Abstract
ABSTRACT These experiments investigate events involved in triggering sugar accumulation in the cold in tubers of Solanum tuberosum L. cv. Desirée. Sugar content, 14 C‐glucose metabolism, metabolite levels and activities of sucrose phosphate synthase (SPS) and starch‐degrading enzymes were followed after transfer to 4°C. (i) Net sucrose accumulation began between 2 and 4 d. By 10 d, reducing sugars were also increasing. From 20 d onwards, sugar accumulation slowed. Sucrose fell, but reducing sugars continued to increase. (ii) To measure unidirectional sucrose synthesis, U‐[ 14 C]glucose was injected into tubers after various times at 4°C. The tubers were then incubated for 6 h. After 1 d at 4°C, both the absolute and the relative (expressed as a percentage of the metabolized label) rates of sucrose synthesis decreased compared to those at 20°C. Between 2 and 4 d at 4°C, labelling of sucrose increased 3‐fold, to over 60% of the metabolized label. This high rate was maintained for up to 50 d in cold storage. When tissue slices were incubated with 2.5 mol m −3 U‐[ 14 C]glucose, the rate of labelling of sucrose in slices from 6 d cold‐stored material was higher than in slices from warm‐stored material, irrespective of whether the incubation occurred at 4°C or at 20°C. (iii) Hexose‐phosphates increased during the first day after transfer to 4°C. Their levels fell during the next 3 d, as sucrose synthesis increased. They then rose (until 20 d) and fell, in parallel with the rise and decline of sucrose levels. UDPglucose remained unaltered during the first 4 d, and then increased and decreased in parallel with sucrose. (iv) SPS activity assayed in optimal conditions and the total amount of SPS protein did not change. However, when assayed in the presence of phosphate and limiting substrate concentrations, activity rose 3–5‐fold between 2 and 4 d. (v) Amylases and phosphorylases were investigated using zymograms to separate isoforms. Phosphorylases did not change. Between 2 and 4 d at 4°C, a new amylolytic activity appeared. (vi) Estimates of the specific activity of the phosphorylated intermediates and the absolute rate of sucrose synthesis (calculated from the 14 C‐labelling data and metabolite analysis) showed that changed kinetic properties of SPS and decreased levels of hexose‐phosphate are accompanied by a 6–8‐fold stimulation of sucrose synthesis. They also show that the final level of sugar is partly determined by a cycle of sugar synthesis and degradation. (vii) It is concluded that the onset of sugar accumulation in cold‐stored tubers is initiated by a change in the kinetic properties of SPS and the appearance of a new amylolytic activity. It is discussed how other factors, including hexose‐phosphate levels and subcellular compartmentalization, could also influence the final levels of sugars by altering the balance of sugar synthesis and remobilization.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 19
Claim · model-written summary
Net sucrose accumulation began after two to four days of cold storage.
- Taxon
- potato
Solanum tuberosumt0 - Organ / stage
- tuberst0
- Outcome
- Net sucrose accumulatione0
- Value
- between 2 and 4 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Net sucrose accumulation began between 2 and 4 d”
t0“potato tubers”
Claim · model-written summary
Reducing sugars increased by day ten.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- reducing sugarse0
- Direction
- increasinge0
- Value
- 10 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By 10 d, reducing sugars were also increasing”
t0“potato tubers”
Claim · model-written summary
Sugar accumulation slowed from day twenty.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- sugar accumulatione0
- Direction
- slowede0
- Value
- 20 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“From 20 d onwards, sugar accumulation slowed”
t0“potato tubers”
Claim · model-written summary
Sucrose fell later in cold storage.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- Sucrosee0
- Direction
- felle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sucrose fell, but reducing sugars continued to increase”
t0“potato tubers”
Claim · model-written summary
Reducing sugars continued to increase later in cold storage.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- reducing sugarse0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sucrose fell, but reducing sugars continued to increase”
t0“potato tubers”
Claim · model-written summary
Absolute and relative sucrose synthesis rates decreased after one day at 4°C compared with 20°C.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- 4°Ce0
- Outcome
- absolute and the relative (expressed as a percentage of the metabolized label) rates of sucrose synthesise0
- Direction
- decreasede0
- Comparator
- 20°Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 1 d at 4°C, both the absolute and the relative (expressed as a percentage of the metabolized label) rates of sucrose synthesis decreased compared to those at 20°C”
t0“potato tubers”
Claim · model-written summary
Sucrose labeling increased threefold to over 60% of metabolized label after two to four days at 4°C.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- labelling of sucrosee0
- Direction
- increasede0
- Value
- 3‐folde0
- Qualifier
- over 60% of the metabolized labele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Between 2 and 4 d at 4°C, labelling of sucrose increased 3‐fold, to over 60% of the metabolized label”
t0“potato tubers”
Claim · model-written summary
The high sucrose synthesis rate persisted for up to 50 days in cold storage.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- high ratee0
- Direction
- maintainede0
- Value
- up to 50 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This high rate was maintained for up to 50 d in cold storage”
t0“potato tubers”
Claim · model-written summary
Sucrose labeling was higher in slices from cold-stored than warm-stored tubers at either incubation temperature.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- 6 d cold‐stored materiale0
- Outcome
- rate of labelling of sucrosee0
- Direction
- highere0
- Comparator
- warm‐stored materiale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the rate of labelling of sucrose in slices from 6 d cold‐stored material was higher than in slices from warm‐stored material, irrespective of whether the incubation occurred at 4°C or at 20°C”
t0“potato tubers”
Claim · model-written summary
Hexose phosphates first increased and then fell over the next three days as sucrose synthesis increased.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- Hexose‐phosphatese0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hexose‐phosphates increased during the first day after transfer to 4°C. Their levels fell during the next 3 d, as sucrose synthesis increased”
t0“potato tubers”
Claim · model-written summary
Hexose phosphate levels later rose until day twenty and fell alongside sucrose levels.
