title: Acute exposure to UV-B sensitizes cucumber, tomato, and Arabidopsis plants to photooxidative stress by inhibiting thermal energy dissipation and antioxidant defense.
abstract: To characterize a change in NPQ upon exposure to ultraviolet-B (UV-B), the xanthophyll cycle-dependent and -independent NPQs were compared in Cucumis sativus, Lycopersicum esculentum, and Arabidopsis thaliana leaves. The xanthophyll cycle-dependent NPQ was dramatically but reversibly suppressed by UV-B radiation. This suppression was correlated more strongly with a marked decrease in photosynthetic electron transport rather than changes in xanthophyll cycle enzymes such as violaxanthin de-epoxidase and zeaxanthin epoxidase. Accordingly, the UV-B-induced suppression of NPQ cannot be attributed to changes in expressions of VDE and ZEP. However, suppression of the xanthophyll cycle-dependent NPQ could only account for the 77 K fluorescence emission spectra of thylakoid membranes and the increased level of (1)O(2) production, but not for the decreased levels of •O(2)(-) production and H(2)O(2) scavenging. These results suggest that a gradual reduction of H(2)O(2) scavenging activity as well as a transient and reversible suppression of thermal energy dissipation may contribute differentially to increased photooxidative damages in cucumber, tomato, and Arabidopsis plants after acute exposure to UV-B radiation.
authors: Advanced Radiation Research Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea.
authors: Yu Ran
authors: YR
authors: Moon
authors: Min Hee
authors: MH
authors: Lee
authors: Altanzaya
authors: A
authors: Tovuu
authors: Choon-Hwan
authors: CH
authors: Lee
authors: Byung Yeoup
authors: BY
authors: Chung
authors: Youn-Il
authors: YI
authors: Park
authors: Jin-Hong
authors: JH
authors: Kim
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000528:radiation effects*; D018553:Cucumis sativus / Q000528:radiation effects; D004583:Electrons; D008027:Light; D018551:Solanum lycopersicum / Q000528:radiation effects; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry; D010788:Photosynthesis; D010858:Pigmentation; D018515:Plant Leaves / Q000528:radiation effects; D013050:Spectrometry, Fluorescence / Q000379:methods; D020524:Thylakoids / Q000378:metabolism; D014466:Ultraviolet Rays; D024341:Xanthophylls / Q000737:chemistry
chemical_list: D000975:Antioxidants; D024341:Xanthophylls; D010088:Oxidoreductases; C097153:zeaxanthin epoxidase; D010100:Oxygen