Abstract
Abstract Arsenic (As) contamination and accumulation in rice is a serious concern causing severe oxidative damage. Melatonin acts as a protective agent in plant defence against multiple abiotic stresses. The mechanism of antioxidant function of melatonin during As stress in rice genotypes is less studied. In this study, hydroponically‐grown As‐susceptible (Khitish) and As‐tolerant (Muktashri) rice cultivars, subjected to 150 µ m arsenate stress, were supplemented with exogenously applied melatonin (20 µ m ) to examine the plant defence mechanism. Melatonin (Mel) increased root and shoot length, fresh and dry weight, chlorophyll a and b content and activated reducing power and free radical scavenging capacity in both rice cultivars. The role of Mel in the sensitive variety appeared to be more prominent with respect to reduced water saturation deficit by reducing endogenous As and H 2 O 2 accumulation, and enhancing overall antioxidant capacity by imposing reduced requirement of catalase for ROS detoxification, and restoring As‐inhibited activity of glutathione‐S‐transferase, glutathione peroxidase and dehydroascorbate reductase. In contrast, melatonin treatment in the tolerant cultivar required reduced involvement of ascorbate peroxidase to deal with As toxicity, and complemented the stress‐mediated inhibition of guaiacol peroxidase activity. Isozyme profiling also established extensive varietal differences with regard to induction of new isoform(s) by Mel during As treatment. This study provides clear insights into mechanistic details of the regulation of antioxidative enzymes by melatonin in contrasting rice genotypes, which may prove helpful in generating As tolerance in susceptible rice varieties grown in marginalized soils, thereby improving crop yield and productivity.
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Claims 12
Claim · model-written summary
Melatonin increased root and shoot length of rice under arsenate stress.
- Taxon
- rice
Oryza sativat0 - Treatment
- Melatonin (Mel)e1
- Outcome
- root and shoot lengthe1
- Direction
- increasede1
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e1“Melatonin (Mel) increased root and shoot length, fresh and dry weight, chlorophyll a and b content and activated reducing power and free radical scavenging capacity in both rice cultivars”
e2“subjected to 150 µ m arsenate stress”
Claim · model-written summary
Melatonin increased fresh and dry weight of rice under arsenate stress.
- Taxon
- riceOryza sativat0
- Treatment
- Melatonin (Mel)e1
- Outcome
- fresh and dry weighte1
- Direction
- increasede1
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e1“Melatonin (Mel) increased root and shoot length, fresh and dry weight, chlorophyll a and b content and activated reducing power and free radical scavenging capacity in both rice cultivars”
e2“subjected to 150 µ m arsenate stress”
Claim · model-written summary
Melatonin increased chlorophyll a and b content of rice under arsenate stress.
- Taxon
- riceOryza sativat0
- Treatment
- Melatonin (Mel)e1
- Outcome
- chlorophyll a and b contente1
- Direction
- increasede1
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e1“Melatonin (Mel) increased root and shoot length, fresh and dry weight, chlorophyll a and b content and activated reducing power and free radical scavenging capacity in both rice cultivars”
e2“subjected to 150 µ m arsenate stress”
Claim · model-written summary
Melatonin activated reducing power and free radical scavenging capacity of rice under arsenate stress.
- Taxon
- riceOryza sativat0
- Treatment
- Melatonin (Mel)e1
- Outcome
- reducing power and free radical scavenging capacitye1
- Direction
- activatede1
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e1“Melatonin (Mel) increased root and shoot length, fresh and dry weight, chlorophyll a and b content and activated reducing power and free radical scavenging capacity in both rice cultivars”
e2“subjected to 150 µ m arsenate stress”
Claim · model-written summary
In the sensitive variety, melatonin reduced water saturation deficit under arsenate stress.
