Abstract
Metabolism in an environment containing of 21% oxygen has a high risk of oxidative damage due to the formation of reactive oxygen species. Therefore, plants have evolved an antioxidant system consisting of metabolites and enzymes that either directly scavenge ROS or recycle the antioxidant metabolites. Ozone is a temporally dynamic molecule that is both naturally occurring as well as an environmental pollutant that is predicted to increase in concentration in the future as anthropogenic precursor emissions rise. It has been hypothesized that any elevation in ozone concentration will cause increased oxidative stress in plants and therefore enhanced subsequent antioxidant metabolism, but evidence for this response is variable. Along with increasing atmospheric ozone concentrations, atmospheric carbon dioxide concentration is also rising and is predicted to continue rising in the future. The effect of elevated carbon dioxide concentrations on antioxidant metabolism varies among different studies in the literature. Therefore, the question of how antioxidant metabolism will be affected in the most realistic future atmosphere, with increased carbon dioxide concentration and increased ozone concentration, has yet to be answered, and is the subject of my thesis research. First, in order to capture as much of the variability in the antioxidant system as possible, I developed a suite of high-throughput quantitative assays for a variety of antioxidant metabolites and enzymes. I optimized these assays for Glycine max (soybean), one of the most important food crops in the world. These assays provide accurate, rapid and high-throughput measures of both the general and specific antioxidant action of plant tissue extracts. Second, I investigated how growth at either elevated carbon dioxide concentration or chronic elevated ozone concentration altered antioxidant metabolism, and the ability of soybean to respond to an acute oxidative stress in a controlled environment study. I found that growth at chronic elevated ozone concentration increased the antioxidant capacity of leaves, but was unchanged or only slightly increased following an acute oxidative stress, suggesting that growth at chronic elevated ozone concentration primed the antioxidant system. Growth at high carbon dioxide concentration decreased the antioxidant capacity of leaves, increased the response of the existing antioxidant enzymes to an acute oxidative stress, but dampened and delayed the transcriptional response, suggesting an entirely different regulation of the antioxidant system. Third, I tested the findings from the controlled environment study in a field setting by investigating the response of the soybean antioxidant system to growth at elevated carbon dioxide concentration, chronic elevated ozone concentration and the combination of elevated carbon dioxide concentration and elevated ozone concentration. In this study, I confirmed that growth at elevated carbon dioxide concentration decreased specific components of antioxidant metabolism in the field. I also verified that increasing ozone concentration is highly correlated with increases in the metabolic and genomic components of antioxidant metabolism, regardless of carbon dioxide concentration environment, but that the response to increasing ozone concentration was dampened at elevated carbon dioxide concentration. In addition, I found evidence suggesting an up regulation of respiratory metabolism at higher ozone concentration, which would supply energy and carbon for detoxification and repair of cellular damage. These results consistently support the conclusion that growth at elevated carbon dioxide concentration decreases antioxidant metabolism while growth at elevated ozone concentration increases antioxidant metabolism.
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Claims 13
Claim · model-written summary
Optimized soybean tissue assays provided accurate, rapid and high-throughput antioxidant measures.
- Taxon
- Glycine max (soybean)
Glycine maxe0 - Outcome
- accurate, rapid and high-throughput measurese0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“I optimized these assays for Glycine max (soybean), one of the most important food crops in the world. These assays provide accurate, rapid and high-throughput measures of both the general and specific antioxidant action of plant tissue extracts.”
Claim · model-written summary
Chronic elevated ozone increased soybean leaf antioxidant capacity.
- Taxon
- soybeanGlycine maxt0
- Treatment
- chronic elevated ozone concentratione0
- Outcome
- antioxidant capacity of leavese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“growth at chronic elevated ozone concentration increased the antioxidant capacity of leaves”
Claim · model-written summary
Following acute oxidative stress, antioxidant capacity was unchanged or only slightly increased in ozone-grown plants.
- Taxon
- soybeanGlycine maxt0
- Treatment
- acute oxidative stresse0
- Outcome
- antioxidant capacitye1
- Direction
- unchanged or only slightly increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“but was unchanged or only slightly increased following an acute oxidative stress”
e1“growth at chronic elevated ozone concentration increased the antioxidant capacity of leaves”
Claim · model-written summary
The author inferred that chronic ozone primed the soybean antioxidant system.
