Vacuoles from Sugarcane Suspension Cultures

Abstract

Vacuoles, isolated from sugarcane (Saccharum sp.) cells took up 3-O-methylglucose and sucrose and apparently specific transport systems for these sugars exist. There was no evidence of sugar efflux from preloaded vacuoles. Vacuoles in situ accumulated 3-O methylglucose, sucrose, glucose and fructose, as shown by incubation of protoplasts with labeled sugar and subsequent analysis of vacuolar and cytoplasmic radioactivity. During the initial minutes of incubation, the amount of concentration of labeled sugar was higher in the cytoplasm than in the vacuole, but subsequently there was active uptake and accumulation into the vacuole. The rate of hexose transfer into the vacuole in situ approached that of hexose uptake by isolated vacuoles; the rate of sucrose uptake by isolated vacuoles was below the in situ rate. The site of sucrose synthesis was in the cytoplasm.