Invertase Activity and its Relation to Hexose Accumulation in Potato Tubers

Hexose accumulation was shown to occur in freshly harvested mature potato tubers (Solanum tuberosum L.) both after storage at 10 °C and when subsequently transferred to low temperature (3 °C) storage. In general, changes in hexoses and sucrose were found to be related to changes in acid invertase activity. Total acid invertase activity (i.e. assayed after destroying the endogenous invertase inhibitor present in the extracts) generally reflected sugar changes more closely than did basal activity (i.e. assayed with the inhibitor present). There was no evidence of a specific alkaline invertase. A comparison of the temperature responses of cultivar Record with that of two SCRI2 clones demonstrated distinct genotypic variation in the extent of hexose accumulation. However, these differences were not always reflected by genotypic differences in total invertase activity.