Abstract
The prevalence of allergic disease is expected to increase with climate change. Grasses, which have highly allergenic pollen, are widely distributed across the globe. Changes in production and allergen content of grass pollen have not been specifically investigated. We tested the effects of elevated carbon dioxide and ozone on growth, pollen and allergen production of Timothy grass (Phleum pratense L.). Timothy is also used as an agricultural forage crop so changes in plant productivity can also affect humans indirectly. Plants were fumigated in eight chambers at two concentrations of ozone (O3; 30 and 80 ppb) and carbon dioxide (CO2; 400 and 800 ppm) to simulate present and future projected levels. Destructive harvests were completed every three weeks to measure productivity. Pollen was collected in polyethylene bags placed around flowers and assessed for pollen number and concentration of the allergenic protein, Phl p 5. We found that elevated CO2 significantly increased the amount of pollen produced per flower regardless of O3 level. In addition, the amount of Phl p 5 allergen per flower was significantly increased in plants grown at elevated CO2 / low O3 conditions. We also found that plants grown in both elevated CO2 and elevated O3 increased the amount of pollen produced per weight of flower. The Phl p 5 allergen content per pollen grain was significantly reduced by elevated O3, as was flower length and weight. However, this was partially ameliorated by elevated CO2. Productivity was affected negatively by elevated O3 throughout the life cycle. CO2 increased shoot productivity during the intermediate stages of life and also ameliorated the negative impacts of elevated O3. We conclude that increasing levels of CO2 will cause a 2.5 times increase in Timothy grass pollen production thus increasing human airborne pollen exposure. Increases in pollen were likely a result of increased shoot biomass in the stages leading up to reproduction. If Timothy grass is a good model for other grasses, this portends for increased allergy suffering worldwide and an important health impact of global climate change.
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Claims 11
Claim · model-written summary
Elevated CO2 significantly increased pollen produced per flower regardless of O3 level.
- Taxon
- Timothy grass (Phleum pratense L.)
Phleum pratensee1 - Treatment
- elevated CO2e0
- Outcome
- amount of pollen produced per flowere0
- Direction
- increasede0
- Qualifier
- regardless of O3 levele0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated CO2 significantly increased the amount of pollen produced per flower regardless of O3 level”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
Elevated CO2 with low O3 significantly increased Phl p 5 allergen per flower.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Treatment
- elevated CO2 / low O3 conditionse0
- Gene
- Phl p 5e0
- Outcome
- amount of Phl p 5 allergen per flowere0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the amount of Phl p 5 allergen per flower was significantly increased in plants grown at elevated CO2 / low O3 conditions”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
Combined elevated CO2 and O3 increased pollen produced per flower weight.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Treatment
- both elevated CO2 and elevated O3e0
- Outcome
- amount of pollen produced per weight of flowere0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plants grown in both elevated CO2 and elevated O3 increased the amount of pollen produced per weight of flower”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
Elevated O3 significantly reduced Phl p 5 allergen content per pollen grain.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Treatment
- elevated O3e0
- Gene
- Phl p 5e0
- Outcome
- Phl p 5 allergen content per pollen graine0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Phl p 5 allergen content per pollen grain was significantly reduced by elevated O3”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
Elevated O3 significantly reduced flower length and weight.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Treatment
- elevated O3e0
- Outcome
- flower length and weighte0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Phl p 5 allergen content per pollen grain was significantly reduced by elevated O3, as was flower length and weight”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
Elevated CO2 partially ameliorated the O3 reductions in allergen content and flower size.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee2
- Treatment
- elevated CO2e0
- Outcome
- flower length and weighte1
- Direction
- amelioratede0
- Comparator
- elevated O3e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, this was partially ameliorated by elevated CO2”
e1“The Phl p 5 allergen content per pollen grain was significantly reduced by elevated O3, as was flower length and weight”
e2“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
Elevated O3 negatively affected productivity throughout the life cycle.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Treatment
- elevated O3e0
- Outcome
- Productivitye0
- Direction
- negativelye0
- Qualifier
- throughout the life cyclee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Productivity was affected negatively by elevated O3 throughout the life cycle”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
CO2 increased shoot productivity at intermediate life stages.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Treatment
- CO2e0
- Outcome
- shoot productivitye0
- Direction
- increasede0
- Qualifier
- intermediate stages of lifee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO2 increased shoot productivity during the intermediate stages of life”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
CO2 ameliorated the negative productivity impacts of elevated O3.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Treatment
- CO2e0
- Outcome
- negative impacts of elevated O3e0
- Direction
- amelioratede0
- Comparator
- elevated O3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO2 increased shoot productivity during the intermediate stages of life and also ameliorated the negative impacts of elevated O3”
e1“Timothy grass (Phleum pratense L.)”
Claim · model-written summary
The authors projected that increasing CO2 would increase Timothy grass pollen production 2.5 times.
- Taxon
- Timothy grassPhleum pratensee0
- Outcome
- pollen productione0
- Direction
- increasee0
- Value
- 2.5 timese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing levels of CO2 will cause a 2.5 times increase in Timothy grass pollen production”
Claim · model-written summary
The authors attributed increased pollen to higher shoot biomass before reproduction.
- Taxon
- Timothy grass (Phleum pratense L.)Phleum pratensee1
- Outcome
- Increases in pollene0
- Qualifier
- increased shoot biomass in the stages leading up to reproductione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increases in pollen were likely a result of increased shoot biomass in the stages leading up to reproduction”
e1“Timothy grass (Phleum pratense L.)”
The same questions in other papers
co2 · yield · Phleum pratense (timothy)Positive and negative results
1 in the opposite direction
- no effect
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.