Abstract
Saline-alkali stress seriously restricts rice growth, development, and production in northern China. The damage of alkaline stress on rice is much greater than that of salt due to ion toxicity, osmotic stress, and especially high pH. As a signal molecule, melatonin (N-acetyl-5-methoxytryptamine, MT) mediates many physiological processes in rice and participates in protecting rice from abiotic stress. The potential mechanism of exogenous melatonin-mediated alkaline stress tolerance is still largely unknown. In this study, the effects of melatonin on the morphological change, physiological property, and corresponding genes expression in rice seedlings were analyzed under alkaline stress (20 mmol L −1 , pH 9.55). The results showed that the expression levels of MT synthesis genes ( TDC2 , T5H , SNAT , ASMT1 , and ASMT2 ) were induced by both exogenous MT and alkaline stress treatment. The cell membrane was protected by MT, and the MT furtherly play role in scavenging reactive oxygen species (ROS), reducing lipoxygenase (LOX) activity, and malondialdehyde (MDA) content. The scavenging of ROS by melatonin is attributed to the coupling of the improvement of redox homeostasis and the enhancement of antioxidant enzyme activity and antioxidant content by upregulating the transcriptional levels of antioxidase genes. In the meantime, MT pretreatment promoted the accumulation of free proline, sucrose, and fructose by regulating the OsP5CS , OsSUS7 , and OsSPS1 gene expression level and increased chlorophyll content upregulating the expression of chlorophyll synthesis-related genes. Ultimately, the alleviating effect of exogenous melatonin on alkaline stress was reflected in increasing the leaf relative water content (RWC) and root-shoot ratio and reducing the leaf tip wilt index (TWI) through a series of physiological and biochemical changes. Melatonin pretreatment changed the expression level of MT synthesis genes which might contribute to MT synthesis in rice, consequently, activated the ROS scavenging system and alleviating the damage of alkaline stress on rice seedlings. Our study comprehensively understands the alleviating effect of exogenous melatonin on rice under alkaline stress.
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Claims 13
Claim · model-written summary
Exogenous melatonin and alkaline stress induced expression of melatonin synthesis genes.
- Taxon
- rice seedlings
Oryza sativat0 - Treatment
- exogenous MT and alkaline stress treatmente0
- Gene
- TDC2 , T5H , SNAT , ASMT1 , and ASMT2e0
- Outcome
- expression levels of MT synthesis genese0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression levels of MT synthesis genes ( TDC2 , T5H , SNAT , ASMT1 , and ASMT2 ) were induced by both exogenous MT and alkaline stress treatment”
t0“Rice Seedlings”
Claim · model-written summary
Melatonin protected the cell membrane under alkaline stress.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- MTe0
- Outcome
- cell membranee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The cell membrane was protected by MT”
t0“Rice Seedlings”
Claim · model-written summary
Melatonin scavenged reactive oxygen species.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- MTe0
- Outcome
- reactive oxygen species (ROS)e0
- Direction
- scavenginge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT furtherly play role in scavenging reactive oxygen species (ROS)”
t0“Rice Seedlings”
Claim · model-written summary
Melatonin reduced lipoxygenase activity.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- Melatonint0
- Gene
- lipoxygenase (LOX)e0
- Outcome
- lipoxygenase (LOX) activitye0
- Direction
- reducinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reducing lipoxygenase (LOX) activity”
t0“Exogenous Melatonin Alleviates Alkaline Stress by Removing Reactive Oxygen Species and Promoting Antioxidant Defence in Rice Seedlings”
Claim · model-written summary
Melatonin reduced malondialdehyde content.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- Melatonint0
- Outcome
- malondialdehyde (MDA) contente0
- Direction
- reducinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reducing lipoxygenase (LOX) activity, and malondialdehyde (MDA) content”
t0“Exogenous Melatonin Alleviates Alkaline Stress by Removing Reactive Oxygen Species and Promoting Antioxidant Defence in Rice Seedlings”
Claim · model-written summary
Melatonin improved redox homeostasis and antioxidant activity and content through antioxidase gene upregulation.
- Taxon
- rice seedlingsOryza sativat0
- Gene
- antioxidase genese0
- Outcome
- scavenging of ROSe0
- Qualifier
- improvement of redox homeostasise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“scavenging of ROS by melatonin is attributed to the coupling of the improvement of redox homeostasis and the enhancement of antioxidant enzyme activity and antioxidant content by upregulating the transcriptional levels of antioxidase genes”
t0“Rice Seedlings”
Claim · model-written summary
Melatonin pretreatment promoted free proline accumulation.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- MT pretreatmente0
- Gene
- OsP5CSe0
- Outcome
- accumulation of free prolinee0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT pretreatment promoted the accumulation of free proline, sucrose, and fructose by regulating the OsP5CS , OsSUS7 , and OsSPS1 gene expression level”
t0“Rice Seedlings”
Claim · model-written summary
Melatonin pretreatment promoted sucrose accumulation.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- MT pretreatmente0
- Gene
- OsSUS7e0
- Outcome
- sucrosee0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT pretreatment promoted the accumulation of free proline, sucrose, and fructose by regulating the OsP5CS , OsSUS7 , and OsSPS1 gene expression level”
t0“Rice Seedlings”
Claim · model-written summary
Melatonin pretreatment promoted fructose accumulation.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- MT pretreatmente0
- Gene
- OsSPS1e0
- Outcome
- fructosee0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT pretreatment promoted the accumulation of free proline, sucrose, and fructose by regulating the OsP5CS , OsSUS7 , and OsSPS1 gene expression level”
t0“Rice Seedlings”
Claim · model-written summary
Melatonin pretreatment increased chlorophyll content with upregulation of chlorophyll synthesis genes.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- Melatonint0
- Gene
- chlorophyll synthesis-related genese0
- Outcome
- chlorophyll contente0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased chlorophyll content upregulating the expression of chlorophyll synthesis-related genes”
t0“Exogenous Melatonin Alleviates Alkaline Stress by Removing Reactive Oxygen Species and Promoting Antioxidant Defence in Rice Seedlings”
Claim · model-written summary
Exogenous melatonin increased leaf relative water content under alkaline stress.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- Exogenous Melatonint0
- Outcome
- leaf relative water content (RWC)e0
- Direction
- increasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing the leaf relative water content (RWC) and root-shoot ratio and reducing the leaf tip wilt index (TWI)”
t0“Exogenous Melatonin Alleviates Alkaline Stress by Removing Reactive Oxygen Species and Promoting Antioxidant Defence in Rice Seedlings”
Claim · model-written summary
Exogenous melatonin increased root-shoot ratio under alkaline stress.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- Exogenous Melatonint0
- Outcome
- root-shoot ratioe0
- Direction
- increasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing the leaf relative water content (RWC) and root-shoot ratio and reducing the leaf tip wilt index (TWI)”
t0“Exogenous Melatonin Alleviates Alkaline Stress by Removing Reactive Oxygen Species and Promoting Antioxidant Defence in Rice Seedlings”
Claim · model-written summary
Exogenous melatonin reduced leaf tip wilt index under alkaline stress.
- Taxon
- rice seedlingsOryza sativat0
- Treatment
- Exogenous Melatonint0
- Outcome
- leaf tip wilt index (TWI)e0
- Direction
- reducinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing the leaf relative water content (RWC) and root-shoot ratio and reducing the leaf tip wilt index (TWI)”
t0“Exogenous Melatonin Alleviates Alkaline Stress by Removing Reactive Oxygen Species and Promoting Antioxidant Defence in Rice Seedlings”
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