THE BIOSYNTHESIS OF CELL WALL CARBOHYDRATES: II. FORMATION OF CELLULOSE AND XYLAN FROM LABELED MONOSACCHARIDES IN WHEAT PLANTS

Abstract

D-Glucose-1-C14, D-allose-1-C14, D-ribose-1-C14, D-xylose-1-C14, and sedoheptulose-2-C14 were administered to Thatcher wheat plants. The cellulose and xylan were isolated after a 5–48 hr. period of metabolism, and converted to glucose and xylose, respectively. The distribution of C14 in both glucose and xylose was then determined by fermentation with Lcuconostoc mesentcroides. Glucose was found to be a better precursor of both cellulose and xylan than any of the other sugars. The distribution of C14 in the products strongly suggested that the main route for synthesis of the xylose units of xylan was by removal of carbon-6 from a hexose and that pentoses were converted to xylan only through a hexose intermediate.