd took advantage of the powerful cellulose solvent system N-methylmorpholine N-oxide/dimethyl sulfoxide which is capable of solubilizing whole cell walls. From the analytical composition of each solubilized fraction and of the corresponding residues, the fate of each type of cell wall polysaccharide constituent was followed at each step of the extraction scheme and the mode of action of the extractant was interpreted. Although the 2 fractionation procedures were very different, they yielded very similar cellulosic complex residues and extracts, thus delimiting 2 blocks of polysaccharides in the cell wall. The cellulose residues still comprised uronic acid-containing polysaccharides and hemicelluloses in association with cellulose. Graded acid hydrolysis provided evidence for the central role of a homogalacturonan core interconnecting xyloglucans and arabinogalactans. A tentative model showing the possible interaction existing between the constituent polysaccharides still associated to cellulose after alkaline extraction is presented. Hydrogen bonding between xyloglucan and cellulose is confirmed and glycosidic linkages between xyloglucans and pectic polymers are suggested.