Abstract
Ascorbic acid (Asc) is a major antioxidant involved in photoprotection and photosynthetic function in plants. Dehydroascorbate reductase (DHAR) catalyzes the regeneration of Asc from its oxidized state and serves as an important regulator of Asc recycling. In this work, we used a molecular biochemical approach to investigate how the efficiency of Asc recycling affects non-photochemical quenching (NPQ). Suppression of DHAR expression resulted in a lower induction of NPQ that correlated with reductions in chlorophyll and xanthophyll pigments, quantum yield of photosystem II, and CO(2) assimilation, whereas the level of reactive oxygen species increased. The quickly reversible component of NPQ decreased and the slowly reversible or irreversible component of NPQ increased following a reduction in DHAR expression. Significant photoinhibition was also observed following exposure to high light. Direct feeding with Asc restored the appropriate induction of NPQ in DHAR-suppressed leaves. In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced. Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light. DHAR activity, therefore, can affect the appropriate induction of NPQ and level of photoprotection during exposure to high light.
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Claims 11
Claim · model-written summary
DHAR suppression lowered NPQ induction.
- Taxon
- plantsViridiplantaee1
- Treatment
- Suppression of DHAR expressione0
- Gene
- DHARe0
- Outcome
- induction of NPQe0
- Direction
- lowere0
Not reportedComparator
Verbatim
e0“Suppression of DHAR expression resulted in a lower induction of NPQ”
t0“Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
DHAR suppression correlated with reduced chlorophyll, xanthophyll, photosystem II yield, and CO(2) assimilation.
- Taxon
- plantsViridiplantaee1
- Gene
- DHARe2
- Outcome
- chlorophyll and xanthophyll pigments, quantum yield of photosystem II, and CO(2) assimilatione0
- Direction
- reductionse0
Verbatim
e0“correlated with reductions in chlorophyll and xanthophyll pigments, quantum yield of photosystem II, and CO(2) assimilation”
t0“Dehydroascorbate Reductase Affects Non-photochemical Quenching and Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
Reactive oxygen species increased after DHAR suppression.
- Taxon
- plantsViridiplantaee1
- Treatment
- Suppression of DHAR expressione2
- Outcome
- level of reactive oxygen speciese0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“whereas the level of reactive oxygen species increased”
t0“Dehydroascorbate Reductase Affects Non-photochemical Quenching and Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
The quickly reversible NPQ component decreased when DHAR expression was reduced.
- Taxon
- plantsViridiplantaee1
- Treatment
- reduction in DHAR expressione4
- Outcome
- quickly reversible component of NPQe0
- Direction
- decreasede0
Not reportedComparator
Verbatim
e0“quickly reversible component of NPQ decreased”
t0“Dehydroascorbate Reductase Affects Non-photochemical Quenching and Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
The slow or irreversible NPQ component increased when DHAR expression was reduced.
- Taxon
- plantsViridiplantaee1
- Treatment
- reduction in DHAR expressione0
- Outcome
- slowly reversible or irreversible component of NPQe0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“slowly reversible or irreversible component of NPQ increased following a reduction in DHAR expression”
t0“Dehydroascorbate Reductase Affects Non-photochemical Quenching and Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
Exposure to high light caused significant photoinhibition.
- Taxon
- plantsViridiplantaee1
- Treatment
- exposure to high lighte0
- Outcome
- photoinhibitione0
Not reportedComparatorDirection
Verbatim
e0“Significant photoinhibition was also observed following exposure to high light”
t0“Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
Direct Asc feeding restored NPQ induction in DHAR-suppressed leaves.
Verbatim
e0“Direct feeding with Asc restored the appropriate induction of NPQ in DHAR-suppressed leaves”
t0“Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
Increasing DHAR expression increased xanthophyll and chlorophyll pools.
- Taxon
- plantsViridiplantaee1
- Treatment
- increasing DHAR expressione0
- Outcome
- pool size of xanthophyll and chlorophyll pigmentse0
- Direction
- increasede0
Not reportedComparator
Verbatim
e0“increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments”
t0“Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
Increasing DHAR expression increased CO(2) assimilation, especially at high light.
- Taxon
- plantsViridiplantaee1
- Treatment
- increasing DHAR expressione3
- Outcome
- rate of CO(2) assimilatione0
- Direction
- increasede3
- Qualifier
- particularly at high light intensitiese0
Not reportedComparator
Verbatim
e0“rate of CO(2) assimilation, particularly at high light intensities”
t0“Dehydroascorbate Reductase Affects Non-photochemical Quenching and Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
Increasing DHAR expression reduced reactive oxygen species.
- Taxon
- plantsViridiplantaee1
- Treatment
- increasing DHAR expressione3
- Outcome
- level of reactive oxygen speciese0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“level of reactive oxygen species was reduced”
t0“Dehydroascorbate Reductase Affects Non-photochemical Quenching and Photosynthetic Performance”
e1“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
e2“Suppression of DHAR expression resulted in a lower induction of NPQ”
e3“In contrast, increasing DHAR expression increased the pool size of xanthophyll and chlorophyll pigments as well as the rate of CO(2) assimilation, particularly at high light intensities, whereas the level of reactive oxygen species was reduced”
e4“following a reduction in DHAR expression”
Claim · model-written summary
Leaves with increased DHAR expression had less photoinhibition than wild type after high light.
Verbatim
e0“Leaves with increased DHAR expression experienced less photoinhibition than did wild-type plants following exposure to high light”
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