Ascorbate degradation in tomato leads to accumulation of oxalate,threonate and oxalyl threonate |
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| Authors: | Vincent Truffault Stephen C. Fry Rebecca G. Stevens Hélène Gautier |
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| Affiliation: | 1. INRA, UR‐1052, Génétique et Amélioration des Fruits et Légumes, Montfavet, France;2. INRA, UR‐1115, Plantes et Systèmes de culture Horticoles, France;3. The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK |
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| Abstract: | 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 [14C]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 [14C]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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| Keywords: | ascorbate degradation monodehydroascorbate reductase light environment tomato [14C]ascorbate labelling high‐voltage paper electrophoresis
Solanum lycopersicum
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