Abstract
The ch1 mutant of Arabidopsis (Arabidopsis thaliana) lacks chlorophyll (Chl) b. Leaves of this mutant are devoid of photosystem II (PSII) Chl-protein antenna complexes and have a very low capacity of nonphotochemical quenching (NPQ) of Chl fluorescence. Lhcb5 was the only PSII antenna protein that accumulated to a significant level in ch1 mutant leaves, but the apoprotein did not assemble in vivo with Chls to form a functional antenna. The abundance of Lhca proteins was also reduced to approximately 20% of the wild-type level. ch1 was crossed with various xanthophyll mutants to analyze the antioxidant activity of carotenoids unbound to PSII antenna. Suppression of zeaxanthin by crossing ch1 with npq1 resulted in oxidative stress in high light, while removing other xanthophylls or the PSII protein PsbS had no such effect. The tocopherol-deficient ch1 vte1 double mutant was as sensitive to high light as ch1 npq1, and the triple mutant ch1 npq1 vte1 exhibited an extreme sensitivity to photooxidative stress, indicating that zeaxanthin and tocopherols have cumulative effects. Conversely, constitutive accumulation of zeaxanthin in the ch1 npq2 double mutant led to an increased phototolerance relative to ch1. Comparison of ch1 npq2 with another zeaxanthin-accumulating mutant (ch1 lut2) that lacks lutein suggests that protection of polyunsaturated lipids by zeaxanthin is enhanced when lutein is also present. During photooxidative stress, alpha-tocopherol noticeably decreased in ch1 npq1 and increased in ch1 npq2 relative to ch1, suggesting protection of vitamin E by high zeaxanthin levels. Our results indicate that the antioxidant activity of zeaxanthin, distinct from NPQ, can occur in the absence of PSII light-harvesting complexes. The capacity of zeaxanthin to protect thylakoid membrane lipids is comparable to that of vitamin E but noticeably higher than that of all other xanthophylls of Arabidopsis leaves.
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Claims 17
Claim · model-written summary
Lhcb5 alone accumulated significantly among PSII antenna proteins in ch1 leaves.
- Taxon
- Arabidopsis
Arabidopsist0 - Material
- ch1e0
- Gene
- Lhcb5e0
- Outcome
- accumulated to a significant levele0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lhcb5 was the only PSII antenna protein that accumulated to a significant level in ch1 mutant leaves”
t0“Arabidopsis”
Claim · model-written summary
The Lhcb5 apoprotein did not assemble with chlorophylls into a functional antenna.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ch1e0
- Gene
- Lhcb5e0
- Outcome
- did not assemble in vivo with Chls to form a functional antennae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lhcb5 was the only PSII antenna protein that accumulated to a significant level in ch1 mutant leaves, but the apoprotein did not assemble in vivo with Chls to form a functional antenna.”
t0“Arabidopsis”
Claim · model-written summary
Lhca protein abundance fell to about 20% of wild type.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- Lhca proteinse0
- Outcome
- abundance of Lhca proteinse0
- Direction
- reducede0
- Value
- approximately 20%e0
- Comparator
- wild-typee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The abundance of Lhca proteins was also reduced to approximately 20% of the wild-type level.”
t0“Arabidopsis”
Claim · model-written summary
Suppressing zeaxanthin in ch1 npq1 caused oxidative stress in high light.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Suppression of zeaxanthin by crossing ch1 with npq1e0
- Outcome
- oxidative stresse0
- Qualifier
- high lighte0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Suppression of zeaxanthin by crossing ch1 with npq1 resulted in oxidative stress in high light”
t0“Arabidopsis”
Claim · model-written summary
Removing other xanthophylls did not produce the same oxidative stress effect.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- removing other xanthophyllse0
- Outcome
- oxidative stresse0
- Direction
- no such effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Suppression of zeaxanthin by crossing ch1 with npq1 resulted in oxidative stress in high light, while removing other xanthophylls or the PSII protein PsbS had no such effect.”
t0“Arabidopsis”
Claim · model-written summary
Removing PsbS did not produce the same oxidative stress effect.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- PSII protein PsbSe0
- Gene
- PsbSe0
- Outcome
- oxidative stresse0
- Direction
- no such effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Suppression of zeaxanthin by crossing ch1 with npq1 resulted in oxidative stress in high light, while removing other xanthophylls or the PSII protein PsbS had no such effect.”
t0“Arabidopsis”
Claim · model-written summary
ch1 vte1 was as sensitive to high light as ch1 npq1.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ch1 vte1e0
- Outcome
- sensitive to high lighte0
- Direction
- as sensitivee0
- Comparator
- ch1 npq1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The tocopherol-deficient ch1 vte1 double mutant was as sensitive to high light as ch1 npq1”
t0“Arabidopsis”
Claim · model-written summary
ch1 npq1 vte1 exhibited extreme photooxidative sensitivity.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ch1 npq1 vte1e0
- Outcome
- extreme sensitivity to photooxidative stresse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the triple mutant ch1 npq1 vte1 exhibited an extreme sensitivity to photooxidative stress, indicating that zeaxanthin and tocopherols have cumulative effects.”
