Abstract
In recent years, it has become apparent that salicylic acid (SA) plays an important role in plant defense responses to pathogen attack. Previous studies have suggested that one of SA's mechanisms of action is the inhibition of catalase, resulting in elevated levels of H2O2, which activate defense-related genes. Here we demonstrate that SA also inhibits ascorbate peroxoidase (APX), the other key enzyme for scavenging H2O2. The synthetic inducer of defense responses, 2,6-dichloroisonicotinic acid (INA), was also found to be an effective inhibitor of APX. In the presence of 750 microM ascorbic acid (AsA), substrate-dependent IC50 values of 78 microM and 95 microM were obtained for SA and INA, respectively. Furthermore, the ability of SA analogues to block APX activity correlated with their ability to induce defense-related genes in tobacco and enhance resistance to tobacco mosaic virus. Inhibition of APX by SA appears to be reversible, thus differing from the time-dependent, irreversible inactivation by suicide substrates such as p-aminophenol. In contrast to APX, the guaiacol-utilizing peroxidases, which participate in the synthesis and crosslinking of cell wall components as part of the defense response, are not inhibited by SA or INA. The inhibition of both catalase and APX, but not guaiacol peroxidases, supports the hypothesis that SA-induced defense responses are mediated, in part, through elevated H2O2 levels or coupled perturbations of the cellular redox state.
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Claims 10
Claim · model-written summary
Salicylic acid inhibits ascorbate peroxidase.
- Taxon
- tobacco
Nicotiana tabacume1 - Treatment
- SAe0
- Gene
- ascorbate peroxoidase (APX)e0
- Outcome
- ascorbate peroxoidase (APX)e0
- Direction
- inhibitse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Here we demonstrate that SA also inhibits ascorbate peroxoidase (APX), the other key enzyme for scavenging H2O2.”
e1“defense-related genes in tobacco and enhance resistance”
Claim · model-written summary
INA inhibits APX.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- 2,6-dichloroisonicotinic acid (INA)e0
- Gene
- APXe0
- Outcome
- APXe0
- Direction
- inhibitore0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The synthetic inducer of defense responses, 2,6-dichloroisonicotinic acid (INA), was also found to be an effective inhibitor of APX.”
e1“defense-related genes in tobacco and enhance resistance”
Claim · model-written summary
SA inhibited APX with an IC50 of 78 microM in 750 microM ascorbic acid.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- SAe0
- Outcome
- IC50e0
- Value
- 78 microMe0
- Qualifier
- 750 microM ascorbic acid (AsA)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the presence of 750 microM ascorbic acid (AsA), substrate-dependent IC50 values of 78 microM and 95 microM were obtained for SA and INA, respectively.”
e1“defense-related genes in tobacco and enhance resistance”
Claim · model-written summary
INA inhibited APX with an IC50 of 95 microM in 750 microM ascorbic acid.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- INAe0
- Outcome
- IC50e0
- Value
- 95 microMe0
- Qualifier
- 750 microM ascorbic acid (AsA)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the presence of 750 microM ascorbic acid (AsA), substrate-dependent IC50 values of 78 microM and 95 microM were obtained for SA and INA, respectively.”
e1“defense-related genes in tobacco and enhance resistance”
Claim · model-written summary
Ability of SA analogues to block APX correlated with defense gene induction.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- SA analoguese0
- Gene
- APXe0
- Outcome
- ability to induce defense-related genese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ability of SA analogues to block APX activity correlated with their ability to induce defense-related genes in tobacco”
Claim · model-written summary
Ability of SA analogues to block APX correlated with resistance to tobacco mosaic virus.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- SA analoguese0
- Interactor
- tobacco mosaic virus
Tobacco mosaic viruse0pathogen - Outcome
- resistance to tobacco mosaic viruse0
- Direction
- enhancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ability of SA analogues to block APX activity correlated with their ability to induce defense-related genes in tobacco and enhance resistance to tobacco mosaic virus.”
Claim · model-written summary
SA inhibition of APX appears reversible.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- SAe0
- Outcome
- Inhibition of APXe0
- Qualifier
- appears to be reversiblee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inhibition of APX by SA appears to be reversible, thus differing from the time-dependent, irreversible inactivation by suicide substrates such as p-aminophenol.”
e1“defense-related genes in tobacco and enhance resistance”
Claim · model-written summary
SA does not inhibit guaiacol-utilizing peroxidases.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- SAe0
- Outcome
- guaiacol-utilizing peroxidasese0
- Direction
- not inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the guaiacol-utilizing peroxidases, which participate in the synthesis and crosslinking of cell wall components as part of the defense response, are not inhibited by SA or INA.”
e1“defense-related genes in tobacco and enhance resistance”
Claim · model-written summary
INA does not inhibit guaiacol-utilizing peroxidases.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- INAe0
- Outcome
- guaiacol-utilizing peroxidasese0
- Direction
- not inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the guaiacol-utilizing peroxidases, which participate in the synthesis and crosslinking of cell wall components as part of the defense response, are not inhibited by SA or INA.”
e1“defense-related genes in tobacco and enhance resistance”
Claim · model-written summary
Selective catalase and APX inhibition supports a role for elevated H2O2 or redox changes in SA-induced defense.
- Taxon
- tobaccoNicotiana tabacume1
- Gene
- catalase and APXe0
- Compound
- H2O2e0
- Outcome
- SA-induced defense responsese0
- Qualifier
- coupled perturbations of the cellular redox statee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The inhibition of both catalase and APX, but not guaiacol peroxidases, supports the hypothesis that SA-induced defense responses are mediated, in part, through elevated H2O2 levels or coupled perturbations of the cellular redox state.”
e1“defense-related genes in tobacco and enhance resistance”
The same questions in other papers
salicylic acid · molecular: metabolites · Nicotiana tabacum (tobacco)Positive and negative results
8 papers in the same direction as this paper · 6 in the opposite direction
- positive
- positive
- negative
11 papers more in this group
See all 15 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.