Direct Evidence for Translocation of Sucrose in Sugarcane Leaves and Stems

Abstract

By supplying sucrose labeled only in the fructose moiety to leaves, then examining the distribution of radioactivity in translocated compounds, conclusive evidence is obtained that the sucrose molecule remains intact during translocation through the vascular tissue of the leaf, sheath and stem of the sugarcane plant. Radioactive glucose and fructose were also supplied to leaves and the distribution of C14 in translocated compounds examined. Sucrose is demonstrated as the predominant component of translocated photosynthate. The translocation velocity for photo-synthate and supplied sugars was between 4 and 6 cm/minute. Randomization of label occurred duringthe movement of fructosyl-U-C14 sucrose from the vascular tissue into the parenchyma cells of th stalk indicating that sucrose is broken down and resynthesized during movement into storage.