Abstract
BACKGROUND: Melatonin is a pleiotropic signaling molecule that plays multifarious roles in plants stress tolerance. The polyamine (PAs) metabolic pathway has been suggested to eliminate the effects of environmental stresses. However, the underlying mechanism of how melatonin and PAs function together under heat stress largely remains unknown. In this study, we investigated the potential role of melatonin in regulating PAs and nitric oxide (NO) biosynthesis, and counterbalancing oxidative damage induced by heat stress in tomato seedlings. RESULTS: ), lowering the lipid peroxidation content (as inferred based on malondialdehyde content) and less membrane injury index (MII). This was associated with increased the enzymatic and non-enzymatic antioxidants activities by regulating their related gene expression and modulating the ascorbate-glutathione cycle. The presence of melatonin induced respiratory burst oxidase (RBOH), heat shock transcription factors A2 (HsfA2), heat shock protein 90 (HSP90), and delta 1-pyrroline-5-carboxylate synthetase (P5CS) gene expression, which helped detoxify excess ROS via the hydrogen peroxide-mediated signaling pathway. In addition, heat stress boosted the endogenous levels of putrescine, spermidine and spermine, and increased the PAs contents, indicating higher metabolic gene expression. Moreover, melatonin-pretreated seedlings had further increased PAs levels and upregulated transcript abundance, which coincided with suppression of catabolic-related genes expression. Under heat stress, exogenous melatonin increased endogenous NO content along with nitrate reductase- and NO synthase-related activities, and expression of their related genes were also elevated. CONCLUSIONS: Melatonin pretreatment positively increased the heat tolerance of tomato seedlings by improving their antioxidant defense mechanism, inducing ascorbate-glutathione cycle, and reprogramming the PAs metabolic and NO biosynthesis pathways. These attributes facilitated the scavenging of excess ROS and increased stability of the cellular membrane, which mitigated heat-induced oxidative stress.
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Claims 12
Claim · model-written summary
Melatonin lowered lipid peroxidation content under heat stress.
- Taxon
- tomato seedlings
Solanum lycopersicumt0 - Treatment
- Melatonint0
- Outcome
- lipid peroxidation contente0
- Direction
- loweringe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lowering the lipid peroxidation content (as inferred based on malondialdehyde content)”
t0“Melatonin alleviates heat-induced damage of tomato seedlings”
Claim · model-written summary
Melatonin was associated with less membrane injury.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- Melatonint0
- Outcome
- membrane injury index (MII)e0
- Direction
- lesse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“less membrane injury index (MII)”
t0“Melatonin alleviates heat-induced damage of tomato seedlings”
Claim · model-written summary
Antioxidant activities increased under melatonin treatment.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Outcome
- enzymatic and non-enzymatic antioxidants activitiese0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased the enzymatic and non-enzymatic antioxidants activities”
t0“tomato seedlings”
Claim · model-written summary
Melatonin induced RBOH, HsfA2, HSP90, and P5CS expression.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- melatonine0
- Gene
- respiratory burst oxidase (RBOH), heat shock transcription factors A2 (HsfA2), heat shock protein 90 (HSP90), and delta 1-pyrroline-5-carboxylate synthetase (P5CS)e0
- Outcome
- gene expressione0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The presence of melatonin induced respiratory burst oxidase (RBOH), heat shock transcription factors A2 (HsfA2), heat shock protein 90 (HSP90), and delta 1-pyrroline-5-carboxylate synthetase (P5CS) gene expression”
t0“tomato seedlings”
Claim · model-written summary
Heat stress increased endogenous putrescine, spermidine, and spermine.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- heat stresse0
- Outcome
- endogenous levels of putrescine, spermidine and sperminee0
- Direction
- boostede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“heat stress boosted the endogenous levels of putrescine, spermidine and spermine”
t0“tomato seedlings”
Claim · model-written summary
Heat stress increased overall polyamine content.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- heat stresse1
- Outcome
- PAs contentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased the PAs contents”
t0“heat-induced damage of tomato seedlings”
e1“heat stress boosted the endogenous levels of putrescine, spermidine and spermine”
Claim · model-written summary
Melatonin-pretreated seedlings had further increased polyamine levels.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- melatonin-pretreatede0
- Outcome
- PAs levelse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“melatonin-pretreated seedlings had further increased PAs levels”
t0“tomato seedlings”
Claim · model-written summary
Melatonin pretreatment upregulated transcript abundance.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- melatonint0
- Outcome
- transcript abundancee0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“upregulated transcript abundance”
t0“Melatonin alleviates heat-induced damage of tomato seedlings”
Claim · model-written summary
Catabolic gene expression was suppressed with melatonin pretreatment.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- melatonint0
- Outcome
- catabolic-related genes expressione0
- Direction
- suppressione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suppression of catabolic-related genes expression”
t0“Melatonin alleviates heat-induced damage of tomato seedlings”
Claim · model-written summary
Exogenous melatonin increased endogenous nitric oxide content during heat stress.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- exogenous melatonine0
- Outcome
- endogenous NO contente0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under heat stress, exogenous melatonin increased endogenous NO content”
t0“tomato seedlings”
Claim · model-written summary
Exogenous melatonin increased nitrate reductase and NO synthase activities.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- exogenous melatonine1
- Outcome
- nitrate reductase- and NO synthase-related activitiese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“along with nitrate reductase- and NO synthase-related activities”
t0“Melatonin alleviates heat-induced damage of tomato seedlings”
e1“Under heat stress, exogenous melatonin increased endogenous NO content”
Claim · model-written summary
Related gene expression rose under exogenous melatonin.
- Taxon
- tomato seedlingsSolanum lycopersicumt0
- Treatment
- exogenous melatonine1
- Outcome
- expression of their related genese0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of their related genes were also elevated”
t0“Melatonin alleviates heat-induced damage of tomato seedlings”
e1“Under heat stress, exogenous melatonin increased endogenous NO content”
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