Journal Article

The Response of Carbohydrate Metabolism in Potato Tubers to Low Temperature

Jacob G. Malone, Valentina Mittova, R. George Ratcliffe and Nicholas J. Kruger

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 47, issue 9, pages 1309-1322
Published in print September 2006 | ISSN: 0032-0781
Published online September 2006 | e-ISSN: 1471-9053 | DOI:
The Response of Carbohydrate Metabolism in Potato Tubers to Low Temperature

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry


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This work investigates the possible causes of cold-induced sweetening in potato by examining the impact of low temperature on carbohydrate metabolism in mature tubers. Metabolism in tuber discs was monitored by determining the redistribution of radiolabel following incubation in [U-14C]glucose. Estimates of flux based on the specific activity of hexose phosphates established that while incubation at 4°C resulted in an immediate restriction in pathways of carbohydrate oxidation relative to activity at 25°C, there was no corresponding increase in flux to soluble sugars. In contrast, prior storage at low temperature stimulated flux to sugars at both 4 and 25°C. Comparison of 14CO2 release from specifically labeled glucose and gluconate fed to tuber discs at 4 and 25°C indicated that flux through glycolysis was preferentially restricted relative to the oxidative pentose phosphate pathway at low temperature, irrespective of prior storage temperature. However, the degree of randomization of label between positions C1 and C6 in the fructosyl moiety of sucrose following metabolism of [1-13C]glucose established that there was no preferential inhibition of the recycling of triose phosphates to hexose phosphates at low temperature. These results indicate that sugar accumulation in tubers during storage in the cold is not a direct consequence of a constraint in carbohydrate oxidation, despite preferential restriction of glycolysis at low temperature. It is concluded that the cold lability of enzymes catalyzing the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate is not a major factor in cold-induced sweetening in plants and that this widely held hypothesis should be abandoned.

Keywords: Carbohydrate metabolism; Cold-induced sweetening; Low-temperature storage; Potato tuber; Solanum tuberosum; Sugar accumulation

Journal Article.  9785 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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