Abstract
Melatonin (MT) plays a critical role in regulating rice responses to heavy metal stress. However, the mechanism by which MT alleviates copper (Cu) toxicity in rice remains insufficiently understood. In this study, excessive Cu increased endogenous MT level in rice roots, accompanied by enhanced gene expression involved in MT biosynthesis, suggesting its role in Cu stress responses. Exogenous MT reduced Cu accumulation and restored root growth in rice under Cu stress, thereby mitigating Cu-induced phytotoxicity. Mechanistically, MT increased the root pectin content and its Cu retention, thereby reducing Cu influx into the cytoplasm. Additionally, exogenous MT upregulated the expression of Heavy Metal ATPase 4 (OsHMA4) involved in vacuolar sequestration, as well as Cu efflux transporter genes OsHMA6 and OsHMA9. Conversely, it downregulated the plasma membrane Cu uptake-associated genes Copper Transporter (OsCOPT1, OsCOPT2, and OsCOPT3), the vacuolar Cu exporter OsCOPT7, and the xylem loading transporter gene OsHMA5, thereby alleviating Cu toxicity in rice. Furthermore, MT elevated nitric oxide (NO) levels in root tips, and application of the exogenous NO scavenger, 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), attenuated the mitigative effect of MT on excess Cu-stressed rice. In summary, MT alleviates Cu toxicity by reducing Cu binding to root cell walls, thereby limiting Cu uptake and translocation from roots to shoots. This process may depend on NO accumulation and provides new insights into the molecular mechanisms underlying MT-induced Cu tolerance in rice.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 14
Claim · model-written summary
Excess copper increased endogenous melatonin in rice roots.
- Taxon
- rice
Oryza sativae0 - Organ / stage
- rootse0
- Treatment
- excessive Cue0
- Outcome
- endogenous MT levele0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“excessive Cu increased endogenous MT level in rice roots”
Claim · model-written summary
Excess copper enhanced expression of genes involved in melatonin biosynthesis in rice roots.
- Taxon
- riceOryza sativae0
- Organ / stage
- rootse0
- Treatment
- excessive Cue0
- Outcome
- gene expression involved in MT biosynthesise0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“excessive Cu increased endogenous MT level in rice roots, accompanied by enhanced gene expression involved in MT biosynthesis”
Claim · model-written summary
Exogenous melatonin reduced copper accumulation in stressed rice.
- Taxon
- riceOryza sativae0
- Treatment
- Exogenous MTe0
- Outcome
- Cu accumulatione0
- Direction
- reducede0
- Qualifier
- under Cu stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous MT reduced Cu accumulation and restored root growth in rice under Cu stress”
Claim · model-written summary
Exogenous melatonin restored rice root growth under copper stress.
- Taxon
- riceOryza sativae0
- Treatment
- Exogenous MTe0
- Outcome
- root growthe0
- Direction
- restorede0
- Qualifier
- under Cu stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous MT reduced Cu accumulation and restored root growth in rice under Cu stress”
Claim · model-written summary
Melatonin increased rice root pectin content.
- Taxon
- riceOryza sativae1
- Treatment
- MTe0
- Outcome
- root pectin contente0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT increased the root pectin content and its Cu retention”
e1“in rice under Cu stress”
Claim · model-written summary
Melatonin increased copper retention in root pectin.
- Taxon
- riceOryza sativae1
- Treatment
- MTe0
- Outcome
- Cu retentione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT increased the root pectin content and its Cu retention”
e1“in rice under Cu stress”
Claim · model-written summary
Melatonin reduced copper influx into the cytoplasm.
- Taxon
- riceOryza sativae1
- Treatment
- MTe2
- Outcome
- Cu influx into the cytoplasme0
- Direction
- reducinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“thereby reducing Cu influx into the cytoplasm”
e1“in rice under Cu stress”
e2“MT increased the root pectin content”
Claim · model-written summary
Exogenous melatonin upregulated OsHMA4 expression.
