Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band Ultraviolet
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<sup>−2</sup> s<sup>−1</sup> was applied to supplement 150 μmol m<sup>...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-07-01
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| Series: | Plants |
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| Online Access: | https://www.mdpi.com/2223-7747/10/8/1570 |
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| author | Arnold Rácz Éva Hideg |
| author_facet | Arnold Rácz Éva Hideg |
| author_sort | Arnold Rácz |
| collection | DOAJ |
| description | 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<sup>−2</sup> s<sup>−1</sup> was applied to supplement 150 μmol m<sup>−2</sup> s<sup>−1</sup> 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 H<sub>2</sub>O<sub>2</sub> production and neutralization, this resulted in an approximately 50% increase in leaf H<sub>2</sub>O<sub>2</sub> content under 2.9–6 μmol m<sup>−2</sup> s<sup>−1</sup> UV-B. Leaf H<sub>2</sub>O<sub>2</sub> decreased to control levels under higher UV-B fluxes due to the onset of increased non-enzymatic H<sub>2</sub>O<sub>2</sub>- 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. |
| first_indexed | 2024-03-10T08:28:31Z |
| format | Article |
| id | doaj.art-9809df6852564dbcaa50e87867adb540 |
| institution | Directory Open Access Journal |
| issn | 2223-7747 |
| language | English |
| last_indexed | 2024-03-10T08:28:31Z |
| publishDate | 2021-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Plants |
| spelling | doaj.art-9809df6852564dbcaa50e87867adb5402023-11-22T09:18:17ZengMDPI AGPlants2223-77472021-07-01108157010.3390/plants10081570Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band UltravioletArnold Rácz0Éva Hideg1Department of Plant Biology, University of Pécs, Ifjúság útja 6, 7624 Pécs, HungaryDepartment of Plant Biology, University of Pécs, Ifjúság útja 6, 7624 Pécs, HungarySupplemental 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<sup>−2</sup> s<sup>−1</sup> was applied to supplement 150 μmol m<sup>−2</sup> s<sup>−1</sup> 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 H<sub>2</sub>O<sub>2</sub> production and neutralization, this resulted in an approximately 50% increase in leaf H<sub>2</sub>O<sub>2</sub> content under 2.9–6 μmol m<sup>−2</sup> s<sup>−1</sup> UV-B. Leaf H<sub>2</sub>O<sub>2</sub> decreased to control levels under higher UV-B fluxes due to the onset of increased non-enzymatic H<sub>2</sub>O<sub>2</sub>- 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.https://www.mdpi.com/2223-7747/10/8/1570UV-Bhydrogen peroxideperoxidasesuperoxide dismutasenon-enzymatic antioxidantsacclimation |
| spellingShingle | Arnold Rácz Éva Hideg Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band Ultraviolet Plants UV-B hydrogen peroxide peroxidase superoxide dismutase non-enzymatic antioxidants acclimation |
| title | Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band Ultraviolet |
| title_full | Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band Ultraviolet |
| title_fullStr | Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band Ultraviolet |
| title_full_unstemmed | Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band Ultraviolet |
| title_short | Narrow-Band 311 nm Ultraviolet-B Radiation Evokes Different Antioxidant Responses from Broad-Band Ultraviolet |
| title_sort | narrow band 311 nm ultraviolet b radiation evokes different antioxidant responses from broad band ultraviolet |
| topic | UV-B hydrogen peroxide peroxidase superoxide dismutase non-enzymatic antioxidants acclimation |
| url | https://www.mdpi.com/2223-7747/10/8/1570 |
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