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 30 degr ees C or 15 degrees C. Subsequently, discs were excised and incubated with a range of labelled precursors at the storage temperatures. With either [U-C-14]glucose or [l-C-14]ribose, less radioactivity was recov ered in glycolytic products (CO2, organic acids, and aminoacids) in di scs from cold-stored tubers than from warm-stored tubers in both culti vars. Genotypic differences were observed in the partitioning of metab olised 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 recy cling (as assessed by C-13-NMR spectroscopy) or metabolism via PPP (as assessed by C-1:C-6 ratio) between discs of the two cultivars at low temperature. It is concluded that low storage temperature has a detrim ental effect on glycolytic metabolism by potato tubers. Genotypic vari ation in the partitioning of excess carbon into starch or sucrose at l ow temperature may ultimately determine the extent of cold-induced swe etening in different potato cultivars.