THE BIOSYNTHESIS OF CELL WALL CARBOHYDRATES: GLUCOSE-C14 AS A CELLULOSE PRECURSOR IN WHEAT PLANTS

Abstract

The formation of cellulose in wheat plants has been studied using as precursors glucose-1-C14, sorbitol-1-C14, and succinic acid-2,3-C14, which were administered to the plant aseptically by injection of sterile solutions into the hollow internodes. Glucose obtained by hydrolysis of the cellulose, isolated after the plants had grown for 24 to 48 hr. following the injection of labelled glucose, showed a concentration of at least 50% of the total C14 in carbon-1. When sorbitol was injected most of the carbon-14 was fairly evenly divided between C-1 and C-6, and when succinic acid was used evidence of a comparatively uniform labelling of the glucose was obtained. The results indicate that there is considerable conversion of glucose to cellulose without skeletal rearrangement, and that there is also appreciable cellulose formation from resynthesized glucose. Sorbitol is not an intermediate between glucose and cellulose; it is suggested that it is converted to glucose largely by way of three-carbon fragments.