Abstract
Acclimation to fluctuating light environment with short (lasting 20 s, at 650 or 1,250 μmol photons m(-2) s(-1), every 6 or 12 min) or long (for 40 min at 650 μmol photons m(-2) s(-1), once a day at midday) sunflecks was studied in Arabidopsis thaliana. The sunfleck treatments were applied in the background daytime light intensity of 50 μmol photons m(-2) s(-1). In order to distinguish the effects of sunflecks from those of increased daily irradiance, constant light treatments at 85 and 120 μmol photons m(-2) s(-1), which gave the same photosynthetically active radiation (PAR) per day as the different sunfleck treatments, were also included in the experiments. The increased daily total PAR in the two higher constant light treatments enhanced photosystem II electron transport and starch accumulation in mature leaves and promoted expansion of young leaves in Columbia-0 plants during the 7-day treatments. Compared to the plants remaining under 50 μmol photons m(-2) s(-1), application of long sunflecks caused upregulation of electron transport without affecting carbon gain in the form of starch accumulation and leaf growth or the capacity of non-photochemical quenching (NPQ). Mature leaves showed marked enhancement of the NPQ capacity under the conditions with short sunflecks, which preceded recovery and upregulation of electron transport, demonstrating the initial priority of photoprotection. The distinct acclimatory responses to constant PAR, long sunflecks, and different combinations of short sunflecks are consistent with acclimatory adjustment of the processes in photoprotection and carbon gain, depending on the duration, frequency, and intensity of light fluctuations. While the responses of leaf expansion to short sunflecks differed among the seven Arabidopsis accessions examined, all plants showed NPQ upregulation, suggesting limited ability of this species to utilize short sunflecks. The increase in the NPQ capacity was accompanied by reduced chlorophyll contents, higher levels of the xanthophyll-cycle pigments, faster light-induced de-epoxidation of violaxanthin to zeaxanthin and antheraxanthin, increased amounts of PsbS protein, as well as enhanced activity of superoxide dismutase. These acclimatory mechanisms, involving reorganization of pigment-protein complexes and upregulation of other photoprotective reactions, are probably essential for Arabidopsis plants to cope with photo-oxidative stress induced by short sunflecks without suffering from severe photoinhibition and lipid peroxidation.
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Claims 13
Claim · model-written summary
Higher constant irradiance enhanced photosystem II electron transport and starch accumulation.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianat0 - Organ / stage
- mature leavese0
- Treatment
- two higher constant light treatmentse0
- Outcome
- photosystem II electron transport and starch accumulatione0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The increased daily total PAR in the two higher constant light treatments enhanced photosystem II electron transport and starch accumulation in mature leaves”
t0“Arabidopsis thaliana”
Claim · model-written summary
Higher constant light promoted young-leaf expansion in Columbia-0.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- Columbia-0e0
- Treatment
- two higher constant light treatmentst1
- Outcome
- expansion of young leavese0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“promoted expansion of young leaves in Columbia-0 plants during the 7-day treatments.”
t0“Arabidopsis thaliana”
t1“two higher constant light treatments”
Claim · model-written summary
Long sunflecks upregulated electron transport relative to low constant light.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- long sunfleckse0
- Outcome
- electron transporte0
- Direction
- upregulatione0
- Comparator
- plants remaining under 50 μmol photons m(-2) s(-1)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to the plants remaining under 50 μmol photons m(-2) s(-1), application of long sunflecks caused upregulation of electron transport”
t0“Arabidopsis thaliana”
Claim · model-written summary
Long sunflecks did not affect starch accumulation, leaf growth or NPQ capacity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- long sunfleckst1
- Outcome
- starch accumulation and leaf growth or the capacity of non-photochemical quenching (NPQ)e0
- Direction
- without affectinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without affecting carbon gain in the form of starch accumulation and leaf growth or the capacity of non-photochemical quenching (NPQ).”
t0“Arabidopsis thaliana”
t1“application of long sunflecks caused”
Claim · model-written summary
Short sunflecks enhanced mature-leaf NPQ capacity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Organ / stage
- Mature leavese0
- Treatment
- short sunfleckse0
- Outcome
- NPQ capacitye0
- Direction
- enhancemente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mature leaves showed marked enhancement of the NPQ capacity under the conditions with short sunflecks”
t0“Arabidopsis thaliana”
Claim · model-written summary
NPQ enhancement preceded electron-transport recovery and upregulation.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- recovery and upregulation of electron transporte0
- Qualifier
- NPQ capacityt1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which preceded recovery and upregulation of electron transport”
t0“Arabidopsis thaliana”
t1“enhancement of the NPQ capacity under the conditions with short sunflecks”
Claim · model-written summary
Short-sunfleck leaf-expansion responses differed among seven accessions.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- short sunfleckse0
- Outcome
- responses of leaf expansione0
- Value
- sevene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“responses of leaf expansion to short sunflecks differed among the seven Arabidopsis accessions examined”
Claim · model-written summary
All tested accessions upregulated NPQ under short sunflecks.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- short sunfleckst1
- Outcome
- NPQe0
- Direction
- upregulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all plants showed NPQ upregulation”
t0“Arabidopsis”
t1“leaf expansion to short sunflecks differed”
Claim · model-written summary
NPQ increase accompanied reduced chlorophyll contents.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- chlorophyll contentse0
- Direction
- reducede0
- Qualifier
- increase in the NPQ capacitye0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The increase in the NPQ capacity was accompanied by reduced chlorophyll contents”
t0“Arabidopsis”
Claim · model-written summary
NPQ increase accompanied higher xanthophyll-cycle pigment levels.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- levels of the xanthophyll-cycle pigmentse0
- Direction
- highere0
- Qualifier
- NPQ capacityt1
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher levels of the xanthophyll-cycle pigments”
t0“Arabidopsis”
t1“The increase in the NPQ capacity”
Claim · model-written summary
NPQ increase accompanied faster violaxanthin de-epoxidation.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- light-induced de-epoxidation of violaxanthin to zeaxanthin and antheraxanthine0
- Direction
- fastere0
- Qualifier
- NPQ capacityt1
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“faster light-induced de-epoxidation of violaxanthin to zeaxanthin and antheraxanthin”
t0“Arabidopsis”
t1“The increase in the NPQ capacity”
Claim · model-written summary
NPQ increase accompanied increased PsbS protein amounts.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- PsbS proteine0
- Outcome
- amounts of PsbS proteine0
- Direction
- increasede0
- Qualifier
- NPQ capacityt1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased amounts of PsbS protein”
t0“Arabidopsis”
t1“The increase in the NPQ capacity”
Claim · model-written summary
NPQ increase accompanied enhanced superoxide dismutase activity.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- superoxide dismutasee0
- Outcome
- activity of superoxide dismutasee0
- Direction
- enhancede0
- Qualifier
- NPQ capacityt1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enhanced activity of superoxide dismutase”
t0“Arabidopsis”
t1“The increase in the NPQ capacity”
The same questions in other papers
light · physiology: photosynthesis · Arabidopsis thaliana (thale cress)Positive and negative results
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- negative
- negative
- negative
26 papers more in this group
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