Abstract
Ozone is a major gaseous pollutant thought to contribute to forest decline. Although the physiological and morphological responses of forest trees to ozone have been well characterized, little is known about the molecular basis for these responses. Our studies compared the response to ozone of ozone-sensitive and ozone-tolerant clones of hybrid poplar (Populus maximowizii x Populus trichocarpa) at the physiological and molecular levels. Gas-exchange analyses demonstrated clear differences between the ozone-sensitive clone 388 and the ozone-tolerant clone 245. Although ozone induced a decrease in photosynthetic rate and stomatal conductance in both clones, the magnitude of the decrease in stomatal conductance was significantly greater in the ozone-tolerant clone. RNA-blot analysis established that ozone-induced mRNA levels for phenylalanine ammonia-lyase, O-methyltransferase, a pathogenesis-related protein, and a wound-inducible gene were significantly higher in the ozone-tolerant than in the ozone-sensitive plants. Wound- and pathogen-induced levels of these mRNAs were also higher in the ozone-tolerant compared with the ozone-sensitive plants. The different physiological and molecular responses to ozone exposure exhibited by clones 245 and 388 suggest that ozone tolerance involves the activation of salicylic-acid- and jasmonic-acid-mediated signaling pathways, which may be important in triggering defense responses against oxidative stress.
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Claims 6
Claim · model-written summary
Ozone decreased photosynthetic rate in both clones.
PopulusNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ozone induced a decrease in photosynthetic rate and stomatal conductance in both clones”
e1“hybrid poplar (Populus maximowizii x Populus trichocarpa)”
Claim · model-written summary
Ozone decreased stomatal conductance in both clones.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ozone induced a decrease in photosynthetic rate and stomatal conductance in both clones”
e1“hybrid poplar (Populus maximowizii x Populus trichocarpa)”
Claim · model-written summary
The ozone-induced decline in stomatal conductance was significantly greater in tolerant clone 245 than sensitive clone 388.
- Material
- ozone-tolerant clone 245e1
- Outcome
- decrease in stomatal conductancee0
- Direction
- greatere0
- Comparator
- ozone-sensitive clone 388e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the magnitude of the decrease in stomatal conductance was significantly greater in the ozone-tolerant clone”
e1“ozone-sensitive clone 388 and the ozone-tolerant clone 245”
e2“hybrid poplar (Populus maximowizii x Populus trichocarpa)”
Claim · model-written summary
Ozone-induced mRNA levels for four defense-related genes were significantly higher in tolerant than sensitive plants.
- Material
- ozone-tolerante0
- Gene
- phenylalanine ammonia-lyase, O-methyltransferase, a pathogenesis-related protein, and a wound-inducible genee0
- Outcome
- mRNA levelse0
- Direction
- highere0
- Comparator
- ozone-sensitive plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ozone-induced mRNA levels for phenylalanine ammonia-lyase, O-methyltransferase, a pathogenesis-related protein, and a wound-inducible gene were significantly higher in the ozone-tolerant than in the ozone-sensitive plants”
e1“hybrid poplar (Populus maximowizii x Populus trichocarpa)”
Claim · model-written summary
Wound-induced mRNA levels for these genes were higher in tolerant plants than sensitive plants.
- Material
- ozone-tolerante0
- Outcome
- Wound- and pathogen-induced levels of these mRNAse0
- Direction
- highere0
- Comparator
- ozone-sensitive plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wound- and pathogen-induced levels of these mRNAs were also higher in the ozone-tolerant compared with the ozone-sensitive plants.”
e1“hybrid poplar (Populus maximowizii x Populus trichocarpa)”
Claim · model-written summary
The authors suggest ozone tolerance involves salicylic-acid- and jasmonic-acid-mediated signaling.
- Outcome
- ozone tolerancee0
- Qualifier
- activation of salicylic-acid- and jasmonic-acid-mediated signaling pathwayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ozone tolerance involves the activation of salicylic-acid- and jasmonic-acid-mediated signaling pathways”
e1“hybrid poplar (Populus maximowizii x Populus trichocarpa)”
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
- no effect
- negative
- positive
14 papers more in this group
See all 18 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.