title: A pharmacological approach to test the diffusible signal activity of reactive oxygen intermediates in elicitor-treated tobacco leaves.
abstract: The capacity of H(2)O(2), the most stable of the reactive oxygen species (ROI), to diffuse freely across biological membranes and to signal gene expression suggests that H(2)O(2) could function as a short-lived second messenger diffusing from cell to cell. We tested this hypothesis in tobacco plants treated with a glycoprotein elicitor. Applied at 50 nM, it induces H(2)O(2) accumulation and the hypersensitive response restricted to the infiltrated zone 1 tissue. Stimulation of a set of defense responses also occurs in the surrounding zone 2 tissue without diffusion of the elicitor. ROI levels in zone 1 were modulated using N-acetyl-L-cysteine (NAC) as a ROI scavenger and Rose Bengal (RB) as a ROI generator. We found that ROI appeared to act as signalling intermediates in pathways leading to salicylic acid accumulation, to PR1, PR5 and 3-hydroxy-3-methylglutarylCoA reductase expression in glycoprotein-treated zone 1 tissues. Compared to the treatment with the elicitor alone, co-infiltration of the glycoprotein and NAC increased the surface of zone 2 showing PR1 and O-methyltransferase expression. Application of RB had the opposite effect. The data suggest that, in our system, ROI did not act as a cell-to-cell diffusible signal to activate PR protein and O-methyltransferase expression in zone 2.
authors.affiliation: Institut de Biologie Moléculaire des Plantes du C.N.R.S., Université Louis Pasteur, 12 rue du Général Zimmer, F-67084 Strasbourg, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Costet
authors.forename: Stephan
authors.initials: S
authors.lastname: Dorey
authors.forename: Bernard
authors.initials: B
authors.lastname: Fritig
authors.forename: Serge
authors.initials: S
authors.lastname: Kauffmann
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D005656:Fungal Proteins / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D025782:Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012395:Rose Bengal / Q000494:pharmacology; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology
chemical_list: D016166:Free Radical Scavengers; D005656:Fungal Proteins; D008562:Membrane Glycoproteins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; C091510:elicitor protein, Phytophthora megasperma; C053376:pathogenesis-related proteins, plant; D012395:Rose Bengal; D006861:Hydrogen Peroxide; D025782:Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent; D005978:Glutathione; D020156:Salicylic Acid; D000111:Acetylcysteine