A pharmacological approach to test the diffusible signal activity of reactive oxygen intermediates in elicitor-treated tobacco leaves.
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.
Costet
Laurent
L
Institut de Biologie Moléculaire des Plantes du C.N.R.S., Université Louis Pasteur, 12 rue du Général Zimmer, F-67084 Strasbourg, France.
Dorey
Stephan
S
Fritig
Bernard
B
Kauffmann
Serge
S
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
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