The storage of exogenous sucrose by corn scutellum slices

Abstract

Corn scutellum slices stored sucrose when incubated in either sucrose or fructose, and similar maximum rates of net storage were obtained with 0·4 M sucrose or 0·2 M fructose. It is concluded that exogenous sucrose is stored without prior inversion. This conclusion is based on the following: (1) The amount of extracellular inversion (as measured by the appearance of glucose and fructose in a 0·3 M sucrose bathing solution) was too low to support a net sucrose synthesis and storage, and (2) sucrose storage in slices bathed in optimal concentrations of fructose or glucose was increased by the addition of sucrose to the bathing medium. Further evidence for the existence of a transport system for exogenous sucrose was obtained in the demonstration of an exchange of sucrose between the bathing solution and the storage compartment. The rate of exchange was increased as the concentration of exogenous sucrose was increased, was doubled in the presence of citrate-phosphate buffer, was little affected by pH in the range 5·0–7·3 and showed no dependence on the net amount of sucrose stored.