A pharmacological approach to test the diffusible signal activity of reactive oxygen intermediates in elicitor-treated tobacco leaves

• Published in: Plant and cell physiology 2002-01, Vol.43 (1), p.91-98
• Main Authors: Costet, L. (Universite Louis Pasteur, Strasbourg (France)), Dorey, S, Fritig, B, Kauffmann, S
• Format: Article
• Language: English
• Subjects: Acetylcysteine - pharmacology; DEFENCE MECHANISMS; diphenylene iodonium; DPI; Free Radical Scavengers - pharmacology; Fungal Proteins - pharmacology; Gene Expression Regulation, Plant - drug effects; Glutathione - metabolism; HYDROGEN PEROXIDE; Hydrogen Peroxide - metabolism; Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent - metabolism; hypersensitive response; Key words: Cell-to-cell signalling — Hydrogen peroxide — Nicotiana tabacum — Tobacco; Membrane Glycoproteins - pharmacology; N-acetyl-l-cysteine; NAC; Nicotiana - cytology; Nicotiana - drug effects; Nicotiana - enzymology; NICOTIANA TABACUM; Oxygen Consumption - drug effects; PHARMACOLOGY; Plant Leaves - cytology; Plant Leaves - drug effects; Plant Leaves - enzymology; Plant Proteins - genetics; Plant Proteins - metabolism; reactive oxygen intermediates; Reactive Oxygen Species - metabolism; ROI; Rose Bengal; Rose Bengal - pharmacology; salicylic acid; Salicylic Acid - metabolism; Signal Transduction
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcf012

The capacity of H2O2, the most stable of the reactive oxygen species (ROI), to diffuse freely across biological membranes and to signal gene expression suggests that H,O2 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 H2O2 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, coinfiltration 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.