title: Hydrogen-peroxide-mediated catalase gene expression in response to wounding.
abstract: The effect of wounding on catalase expression was examined in embryos and leaves of maize. All three Cat genes are upregulated in response to wounding in immature embryos. Cat expression also increased in response to jasmonic acid (JA), raising the possibility that JA and wounding may share a common signal transduction pathway in upregulating Cat mRNA in immature embryos. In young leaves, only Cat1 and Cat3 transcripts increase in response to wounding, but JA does not play a role. Cat1 and Cat3 transcript accumulation also increases in response to wounding in both wild-type and mutant leaves deficient in abscisic acid (ABA), implying that Cat1 and Cat3 induction in response to wounding is not mediated by ABA in leaves. Transient assays using the Cat1 promoter fused with the reporter gene Gus, showed that the DNA sequence motif responsible for Cat1 upregulation by wounding overlaps with the ABA-responsive element (ABRE, G-box) in the Cat1 promoter. The exact nature of the signals triggering the Cat responses to wounding is not clear at this point, but some evidence indicates that reactive oxygen species (ROS) play a role in this response. In fact, we have found that endogenous H(2)O(2) levels increase in wounded leaves. Thus, wounding may indirectly induce the production of H(2)O(2) in leaves, triggering the antioxidant response.
authors.affiliation: Department of Genetics, North Carolina State University, Raleigh, NC 27695-7614, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Guan
authors.forename: J G
authors.initials: JG
authors.lastname: Scandalios
mesh_terms: D000040:Abscisic Acid / Q000235:genetics / Q000502:physiology; D002374:Catalase / Q000096:biosynthesis* / Q000235:genetics; D003517:Cyclopentanes / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D054883:Oxylipins; D010935:Plant Diseases / Q000235:genetics*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D017382:Reactive Oxygen Species; D017384:Sequence Deletion; D015398:Signal Transduction / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects; D003313:Zea mays / Q000187:drug effects / Q000196:embryology / Q000201:enzymology / Q000235:genetics
chemical_list: D003517:Cyclopentanes; D007527:Isoenzymes; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D017382:Reactive Oxygen Species; C011006:jasmonic acid; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D002374:Catalase