Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acyltransferases / genetics
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Arabidopsis / genetics
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Arabidopsis / metabolism
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Arabidopsis / radiation effects*
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Catalase / pharmacology
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Dose-Response Relationship, Drug
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Free Radical Scavengers / pharmacology
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Gene Expression Regulation, Plant / drug effects
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Gene Expression Regulation, Plant / radiation effects
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Glutathione / analogs & derivatives*
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Glutathione / pharmacology
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Hydrogen Peroxide / metabolism
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NG-Nitroarginine Methyl Ester / pharmacology
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Nitric Oxide / metabolism
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Nitric Oxide / physiology
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Nitroso Compounds / pharmacology
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Photosynthetic Reaction Center Complex Proteins / genetics
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Plant Proteins / genetics
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RNA, Ribosomal, 18S / genetics
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Reactive Oxygen Species / metabolism
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Reactive Oxygen Species / physiology
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S-Nitrosoglutathione
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Salicylamides / pharmacology
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Signal Transduction / drug effects
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Signal Transduction / radiation effects*
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Superoxide Dismutase / pharmacology
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Superoxides / metabolism
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Ultraviolet Rays*
Substances
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Free Radical Scavengers
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Nitroso Compounds
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Photosynthetic Reaction Center Complex Proteins
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Plant Proteins
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RNA, Ribosomal, 18S
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Reactive Oxygen Species
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Salicylamides
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pathogenesis-related proteins, plant
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Superoxides
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Nitric Oxide
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S-Nitrosoglutathione
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salicylhydroxamic acid
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Hydrogen Peroxide
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Catalase
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Superoxide Dismutase
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Acyltransferases
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flavanone synthetase
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Glutathione
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NG-Nitroarginine Methyl Ester