Abstract
To examine the effects of chilling of leaves of cucumber (Cucumis sativus L.) in moderate light on the coupling state of thylakoids in situ, changes in fluorescence, changes in light scattering and flash-induced changes in absorbance at 518 nm were examined in intact leaves. After chilling of leaves at 5°C in the light for 5 h, the non-photochemical quenching of fluorescence, a measure of energisation of thylakoids, was largely suppressed. The treatment also caused a suppression of light-induced changes in the light scattering by leaves, which depends on the formation of a pH gradient across thylakoid membranes. When thylakoids were prepared by very gentle methods from the leaves chilled in the light, through a step of preparation of intact chloro-plasts, the transport of electrons from H2O to ferricyanide was uncoupled, being insensitive to an uncoupler, methylamine. These data provide consistent evidence that the thylakoids are uncoupled in situ by the chilling of leaves in the light and, as a consequence of the uncoupling, the energisation of the membranes is suppressed. However, the decay of the flash-induced change in absorbance at 518 nm in leaves was not markedly accelerated by the treatment. The thylakoids isolated from leaves chilled in the light, which were in the uncoupled state, also did not show a rapid decay, unless an efficient uncoupler such as gramicidin was added. These results suggest that even a considerable uncoupling of thylakoids, brought about by chilling of leaves in the light, is not sufficient to cause a marked acceleration of the decay of the flash-induced change in absorbance at 518 nm. Therefore, analysis at 518 nm is not always a sensitive method for assessing the coupling state of thylakoids.
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Claims 7
Claim · model-written summary
Chilling suppressed non-photochemical fluorescence quenching.
- Taxon
- Cucumis sativus L.
Cucumis sativust0 - Treatment
- chilling of leaves at 5°C in the light for 5 he0
- Outcome
- non-photochemical quenching of fluorescencee0
- Direction
- suppressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After chilling of leaves at 5°C in the light for 5 h, the non-photochemical quenching of fluorescence, a measure of energisation of thylakoids, was largely suppressed.”
t0“Cucumis sativus L.”
Claim · model-written summary
Chilling suppressed light-induced changes in leaf light scattering.
- Taxon
- Cucumis sativus L.Cucumis sativust0
- Treatment
- chilling of leaves at 5°C in the light for 5 he1
- Outcome
- light-induced changes in the light scattering by leavese0
- Direction
- suppressione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The treatment also caused a suppression of light-induced changes in the light scattering by leaves”
e1“After chilling of leaves at 5°C in the light for 5 h”
t0“Cucumis sativus L.”
Claim · model-written summary
Electron transport in gently prepared thylakoids from chilled leaves was uncoupled and insensitive to methylamine.
- Taxon
- Cucumis sativus L.Cucumis sativust0
- Organ / stage
- leavese1
- Outcome
- transport of electrons from H2O to ferricyanide was uncoupled, being insensitive to an uncoupler, methylaminee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the transport of electrons from H2O to ferricyanide was uncoupled, being insensitive to an uncoupler, methylamine”
e1“from the leaves chilled in the light”
t0“Cucumis sativus L.”
Claim · model-written summary
Chilling in light uncoupled thylakoids in situ and suppressed membrane energisation.
- Taxon
- Cucumis sativus L.Cucumis sativust0
- Treatment
- chilling of leaves in the lighte0
- Outcome
- energisation of the membranese0
- Direction
- suppressede0
- Qualifier
- uncouplinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the thylakoids are uncoupled in situ by the chilling of leaves in the light and, as a consequence of the uncoupling, the energisation of the membranes is suppressed”
t0“Cucumis sativus L.”
Claim · model-written summary
Chilling did not markedly accelerate decay of the flash-induced absorbance change at 518 nm in leaves.
- Taxon
- Cucumis sativus L.Cucumis sativust0
- Treatment
- chilling of leaves at 5°C in the light for 5 he1
- Outcome
- decay of the flash-induced change in absorbance at 518 nme0
- Direction
- not markedly acceleratede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the decay of the flash-induced change in absorbance at 518 nm in leaves was not markedly accelerated by the treatment”
e1“After chilling of leaves at 5°C in the light for 5 h”
t0“Cucumis sativus L.”
Claim · model-written summary
Uncoupled thylakoids isolated from chilled leaves did not decay rapidly unless gramicidin was added.
- Taxon
- Cucumis sativus L.Cucumis sativust0
- Treatment
- leaves chilled in the lighte0
- Outcome
- rapid decaye0
- Direction
- did not showe0
- Comparator
- gramicidine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The thylakoids isolated from leaves chilled in the light, which were in the uncoupled state, also did not show a rapid decay, unless an efficient uncoupler such as gramicidin was added.”
t0“Cucumis sativus L.”
Claim · model-written summary
Absorbance analysis at 518 nm was judged not always sensitive for assessing thylakoid coupling.
- Taxon
- Cucumis sativus L.Cucumis sativust0
- Outcome
- sensitive method for assessing the coupling state of thylakoidse0
- Qualifier
- not alwayse0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“analysis at 518 nm is not always a sensitive method for assessing the coupling state of thylakoids”
t0“Cucumis sativus L.”
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See all 11 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.