Abstract
Understanding how the fruit microclimate affects ascorbate (AsA) biosynthesis, oxidation and recycling is a great challenge in improving fruit nutritional quality. For this purpose, tomatoes at breaker stage were harvested and placed in controlled environment conditions at different temperatures (12, 17, 23, 27 and 31 °C) and irradiance regimes (darkness or 150 µmol m(-2) s(-1)). Fruit pericarp tissue was used to assay ascorbate, glutathione, enzymes related to oxidative stress and the AsA/glutathione cycle and follow the expression of genes coding for 5 enzymes of the AsA biosynthesis pathway (GME, VTC2, GPP, L-GalDH, GLDH). The AsA pool size in pericarp tissue was significantly higher under light at temperatures below 27 °C. In addition, light promoted glutathione accumulation at low and high temperatures. At 12 °C, increased AsA content was correlated with the enhanced expression of all genes of the biosynthesis pathway studied, combined with higher DHAR and MDHAR activities and increased enzymatic activities related to oxidative stress (CAT and APX). In contrast, at 31 °C, MDHAR and GR activities were significantly reduced under light indicating that enzymes of the AsA/glutathione cycle may limit AsA recycling and pool size in fruit pericarp, despite enhanced expression of genes coding for AsA biosynthesis enzymes. In conclusion, this study confirms the important role of fruit microclimate in the regulation of fruit pericarp AsA content, as under oxidative conditions (12 °C, light) total fruit pericarp AsA content increased up to 71%. Moreover, it reveals that light and temperature interact to regulate both AsA biosynthesis gene expression in tomato fruits and AsA oxidation and recycling.
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Claims 9
Claim · model-written summary
Light increased pericarp ascorbate pool size below 27 °C.
- Taxon
- Tomato
Solanum lycopersicumt0 - Organ / stage
- pericarp tissuee0
- Treatment
- lighte0
- Outcome
- AsA pool sizee0
- Direction
- highere0
- Qualifier
- temperatures below 27 °Ce0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The AsA pool size in pericarp tissue was significantly higher under light at temperatures below 27 °C”
t0“Tomato”
Claim · model-written summary
Light promoted glutathione accumulation at low and high temperatures.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- lighte0
- Outcome
- glutathione accumulatione0
- Direction
- promotede0
- Qualifier
- low and high temperaturese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“light promoted glutathione accumulation at low and high temperatures”
t0“Tomato”
Claim · model-written summary
At 12 °C, higher ascorbate content correlated with increased expression of the studied biosynthesis genes.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- genes of the biosynthesis pathwaye0
- Outcome
- AsA contente0
- Direction
- increasede0
- Qualifier
- 12 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 12 °C, increased AsA content was correlated with the enhanced expression of all genes of the biosynthesis pathway studied”
t0“Tomato”
Claim · model-written summary
At 12 °C, increased ascorbate content correlated with higher DHAR and MDHAR activities.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- DHAR and MDHARe0
- Outcome
- AsA contente0
- Direction
- increasede0
- Qualifier
- 12 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 12 °C, increased AsA content was correlated with the enhanced expression of all genes of the biosynthesis pathway studied, combined with higher DHAR and MDHAR activities”
t0“Tomato”
Claim · model-written summary
At 12 °C, increased ascorbate content coincided with increased CAT and APX activities.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- CAT and APXe0
- Outcome
- AsA contente0
- Direction
- increasede0
- Qualifier
- 12 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 12 °C, increased AsA content was correlated with the enhanced expression of all genes of the biosynthesis pathway studied, combined with higher DHAR and MDHAR activities and increased enzymatic activities related to oxidative stress (CAT and APX)”
t0“Tomato”
Claim · model-written summary
At 31 °C, light significantly reduced MDHAR activity.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- lighte0
- Gene
- MDHARe0
- Outcome
- MDHARe0
- Direction
- reducede0
- Qualifier
- 31 °Ce0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at 31 °C, MDHAR and GR activities were significantly reduced under light”
t0“Tomato”
Claim · model-written summary
At 31 °C, light significantly reduced GR activity.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- lighte0
- Gene
- GRe0
- Outcome
- GR activitiese0
- Direction
- reducede0
- Qualifier
- 31 °Ce0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at 31 °C, MDHAR and GR activities were significantly reduced under light”
t0“Tomato”
Claim · model-written summary
Under 12 °C and light, total tomato pericarp ascorbate content increased by up to 71%.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- fruit pericarpe0
- Treatment
- 12 °C, lighte0
- Outcome
- AsA contente0
- Direction
- increasede0
- Value
- 71%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under oxidative conditions (12 °C, light) total fruit pericarp AsA content increased up to 71%”
t0“Tomato”
Claim · model-written summary
Light and temperature jointly regulated ascorbate biosynthesis gene expression and oxidation and recycling in tomato fruit.
- Taxon
- tomatoSolanum lycopersicume0
- Treatment
- light and temperaturee0
- Outcome
- AsA biosynthesis gene expressione0
- Qualifier
- AsA oxidation and recyclinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“light and temperature interact to regulate both AsA biosynthesis gene expression in tomato fruits and AsA oxidation and recycling”
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