Abstract
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-(14)C]glucose. Estimates of flux based on the specific activity of hexose phosphates established that while incubation at 4 degrees C resulted in an immediate restriction in pathways of carbohydrate oxidation relative to activity at 25 degrees 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 degrees C. Comparison of (14)CO(2) release from specifically labeled glucose and gluconate fed to tuber discs at 4 and 25 degrees 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-(13)C]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.
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Claims 7
Claim · model-written summary
Incubation at 4 degrees C immediately restricted carbohydrate oxidation relative to 25 degrees C.
- Taxon
- potato
Solanum tuberosumt0 - Treatment
- incubation at 4 degrees Ce0
- Outcome
- pathways of carbohydrate oxidatione0
- Direction
- restrictione0
- Comparator
- 25 degrees Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“incubation at 4 degrees C resulted in an immediate restriction in pathways of carbohydrate oxidation relative to activity at 25 degrees C”
t0“Potato Tubers”
Claim · model-written summary
Incubation at 4 degrees C did not correspondingly increase soluble sugar flux.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- incubation at 4 degrees Ce1
- Outcome
- flux to soluble sugarse0
- Direction
- no corresponding increasee0
- Comparator
- 25 degrees Ce1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was no corresponding increase in flux to soluble sugars”
t0“Potato Tubers”
e1“incubation at 4 degrees C resulted in an immediate restriction in pathways of carbohydrate oxidation relative to activity at 25 degrees C”
Claim · model-written summary
Prior low temperature storage stimulated sugar flux at both incubation temperatures.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- prior storage at low temperaturee0
- Outcome
- flux to sugarse0
- Direction
- stimulatede0
- Qualifier
- at both 4 and 25 degrees Ce0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“prior storage at low temperature stimulated flux to sugars at both 4 and 25 degrees C”
t0“Potato Tubers”
Claim · model-written summary
Low temperature preferentially restricted glycolysis relative to the oxidative pentose phosphate pathway.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- low temperaturee0
- Outcome
- flux through glycolysise0
- Direction
- restrictede0
- Qualifier
- irrespective of prior storage temperaturee0
- Comparator
- oxidative pentose phosphate pathwaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“flux through glycolysis was preferentially restricted relative to the oxidative pentose phosphate pathway at low temperature, irrespective of prior storage temperature”
t0“Potato Tubers”
Claim · model-written summary
Low temperature did not preferentially inhibit triose phosphate recycling to hexose phosphates.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- low temperaturee0
- Outcome
- recycling of triose phosphates to hexose phosphatese0
- Direction
- no preferential inhibitione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was no preferential inhibition of the recycling of triose phosphates to hexose phosphates at low temperature”
t0“Potato Tubers”
Claim · model-written summary
Cold storage sugar accumulation was not a direct consequence of constrained carbohydrate oxidation.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- sugar accumulation in tuberse0
- Qualifier
- not a direct consequence of a constraint in carbohydrate oxidatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sugar accumulation in tubers during storage in the cold is not a direct consequence of a constraint in carbohydrate oxidation”
t0“Potato Tubers”
Claim · model-written summary
Cold lability of enzymes converting fructose 6-phosphate to fructose 1,6-bisphosphate was not a major cause of cold sweetening.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- cold-induced sweeteninge0
- Qualifier
- cold lability of enzymes catalyzing the conversion of fructose 6-phosphate to fructose 1,6-bisphosphatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
t0“Potato Tubers”
The same questions in other papers
cold · molecular: metabolites · Solanum tuberosum (potato)Positive and negative results
7 papers in the same direction as this paper · 5 in the opposite direction
- positive
- positive
- negative
9 papers more in this group
See all 13 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.