Abstract
Available evidence suggests that the stress‐induced increase in the activity of glucose‐6‐phosphate dehydrogenase (G6PDH, EC 1.1.1.49), the key regulatory enzyme of the oxidative pentose phosphate pathway, might often be related to the presence of plant water deficit. The response of G6PDH to dark chilling in chilling sensitive plant species is still unknown. In this communication we report on this response and its dependence on the presence of chill‐induced drought stress. A chilling sensitive soybean (Glycine max L. Merr.) genotype was exposed to dark chilling of the entire plant (whole‐chilled) or only the shoots and leaves (shoot‐chilled). The development of chill‐induced drought stress upon illumination was quantified by measurement of proline and relative water content (RWC). Chill‐induced drought stress (decrease in RWC and increase in proline content) developed with time in whole‐chilled plants, but not in shoot‐chilled plants. The response of the above‐mentioned treatments on G6PDH activity in fully expanded leaves was assessed. In parallel, the effects on CO 2 assimilation, PSII activity and chloroplast fructose‐1,6‐bisphosphatase (FBPase EC 3.1.3.11) and ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco EC 4.1.1.39) activity were quantified. A decrease in CO 2 assimilation rate, FBPase activity and ribulose‐1,5‐bisphosphate (RuBP) content was observed in whole‐chilled but not in shoot‐chilled plants. However, in shoot‐chilled plants regulation of diurnal PSII activity was altered. The increase in the activation state of NADP‐dependent malate dehydrogenase (NADP‐MDH EC 1.1.1.82) in shoot‐chilled plants suggests an increase in stromal redox state. Although the two different dark chilling treatments resulted in distinct physiological and biochemical effects, both induced an increase in foliar G6PDH activity, suggesting an important role of this enzyme during and following dark chilling stress, irrespective of the presence of chill‐induced drought stress.
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Claims 9
Claim · model-written summary
Whole plant chilling decreased relative water content and increased proline over time.
- Taxon
- soybean
Glycine maxt0 - Treatment
- whole‐chilled plantse0
- Outcome
- RWCe0
- Direction
- decreasee0
- Comparator
- shoot‐chilled plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chill‐induced drought stress (decrease in RWC and increase in proline content) developed with time in whole‐chilled plants, but not in shoot‐chilled plants.”
t0“soybean”
Claim · model-written summary
Whole plant chilling increased proline content over time, unlike shoot chilling.
- Taxon
- soybeanGlycine maxt0
- Treatment
- whole‐chilled plantse0
- Outcome
- proline contente0
- Direction
- increasee0
- Comparator
- shoot‐chilled plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chill‐induced drought stress (decrease in RWC and increase in proline content) developed with time in whole‐chilled plants, but not in shoot‐chilled plants.”
t0“soybean”
Claim · model-written summary
Whole plant chilling reduced carbon dioxide assimilation rate, unlike shoot chilling.
- Taxon
- soybeanGlycine maxt0
- Treatment
- whole‐chillede0
- Outcome
- CO 2 assimilation ratee0
- Direction
- decreasee0
- Comparator
- shoot‐chilled plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A decrease in CO 2 assimilation rate, FBPase activity and ribulose‐1,5‐bisphosphate (RuBP) content was observed in whole‐chilled but not in shoot‐chilled plants.”
t0“soybean”
Claim · model-written summary
Whole plant chilling reduced FBPase activity, unlike shoot chilling.
- Taxon
- soybeanGlycine maxt0
- Treatment
- whole‐chillede0
- Gene
- FBPasee0
- Outcome
- FBPase activitye0
- Direction
- decreasee0
- Comparator
- shoot‐chilled plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A decrease in CO 2 assimilation rate, FBPase activity and ribulose‐1,5‐bisphosphate (RuBP) content was observed in whole‐chilled but not in shoot‐chilled plants.”
t0“soybean”
Claim · model-written summary
Whole plant chilling reduced RuBP content, unlike shoot chilling.
- Taxon
- soybeanGlycine maxt0
- Treatment
- whole‐chillede0
- Outcome
- ribulose‐1,5‐bisphosphate (RuBP) contente0
- Direction
- decreasee0
- Comparator
- shoot‐chilled plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A decrease in CO 2 assimilation rate, FBPase activity and ribulose‐1,5‐bisphosphate (RuBP) content was observed in whole‐chilled but not in shoot‐chilled plants.”
t0“soybean”
Claim · model-written summary
Shoot chilling altered diurnal regulation of PSII activity.
- Taxon
- soybeanGlycine maxt0
- Treatment
- shoot‐chilled plantse0
- Outcome
- regulation of diurnal PSII activitye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in shoot‐chilled plants regulation of diurnal PSII activity was altered.”
t0“soybean”
Claim · model-written summary
Shoot chilling increased activation of NADP dependent malate dehydrogenase.
- Taxon
- soybeanGlycine maxt0
- Treatment
- shoot‐chilled plantse0
- Gene
- NADP‐dependent malate dehydrogenasee0
- Outcome
- activation state of NADP‐dependent malate dehydrogenasee0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The increase in the activation state of NADP‐dependent malate dehydrogenase (NADP‐MDH EC 1.1.1.82) in shoot‐chilled plants suggests an increase in stromal redox state.”
t0“soybean”
Claim · model-written summary
Shoot chilling was interpreted to increase stromal redox state.
- Taxon
- soybeanGlycine maxt0
- Outcome
- stromal redox statee0
- Direction
- increasee0
- Qualifier
- stromal redox statee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggests an increase in stromal redox state”
t0“soybean”
Claim · model-written summary
Both dark chilling treatments increased foliar G6PDH activity.
- Taxon
- soybeanGlycine maxt0
- Treatment
- bothe0
- Gene
- G6PDHe0
- Outcome
- foliar G6PDH activitye0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both induced an increase in foliar G6PDH activity”
t0“soybean”