Effect of temperature on pathways of carbohydrate metabolism in tubers of potato (Solanum tuberosum L.)

Metabolism of labelled precursors by potato tubers from two cultivars with high (cv. Record) or low (cv. Brodick) capacity for cold-induced sweetening was investigated. Tubers were stored for 8 weeks at 3°C or 15°C. Subsequently, discs were excised and incubated with a range of labelled precursors at the storage temperatures. With either [U- 14 C]glucose or [1- 14 C]ribose, less radioactivity was recovered in glycolytic products (CO 2 , organic acids, and aminoacids) in discs from cold-stored tubers than from warm-stored tubers in both culitvars. Genotypic differences were observed in the partitioning of metabolised label between starch and sucrose at low temperature: relatively more radioactivity was recovered in starch with discs of cv. Brodick while more label was recovered in sucrose with discs of cv. Record. No genotypic differences were observed in the capacity for triose-P recycling (as assessed by 13 C-NMR spectroscopy) or metabolism via PPP (as assessed by C 1 :C 6 ratio) between discs of the two culitvars at low temperature. It is concluded that low storage temperature has a detrimental effect on glycolytic metabolism by potato tubers. Genotypic variation in the partitioning of excess carbon into starch or sucrose at low temperature may ultimately determine the extent of cold-induced sweetening in different potato cultivars.