Abstract
The effects of reduced CO2 assimilation capacity on the leaf pigment composition and the dissipation of light energy were studied using transgenic tobacco ( Nicotiana tabacum L. cv. W38). Two plant types were used: anti-SSu plants with reduced amounts of Rubisco and anti-GAPDH plants with reduced activity of chloroplast glycer-aldehyde 3-phosphate dehydrogenase. A moderate reduction in the photosynthetic capacity increased the de-epoxidation state of the xanthophyll-cycle pigments. In contrast, there was no large effect on the leaf pigment composition and the ratio of the xanthophyll cycle pigments to chlorophyll, and total carotenoids increased only in the most severe transgenic plants. The light induction of photosynthesis, fluorescence quenching and de-epoxida ion of the xanthophyll cycle pigments were also followed in wild-type and anti-SSu plants. Anti-SSu plants maintained high nonphotochemical quenching and increased xanthophyll de-epoxidation in the light but the reduction state of QA remained high. For both wild-type and anti-SSu plants, the electron transport rate estimated from chlorophyll a fluorescence appeared to be much higher than that required to support the observed rate of CO2 assimilation and photorespiration during the early phase of photosynthetic induction. However, the two estimates converged with the onset of steady-state photosynthesis.
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Claims 8
Claim · model-written summary
Moderately reduced photosynthetic capacity increased xanthophyll pigment de-epoxidation state.
- Taxon
- tobacco
Nicotiana tabacumt0 - Treatment
- moderate reduction in the photosynthetic capacitye0
- Outcome
- de-epoxidation state of the xanthophyll-cycle pigmentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A moderate reduction in the photosynthetic capacity increased the de-epoxidation state of the xanthophyll-cycle pigments”
t0“tobacco”
Claim · model-written summary
Reduced photosynthetic capacity had no large effect on pigment composition or xanthophyll-to-chlorophyll ratio.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- reduced CO2 assimilation capacitye1
- Outcome
- leaf pigment composition and the ratio of the xanthophyll cycle pigments to chlorophylle0
- Direction
- no large effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was no large effect on the leaf pigment composition and the ratio of the xanthophyll cycle pigments to chlorophyll”
t0“tobacco”
e1“reduced CO2 assimilation capacity”
Claim · model-written summary
Total carotenoids increased only in the most severe transgenic plants.
- Taxon
- tobaccoNicotiana tabacumt0
- Material
- most severe transgenic plantse0
- Outcome
- total carotenoidse0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total carotenoids increased only in the most severe transgenic plants”
t0“tobacco”
Claim · model-written summary
Anti-SSu plants maintained high nonphotochemical quenching in light.
Verbatim
e0“Anti-SSu plants maintained high nonphotochemical quenching and increased xanthophyll de-epoxidation in the light”
Claim · model-written summary
Anti-SSu plants increased xanthophyll de-epoxidation in light.
- Taxon
- plantsViridiplantaee0
- Material
- Anti-SSu plantse0
- Outcome
- xanthophyll de-epoxidatione0
- Direction
- increasede0
Verbatim
e0“Anti-SSu plants maintained high nonphotochemical quenching and increased xanthophyll de-epoxidation in the light”
Claim · model-written summary
The reduction state of QA remained high in anti-SSu plants.
- Taxon
- plantsViridiplantaee1
- Material
- Anti-SSu plantse1
- Outcome
- reduction state of QAe0
- Direction
- remained highe0
Verbatim
e0“but the reduction state of QA remained high”
e1“Anti-SSu plants maintained high nonphotochemical quenching”
Claim · model-written summary
Early in induction, fluorescence-estimated electron transport exceeded that required for observed assimilation and photorespiration in wild-type and anti-SSu plants.
Verbatim
e0“For both wild-type and anti-SSu plants, the electron transport rate estimated from chlorophyll a fluorescence appeared to be much higher than that required to support the observed rate of CO2 assimilation and photorespiration during the early phase of photosynthetic induction”
Claim · model-written summary
The two electron transport estimates converged at steady-state photosynthesis.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- two estimatese0
- Direction
- convergede0
- Qualifier
- with the onset of steady-state photosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the two estimates converged with the onset of steady-state photosynthesis”
t0“tobacco”
The same questions in other papers
co2 · physiology: pigments · Nicotiana tabacum (tobacco)Positive and negative results
3 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- negative
1 paper more in this group
See all 5 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.