Abstract
Gross O2 evolution and uptake by attached, drought-stressed leaves of wheat (Triticum aestivum) were measured using a 16O2/ 18O2 isotope technique and mass spectrometry. The activity of photosystem II, determined from the rate of 16O2 evolution, is only slightly affected under drought conditions. During drought stress, net CO2 uptake decreases due to stomatal closure, whereas the uptake of 18O2 is stimulated. The main O2-consuming reactions in the light are the Mehler-peroxidase (MP) reaction and the photorespiratory pathway. From measurements of the rate of carbon flux through the photorespiratory pathway, estimated by the analysis of the specific radioactivities of glycolate, we conclude that the rate of photorespiration is decreased with drought stress. Therefore, the O2 taken up in the light appears to be preferentially used by the MP reaction. In stressed leaves, 29.1% of the photosynthetic electrons are consumed in the MP reaction and 18.4% drive the photorespiratory pathway. Thus, overreduction of the electron transport chain is avoided preferably by the MP reaction when drought stress restricts CO2 reduction.
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Claims 8
Claim · model-written summary
Drought only slightly affected photosystem II activity.
- Taxon
- Wheat
Triticum aestivumt0 - Treatment
- drought conditionse0
- Outcome
- activity of photosystem IIe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activity of photosystem II, determined from the rate of 16O2 evolution, is only slightly affected under drought conditions.”
t0“Wheat”
Claim · model-written summary
Net CO2 uptake decreased during drought because of stomatal closure.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- drought stresse0
- Outcome
- net CO2 uptakee0
- Direction
- decreasese0
- Qualifier
- stomatal closuree0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During drought stress, net CO2 uptake decreases due to stomatal closure”
t0“Wheat”
Claim · model-written summary
18O2 uptake was stimulated during drought.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- drought stresse1
- Outcome
- uptake of 18O2e0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas the uptake of 18O2 is stimulated”
e1“During drought stress”
t0“Wheat”
Claim · model-written summary
The photorespiration rate decreased with drought stress.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- drought stresse0
- Outcome
- rate of photorespiratione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the rate of photorespiration is decreased with drought stress”
t0“Wheat”
Claim · model-written summary
Oxygen consumed in the light appeared to be used preferentially by the MP reaction.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- O2 taken up in the lighte0
- Qualifier
- preferentially used by the MP reactione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the O2 taken up in the light appears to be preferentially used by the MP reaction”
t0“Wheat”
Claim · model-written summary
In stressed leaves, 29.1% of photosynthetic electrons were consumed in the MP reaction.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- leavese0
- Outcome
- photosynthetic electrons are consumed in the MP reactione0
- Value
- 29.1%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In stressed leaves, 29.1% of the photosynthetic electrons are consumed in the MP reaction”
t0“Wheat”
Claim · model-written summary
In stressed leaves, 18.4% of photosynthetic electrons drove photorespiration.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- leavese1
- Outcome
- photorespiratory pathwaye0
- Value
- 18.4%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“18.4% drive the photorespiratory pathway”
e1“In stressed leaves, 29.1% of the photosynthetic electrons are consumed in the MP reaction and 18.4% drive the photorespiratory pathway”
t0“Wheat”
Claim · model-written summary
The MP reaction preferentially prevented electron transport chain overreduction when drought restricted CO2 reduction.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- drought stresse0
- Outcome
- overreduction of the electron transport chain is avoidede0
- Qualifier
- MP reactione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overreduction of the electron transport chain is avoided preferably by the MP reaction when drought stress restricts CO2 reduction”
t0“Wheat”
The same questions in other papers
drought · nutrient: content · Triticum aestivum (wheat)Positive and negative results
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See all 60 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.