Early signaling components in ultraviolet-B responses: distinct roles for different reactive oxygen species and nitric oxide.
The nature and origin of the reactive oxygen species (ROS) involved in the early part of Ultraviolet-B (UV-B)-induced signaling pathways were investigated in Arabidopsis thaliana using a range of enzyme inhibitors and free radical scavengers. The increase in PR-1 transcript and decrease in Lhcb transcript in response to UV-B exposure was shown to be mediated through pathways involving hydrogen peroxide (H(2)O(2)) derived from superoxide (O(2)(&z.rad;-)). In contrast, the up-regulation of PDF1.2 transcript was mediated through a pathway involving O(2)(&z.rad;-) directly. The origins of the ROS were also shown to be distinct and to involve NADPH oxidase and peroxidase(s). The up-regulation of Chs by UV-B was not affected by ROS scavengers, but was reduced by inhibitors of nitric oxide synthase (NOS) or NO scavengers. Together these results suggest that UV-B exposure leads to the generation of ROS, from multiple sources, and NO, through increased NOS activity, giving rise to parallel signaling pathways mediating responses of specific genes to UV-B radiation.
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Department of Plant Genetics and Biotechnology, Horticulture Research International, Wellesbourne, Warwick, UK. s.amin-hanjani@maff.gsi.gov.uk
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Jordan
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Thomas
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D000217:Acyltransferases / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D002374:Catalase / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology; D009603:Nitroso Compounds / Q000494:pharmacology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000502:physiology; D026422:S-Nitrosoglutathione; D012457:Salicylamides / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D014466:Ultraviolet Rays
D016166:Free Radical Scavengers; D009603:Nitroso Compounds; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins; D012337:RNA, Ribosomal, 18S; D017382:Reactive Oxygen Species; D012457:Salicylamides; C053376:pathogenesis-related proteins, plant; D013481:Superoxides; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; C005703:salicylhydroxamic acid; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D000217:Acyltransferases; C020141:flavanone synthetase; D005978:Glutathione; D019331:NG-Nitroarginine Methyl Ester