- Taxon
- soybeanGlycine maxt0
- Treatment
- chronic elevated ozone concentratione0
- Outcome
- antioxidant systeme0
- Direction
- primede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“growth at chronic elevated ozone concentration primed the antioxidant system”
Claim · model-written summary
High carbon dioxide decreased soybean leaf antioxidant capacity.
- Taxon
- soybeanGlycine maxt0
- Treatment
- high carbon dioxide concentratione0
- Outcome
- antioxidant capacity of leavese0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“Growth at high carbon dioxide concentration decreased the antioxidant capacity of leaves”
Claim · model-written summary
High carbon dioxide increased the existing antioxidant enzyme response to acute oxidative stress.
- Taxon
- soybeanGlycine maxt0
- Treatment
- high carbon dioxide concentratione1
- Outcome
- response of the existing antioxidant enzymese0
- Direction
- increasede0
- Qualifier
- acute oxidative stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“increased the response of the existing antioxidant enzymes to an acute oxidative stress”
e1“Growth at high carbon dioxide concentration decreased the antioxidant capacity of leaves”
Claim · model-written summary
High carbon dioxide dampened the transcriptional response to acute oxidative stress.
- Taxon
- soybeanGlycine maxt0
- Treatment
- high carbon dioxide concentratione1
- Outcome
- transcriptional responsee0
- Direction
- dampenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“dampened and delayed the transcriptional response”
e1“Growth at high carbon dioxide concentration decreased the antioxidant capacity of leaves”
Claim · model-written summary
High carbon dioxide delayed the transcriptional response to acute oxidative stress.
- Taxon
- soybeanGlycine maxt0
- Treatment
- high carbon dioxide concentratione1
- Outcome
- transcriptional responsee0
- Direction
- delayede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“dampened and delayed the transcriptional response”
e1“Growth at high carbon dioxide concentration decreased the antioxidant capacity of leaves”
Claim · model-written summary
Elevated carbon dioxide decreased specific antioxidant metabolism components in the field.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated carbon dioxide concentratione0
- Outcome
- specific components of antioxidant metabolisme0
- Direction
- decreasede0
- Setting
- in the fielde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“growth at elevated carbon dioxide concentration decreased specific components of antioxidant metabolism in the field”
Claim · model-written summary
Increasing ozone correlated with increased metabolic antioxidant components regardless of carbon dioxide environment.
- Taxon
- soybeanGlycine maxt0
- Treatment
- increasing ozone concentratione0
- Outcome
- metabolice0
- Direction
- increasese0
- Qualifier
- regardless of carbon dioxide concentration environmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“increasing ozone concentration is highly correlated with increases in the metabolic and genomic components of antioxidant metabolism, regardless of carbon dioxide concentration environment”
Claim · model-written summary
Increasing ozone correlated with increased genomic antioxidant components regardless of carbon dioxide environment.
- Taxon
- soybeanGlycine maxt0
- Treatment
- increasing ozone concentratione0
- Outcome
- genomic components of antioxidant metabolisme0
- Direction
- increasese0
- Qualifier
- regardless of carbon dioxide concentration environmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“increasing ozone concentration is highly correlated with increases in the metabolic and genomic components of antioxidant metabolism, regardless of carbon dioxide concentration environment”
Claim · model-written summary
Elevated carbon dioxide dampened the antioxidant response to increasing ozone.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated carbon dioxide concentratione0
- Outcome
- response to increasing ozone concentratione0
- Direction
- dampenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“the response to increasing ozone concentration was dampened at elevated carbon dioxide concentration”
Claim · model-written summary
Higher ozone may upregulate respiratory metabolism, supplying energy and carbon for detoxification and repair.
- Taxon
- soybeanGlycine maxt0
- Treatment
- higher ozone concentratione0
- Outcome
- respiratory metabolisme0
- Direction
- up regulatione0
- Qualifier
- supply energy and carbon for detoxification and repair of cellular damagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e0“evidence suggesting an up regulation of respiratory metabolism at higher ozone concentration, which would supply energy and carbon for detoxification and repair of cellular damage”
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See all 23 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.