Abstract
A complementary DNA for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was cloned from tobacco (Nicotiana tabacum) and fused in the antisense orientation to the cauliflower mosaic virus 35S promoter. This antisense gene was introduced into the tobacco genome, and the resulting transgenic plants were analyzed to assess the effect of the antisense RNA on Rubisco activity and photosynthesis. The mean content of extractable Rubisco activity from the leaves of 10 antisense plants was 18% of the mean level of activity of control plants. The soluble protein content of the leaves of anti-small subunit plants was reduced by the amount equivalent to the reduction in Rubisco. There was little change in phosphoribulokinase activity, electron transport, and chlorophyll content, indicating that the loss of Rubisco did not affect these other components of photosynthesis. However, there was a significant reduction in carbonic anhydrase activity. The rate of CO(2) assimilation measured at 1000 micromoles quanta per square meter per second, 350 microbars CO(2), and 25 degrees C was reduced by 63% (mean value) in the antisense plants and was limited by Rubisco activity over a wide range of intercellular CO(2) partial pressures (p(i)). In control leaves, Rubisco activity only limited the rate of CO(2) assimilation below a p(i) of 400 microbars. Despite the decrease in photosynthesis, there was no reduction in stomatal conductance in the antisense plants, and the stomata still responded to changes in p(i). The unchanged conductance and lower CO(2) assimilation resulted in a higher p(i), which was reflected in greater carbon isotope discrimination in the leaves of the antisense plants. These results suggest that stomatal function is independent of total leaf Rubisco activity.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 12
Claim · model-written summary
Extractable Rubisco activity in antisense leaves was 18% of controls.
- Taxon
- Tobacco Plants
Nicotiana tabacumt0 - Treatment
- antisense plantse0
- Outcome
- extractable Rubisco activitye0
- Value
- 18%e0
- Comparator
- control plantse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mean content of extractable Rubisco activity from the leaves of 10 antisense plants was 18% of the mean level of activity of control plants.”
t0“Tobacco Plants”
Claim · model-written summary
Leaf soluble protein was reduced in proportion to Rubisco.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Treatment
- anti-small subunit plantse0
- Outcome
- soluble protein contente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The soluble protein content of the leaves of anti-small subunit plants was reduced by the amount equivalent to the reduction in Rubisco.”
t0“Tobacco Plants”
Claim · model-written summary
Phosphoribulokinase activity, electron transport and chlorophyll content changed little.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Treatment
- loss of Rubiscoe0
- Outcome
- phosphoribulokinase activity, electron transport, and chlorophyll contente0
- Direction
- little changee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was little change in phosphoribulokinase activity, electron transport, and chlorophyll content, indicating that the loss of Rubisco did not affect these other components of photosynthesis.”
t0“Tobacco Plants”
Claim · model-written summary
Carbonic anhydrase activity declined significantly.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Outcome
- carbonic anhydrase activitye0
- Direction
- reductione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, there was a significant reduction in carbonic anhydrase activity.”
t0“Tobacco Plants”
Claim · model-written summary
Antisense plant CO2 assimilation fell by 63%.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Treatment
- antisense plantse0
- Outcome
- rate of CO(2) assimilatione0
- Direction
- reducede0
- Value
- 63%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of CO(2) assimilation measured at 1000 micromoles quanta per square meter per second, 350 microbars CO(2), and 25 degrees C was reduced by 63% (mean value) in the antisense plants”
t0“Tobacco Plants”
Claim · model-written summary
Rubisco limited assimilation across a broad range of intercellular CO2 pressure in antisense plants.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Outcome
- Rubisco activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“was limited by Rubisco activity over a wide range of intercellular CO(2) partial pressures (p(i)).”
t0“Tobacco Plants”
Claim · model-written summary
In control leaves Rubisco limited assimilation below 400 microbars.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Outcome
- rate of CO(2) assimilatione0
- Value
- 400 microbarse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In control leaves, Rubisco activity only limited the rate of CO(2) assimilation below a p(i) of 400 microbars.”
t0“Tobacco Plants”
Claim · model-written summary
Stomatal conductance did not decline in antisense plants.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Treatment
- antisense plantse0
- Outcome
- stomatal conductancee0
- Direction
- no reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Despite the decrease in photosynthesis, there was no reduction in stomatal conductance in the antisense plants”
t0“Tobacco Plants”
Claim · model-written summary
Stomata still responded to intercellular CO2 changes.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Outcome
- stomata still responded to changes in p(i)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the stomata still responded to changes in p(i).”
t0“Tobacco Plants”
Claim · model-written summary
Unchanged conductance and lower assimilation resulted in higher intercellular CO2.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Outcome
- higher p(i)e0
- Qualifier
- unchanged conductance and lower CO(2) assimilatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The unchanged conductance and lower CO(2) assimilation resulted in a higher p(i)”
t0“Tobacco Plants”
Claim · model-written summary
Antisense leaves showed greater carbon isotope discrimination.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Outcome
- carbon isotope discriminatione0
- Direction
- greatere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which was reflected in greater carbon isotope discrimination in the leaves of the antisense plants.”
t0“Tobacco Plants”
Claim · model-written summary
Stomatal function appeared independent of total leaf Rubisco activity.
- Taxon
- Tobacco PlantsNicotiana tabacumt0
- Outcome
- stomatal function is independent of total leaf Rubisco activitye0
- Qualifier
- total leaf Rubisco activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results suggest that stomatal function is independent of total leaf Rubisco activity.”
t0“Tobacco Plants”
The same questions in other papers
loss of function · physiology: gas exchange · Nicotiana tabacum (tobacco)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
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.