title: Antioxidant defence in UV-irradiated tobacco leaves is centred on hydrogen-peroxide neutralization.
abstract: Greenhouse grown tobacco (Nicotiana tabacum L. cv. Petit Havana) plants were exposed to supplemental UV centred at 318 nm and corresponding to 13.6 kJ m(-2) d(-1) biologically effective UV-B (280-315 nm) radiation. After 6 days this treatment decreased photosynthesis by 30%. Leaves responded by a large increase in UV-absorbing pigment content and antioxidant capacities. UV-stimulated defence against ROS was strongest in chloroplasts, since activities of plastid enzymes FeSOD and APX had larger relative increases than other, non-plastid specific SODs or peroxidases. In addition, non-enzymatic defence against hydroxyl radicals was doubled in UV treated leaves as compared to controls. In UV treated leaves, the extent of activation of ROS neutralizing capacities followed a peroxidases > hydroxyl-radical neutralization > SOD order. These results suggest that highly effective hydrogen peroxide neutralization is the focal point of surviving UV-inducible oxidative stress and argue against a direct signalling role of hydrogen peroxide in maintaining adaptation to UV, at least in laboratory experiments.
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
authors.forename: Petra
authors.initials: P
authors.lastname: Majer
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary; Department of Plant Biology, Institute of Biology, University of Pécs, Pécs, Hungary.
authors.forename: Gyula
authors.initials: G
authors.lastname: Czégény
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
authors.forename: Györgyi
authors.initials: G
authors.lastname: Sándor
authors.affiliation: Biology Department, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Dix
authors.affiliation: Department of Plant Biology, Institute of Biology, University of Pécs, Pécs, Hungary. Electronic address: ehideg@gamma.ttk.pte.hu.
authors.forename: Eva
authors.initials: E
authors.lastname: Hideg
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000528:radiation effects; D018384:Oxidative Stress / Q000528:radiation effects; D010544:Peroxidases / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism* / Q000528:radiation effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism* / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases
keywords: Antioxidant; Hydrogen peroxide; Peroxidase; Photosynthesis; Reactive oxygen species; Tobacco; UV treatment