Abstract
One goal of phytohormonal ecology is to study the interactions between biotic and abiotic stress at hierarchical levels of biological organization. From an ecological perspective, exposure to one stress may alter the plant's probability of being exposed to another stress. From a mechanistic perspective, hormonal and biochemical signaling interactions between responses to each stress may influence the severity or ability to adaptively respond to the subsequent stress. In this article, we consider the relationship between plant water and salt stress and attack by pathogens and herbivores. Empirical data suggest that water stress and the probability of attack by pathogens and herbivores are correlated between habitats. Biochemical interactions between plant responses to water and salt stress and insect and pathogen attack are also interrelated. Initial biochemical models indicated that abscisic acid (ABA), an important hormone in responses to water and salt stress, had a synergistic positive role with jasmonate-induced defenses against herbivores and an antagonistic role with salicylate-based resistance to some pathogens. Based on this background, we developed predictions about how water and salt stress would alter plant resistance to insects and pathogens and tested the predictions using tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato. We have two key findings. First, ABA-deficient plants had higher levels of salicylate-mediated responses and were more resistant to bacterial speck disease, consistent with the proposed role of salicylate in defense against pathogens. This suggests linkage between water availability to the plant and salicylate action in pathogenesis through ABA signaling. ABA-deficient plants had reduced resistance to the insect Spodoptera exigua, suggesting a positive correlation between responses to water stress and herbivory. The lack of difference in chemical expression of the jasmonate (JA) response (polyphenol oxidase activity) between wild-type and ABA-deficient plants did not support the proposed mechanism of synergism with the jasmonate response. Second, salt stress reduced the chemical induction (e.g., pathogenesis-related protein P4) of the salicylate response, but this did not affect resistance to the pathogen. Salt stress did not alter resistance to the herbivore Trichoplusia ni, but did alter the negative signal interaction between the jasmonate and salicylate responses. Under control conditions, the jasmonate and salicylate responses are antagonistic to one another, with induction of one response reducing the inducibility of the other. Under salt stress conditions, the negative effect of salicylate on the jasmonate response was reduced. Thus, complex interactions occur between ABA, JA, and SA, hormones that are important regulators of abiotic and biotic stress responses. Phytohormonal ecology is attempting to link ecological and hormonal interactions to develop a predictive framework for how and why plants coordinate responses to the environment.
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Claims 8
Claim · model-written summary
ABA-deficient plants had higher salicylate-mediated responses.
- Taxon
- tomato plants
Solanum lycopersicume1 - Material
- ABA-deficient plantse0
- Outcome
- salicylate-mediated responsese0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ABA-deficient plants had higher levels of salicylate-mediated responses”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
Claim · model-written summary
ABA-deficient plants resisted bacterial speck disease more strongly.
- Taxon
- tomato plantsSolanum lycopersicume1
- Material
- ABA-deficient plantse0
- Interactor
- Pseudomonas syringae pv. tomato
Pseudomonas syringae pv. tomatoe1pathogene0 - Outcome
- bacterial speck diseasee0
- Direction
- more resistante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ABA-deficient plants had higher levels of salicylate-mediated responses and were more resistant to bacterial speck disease”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
Claim · model-written summary
ABA-deficient plants had reduced resistance to Spodoptera exigua.
- Taxon
- tomato plantsSolanum lycopersicume1
- Material
- ABA-deficient plantse0
- Interactor
- Spodoptera exigua
Spodoptera exiguae0herbivore - Outcome
- resistance to the insect Spodoptera exiguae0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ABA-deficient plants had reduced resistance to the insect Spodoptera exigua”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
Claim · model-written summary
Polyphenol oxidase activity did not differ between wild type and ABA-deficient plants.
- Taxon
- tomato plantsSolanum lycopersicume1
- Material
- ABA-deficient plantse0
- Gene
- polyphenol oxidasee0
- Outcome
- polyphenol oxidase activitye0
- Direction
- lack of differencee0
- Comparator
- wild-typee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lack of difference in chemical expression of the jasmonate (JA) response (polyphenol oxidase activity) between wild-type and ABA-deficient plants”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
Claim · model-written summary
Salt stress reduced induction of pathogenesis-related protein P4.
- Taxon
- tomato plantsSolanum lycopersicume1
- Treatment
- salt stresse0
- Gene
- pathogenesis-related protein P4e0
- Outcome
- chemical induction (e.g., pathogenesis-related protein P4) of the salicylate responsee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“salt stress reduced the chemical induction (e.g., pathogenesis-related protein P4) of the salicylate response”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
Claim · model-written summary
Salt stress did not affect resistance to the pathogen.
- Taxon
- tomato plantsSolanum lycopersicume1
- Treatment
- salt stresse0
- Interactor
- Pseudomonas syringae pv. tomatoPseudomonas syringae pv. tomatoe1pathogene0
- Outcome
- resistance to the pathogene0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“salt stress reduced the chemical induction (e.g., pathogenesis-related protein P4) of the salicylate response, but this did not affect resistance to the pathogen”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
Claim · model-written summary
Salt stress did not alter resistance to Trichoplusia ni.
- Taxon
- tomato plantsSolanum lycopersicume1
- Treatment
- Salt stresse0
- Interactor
- Trichoplusia ni
Trichoplusia nie0herbivore - Outcome
- resistance to the herbivore Trichoplusia nie0
- Direction
- did not altere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Salt stress did not alter resistance to the herbivore Trichoplusia ni”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
Claim · model-written summary
Under salt stress, salicylate less strongly suppressed the jasmonate response.
- Taxon
- tomato plantsSolanum lycopersicume1
- Treatment
- salt stresse0
- Compound
- salicylatee0
- Outcome
- negative effect of salicylate on the jasmonate responsee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under salt stress conditions, the negative effect of salicylate on the jasmonate response was reduced.”
e1“tomato plants as a model system. We used polyphenol oxidase activity as a marker of the jasmonate response and pathogenesis-related protein P4 as a marker of the salicylate response. First, we examined levels of chemical defense in wild-type and ABA-deficient plants and the ability of these plants to resist insect and pathogen attack. In the second experiment, we exposed plants to short-term salinity stress and tested their subsequent resistance to a chewing insect Spodoptera exigua and the bacterial speck pathogen Pseudomonas syringae pv. tomato.”
The same questions in other papers
salinity · quality: protein · Solanum lycopersicum (tomato)Results differ
12 papers in the same direction as this paper · 1 in the opposite direction
- positive
- negative
- negative
10 papers more in this group
See all 14 papers →salinity · Pseudomonas syringae pv. tomato · Solanum lycopersicum (tomato)Results agree
1 paper in the same direction as this paper
- negative
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.