- Taxon
- riceOryza sativat0
- Material
- sensitive varietye3
- Treatment
- Mele3
- Outcome
- water saturation deficite4
- Direction
- reducede4
- Qualifier
- appeared to be more prominente3
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e2“subjected to 150 µ m arsenate stress”
e3“The role of Mel in the sensitive variety appeared to be more prominent”
e4“with respect to reduced water saturation deficit”
Claim · model-written summary
In the sensitive variety, melatonin reduced endogenous As and H2O2 accumulation.
- Taxon
- riceOryza sativat0
- Material
- sensitive varietye3
- Treatment
- Mele3
- Outcome
- endogenous As and H 2 O 2 accumulatione5
- Direction
- reducinge5
- Qualifier
- appeared to be more prominente3
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e2“subjected to 150 µ m arsenate stress”
e3“The role of Mel in the sensitive variety appeared to be more prominent”
e5“by reducing endogenous As and H 2 O 2 accumulation”
Claim · model-written summary
In the sensitive variety, melatonin enhanced overall antioxidant capacity.
- Taxon
- riceOryza sativat0
- Material
- sensitive varietye3
- Treatment
- Mele3
- Outcome
- overall antioxidant capacitye6
- Direction
- enhancinge6
- Qualifier
- appeared to be more prominente3
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e2“subjected to 150 µ m arsenate stress”
e3“The role of Mel in the sensitive variety appeared to be more prominent”
e6“enhancing overall antioxidant capacity”
Claim · model-written summary
In the sensitive variety, melatonin reduced the requirement of catalase for ROS detoxification.
- Taxon
- riceOryza sativat0
- Material
- sensitive varietye3
- Treatment
- Mele3
- Gene
- catalasee7
- Outcome
- requirement of catalasee7
- Direction
- reducede7
- Qualifier
- appeared to be more prominente3
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e2“subjected to 150 µ m arsenate stress”
e3“The role of Mel in the sensitive variety appeared to be more prominent”
e7“reduced requirement of catalase for ROS detoxification”
Claim · model-written summary
In the sensitive variety, melatonin restored the As-inhibited activity of glutathione-related enzymes.
- Taxon
- riceOryza sativat0
- Material
- sensitive varietye3
- Treatment
- Mele3
- Gene
- glutathione peroxidase and dehydroascorbate reductasee4
- Outcome
- activity of glutathionee6
- Direction
- restoringe5
- Qualifier
- appeared to be more prominente3
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e2“subjected to 150 µ m arsenate stress”
e3“The role of Mel in the sensitive variety appeared to be more prominent”
e4“glutathione peroxidase and dehydroascorbate reductase”
e5“restoring”
e6“activity of glutathione”
Claim · model-written summary
In the tolerant cultivar, melatonin reduced the involvement of ascorbate peroxidase during arsenate stress.
- Taxon
- riceOryza sativat0
- Material
- tolerant cultivare4
- Treatment
- melatonin treatmente4
- Outcome
- involvement of ascorbate peroxidasee4
- Direction
- reducede4
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e2“subjected to 150 µ m arsenate stress”
e4“In contrast, melatonin treatment in the tolerant cultivar required reduced involvement of ascorbate peroxidase”
Claim · model-written summary
In the tolerant cultivar, melatonin complemented the stress-mediated inhibition of guaiacol peroxidase activity.
- Taxon
- riceOryza sativat0
- Material
- tolerant cultivare4
- Treatment
- melatonin treatmente4
- Outcome
- guaiacol peroxidase activitye5
- Direction
- complementede6
- Comparator
- arsenate stresse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e2“subjected to 150 µ m arsenate stress”
e4“In contrast, melatonin treatment in the tolerant cultivar required reduced involvement of ascorbate peroxidase”
e5“guaiacol peroxidase activity”
e6“complemented”
Claim · model-written summary
Melatonin induced new isoforms with extensive differences between rice varieties during arsenate treatment.
- Taxon
- riceOryza sativat0
- Treatment
- Mele1
- Outcome
- induction of new isoform(s)e1
- Qualifier
- extensive varietal differencese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in indica rice varieties”
e1“Isozyme profiling also established extensive varietal differences with regard to induction of new isoform(s) by Mel during As treatment”
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