Abstract
Experiments were conducted during the growing seasons of 1993-1995 to determine whether exposure to ozone (O(3)) affected the synthesis of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245. As the canopy aged, the concentration of Rubisco decreased at a more rapid rate in lower leaves of hyrid poplar ramets subjected to chronic O(3) exposure in open-top chambers than in comparable foliage of plants grown in charcoal-filtered air. There was no difference in rate of synthesis of Rubisco between treatments, suggesting that loss of this protein in O(3)-treated leaves was caused by an accelerated rate of proteolysis. In foliage higher in the canopy, both concentration and rate of synthesis of Rubisco were stimulated by O(3) for a brief period when the leaves were young. Quantification of mRNA for the small (rbcS) and large (rbcL) transcripts of Rubisco did not reveal changes that were likely to reflect altered synthesis of Rubisco as a prime response to O(3). Analyses of Rubisco concentration and rate of Rubisco synthesis in foliage connected by vascular traces within the canopy indicated that loss of Rubisco in older leaves was associated with an increase in this protein in younger leaves higher in the canopy. These data support the notion that accelerated senescence may provide some compensatory benefit to the plant. In 1995, the rate of synthesis of Rubisco was almost always higher in O(3)-treated foliage than in nontreated foliage, even when the concentration of Rubisco was adversely affected by the O(3) treatment. Because accelerated foliar abscission in response to O(3) was minimal in 1995 compared to other years, we speculate that, when abscission is delayed, Rubisco synthesis and concentration become uncoupled.
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Claims 10
Claim · model-written summary
Chronic O3 exposure decreased Rubisco concentration in lower leaves of hybrid poplar at a more rapid rate than in charcoal-filtered air as the canopy aged.
- Organ / stage
- lower leavese1
- Treatment
- chronic O(3) exposure in open-top chamberse1
- Outcome
- concentration of Rubiscoe1
- Direction
- decreased at a more rapid ratee1
- Comparator
- charcoal-filtered aire1
PopulusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e1“As the canopy aged, the concentration of Rubisco decreased at a more rapid rate in lower leaves of hyrid poplar ramets subjected to chronic O(3) exposure in open-top chambers than in comparable foliage of plants grown in charcoal-filtered air”
Claim · model-written summary
Rubisco rate of synthesis in hybrid poplar did not differ between O3-treated and control foliage.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e2“There was no difference in rate of synthesis of Rubisco between treatments”
e3“suggesting that loss of this protein in O(3)-treated leaves was caused by an accelerated rate of proteolysis”
Claim · model-written summary
Loss of Rubisco in O3-treated hybrid poplar leaves is suggested to be caused by an accelerated rate of proteolysis.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e3“suggesting that loss of this protein in O(3)-treated leaves was caused by an accelerated rate of proteolysis”
Claim · model-written summary
Chronic O3 briefly stimulated Rubisco concentration and rate of synthesis in young higher-canopy foliage of hybrid poplar.
- Organ / stage
- foliage higher in the canopye4
- Treatment
- O(3)e4
- Outcome
- concentration and rate of synthesis of Rubiscoe4
- Direction
- stimulatede4
- Qualifier
- for a brief period when the leaves were younge4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e4“In foliage higher in the canopy, both concentration and rate of synthesis of Rubisco were stimulated by O(3) for a brief period when the leaves were young”
Claim · model-written summary
O3 did not reveal changes in rbcS and rbcL mRNA of hybrid poplar Rubisco.
- Treatment
- O(3)e5
- Outcome
- mRNA for the small (rbcS) and large (rbcL) transcripts of Rubiscoe5
- Direction
- did not reveal changese5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e5“Quantification of mRNA for the small (rbcS) and large (rbcL) transcripts of Rubisco did not reveal changes that were likely to reflect altered synthesis of Rubisco as a prime response to O(3)”
Claim · model-written summary
Loss of Rubisco in older leaves of hybrid poplar was associated with an increase in Rubisco in younger leaves higher in the canopy.
- Organ / stage
- younger leaves higher in the canopye6
- Outcome
- this protein in younger leavese6
- Direction
- increasee6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e6“loss of Rubisco in older leaves was associated with an increase in this protein in younger leaves higher in the canopy”
Claim · model-written summary
Accelerated senescence may provide a compensatory benefit to hybrid poplar under O3.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e7“These data support the notion that accelerated senescence may provide some compensatory benefit to the plant”
Claim · model-written summary
In 1995, the rate of Rubisco synthesis was higher in O3-treated hybrid poplar foliage than in nontreated foliage, even when Rubisco concentration was adversely affected.
- Treatment
- O(3)-treated foliagee1
- Outcome
- rate of synthesis of Rubiscoe1
- Direction
- highere1
- Qualifier
- even when the concentration of Rubisco was adversely affected by the O(3) treatmente1
- Comparator
- nontreated foliagee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e1“In 1995, the rate of synthesis of Rubisco was almost always higher in O(3)-treated foliage than in nontreated foliage, even when the concentration of Rubisco was adversely affected by the O(3) treatment”
Claim · model-written summary
Accelerated foliar abscission in response to O3 was minimal in 1995 compared with other years in hybrid poplar.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e1“Because accelerated foliar abscission in response to O(3) was minimal in 1995 compared to other years, we speculate that, when abscission is delayed, Rubisco synthesis and concentration become uncoupled”
Claim · model-written summary
Rubisco synthesis and concentration may become uncoupled in hybrid poplar when abscission is delayed.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245”
e1“Because accelerated foliar abscission in response to O(3) was minimal in 1995 compared to other years, we speculate that, when abscission is delayed, Rubisco synthesis and concentration become uncoupled”
The same questions in other papers
ozone · physiology: photosynthesis · Populus (poplar)Results differ
16 papers in the same direction as this paper · 1 in the opposite direction
- negative
- negative
- positive
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See all 18 papers →ozone · molecular: expression · Populus (poplar)Results agree
1 paper in the same direction as this paper
- negative
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.