- Taxon
- riceOryza sativae1
- Treatment
- exogenous MTe0
- Gene
- OsHMA4e0
- Outcome
- expression of Heavy Metal ATPase 4 (OsHMA4)e0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenous MT upregulated the expression of Heavy Metal ATPase 4 (OsHMA4)”
e1“in rice under Cu stress”
Claim · model-written summary
Exogenous melatonin upregulated OsHMA6 and OsHMA9 expression.
- Taxon
- riceOryza sativae1
- Treatment
- exogenous MTe2
- Gene
- OsHMA6 and OsHMA9e0
- Outcome
- Cu efflux transporter genes OsHMA6 and OsHMA9e0
- Direction
- upregulatede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“as well as Cu efflux transporter genes OsHMA6 and OsHMA9”
e1“in rice under Cu stress”
e2“exogenous MT upregulated”
Claim · model-written summary
Exogenous melatonin downregulated OsCOPT1, OsCOPT2, and OsCOPT3 expression.
- Taxon
- riceOryza sativae1
- Treatment
- exogenous MTe2
- Gene
- OsCOPT1, OsCOPT2, and OsCOPT3e0
- Outcome
- plasma membrane Cu uptake-associated genese0
- Direction
- downregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it downregulated the plasma membrane Cu uptake-associated genes Copper Transporter (OsCOPT1, OsCOPT2, and OsCOPT3)”
e1“in rice under Cu stress”
e2“exogenous MT upregulated”
e3“it downregulated”
Claim · model-written summary
Exogenous melatonin downregulated OsCOPT7 expression.
- Taxon
- riceOryza sativae1
- Treatment
- exogenous MTe2
- Gene
- OsCOPT7e0
- Outcome
- vacuolar Cu exporter OsCOPT7e0
- Direction
- downregulatede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the vacuolar Cu exporter OsCOPT7”
e1“in rice under Cu stress”
e2“exogenous MT upregulated”
e3“it downregulated”
Claim · model-written summary
Exogenous melatonin downregulated OsHMA5 expression.
- Taxon
- riceOryza sativae1
- Treatment
- exogenous MTe2
- Gene
- OsHMA5e0
- Outcome
- xylem loading transporter gene OsHMA5e0
- Direction
- downregulatede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the xylem loading transporter gene OsHMA5”
e1“in rice under Cu stress”
e2“exogenous MT upregulated”
e3“it downregulated”
Claim · model-written summary
Melatonin elevated nitric oxide levels in rice root tips.
- Taxon
- riceOryza sativae1
- Organ / stage
- root tipse0
- Treatment
- MTe0
- Outcome
- nitric oxide (NO) levelse0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT elevated nitric oxide (NO) levels in root tips”
e1“alleviating Cu toxicity in rice.”
Claim · model-written summary
The nitric oxide scavenger attenuated the copper-stress mitigation from melatonin in rice.
- Taxon
- riceOryza sativae0
- Treatment
- exogenous NO scavengere0
- Outcome
- mitigative effect of MTe0
- Direction
- attenuatede0
- Qualifier
- excess Cu-stressed ricee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“application of the exogenous NO scavenger, 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), attenuated the mitigative effect of MT on excess Cu-stressed rice”
The same questions in other papers
copper atom · molecular: metabolites · Oryza sativa (rice)Positive and negative results
4 papers in the same direction as this paper · 7 in the opposite direction
- negative
- negative
- negative
8 papers more in this group
See all 12 papers →nitric oxide · molecular: metabolites · Oryza sativa (rice)Positive and negative results
4 papers in the same direction as this paper · 8 in the opposite direction
- positive
- positive
- positive
9 papers more in this group
See all 13 papers →melatonin · molecular: metabolites · Oryza sativa (rice)Positive and negative results
13 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- no effect
- positive
12 papers more in this group
See all 16 papers →melatonin · nutrient: content · Oryza sativa (rice)Results agree
12 papers in the same direction as this paper
- positive
- positive
- positive
9 papers more in this group
See all 13 papers →melatonin · molecular: expression · Oryza sativa (rice)Results agree
19 papers in the same direction as this paper
- positive
- positive
- positive
16 papers more in this group
See all 20 papers →melatonin · growth · Oryza sativa (rice)Results agree
27 papers in the same direction as this paper
- positive
- positive
- positive
24 papers more in this group
See all 28 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.