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 (H₂O₂) derived from superoxide (O₂⁻). In contrast, the up-regulation of PDF1.2 transcript was mediated through a pathway involving O₂⁻ 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.... [Show full abstract]
Keywordsgene expression; nitric oxide; reactive oxygen species; signal transduction; ultraviolet-B; Biochemistry & Molecular Biology; Arabidopsis; Hydrogen Peroxide; Superoxides; Salicylamides; Nitroso Compounds; S-Nitrosoglutathione; Photosynthetic Reaction Center Complex Proteins; Catalase; Superoxide Dismutase; Acyltransferases; NG-Nitroarginine Methyl Ester; Glutathione; Plant Proteins; RNA, Ribosomal, 18S; Free Radical Scavengers; Ultraviolet Rays; Gene Expression Regulation, Plant; Dose-Response Relationship, Drug
Fields of Research0607 Plant Biology
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