- Taxon
- potatoSolanum tuberosumt0
- Compound
- sucrosee0
- Outcome
- rise and decline of sucrose levelse0
- Direction
- rise and declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They then rose (until 20 d) and fell, in parallel with the rise and decline of sucrose levels”
t0“potato tubers”
Claim · model-written summary
UDPglucose remained unchanged for four days and then varied in parallel with sucrose.
- Taxon
- potatoSolanum tuberosumt0
- Compound
- sucrosee0
- Outcome
- UDPglucosee0
- Direction
- increased and decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UDPglucose remained unaltered during the first 4 d, and then increased and decreased in parallel with sucrose”
t0“potato tubers”
Claim · model-written summary
Optimal-assay SPS activity and total SPS protein did not change.
- Taxon
- potatoSolanum tuberosumt0
- Gene
- SPSe0
- Outcome
- SPS activity assayed in optimal conditions and the total amount of SPS proteine0
- Direction
- did not changee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SPS activity assayed in optimal conditions and the total amount of SPS protein did not change”
t0“potato tubers”
Claim · model-written summary
Under phosphate and limiting substrate, SPS activity rose three to fivefold between days two and four.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when assayed in the presence of phosphate and limiting substrate concentrations, activity rose 3–5‐fold between 2 and 4 d”
e1“SPS activity assayed in optimal conditions”
t0“potato tubers”
Claim · model-written summary
Phosphorylases did not change.
- Taxon
- potatoSolanum tuberosumt0
- Gene
- Phosphorylasese0
- Outcome
- Phosphorylasese0
- Direction
- did not changee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phosphorylases did not change”
t0“potato tubers”
Claim · model-written summary
A new amylolytic activity appeared between days two and four at 4°C.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- new amylolytic activity appearede0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Between 2 and 4 d at 4°C, a new amylolytic activity appeared”
t0“potato tubers”
Claim · model-written summary
Changed SPS kinetics and reduced hexose phosphate coincided with six to eightfold stimulation of sucrose synthesis.
- Taxon
- potatoSolanum tuberosumt0
- Gene
- SPSe0
- Outcome
- stimulation of sucrose synthesise0
- Direction
- stimulatione0
- Value
- 6–8‐folde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changed kinetic properties of SPS and decreased levels of hexose‐phosphate are accompanied by a 6–8‐fold stimulation of sucrose synthesis”
t0“potato tubers”
Claim · model-written summary
The final sugar level is partly determined by cycling between sugar synthesis and degradation.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- final level of sugare0
- Qualifier
- cycle of sugar synthesis and degradatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the final level of sugar is partly determined by a cycle of sugar synthesis and degradation”
t0“potato tubers”
Claim · model-written summary
The onset of cold-storage sugar accumulation was attributed to altered SPS kinetics and a new amylolytic activity.
- Taxon
- potatoSolanum tuberosumt0
- Gene
- SPSe0
- Outcome
- onset of sugar accumulatione0
- Qualifier
- appearance of a new amylolytic activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the onset of sugar accumulation in cold‐stored tubers is initiated by a change in the kinetic properties of SPS and the appearance of a new amylolytic activity”
t0“potato tubers”
The same questions in other papers
cold · molecular: metabolites · Solanum tuberosum (potato)Positive and negative results
4 papers in the same direction as this paper · 7 in the opposite direction · 1 reporting no difference from an alternative
- no effect
- 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.