t0“Arabidopsis”
Claim · model-written summary
Zeaxanthin and tocopherols have cumulative protective effects.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- zeaxanthin and tocopherolse0
- Outcome
- cumulative effectse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the triple mutant ch1 npq1 vte1 exhibited an extreme sensitivity to photooxidative stress, indicating that zeaxanthin and tocopherols have cumulative effects.”
t0“Arabidopsis”
Claim · model-written summary
Constitutive zeaxanthin accumulation increased phototolerance in ch1 npq2 relative to ch1.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ch1 npq2e0
- Treatment
- constitutive accumulation of zeaxanthine0
- Outcome
- phototolerancee0
- Direction
- increasede0
- Comparator
- ch1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“constitutive accumulation of zeaxanthin in the ch1 npq2 double mutant led to an increased phototolerance relative to ch1.”
t0“Arabidopsis”
Claim · model-written summary
Lutein presence appears to enhance zeaxanthin protection of polyunsaturated lipids.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- luteine0
- Outcome
- protection of polyunsaturated lipids by zeaxanthine0
- Direction
- enhancede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of ch1 npq2 with another zeaxanthin-accumulating mutant (ch1 lut2) that lacks lutein suggests that protection of polyunsaturated lipids by zeaxanthin is enhanced when lutein is also present.”
t0“Arabidopsis”
Claim · model-written summary
Alpha-tocopherol decreased in ch1 npq1 during photooxidative stress relative to ch1.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ch1 npq1e0
- Outcome
- alpha-tocopherole0
- Direction
- decreasede0
- Qualifier
- During photooxidative stresse0
- Comparator
- ch1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During photooxidative stress, alpha-tocopherol noticeably decreased in ch1 npq1 and increased in ch1 npq2 relative to ch1, suggesting protection of vitamin E by high zeaxanthin levels.”
t0“Arabidopsis”
Claim · model-written summary
Alpha-tocopherol increased in ch1 npq2 during photooxidative stress relative to ch1.
- Taxon
- ArabidopsisArabidopsist0
- Material
- ch1 npq2e0
- Outcome
- alpha-tocopherole0
- Direction
- increasede0
- Qualifier
- During photooxidative stresse0
- Comparator
- ch1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During photooxidative stress, alpha-tocopherol noticeably decreased in ch1 npq1 and increased in ch1 npq2 relative to ch1, suggesting protection of vitamin E by high zeaxanthin levels.”
t0“Arabidopsis”
Claim · model-written summary
High zeaxanthin levels appear to protect vitamin E.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- zeaxanthine0
- Outcome
- protection of vitamin Ee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggesting protection of vitamin E by high zeaxanthin levels.”
t0“Arabidopsis”
Claim · model-written summary
Zeaxanthin antioxidant activity can occur without PSII light-harvesting complexes independently of NPQ.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- zeaxanthine0
- Outcome
- antioxidant activitye0
- Qualifier
- in the absence of PSII light-harvesting complexese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Our results indicate that the antioxidant activity of zeaxanthin, distinct from NPQ, can occur in the absence of PSII light-harvesting complexes.”
t0“Arabidopsis”
Claim · model-written summary
Zeaxanthin lipid protection is comparable to vitamin E.
- Taxon
- ArabidopsisArabidopsise0
- Compound
- zeaxanthine0
- Outcome
- capacity of zeaxanthin to protect thylakoid membrane lipidse0
- Direction
- comparablee0
- Comparator
- vitamin Ee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of zeaxanthin to protect thylakoid membrane lipids is comparable to that of vitamin E but noticeably higher than that of all other xanthophylls of Arabidopsis leaves.”
Claim · model-written summary
Zeaxanthin lipid protection is higher than that of other Arabidopsis xanthophylls.
- Taxon
- ArabidopsisArabidopsise0
- Compound
- zeaxanthine0
- Outcome
- capacity of zeaxanthin to protect thylakoid membrane lipidse0
- Direction
- highere0
- Comparator
- all other xanthophyllse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of zeaxanthin to protect thylakoid membrane lipids is comparable to that of vitamin E but noticeably higher than that of all other xanthophylls of Arabidopsis leaves.”
The same questions in other papers
zeaxanthin · physiology: oxidative · ArabidopsisResults agree
1 paper in the same direction as this paper
- negative
loss of function · physiology: oxidative · ArabidopsisPositive and negative results
18 papers in the same direction as this paper · 3 in the opposite direction
- negative
- positive
- positive
18 papers more in this group
See all 22 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.