Abstract
Supplemental narrow-band 311 nm UV-B radiation was applied in order to study the effect of this specific wavelength on tobacco as a model plant. UV-B at photon fluxes varying between 2.9 and 9.9 μmol m−2 s−1 was applied to supplement 150 μmol m−2 s−1 photosynthetically active radiation (PAR) for four hours in the middle of the light period for four days. Narrow-band UV-B increased leaf flavonoid and phenolic acid contents. In leaves exposed to 311 nm radiation, superoxide dismutase activity increased, but phenolic peroxidase activity decreased, and the changes were proportional to the UV flux. Ascorbate peroxidase activities were not significantly affected. Narrow-band UV-B caused a dose-dependent linear decrease in the quantum efficiency of photosystem II, up to approximately 10% loss. A parallel decrease in non-regulated non-photochemical quenching indicates potential electron transfer to oxygen in UV-treated leaves. In addition to a flux-dependent increase in the imbalance between enzymatic H2O2 production and neutralization, this resulted in an approximately 50% increase in leaf H2O2 content under 2.9–6 μmol m−2 s−1 UV-B. Leaf H2O2 decreased to control levels under higher UV-B fluxes due to the onset of increased non-enzymatic H2O2- and superoxide-neutralizing capacities, which were not observed under lower fluxes. These antioxidant responses to 311 nm UV-B were different from our previous findings in plants exposed to broad-band UV-B. The results suggest that signaling pathways activated by 311 nm radiation are distinct from those stimulated by other wavelengths and support the heterogeneous regulation of plant UV responses.
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Claims 11
Claim · model-written summary
Narrow-band UV-B increased leaf flavonoid and phenolic acid contents.
- Taxon
- tobacco
Nicotiana tabacume2 - Treatment
- Narrow-band UV-Be0
- Outcome
- leaf flavonoid and phenolic acid contentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Narrow-band UV-B increased leaf flavonoid and phenolic acid contents.”
e2“tobacco as a model plant”
Claim · model-written summary
Superoxide dismutase activity increased with UV flux.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- 311 nm radiatione1
- Outcome
- superoxide dismutase activitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“superoxide dismutase activity increased, but phenolic peroxidase activity decreased, and the changes were proportional to the UV flux”
e2“tobacco as a model plant”
e1“In leaves exposed to 311 nm radiation, superoxide dismutase activity increased, but phenolic peroxidase activity decreased, and the changes were proportional to the UV flux.”
Claim · model-written summary
Phenolic peroxidase activity decreased with UV flux.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- 311 nm radiatione1
- Outcome
- phenolic peroxidase activitye0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phenolic peroxidase activity decreased, and the changes were proportional to the UV flux”
e2“tobacco as a model plant”
e1“In leaves exposed to 311 nm radiation, superoxide dismutase activity increased, but phenolic peroxidase activity decreased, and the changes were proportional to the UV flux.”
Claim · model-written summary
Ascorbate peroxidase activities were not significantly affected.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- Narrow-band UV-Be1
- Outcome
- Ascorbate peroxidase activitiese0
- Direction
- not significantly affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ascorbate peroxidase activities were not significantly affected.”
e2“tobacco as a model plant”
e1“Narrow-band UV-B increased leaf flavonoid and phenolic acid contents.”
Claim · model-written summary
Narrow-band UV-B caused a dose-dependent decrease in photosystem II quantum efficiency, up to about 10%.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- Narrow-band UV-Be0
- Outcome
- quantum efficiency of photosystem IIe0
- Direction
- decreasee0
- Value
- approximately 10%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Narrow-band UV-B caused a dose-dependent linear decrease in the quantum efficiency of photosystem II, up to approximately 10% loss.”
e2“tobacco as a model plant”
Claim · model-written summary
Non-regulated non-photochemical quenching decreased in parallel.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- UV-treatede1
- Outcome
- non-regulated non-photochemical quenchinge0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A parallel decrease in non-regulated non-photochemical quenching”
e2“tobacco as a model plant”
e1“A parallel decrease in non-regulated non-photochemical quenching indicates potential electron transfer to oxygen in UV-treated leaves.”
Claim · model-written summary
Imbalance between enzymatic H2O2 production and neutralization increased with UV flux.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- UV-Be1
- Outcome
- imbalance between enzymatic H2O2 production and neutralizatione0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a flux-dependent increase in the imbalance between enzymatic H2O2 production and neutralization”
e2“tobacco as a model plant”
e1“Narrow-band UV-B caused a dose-dependent linear decrease in the quantum efficiency of photosystem II, up to approximately 10% loss.”
Claim · model-written summary
Leaf H2O2 content increased approximately 50% under 2.9–6 μmol m−2 s−1 UV-B.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- 2.9–6 μmol m−2 s−1 UV-Be0
- Outcome
- leaf H2O2 contente0
- Direction
- increasee0
- Value
- approximately 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“approximately 50% increase in leaf H2O2 content under 2.9–6 μmol m−2 s−1 UV-B”
e2“tobacco as a model plant”
Claim · model-written summary
Leaf H2O2 decreased to control levels at higher UV-B fluxes.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- higher UV-B fluxese0
- Outcome
- Leaf H2O2e0
- Direction
- decreasede0
- Comparator
- control levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf H2O2 decreased to control levels under higher UV-B fluxes”
e2“tobacco as a model plant”
Claim · model-written summary
Non-enzymatic H2O2- and superoxide-neutralizing capacities increased at higher UV-B fluxes.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- higher UV-B fluxese1
- Outcome
- non-enzymatic H2O2- and superoxide-neutralizing capacitiese0
- Direction
- increasede0
- Comparator
- lower fluxese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased non-enzymatic H2O2- and superoxide-neutralizing capacities, which were not observed under lower fluxes”
e2“tobacco as a model plant”
e1“Leaf H2O2 decreased to control levels under higher UV-B fluxes due to the onset of increased non-enzymatic H2O2- and superoxide-neutralizing capacities, which were not observed under lower fluxes.”
Claim · model-written summary
Antioxidant responses to 311 nm UV-B differed from previous broad-band UV-B findings.
- Taxon
- tobaccoNicotiana tabacume2
- Outcome
- antioxidant responsese0
- Comparator
- broad-band UV-Be0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These antioxidant responses to 311 nm UV-B were different from our previous findings in plants exposed to broad-band UV-B.”
e2“tobacco as a model plant”
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