Abstract
In Arabidopsis leaves, high light stress induces rapid expression of a gene encoding a cytosolic ascorbate peroxidase (APX2), whose expression is restricted to bundle sheath cells of the vascular tissue. Imaging of chlorophyll fluorescence and the production of reactive oxygen species (ROS) indicated that APX2 expression followed a localised increase in hydrogen peroxide (H2O2) resulting from photosynthetic electron transport in the bundle sheath cells. Furthermore, leaf transpiration rate also increased prior to APX2 expression, suggesting that water status may also be involved in the signalling pathway. Abscisic acid stimulated APX2 expression. Exposure of ABA-insensitive mutants (abi1-1, abi2-1) to excess light resulted in reduced levels of APX2 expression and confirmed a role for ABA in the signalling pathway. ABA appears to augment the role of H2O2 in initiating APX2 expression. This regulation of APX2 may reflect a functional organisation of the leaf to resolve two conflicting physiological requirements of protecting the sites of primary photosynthesis from ROS and, at the same time, stimulating ROS accumulation to signal responses to changes in the light environment.
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Claims 8
Claim · model-written summary
High light rapidly induced APX2 expression in Arabidopsis leaves.
- Taxon
- Arabidopsis
Arabidopsise0 - Organ / stage
- leavese0
- Treatment
- high light stresse0
- Gene
- APX2e0
- Outcome
- rapid expressione0
- Direction
- inducese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In Arabidopsis leaves, high light stress induces rapid expression of a gene encoding a cytosolic ascorbate peroxidase (APX2)”
Claim · model-written summary
APX2 expression was restricted to bundle sheath cells.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- bundle sheath cells of the vascular tissuee0
- Gene
- Ascorbate Peroxidase 2t0
- Outcome
- expression is restrictede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whose expression is restricted to bundle sheath cells of the vascular tissue”
t0“Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves”
Claim · model-written summary
APX2 expression followed a localized increase in hydrogen peroxide from photosynthetic electron transport in bundle sheath cells.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- bundle sheath cellse0
- Gene
- APX2e0
- Compound
- hydrogen peroxide (H2O2)e0
- Outcome
- APX2 expressione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“APX2 expression followed a localised increase in hydrogen peroxide (H2O2) resulting from photosynthetic electron transport in the bundle sheath cells”
t0“Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves”
Claim · model-written summary
Leaf transpiration increased before APX2 expression.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- leafe0
- Gene
- APX2e0
- Outcome
- transpiration ratee0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaf transpiration rate also increased prior to APX2 expression”
t0“Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves”
Claim · model-written summary
Abscisic acid stimulated APX2 expression.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Abscisic acide0
- Gene
- APX2e0
- Outcome
- APX2 expressione0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Abscisic acid stimulated APX2 expression”
t0“Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves”
Claim · model-written summary
ABA-insensitive abi1-1 and abi2-1 mutants had reduced APX2 expression under excess light.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ABA-insensitive mutants (abi1-1, abi2-1)e0
- Treatment
- excess lighte0
- Gene
- APX2e0
- Outcome
- APX2 expressione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure of ABA-insensitive mutants (abi1-1, abi2-1) to excess light resulted in reduced levels of APX2 expression”
t0“Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves”
Claim · model-written summary
ABA appears to augment the role of H2O2 in initiating APX2 expression.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- APX2e0
- Compound
- H2O2e0
- Outcome
- APX2 expressione0
- Qualifier
- ABA appears to augmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ABA appears to augment the role of H2O2 in initiating APX2 expression”
t0“Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves”
Claim · model-written summary
APX2 regulation may reflect functional leaf organization that protects photosynthesis sites while permitting ROS signaling.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- leafe0
- Gene
- APX2e0
- Outcome
- functional organisation of the leafe0
- Qualifier
- protecting the sites of primary photosynthesis from ROSe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This regulation of APX2 may reflect a functional organisation of the leaf to resolve two conflicting physiological requirements of protecting the sites of primary photosynthesis from ROS and, at the same time, stimulating ROS accumulation to signal responses to changes in the light environment”
t0“Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves”
The same questions in other papers
light · molecular: expression · ArabidopsisPositive and negative results
54 papers in the same direction as this paper · 21 in the opposite direction · 4 reporting no difference from an alternative
- no effect
- positive
- negative
76 papers more in this group
See all 80 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.