Abstract
Summary Ascorbate content in plants is controlled by its synthesis from carbohydrates, recycling of the oxidized forms and degradation. Of these pathways, ascorbate degradation is the least studied and represents a lack of knowledge that could impair improvement of ascorbate content in fruits and vegetables as degradation is non‐reversible and leads to a depletion of the ascorbate pool. The present study revealed the nature of degradation products using [ 14 C]ascorbate labelling in tomato, a model plant for fleshy fruits; oxalate and threonate are accumulated in leaves, as is oxalyl threonate. Carboxypentonates coming from diketogulonate degradation were detected in relatively insoluble (cell wall‐rich) leaf material. No [ 14 C]tartaric acid was found in tomato leaves. Ascorbate degradation was stimulated by darkness, and the degradation rate was evaluated at 63% of the ascorbate pool per day, a percentage that was constant and independent of the initial ascorbate or dehydroascorbic acid concentration over periods of 24 h or more. Furthermore, degradation could be partially affected by the ascorbate recycling pathway, as lines under‐expressing monodehydroascorbate reductase showed a slight decrease in degradation product accumulation.
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Claims 7
Claim · model-written summary
Oxalate, threonate and oxalyl threonate accumulate in tomato leaves.
- Taxon
- tomato
Solanum lycopersicume1 - Organ / stage
- leavese2
- Outcome
- oxalate and threonate are accumulated in leaves, as is oxalyl threonatee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using [ 14 C]ascorbate labelling in tomato”
e2“oxalate and threonate are accumulated in leaves, as is oxalyl threonate”
Claim · model-written summary
No [14C]tartaric acid was found in tomato leaves.
- Taxon
- tomatoSolanum lycopersicume1
- Organ / stage
- leavese3
- Outcome
- [ 14 C]tartaric acide3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using [ 14 C]ascorbate labelling in tomato”
e3“No [ 14 C]tartaric acid was found in tomato leaves”
Claim · model-written summary
Carboxypentonates from diketogulonate degradation are detected in relatively insoluble leaf material of tomato.
- Taxon
- tomatoSolanum lycopersicume1
- Organ / stage
- leaf materiale5
- Outcome
- Carboxypentonatese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using [ 14 C]ascorbate labelling in tomato”
e4“Carboxypentonates coming from diketogulonate degradation were detected”
e5“leaf material”
Claim · model-written summary
Darkness stimulates ascorbate degradation in tomato.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- darknesse6
- Outcome
- Ascorbate degradatione6
- Direction
- stimulatede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using [ 14 C]ascorbate labelling in tomato”
e6“Ascorbate degradation was stimulated by darkness”
Claim · model-written summary
Ascorbate degradation rate in tomato is 63% of the ascorbate pool per day.
- Taxon
- tomatoSolanum lycopersicume1
- Outcome
- degradation ratee7
- Value
- 63% of the ascorbate pool per daye7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using [ 14 C]ascorbate labelling in tomato”
e7“the degradation rate was evaluated at 63% of the ascorbate pool per day”
Claim · model-written summary
The degradation percentage is constant over periods of 24 h or more and independent of the initial ascorbate or dehydroascorbic acid concentration.
- Taxon
- tomatoSolanum lycopersicume1
- Outcome
- a percentage that was constante2
- Qualifier
- independent of the initial ascorbate or dehydroascorbic acid concentration over periods of 24 h or moree2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using [ 14 C]ascorbate labelling in tomato”
e2“a percentage that was constant and independent of the initial ascorbate or dehydroascorbic acid concentration over periods of 24 h or more”
Claim · model-written summary
Lines under-expressing monodehydroascorbate reductase show a slight decrease in degradation product accumulation.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- lines under‐expressing monodehydroascorbate reductasee3
- Gene
- monodehydroascorbate reductasee3
- Outcome
- degradation product accumulatione2
- Direction
- decreasee2
- Qualifier
- slighte2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“using [ 14 C]ascorbate labelling in tomato”
e2“showed a slight decrease in degradation product accumulation”
e3“lines under‐expressing monodehydroascorbate reductase”