Abstract
The roles of salicylic acid (SA) and H2O2 in the induction of PR proteins in tobacco have been examined. Studies were conducted on wild-type tobacco and plants engineered to express a bacterial salicylate hydroxylase capable of metabolizing SA to catechol (SH-L plants). Wild-type and PR-1a-GUS-transformed plants express PR-1a following challenge with Pseudomonas syringae pathovar syringae, SA or 2,6-dichloro-isonicotinic acid (INA). In contrast, SH-L plants failed to respond to SA but did express PR-1a following INA treatment. H2O2 and the irreversible catalase inhibitor 3-amino-1,2,4-triazole (3-AT) were found to be weak inducers of PR-1a expression (relative to SA) in wild-type tobacco but were unable to induce PR-1a in SH-L plants, suggesting that the action of these compounds depends upon the accumulation of SA. A model has been proposed suggesting that SA binds to and inhibits a catalase inducing an increase in H2O2 leading to PR protein expression. Catalase activity has been measured in tobacco and no significant changes in activity following infection with P. syringae pv. syringae were detected. Furthermore, inhibition of catalase activity in vitro in plant extracts requires pre-incubation and only occurs at SA concentrations above 250 microM. Leaf disks preincubated with 1 mM SA do accumulate SA to these levels and PR-1a is efficiently induced but there is no apparent inhibition of catalase activity. It is also shown that a SA-responsive gene, PR-1a, and a H2O2-sensitive gene, AoPR-1, are both relatively insensitive to 3-AT suggesting that induction of these genes is unlikely to be due entirely to inhibition of an endogenous catalase.
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Claims 15
Claim · model-written summary
Pathogen challenge induced PR-1a in wild-type and PR-1a-GUS tobacco.
- Taxon
- tobacco
Nicotiana tabacume1 - Treatment
- challenge with Pseudomonas syringae pathovar syringaee0
- Interactor
- Pseudomonas syringae pathovar syringae
Pseudomonas syringaee0pathogen - Outcome
- express PR-1ae0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wild-type and PR-1a-GUS-transformed plants express PR-1a following challenge with Pseudomonas syringae pathovar syringae, SA or 2,6-dichloro-isonicotinic acid (INA).”
e1“PR proteins in tobacco”
Claim · model-written summary
SA induced PR-1a in wild-type and reporter tobacco.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- SAe0
- Outcome
- express PR-1ae0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wild-type and PR-1a-GUS-transformed plants express PR-1a following challenge with Pseudomonas syringae pathovar syringae, SA or 2,6-dichloro-isonicotinic acid (INA).”
e1“PR proteins in tobacco”
Claim · model-written summary
INA induced PR-1a in wild-type and reporter tobacco.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- 2,6-dichloro-isonicotinic acid (INA)e0
- Outcome
- express PR-1ae0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wild-type and PR-1a-GUS-transformed plants express PR-1a following challenge with Pseudomonas syringae pathovar syringae, SA or 2,6-dichloro-isonicotinic acid (INA).”
e1“PR proteins in tobacco”
Claim · model-written summary
SA failed to induce PR-1a in SH-L tobacco.
- Taxon
- tobaccoNicotiana tabacume1
- Material
- SH-L plantse0
- Treatment
- SAe0
- Outcome
- failed to respond to SAe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast, SH-L plants failed to respond to SA but did express PR-1a following INA treatment.”
e1“PR proteins in tobacco”
Claim · model-written summary
INA induced PR-1a in SH-L tobacco.
- Taxon
- tobaccoNicotiana tabacume1
- Material
- SH-L plantse0
- Treatment
- INA treatmente0
- Outcome
- express PR-1ae0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast, SH-L plants failed to respond to SA but did express PR-1a following INA treatment.”
e1“PR proteins in tobacco”
Claim · model-written summary
H2O2 weakly induced PR-1a in wild-type tobacco relative to SA.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- H2O2e0
- Outcome
- PR-1a expressione0
- Direction
- weak inducerse0
- Comparator
- SAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“H2O2 and the irreversible catalase inhibitor 3-amino-1,2,4-triazole (3-AT) were found to be weak inducers of PR-1a expression (relative to SA) in wild-type tobacco but were unable to induce PR-1a in SH-L plants”
Claim · model-written summary
3-AT weakly induced PR-1a in wild-type tobacco relative to SA.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- 3-amino-1,2,4-triazole (3-AT)e0
- Outcome
- PR-1a expressione0
- Direction
- weak inducerse0
- Comparator
- SAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“H2O2 and the irreversible catalase inhibitor 3-amino-1,2,4-triazole (3-AT) were found to be weak inducers of PR-1a expression (relative to SA) in wild-type tobacco but were unable to induce PR-1a in SH-L plants”
Claim · model-written summary
H2O2 did not induce PR-1a in SH-L tobacco.
