Some characteristics of the sucrose uptake system of excised tomato roots

Uptake of sucrose by excised tomato roots showed saturation kinetics and could proceed against an internal sucrose concentration of approximately 0.046 M. It was inhibited by a number of compounds structurally related to sucrose and was largely but not totally dependent on respiration. It is concluded that sucrose was taken up mainly by an active process and to a lesser extent also by a passive process. Low pH markedly increased the uptake and sodium ions, and ouabain had no appreciable effect.