The Uptake of Sucrose By Bean Leaf Tissue I. The General Nature of The Uptake

Abstract

Several techniques were evaluated and used to obtain general information on the nature of sucrose uptake. A simple, rapid method for the estimation of sucrose uptake by leaf tissue of Phaseolu8 vulgaris L., which reduces errors due to the length of the diffusion path and to poor aeration of the tissue, is described. The tissue took up sucrose from a 1 % (wjv) solution at first by a rapid osmotic process into the free space of the t,issue and then by a slower non-osmotic process into the osmotic volume. The rate of non-osmotic uptake, on a fresh weight basis, was independent of the physiological age of the tissue, within certain limits. The rate of non·osmotic uptake was decreased by storage for several days at 5°C in distilled water. The non· osmotic uptake was inhibited by cyanide, azide, 2,4-dinitrophenol, but not by phlorizin. About two· thirds of the sucrose taken up by the tissue over a period of {) hI' could be recovered; smaller proportions could be recovered as reducing sugars or accounted for by respiration.