Abstract
Ozone is a major gaseous pollutant known 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.To determine the underlying molecular mechanisms involved in ozone tolerance in tree species, comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones.Gene expression analysis using marker genes for known plant defense response pathways resulted in the finding that ozone-, pathogen-, and wound-induced expression of both salicylic acid-(SA) and jasmonic acid-(JA) regulated defense genes is attenuated in N E-388.Experiments using exogenous SA and methyl jasmonate (MeJA; a biologically active methyl derivative of JA) demonstrated that the attenuated expression of defense response genes in this clone was due to an insensitivity to both SA and JA.This finding was confirmed by quantitative analysis of endogenous levels of SA and JA that determined that both clones made similar amounts of these molecules in response to ozone.TUNEL assays were performed to detect DMA fragmentation associated with programmed cell death (PCD) that is characteristic of SA-dependent activation of a hypersensitive response (HR).DNA fragmentation was detected in both ozone-treated and pathogen-inoculated tissue from the tolerant clone but not in the sensitive clone.In addition to providing supporting evidence for the insensitivity of NE-388 to SA, these results also indicate that the mechanism of lesion formation differs between the two clones.Cell death in the tolerant clone is caused by the Induction of an SA-dependent PCD pathway, while cell death in the sensitive clone is likely to be necrosis caused by the lack of induction of antioxidant defenses to a level that is sufficient to prevent the formation of toxic ozoneinduced active oxygen species.Treatment of these clones with MeJA prior to ozone fumigation resulted in a decrease in visible symptom development only in the tolerant clone, indicating that the SA-mediated activation of PCD may be inhibited by JA.Finally, experiments were performed that ruled out a deficiency in ethylene biosynthesis as having a role in the SA/JA-insensitivity of the ozonesensitive clone.Ill Dedicated to my parents, my husband and my children.
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 9
Claim · model-written summary
Ozone-, pathogen- and wound-induced expression of SA- and JA-regulated defense genes is attenuated in the sensitive clone NE-388 compared with NE-245.
- Material
- NE-388e2
- Treatment
- ozone-, pathogen-, and wound-inducede2
- Outcome
- expression of both salicylic acid-(SA) and jasmonic acid-(JA) regulated defense genese2
- Direction
- attenuatede2
- Comparator
- NE-245e1
PopulusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e2“ozone-, pathogen-, and wound-induced expression of both salicylic acid-(SA) and jasmonic acid-(JA) regulated defense genes is attenuated in N E-388”
Claim · model-written summary
Attenuated defense-response gene expression in the sensitive clone is due to insensitivity to both SA and JA, shown with exogenous SA and MeJA.
- Treatment
- exogenous SA and methyl jasmonatee3
- Outcome
- attenuated expression of defense response genese3
- Qualifier
- insensitivity to both SA and JAe3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e3“Experiments using exogenous SA and methyl jasmonate (MeJA; a biologically active methyl derivative of JA) demonstrated that the attenuated expression of defense response genes in this clone was due to an insensitivity to both SA and JA”
Claim · model-written summary
Endogenous SA and JA levels were similar in both clones in response to ozone.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e4“This finding was confirmed by quantitative analysis of endogenous levels of SA and JA that determined that both clones made similar amounts of these molecules in response to ozone.”
Claim · model-written summary
DNA fragmentation was detected in ozone-treated tolerant-clone tissue but not in the sensitive clone.
- Material
- tolerant clonee5
- Treatment
- ozone-treatede5
- Outcome
- DNA fragmentatione5
- Comparator
- the sensitive clonee5
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e5“DNA fragmentation was detected in both ozone-treated and pathogen-inoculated tissue from the tolerant clone but not in the sensitive clone.”
Claim · model-written summary
MeJA applied before ozone fumigation decreased visible symptom development only in the tolerant clone.
- Material
- tolerant clonee6
- Treatment
- MeJA prior to ozone fumigatione6
- Outcome
- visible symptom developmente6
- Direction
- decreasee6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e6“Treatment of these clones with MeJA prior to ozone fumigation resulted in a decrease in visible symptom development only in the tolerant clone”
Claim · model-written summary
SA-mediated activation of PCD may be inhibited by JA.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e7“the SA-mediated activation of PCD may be inhibited by JA”
Claim · model-written summary
Cell death in the tolerant clone is caused by induction of an SA-dependent PCD pathway.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e2“Cell death in the tolerant clone is caused by the Induction of an SA-dependent PCD pathway”
Claim · model-written summary
Cell death in the sensitive clone is likely necrosis caused by lack of induction of antioxidant defenses.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e2“Cell death in the sensitive clone is likely to be necrosis caused by the lack of induction of antioxidant defenses to a level that is sufficient to prevent the formation of toxic ozoneinduced active oxygen species”
Claim · model-written summary
A deficiency in ethylene biosynthesis was ruled out as a cause of the SA/JA insensitivity of the ozone-sensitive clone.
- Outcome
- a deficiency in ethylene biosynthesise2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“comparisons were m ade between ozonetolerant (NE-245) and ozone-sensitive (NE-388) hybrid poplar clones”
e2“experiments were performed that ruled out a deficiency in ethylene biosynthesis as having a role in the SA/JA-insensitivity of the ozonesensitive clone”
The same questions in other papers
(-)-methyl jasmonate · disease · Populus (poplar)Results agree
1 paper in the same direction as this paper
- positive
solarization · disease · Populus (poplar)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
mechanical · molecular: expression · Populus (poplar)Positive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
1 paper more in this group
See all 5 papers →ozone · disease · Populus (poplar)Positive and negative results
1 paper in the same direction as this paper · 5 in the opposite direction
- negative
- negative
- negative
3 papers more in this group
See all 7 papers →ozone · molecular: expression · Populus (poplar)Results agree
1 paper in the same direction as this paper
- 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.