Abstract
Ascorbic acid (Asc) is a major antioxidant in plants that detoxifies reactive oxygen species (ROS) and maintains photosynthetic function. Expression of dehydroascorbate reductase (DHAR), responsible for regenerating Asc from an oxidized state, regulates the cellular Asc redox state, which in turn affects cell responsiveness and tolerance to environmental ROS. Because of its role in Asc recycling, we examined whether DHAR is important for plant growth. Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation. As a consequence, a slower rate of leaf expansion and reduced foliar dry weight were observed. In addition, an accelerated rate of loss of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning was observed in mature leaves, resulting in premature leaf aging. Reduced growth rate as measured by plant height and leaf number was consistent with the DHAR-mediated reduction of photosynthetic function. Increasing DHAR expression maintained higher levels of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning, resulting in delayed leaf aging. The effect of DHAR expression on leaf aging inversely correlated with the level of lipid peroxidation, indicating that DHAR functions to protect against ROS-mediated damage. These observations support the conclusion that through its Asc recycling function, DHAR affects the level of foliar ROS and photosynthetic activity during leaf development and as a consequence, influences the rate of plant growth and leaf aging.
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Claims 15
Claim · model-written summary
Suppressing DHAR expression reduced chlorophyll a in plants.
- Taxon
- plantsViridiplantaee0
- Treatment
- Suppression of DHAR expressione1
- Gene
- DHARe1
- Outcome
- chlorophyll ae1
- Direction
- decreaseinferrede1
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e1“Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation”
Claim · model-written summary
Suppressing DHAR expression lowered the steady state of Rubisco, measured as the amount of the large subunit of Rubisco.
- Taxon
- plantsViridiplantaee0
- Treatment
- Suppression of DHAR expressione1
- Gene
- DHARe1
- Outcome
- steady state of Rubiscoe1
- Direction
- lowere1
- Qualifier
- as measured by the amount of the large subunit of Rubisco (RbcL)e1
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e1“Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation”
Claim · model-written summary
Suppressing DHAR expression lowered the rate of CO2 assimilation.
- Taxon
- plantsViridiplantaee0
- Treatment
- Suppression of DHAR expressione1
- Gene
- DHARe1
- Outcome
- rate of CO(2) assimilatione1
- Direction
- lowere1
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e1“Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation”
Claim · model-written summary
Suppressing DHAR expression slowed the rate of leaf expansion.
- Taxon
- plantsViridiplantaee0
- Treatment
- Suppression of DHAR expressione1
- Gene
- DHARe1
- Outcome
- rate of leaf expansione2
- Direction
- slowere2
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e1“Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation”
e2“a slower rate of leaf expansion and reduced foliar dry weight were observed”
Claim · model-written summary
Suppressing DHAR expression reduced foliar dry weight.
- Taxon
- plantsViridiplantaee0
- Treatment
- Suppression of DHAR expressione1
- Gene
- DHARe1
- Outcome
- foliar dry weighte2
- Direction
- reducede2
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e1“Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation”
e2“a slower rate of leaf expansion and reduced foliar dry weight were observed”
Claim · model-written summary
Reduced growth rate, measured as plant height and leaf number, was seen with suppressed DHAR expression.
- Taxon
- plantsViridiplantaee0
- Treatment
- Suppression of DHAR expressione1
- Gene
- DHARe3
- Outcome
- growth rate as measured by plant height and leaf numbere3
- Direction
- Reducede3
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e1“Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation”
e3“Reduced growth rate as measured by plant height and leaf number was consistent with the DHAR-mediated reduction of photosynthetic function”
Claim · model-written summary
An accelerated loss of chlorophyll, RbcL and light-harvesting complex II was observed in mature leaves.
- Taxon
- plantsViridiplantaee0
- Organ / stage
- mature leavese4
- Outcome
- loss of chlorophyll, RbcL, light-harvesting complex IIe4
- Direction
- acceleratede4
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e4“an accelerated rate of loss of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning was observed in mature leaves, resulting in premature leaf aging”
Claim · model-written summary
An accelerated loss of photosynthetic functioning was observed in mature leaves.
- Taxon
- plantsViridiplantaee0
- Organ / stage
- mature leavese4
- Outcome
- photosynthetic functioninge4
- Direction
- acceleratede4
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e4“an accelerated rate of loss of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning was observed in mature leaves, resulting in premature leaf aging”
Claim · model-written summary
Premature leaf aging was observed in mature leaves.
- Taxon
- plantsViridiplantaee0
- Organ / stage
- mature leavese4
- Outcome
- premature leaf aginge4
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e4“an accelerated rate of loss of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning was observed in mature leaves, resulting in premature leaf aging”
Claim · model-written summary
Increasing DHAR expression maintained higher levels of chlorophyll, RbcL and light-harvesting complex II.
- Taxon
- plantsViridiplantaee0
- Treatment
- Increasing DHAR expressione5
- Gene
- DHARe5
- Outcome
- chlorophyll, RbcL, light-harvesting complex IIe5
- Direction
- highere5
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e5“Increasing DHAR expression maintained higher levels of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning, resulting in delayed leaf aging”
Claim · model-written summary
Increasing DHAR expression maintained higher photosynthetic functioning.
- Taxon
- plantsViridiplantaee0
- Treatment
- Increasing DHAR expressione5
- Gene
- DHARe5
- Outcome
- photosynthetic functioninge5
- Direction
- highere5
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e5“Increasing DHAR expression maintained higher levels of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning, resulting in delayed leaf aging”
Claim · model-written summary
Increasing DHAR expression delayed leaf aging.
- Taxon
- plantsViridiplantaee0
- Treatment
- Increasing DHAR expressione5
- Gene
- DHARe5
- Outcome
- leaf aginge5
- Direction
- delayede5
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e5“Increasing DHAR expression maintained higher levels of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning, resulting in delayed leaf aging”
Claim · model-written summary
The effect of DHAR expression on leaf aging was inversely correlated with the level of lipid peroxidation.
- Taxon
- plantsViridiplantaee0
- Treatment
- DHAR expressione6
- Outcome
- level of lipid peroxidatione6
- Direction
- inversely correlatede6
Not reportedComparator
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e6“The effect of DHAR expression on leaf aging inversely correlated with the level of lipid peroxidation, indicating that DHAR functions to protect against ROS-mediated damage”
Claim · model-written summary
DHAR is interpreted to protect plants against ROS-mediated damage.
- Taxon
- plantsViridiplantaee0
- Gene
- DHARe6
- Outcome
- ROS-mediated damagee6
- Qualifier
- functions to protect againste6
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e6“The effect of DHAR expression on leaf aging inversely correlated with the level of lipid peroxidation, indicating that DHAR functions to protect against ROS-mediated damage”
Claim · model-written summary
Through its Asc recycling function, DHAR is interpreted to affect foliar ROS and photosynthetic activity and thereby the rate of plant growth and leaf aging.
- Taxon
- plantsViridiplantaee0
- Gene
- DHARe7
- Outcome
- rate of plant growth and leaf aginge7
- Qualifier
- through its Asc recycling functione7
Verbatim
e0“Ascorbic acid (Asc) is a major antioxidant in plants”
e7“These observations support the conclusion that through its Asc recycling function, DHAR affects the level of foliar ROS and photosynthetic activity during leaf development and as a consequence, influences the rate of plant growth and leaf aging”
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2 papers in the same direction as this paper
- no effect
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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.