Abstract
Salt stress severely impairs photosynthesis and development in tomato seedlings. This study investigated the regulatory role of exogenous melatonin (MT) on photosynthetic performance under salt stress by determining chlorophyll content, chlorophyll a fluorescence parameters, Calvin cycle enzyme activities, and related gene expression. Results showed that salt stress significantly reduced chlorophyll content and impaired photosystem II (PSII) functionality, as evidenced by the increased minimum fluorescence (Fo) and decreased maximum quantum efficiency of PSII (Fv/Fm) and effective PSII quantum yield (ΦPSII). MT application mitigated these negative effects, as reflected by higher Fv/Fm, increased chlorophyll content, and lower non-photochemical quenching (NPQ). In addition, MT-treated plants exhibited improved PSII electron transport and more efficient use of absorbed light energy, as shown by elevated ΦPSII and qP values. These changes suggest improved PSII functional stability and reduced excess thermal energy dissipation. Furthermore, MT significantly enhanced both the activity and expression of key enzymes involved in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Rubisco activase (RCA), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fructose-1,6-bisphosphatase (FBPase), fructose-bisphosphate aldolase (FBA), transketolase (TK), and sedoheptulose-1,7-bisphosphatase (SBPase), thereby promoting carbon fixation and ribulose-1,5-bisphosphate (RuBP) regeneration under salt stress. Conversely, inhibition of endogenous MT synthesis by p-CPA exacerbated salt stress damage, further confirming MT’s crucial role in salt tolerance. These findings demonstrate that exogenous MT enhances salt tolerance in tomato seedlings by simultaneously improving photosynthetic electron transport efficiency and upregulating the activity and gene expression of key Calvin cycle enzymes, thereby promoting the coordination between light reactions and carbon fixation processes. This study provides valuable insights into the comprehensive regulatory role of MT in maintaining photosynthetic performance under saline conditions.
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Claims 8
Claim · model-written summary
Salt stress reduced chlorophyll content.
- Taxon
- tomato seedlings
Solanum lycopersicume1 - Treatment
- salt stresse0
- Outcome
- chlorophyll contente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“salt stress significantly reduced chlorophyll content”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
Claim · model-written summary
Salt stress increased minimum fluorescence.
- Taxon
- tomato seedlingsSolanum lycopersicume1
- Outcome
- minimum fluorescence (Fo)e0
- Direction
- increasede0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased minimum fluorescence (Fo)”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
Claim · model-written summary
Salt stress decreased maximum and effective PSII quantum yields.
- Taxon
- tomato seedlingsSolanum lycopersicume1
- Outcome
- maximum quantum efficiency of PSII (Fv/Fm) and effective PSII quantum yield (ΦPSII)e0
- Direction
- decreasede0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased maximum quantum efficiency of PSII (Fv/Fm) and effective PSII quantum yield (ΦPSII)”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
Claim · model-written summary
Melatonin raised Fv/Fm and chlorophyll content under salt stress.
- Taxon
- tomato seedlingsSolanum lycopersicume1
- Treatment
- MT applicatione0
- Outcome
- Fv/Fm, increased chlorophyll contente0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT application mitigated these negative effects, as reflected by higher Fv/Fm, increased chlorophyll content”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
Claim · model-written summary
Melatonin lowered non-photochemical quenching.
- Taxon
- tomato seedlingsSolanum lycopersicume1
- Outcome
- non-photochemical quenching (NPQ)e0
- Direction
- lowere0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lower non-photochemical quenching (NPQ)”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
Claim · model-written summary
Melatonin elevated ΦPSII and qP values.
- Taxon
- tomato seedlingsSolanum lycopersicume1
- Treatment
- MT-treatede0
- Outcome
- ΦPSII and qP valuese0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT-treated plants exhibited improved PSII electron transport and more efficient use of absorbed light energy, as shown by elevated ΦPSII and qP values”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
Claim · model-written summary
Melatonin enhanced Calvin cycle enzyme activity and expression.
- Taxon
- tomato seedlingsSolanum lycopersicume1
- Treatment
- MTe0
- Outcome
- activity and expression of key enzymes involved in the Calvin cyclee0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT significantly enhanced both the activity and expression of key enzymes involved in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Rubisco activase (RCA), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fructose-1,6-bisphosphatase (FBPase), fructose-bisphosphate aldolase (FBA), transketolase (TK), and sedoheptulose-1,7-bisphosphatase (SBPase)”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
Claim · model-written summary
Inhibition of endogenous melatonin synthesis exacerbated salt damage.
- Taxon
- tomato seedlingsSolanum lycopersicume1
- Treatment
- p-CPAe0
- Outcome
- salt stress damagee0
- Direction
- exacerbatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inhibition of endogenous MT synthesis by p-CPA exacerbated salt stress damage”
e1“Salt stress severely impairs photosynthesis and development in tomato seedlings.”
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See all 71 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.