Abstract
Soil salinity is a severe threat to agricultural production. Most saline soils turn alkaline, increasing the soil pH and, in turn, hampering the growth and development of crops. In this study, the effects of a foliar spray of melatonin (MT; 100 μmol·L−1) on the pH of the root environment, growth of tomato seedlings, endogenous MT levels, rapid chlorophyll fluorescence induction kinetics, and key enzymes of the Calvin cycle under alkaline (60 mmol·L−1 NaHCO3) stress were studied in Riegel 87-5 tomatoes. The results revealed that the growth and photosynthesis of tomato seedlings were inhibited by increased pH in the root environment under alkali stress; however, the application of exogenous MT reduced the pH of the root environment, alleviated the inhibition of growth of tomato seedlings under alkali stress, increased the content of photosynthetic pigments, alleviated the damage of the donor and acceptor sides of the photosynthetic electron transport chain, increased the activity and efficiency of photosynthetic electron transport, and optimized the share of the light energy allocated to PSII reaction centers. Increased expression levels of Calvin-cycle enzymes, including fructose-1,6-bisphosphate aldolase (FBA), fructose-1,6-bisphosphate esterase (FBP), and phosphoglycerate kinase (PGK), led to enhanced photosynthetic performance in tomato seedlings. Exogenous MT boosted endogenous MT levels and stimulated the production and secretion of organic acids in the root system. This regulation of organic acid content reduced the environmental pH in the inter-root zone, alleviating the damage caused by alkali stress. This study indicated that the exogenous administration of MT may mediate an increase in endogenous MT levels, regulate the efficiency of photosynthesis and root pH levels, and play a crucial role in mitigating injury caused by alkali stress in tomato seedlings.
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Claims 14
Claim · model-written summary
Alkali stress inhibited tomato seedling growth.
- Taxon
- tomato
Solanum lycopersicume0 - Treatment
- alkali stresse0
- Outcome
- growthe0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the growth and photosynthesis of tomato seedlings were inhibited by increased pH in the root environment under alkali stress”
Claim · model-written summary
Alkali stress inhibited tomato seedling photosynthesis.
- Taxon
- tomatoSolanum lycopersicume0
- Treatment
- alkali stresse0
- Outcome
- photosynthesise0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the growth and photosynthesis of tomato seedlings were inhibited by increased pH in the root environment under alkali stress”
Claim · model-written summary
Exogenous melatonin lowered root environment pH under alkali stress.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- exogenous MTe0
- Outcome
- pH of the root environmente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the application of exogenous MT reduced the pH of the root environment”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Exogenous melatonin alleviated inhibition of tomato seedling growth under alkali stress.
- Taxon
- tomatoSolanum lycopersicume0
- Treatment
- Exogenous Melatonint0
- Outcome
- growth of tomato seedlingse0
- Direction
- alleviatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alleviated the inhibition of growth of tomato seedlings under alkali stress”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Exogenous melatonin raised photosynthetic pigment content.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- Exogenous Melatonint0
- Outcome
- content of photosynthetic pigmentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased the content of photosynthetic pigments”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Exogenous melatonin alleviated damage to both sides of the photosynthetic electron transport chain.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- Exogenous Melatonint0
- Outcome
- damage of the donor and acceptor sides of the photosynthetic electron transport chaine0
- Direction
- alleviatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alleviated the damage of the donor and acceptor sides of the photosynthetic electron transport chain”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Exogenous melatonin increased photosynthetic electron transport activity and efficiency.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- Exogenous Melatonint0
- Outcome
- activity and efficiency of photosynthetic electron transporte0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased the activity and efficiency of photosynthetic electron transport”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Exogenous melatonin optimized allocation of light energy to PSII reaction centers.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- Exogenous Melatonint0
- Outcome
- share of the light energy allocated to PSII reaction centerse0
- Direction
- optimizede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“optimized the share of the light energy allocated to PSII reaction centers”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Calvin cycle enzyme expression rose in tomato seedlings.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- fructose-1,6-bisphosphate aldolase (FBA), fructose-1,6-bisphosphate esterase (FBP), and phosphoglycerate kinase (PGK)e0
- Outcome
- expression levels of Calvin-cycle enzymese0
- Direction
- Increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased expression levels of Calvin-cycle enzymes, including fructose-1,6-bisphosphate aldolase (FBA), fructose-1,6-bisphosphate esterase (FBP), and phosphoglycerate kinase (PGK)”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Increased Calvin cycle enzyme expression enhanced tomato seedling photosynthetic performance.
- Taxon
- tomatoSolanum lycopersicume0
- Gene
- Calvin-cycle enzymese0
- Outcome
- photosynthetic performancee0
- Direction
- enhancede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased expression levels of Calvin-cycle enzymes, including fructose-1,6-bisphosphate aldolase (FBA), fructose-1,6-bisphosphate esterase (FBP), and phosphoglycerate kinase (PGK), led to enhanced photosynthetic performance in tomato seedlings”
Claim · model-written summary
Exogenous melatonin raised endogenous melatonin levels.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- Exogenous MTe0
- Outcome
- endogenous MT levelse0
- Direction
- boostede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous MT boosted endogenous MT levels”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Exogenous melatonin stimulated root organic acid production and secretion.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- Exogenous Melatonint0
- Outcome
- production and secretion of organic acids in the root systeme0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stimulated the production and secretion of organic acids in the root system”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Organic acid regulation reduced inter-root zone pH.
- Taxon
- TomatoSolanum lycopersicumt0
- Compound
- organic acide0
- Outcome
- environmental pH in the inter-root zonee0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This regulation of organic acid content reduced the environmental pH in the inter-root zone”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
Claim · model-written summary
Organic acid regulation alleviated alkali stress damage.
- Taxon
- TomatoSolanum lycopersicumt0
- Compound
- organic acide0
- Outcome
- damage caused by alkali stresse0
- Direction
- alleviatinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This regulation of organic acid content reduced the environmental pH in the inter-root zone, alleviating the damage caused by alkali stress”
t0“Exogenous Melatonin Alleviates the Inhibitory Effect of NaHCO3 on Tomato Growth”
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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.