Accumulation Of Sugars In Potato Tubers Research Articles

Increase in phosphorylase activity during cold-induced sugar accumulation in potato tubers

The accumulation of reducing sugars, sucrose and hexose phosphates in cv. Bintje and genotype KW77-2916 during storage at 2, 4, or 8°C was studied in relation to several catalytic activities. Bintje tubers accumulated sugars during storage at 2 or 4°C, whereas KW77-2916 showed reduced cold-sweetening at 2°C. The increase in glucose 6-phosphate and sucrose occurred concurrently and preceded the increase in reducing sugar concentration. Phosphorylase activity showed a strong interaction with temperature, storage duration and sugar accumulation in both genotypes. Invertase activity increased in Bintje concomitantly with the increase in reducing sugars, but this effect was less obvious in KW77-2916. The activities of other glycolytic and Krebs cycle enzymes showed no obvious correlation with sugar accumulation. It is suggested that the increase in phosphorylase activity acts as a triggering event in the sweetening of potato tubers during cold storage.

TEMPORARY ANOXIA AS A MEANS OF PREVENTING SUGAR ACCUMULATION DURING STORAGE AT 4°C

ABSTRACTTemporary anoxia (about 20 days) was found to be an effective means to prevent sugar accumulation in potato tubers during storage at 4°C. The sugar level of such tubers re‐exposed to normal atmosphere remained low during additional storage at 4°C for 3 months. During this time, the high level of lactic acid which had accumulated in tubers during temporary anoxia was greatly reduced.

Respiration, ATP level, and sugar accumulation in potato tubers during storage at 4°

A kinetic study was made of the relationship between respiration rate, sugar content and ATP levels, in fresh and aged potato tubers stored at 4°. The ATP content in tubers rose rapidly immediately after the chilling stress, while respiration rate decreased below the initial rate and sugar accumulation was not detected. After 4 days of storage, the ATP level declined and the sugars started to accumulate. The typical increase in respiration rate that usually follows chilling stress, appeared only in fresh tubers (at about the 6th day of storage). In dinitrophenol-treated tubers, the ATP level remained below the initial level and sugar accumulation was blocked completely. The evidence presented suggests that ATP elevation is not generated by the respiration burst.