Abstract
BACKGROUND AND AIMS: Mercury (Hg) is an extremely toxic pollutant, especially in the form of methylmercury (MeHg), whereas selenium (Se) is an essential trace element in the human diet. This study aimed to ascertain whether addition of Se can produce rice with enriched Se and lowered Hg content when growing in Hg-contaminated paddy fields and, if so, to determine the possible mechanisms behind these effects. METHODS: Two cultivars of rice (Oryza sativa, japonica and indica) were grown in either hydroponic solutions or soil rhizobags with different Se and Hg treatments. Concentrations of total Hg, MeHg and Se were determined in the roots, shoots and brown rice, together with Hg uptake kinetics and Hg bioavailability in the soil. Root anatonmy was also studied. KEY RESULTS: The high Se treatment (5 μg g(-1)) significantly increased brown rice yield by 48 % and total Se content by 2·8-fold, and decreased total Hg and MeHg by 47 and 55 %, respectively, compared with the control treatments. The high Se treatment also markedly reduced 'water-soluble' Hg and MeHg concentrations in the rhizosphere soil, decreased the uptake capacity of Hg by roots and enhanced the development of apoplastic barriers in the root endodermis. CONCLUSIONS: Addition of Se to Hg-contaminated soil can help produce brown rice that is simultaneously enriched in Se and contains less total Hg and MeHg. The lowered accumulation of total Hg and MeHg appears to be the result of reduced bioavailability of Hg and production of MeHg in the rhizosphere, suppression of uptake of Hg into the root cells and an enhancement of the development of apoplastic barriers in the endodermis of the roots.
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Claims 11
Claim · model-written summary
High selenium treatment increased brown rice yield by 48% versus controls.
- Taxon
- rice
Oryza sativae1 - Treatment
- high Se treatment (5 μg g(-1))e0
- Outcome
- brown rice yielde0
- Direction
- increasede0
- Value
- 48 %e0
- Comparator
- control treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment (5 μg g(-1)) significantly increased brown rice yield by 48 % and total Se content by 2·8-fold, and decreased total Hg and MeHg by 47 and 55 %, respectively, compared with the control treatments.”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
High selenium treatment increased total selenium content 2.8-fold versus controls.
- Taxon
- riceOryza sativae1
- Treatment
- high Se treatment (5 μg g(-1))e0
- Outcome
- total Se contente0
- Direction
- increasede0
- Value
- 2·8-folde0
- Comparator
- control treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment (5 μg g(-1)) significantly increased brown rice yield by 48 % and total Se content by 2·8-fold, and decreased total Hg and MeHg by 47 and 55 %, respectively, compared with the control treatments.”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
High selenium treatment decreased total mercury by 47% versus controls.
- Taxon
- riceOryza sativae1
- Treatment
- high Se treatment (5 μg g(-1))e0
- Outcome
- total Hge0
- Direction
- decreasede0
- Value
- 47e0
- Comparator
- control treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment (5 μg g(-1)) significantly increased brown rice yield by 48 % and total Se content by 2·8-fold, and decreased total Hg and MeHg by 47 and 55 %, respectively, compared with the control treatments.”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
High selenium treatment decreased methylmercury by 55% versus controls.
- Taxon
- riceOryza sativae1
- Treatment
- high Se treatment (5 μg g(-1))e0
- Outcome
- MeHge0
- Direction
- decreasede0
- Value
- 55 %e0
- Comparator
- control treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment (5 μg g(-1)) significantly increased brown rice yield by 48 % and total Se content by 2·8-fold, and decreased total Hg and MeHg by 47 and 55 %, respectively, compared with the control treatments.”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
High selenium reduced water-soluble mercury in rhizosphere soil.
- Taxon
- riceOryza sativae1
- Treatment
- high Se treatmente0
- Outcome
- 'water-soluble' Hge0
- Direction
- reducede0
- Setting
- rhizosphere soile0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment also markedly reduced 'water-soluble' Hg and MeHg concentrations in the rhizosphere soil”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
High selenium reduced water-soluble methylmercury in rhizosphere soil.
- Taxon
- riceOryza sativae1
- Treatment
- high Se treatmente0
- Outcome
- MeHg concentrations in the rhizosphere soile0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment also markedly reduced 'water-soluble' Hg and MeHg concentrations in the rhizosphere soil”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
High selenium decreased root mercury uptake capacity.
- Taxon
- riceOryza sativae1
- Treatment
- high Se treatmente0
- Outcome
- uptake capacity of Hg by rootse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment also markedly reduced 'water-soluble' Hg and MeHg concentrations in the rhizosphere soil, decreased the uptake capacity of Hg by roots”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
High selenium enhanced development of apoplastic barriers in root endodermis.
- Taxon
- riceOryza sativae1
- Organ / stage
- root endodermise0
- Treatment
- high Se treatmente0
- Outcome
- development of apoplastic barrierse0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high Se treatment also markedly reduced 'water-soluble' Hg and MeHg concentrations in the rhizosphere soil, decreased the uptake capacity of Hg by roots and enhanced the development of apoplastic barriers in the root endodermis.”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
The authors attribute reduced rice mercury accumulation to reduced rhizosphere mercury bioavailability and methylmercury production.
- Taxon
- riceOryza sativae1
- Outcome
- lowered accumulation of total Hg and MeHge0
- Qualifier
- reduced bioavailability of Hg and production of MeHg in the rhizospheree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lowered accumulation of total Hg and MeHg appears to be the result of reduced bioavailability of Hg and production of MeHg in the rhizosphere”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
The authors attribute reduced rice mercury accumulation to suppressed root-cell uptake.
- Taxon
- riceOryza sativae1
- Outcome
- lowered accumulation of total Hg and MeHge0
- Qualifier
- suppression of uptake of Hg into the root cellse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lowered accumulation of total Hg and MeHg appears to be the result of reduced bioavailability of Hg and production of MeHg in the rhizosphere, suppression of uptake of Hg into the root cells”
e1“rice (Oryza sativa, japonica and indica)”
Claim · model-written summary
The authors attribute reduced rice mercury accumulation to stronger endodermal apoplastic barriers.
- Taxon
- riceOryza sativae1
- Outcome
- lowered accumulation of total Hg and MeHge0
- Qualifier
- enhancement of the development of apoplastic barriers in the endodermis of the rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lowered accumulation of total Hg and MeHg appears to be the result of reduced bioavailability of Hg and production of MeHg in the rhizosphere, suppression of uptake of Hg into the root cells and an enhancement of the development of apoplastic barriers in the endodermis of the roots.”
e1“rice (Oryza sativa, japonica and indica)”
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See all 31 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.