Abstract
Using the vascular plant Cucumis sativus (cucumber) as a model, we studied the effects of high (intense and excess) light upon chlorophyll biosynthesis during de-etiolation. When illuminated with high light (1500-1600 microE/m2/s), etiolated cucumber cotyledons failed to synthesize chlorophyll entirely. However, upon transfer to low light conditions (40-45 microE/m2/s), chlorophyll biosynthesis and subsequent accumulation resumed following an initial 2-12 h delay. Duration of high light treatment negatively correlated with chlorophyll biosynthetic activity. Specifically, we found that high light severely inhibited 5-aminolevulinic acid (ALA) synthesis. This effect partly could be because of the decrease in protein level of glutamyl-tRNA reductase (GluTR) observed. Protein level of glutamate-1-semialdehyde (GSA-AT) remained unchanged. It was also found that high light did not suppress HEMA 1 expression. Therefore, we speculated that this significant inhibition of ALA synthesis might have occurred mainly because of concomitant inactivation of GluTR and/or inhibition of complex formation between GluTR and GSA-AT. Our further observation that both methyl viologen and rose bengal similarly inhibit ALA synthesis under low light conditions suggested that reactive oxygen species (ROS) could be responsible for the inhibition of ALA synthesis in cotyledons exposed to high light conditions.
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Claims 9
Claim · model-written summary
High light prevented chlorophyll synthesis in etiolated cucumber cotyledons.
- Taxon
- cucumber
Cucumis sativuse0 - Organ / stage
- cotyledonse0
- Treatment
- high light (1500-1600 microE/m2/s)e0
- Outcome
- failed to synthesize chlorophyll entirelye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When illuminated with high light (1500-1600 microE/m2/s), etiolated cucumber cotyledons failed to synthesize chlorophyll entirely.”
Claim · model-written summary
Chlorophyll biosynthesis resumed after transfer to low light, following a 2-12 h delay.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Treatment
- low light conditions (40-45 microE/m2/s)e0
- Outcome
- chlorophyll biosynthesis and subsequent accumulatione0
- Direction
- resumede0
- Value
- 2-12 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“upon transfer to low light conditions (40-45 microE/m2/s), chlorophyll biosynthesis and subsequent accumulation resumed following an initial 2-12 h delay.”
t0“Cucumber (Cucumis sativus)”
Claim · model-written summary
Longer high light treatment correlated with lower chlorophyll biosynthetic activity.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Treatment
- Duration of high light treatmente0
- Outcome
- chlorophyll biosynthetic activitye0
- Direction
- negatively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Duration of high light treatment negatively correlated with chlorophyll biosynthetic activity.”
t0“Cucumber (Cucumis sativus)”
Claim · model-written summary
High light severely inhibited ALA synthesis.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Treatment
- high lighte0
- Outcome
- 5-aminolevulinic acid (ALA) synthesise0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high light severely inhibited 5-aminolevulinic acid (ALA) synthesis.”
t0“Cucumber (Cucumis sativus)”
Claim · model-written summary
The GluTR protein level decreased under high light.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Gene
- glutamyl-tRNA reductase (GluTR)e0
- Outcome
- protein levele0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decrease in protein level of glutamyl-tRNA reductase (GluTR) observed.”
t0“Cucumber (Cucumis sativus)”
Claim · model-written summary
GSA-AT protein level remained unchanged.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Gene
- glutamate-1-semialdehyde (GSA-AT)e0
- Outcome
- Protein levele0
- Direction
- remained unchangede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Protein level of glutamate-1-semialdehyde (GSA-AT) remained unchanged.”
t0“Cucumber (Cucumis sativus)”
Claim · model-written summary
High light did not suppress HEMA 1 expression.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Treatment
- high lighte0
- Gene
- HEMA 1e0
- Outcome
- HEMA 1 expressione0
- Direction
- did not suppresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high light did not suppress HEMA 1 expression.”
t0“Cucumber (Cucumis sativus)”
Claim · model-written summary
methyl viologen inhibited ALA synthesis under low light.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Treatment
- methyl viologene0
- Outcome
- ALA synthesise0
- Direction
- inhibite0
- Qualifier
- under low light conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both methyl viologen and rose bengal similarly inhibit ALA synthesis under low light conditions”
t0“Cucumber (Cucumis sativus)”
Claim · model-written summary
rose bengal inhibited ALA synthesis under low light.
- Taxon
- Cucumber (Cucumis sativus)Cucumis sativust0
- Treatment
- rose bengale0
- Outcome
- ALA synthesise0
- Direction
- inhibite0
- Qualifier
- under low light conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both methyl viologen and rose bengal similarly inhibit ALA synthesis under low light conditions”
t0“Cucumber (Cucumis sativus)”
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