title: Hydrogen peroxide activates cell death and defense gene expression in birch.
abstract: The function of hydrogen peroxide (H(2)O(2)) as a signal molecule regulating gene expression and cell death induced by external stresses was studied in birch (Betula pendula). Ozone (O(3)), Pseudomonas syringae pv syringae (Pss), and wounding all induced cell death of various extents in birch leaves. This was temporally preceded and closely accompanied by H(2)O(2) accumulation at, and especially surrounding, the lesion sites. O(3) and Pss, along with an artificial H(2)O(2) producing system glucose (Glc)/Glc oxidase, elicited elevated mRNA levels corresponding to genes encoding reactive oxygen species detoxifying enzymes, Pal, Ypr10, and mitochondrial phosphate translocator 1. In addition to the regulation of gene expression, Glc/Glc oxidase also induced endogenous H(2)O(2) production in birch leaves, accompanied by cell death that resembled O(3) and Pss damage. Wound-induced gene expression differed from that induced by O(3) and Pss. Thus, it appears that at least two separate defense pathways can be activated in birch leaves by stress factors, even though the early H(2)O(2) accumulation response is common among them all.
authors.affiliation: Institute of Biotechnology and Department of Biosciences, Division of Genetics, P.O. Box 56, FIN-00014 University of Helsinki, Finland.
authors.forename: Riikka I
authors.initials: RI
authors.lastname: Pellinen
authors.forename: Minna-Sisko
authors.initials: MS
authors.lastname: Korhonen
authors.forename: Airi A
authors.initials: AA
authors.lastname: Tauriainen
authors.forename: E Tapio
authors.initials: ET
authors.lastname: Palva
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kangasjärvi
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D029662:Betula / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D005949:Glucose Oxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D007113:Immunity, Innate / Q000187:drug effects / Q000235:genetics; D008278:Magnesium Sulfate / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D010126:Ozone / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D011549:Pseudomonas / Q000254:growth & development; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013314:Stress, Mechanical
chemical_list: D002712:Chlorides; D017382:Reactive Oxygen Species; D002586:Cesium; D010126:Ozone; D008278:Magnesium Sulfate; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; C028019:cesium chloride; D005947:Glucose; D010100:Oxygen