- Taxon
- tobaccoNicotiana tabacume0
- Material
- SH-L plantse0
- Treatment
- H2O2e0
- Outcome
- PR-1ae0
- Direction
- unable to inducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“H2O2 and the irreversible catalase inhibitor 3-amino-1,2,4-triazole (3-AT) were found to be weak inducers of PR-1a expression (relative to SA) in wild-type tobacco but were unable to induce PR-1a in SH-L plants”
Claim · model-written summary
3-AT did not induce PR-1a in SH-L tobacco.
- Taxon
- tobaccoNicotiana tabacume0
- Material
- SH-L plantse0
- Treatment
- 3-amino-1,2,4-triazole (3-AT)e0
- Outcome
- PR-1ae0
- Direction
- unable to inducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“H2O2 and the irreversible catalase inhibitor 3-amino-1,2,4-triazole (3-AT) were found to be weak inducers of PR-1a expression (relative to SA) in wild-type tobacco but were unable to induce PR-1a in SH-L plants”
Claim · model-written summary
The effects of peroxide and 3-AT were interpreted as depending on SA accumulation.
- Taxon
- tobaccoNicotiana tabacume1
- Compound
- SAe0
- Outcome
- action of these compoundse0
- Qualifier
- accumulation of SAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggesting that the action of these compounds depends upon the accumulation of SA.”
e1“PR proteins in tobacco”
Claim · model-written summary
Catalase activity showed no significant change after P. syringae infection.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- infection with P. syringae pv. syringaee0
- Interactor
- P. syringae pv. syringaePseudomonas syringae pv. syringaee0pathogen
- Outcome
- Catalase activitye0
- Direction
- no significant changese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Catalase activity has been measured in tobacco and no significant changes in activity following infection with P. syringae pv. syringae were detected.”
Claim · model-written summary
In vitro SA inhibited tobacco catalase only after preincubation and above 250 microM.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- SA concentrations above 250 microMe0
- Outcome
- catalase activitye0
- Direction
- inhibitione0
- Qualifier
- requires pre-incubatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inhibition of catalase activity in vitro in plant extracts requires pre-incubation and only occurs at SA concentrations above 250 microM.”
e1“PR proteins in tobacco”
Claim · model-written summary
Leaf disks given 1 mM SA accumulated SA and efficiently induced PR-1a without apparent catalase inhibition.
- Taxon
- tobaccoNicotiana tabacume1
- Organ / stage
- Leaf diskse0
- Treatment
- 1 mM SAe0
- Outcome
- PR-1a is efficiently inducede0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf disks preincubated with 1 mM SA do accumulate SA to these levels and PR-1a is efficiently induced but there is no apparent inhibition of catalase activity.”
e1“PR proteins in tobacco”
Claim · model-written summary
SA-treated leaf disks showed no apparent catalase inhibition.
- Taxon
- tobaccoNicotiana tabacume1
- Organ / stage
- Leaf diskse0
- Treatment
- 1 mM SAe0
- Outcome
- catalase activitye0
- Direction
- no apparent inhibitione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf disks preincubated with 1 mM SA do accumulate SA to these levels and PR-1a is efficiently induced but there is no apparent inhibition of catalase activity.”
e1“PR proteins in tobacco”
Claim · model-written summary
PR-1a and AoPR-1 were relatively insensitive to 3-AT.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- 3-ATe0
- Outcome
- PR-1a, and a H2O2-sensitive gene, AoPR-1e0
- Direction
- relatively insensitivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It is also shown that a SA-responsive gene, PR-1a, and a H2O2-sensitive gene, AoPR-1, are both relatively insensitive to 3-AT suggesting that induction of these genes is unlikely to be due entirely to inhibition of an endogenous catalase.”
e1“PR proteins in tobacco”
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