Abstract
Melatonin is a small-molecule indole hormone that plays an important role in participating in biotic and abiotic stress resistance. Melatonin has been confirmed to promote the normal development of plants under adversity stress by mediating physiological regulation mechanisms. However, the mechanisms by which exogenous melatonin mediates salt tolerance via regulation of antioxidant activity and osmosis in cotton seedlings remain largely unknown. In this study, the regulatory effects of melatonin on reactive oxygen species (ROS), the antioxidant system, and osmotic modulators of cotton seedlings were determined under 0–500 µM melatonin treatments with salt stress induced by 150 mM NaCl treatment. Cotton seedlings under salt stress exhibited an inhibition of growth, excessive hydrogen peroxide (H 2 O 2 ), superoxide anion (O 2 − ), and malondialdehyde (MDA) accumulations in leaves, increased activity levels of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and elevated ascorbic acid (AsA) and glutathione (GSH) content in leaves. However, the content of osmotic regulators (i.e., soluble sugars and proteins) in leaves was reduced under salt stress. This indicates high levels of ROS were produced, and the cell membrane was damaged. Additionally, osmotic regulatory substance content was reduced, resulting in osmotic stress, which seriously affected cotton seedling growth under salt stress. However, exogenous melatonin at different concentrations reduced the contents of H 2 O 2 , O 2 − , and MDA in cotton leaves, increased the activity of antioxidant enzymes and the content of reductive substances (i.e., AsA and GSH), and promoted the accumulation of osmotic regulatory substances in leaves under salt stress. These results suggest that melatonin can inhibit ROS production in cotton seedlings, improve the activity of the antioxidant enzyme system, raise the content of osmotic regulation substances, reduce the level of membrane lipid peroxidation, and protect the integrity of the lipid membrane under salt stress, which reduces damage caused by salt stress to seedlings and effectively enhances inhibition of salt stress on cotton seedling growth. These results indicate that 200 µM melatonin treatment has the best effect on the growth and salt tolerance of cotton seedlings.
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Claims 10
Claim · model-written summary
Salt stress inhibited cotton seedling growth.
- Taxon
- Cotton
Gossypium hirsutume0 - Treatment
- salt stresse0
- Outcome
- growthe0
- Direction
- inhibitione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cotton seedlings under salt stress exhibited an inhibition of growth”
Claim · model-written summary
Salt stress increased leaf hydrogen peroxide, superoxide and MDA accumulation.
- Taxon
- cottonGossypium hirsutumt0
- Organ / stage
- leavese0
- Treatment
- salt stresst0
- Outcome
- hydrogen peroxide (H 2 O 2 ), superoxide anion (O 2 − ), and malondialdehyde (MDA) accumulationse0
- Direction
- excessivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“excessive hydrogen peroxide (H 2 O 2 ), superoxide anion (O 2 − ), and malondialdehyde (MDA) accumulations in leaves”
t0“salt stress adaptation of cotton seedlings”
Claim · model-written summary
Salt stress raised SOD, POD, CAT and APX activity in cotton leaves.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- salt stresst0
- Gene
- superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)e0
- Outcome
- activity levelse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased activity levels of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)”
t0“salt stress adaptation of cotton seedlings”
Claim · model-written summary
Salt stress elevated leaf ascorbic acid and glutathione content.
- Taxon
- cottonGossypium hirsutumt0
- Organ / stage
- leavese0
- Treatment
- salt stresst0
- Outcome
- ascorbic acid (AsA) and glutathione (GSH) contente0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated ascorbic acid (AsA) and glutathione (GSH) content in leaves.”
t0“salt stress adaptation of cotton seedlings”
Claim · model-written summary
Salt stress reduced soluble sugars and proteins in cotton leaves.
- Taxon
- cottonGossypium hirsutumt0
- Organ / stage
- leavese0
- Treatment
- salt stresse0
- Outcome
- content of osmotic regulators (i.e., soluble sugars and proteins)e0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the content of osmotic regulators (i.e., soluble sugars and proteins) in leaves was reduced under salt stress.”
t0“cotton seedlings”
Claim · model-written summary
Melatonin reduced hydrogen peroxide, superoxide and MDA in salt stressed cotton leaves.
- Taxon
- cottonGossypium hirsutume0
- Organ / stage
- leavese0
- Treatment
- exogenous melatonin at different concentrationse0
- Outcome
- contents of H 2 O 2 , O 2 − , and MDAe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenous melatonin at different concentrations reduced the contents of H 2 O 2 , O 2 − , and MDA in cotton leaves”
Claim · model-written summary
Melatonin increased antioxidant enzyme activity under salt stress.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- melatonint0
- Outcome
- activity of antioxidant enzymese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased the activity of antioxidant enzymes and the content of reductive substances (i.e., AsA and GSH)”
t0“melatonin improves salt stress adaptation of cotton seedlings”
Claim · model-written summary
Melatonin increased ascorbate and glutathione content under salt stress.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- melatonint0
- Outcome
- content of reductive substances (i.e., AsA and GSH)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased the activity of antioxidant enzymes and the content of reductive substances (i.e., AsA and GSH)”
t0“melatonin improves salt stress adaptation of cotton seedlings”
Claim · model-written summary
Melatonin promoted accumulation of osmotic regulatory substances in leaves.
- Taxon
- cottonGossypium hirsutumt0
- Organ / stage
- leavese0
- Treatment
- melatonint0
- Outcome
- accumulation of osmotic regulatory substancese0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“promoted the accumulation of osmotic regulatory substances in leaves under salt stress.”
t0“melatonin improves salt stress adaptation of cotton seedlings”
Claim · model-written summary
A 200 µM melatonin treatment had the best effect on cotton seedling growth and salt tolerance.
- Taxon
- cottonGossypium hirsutume0
- Treatment
- 200 µM melatonin treatmente0
- Outcome
- growth and salt tolerancee0
- Direction
- best effecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“200 µM melatonin treatment has the best effect on the growth and salt tolerance of cotton seedlings.”
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