Hydrogen peroxide from the oxidative burst is neither necessary nor sufficient for hypersensitive cell death induction, phenylalanine ammonia lyase stimulation, salicylic acid accumulation, or scopoletin consumption in cultured tobacco cells treated with elicitin

• Published in: Plant physiology (Bethesda) Vol. 121; no. 1; pp. 163 - 171
• Main Authors: Dorey, S, Kopp, M, Geoffroy, P, Fritig, B, Kauffmann, S
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.09.1999; American Society of Plant Biologists
• Subjects: Accumulation; Agronomy. Soil science and plant productions; Algal Proteins - pharmacology; Ammonia; apoptosis; biochemical pathways; Biological and medical sciences; biosynthesis; Cell culture techniques; Cell death; Cell Death - drug effects; Cells, Cultured; Cultured cells; defense mechanisms; Economic plant physiology; Enzyme Activation - drug effects; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Glycoproteins; Glycoproteins - pharmacology; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Hypersensitive response; Metabolism; Metabolism. Physicochemical requirements; metabolites; Mortality; Nicotiana - cytology; Nicotiana - drug effects; Nicotiana - enzymology; Nicotiana - metabolism; Nicotiana tabacum; Nitrogen metabolism and other ones (excepting carbon metabolism); Nutrition. Photosynthesis. Respiration. Metabolism; Oxidases; oxidation; Pathogens; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; phenylalanine ammonia-lyase; Phenylalanine Ammonia-Lyase - metabolism; Phytopathology. Animal pests. Plant and forest protection; Phytophthora; Phytophthora megasperma; Plant cells; Plant Diseases - chemically induced; Plant Growth Regulators - pharmacology; Plant Leaves - cytology; Plant Leaves - drug effects; Plant Leaves - enzymology; Plant Leaves - metabolism; Plant physiology and development; Plant-Microbe and Plant-Insect Interactions; Plants; Plants, Toxic; proteins; Reactive oxygen species; Respiratory Burst - drug effects; salicylic acid; Salicylic Acid - metabolism; Scopoletin - metabolism; Tobacco; Cell culture; Phenylalanine ammonia-lyase; Plant pathogen; Phycomycetes; Stimulant plant; Lyases; Activation; Elicitor; Nicotiana tabacum; Fungi; Dicotyledones; Angiospermae; Solanaceae; Phytophthora megasperma; Thallophyta; Salicylic acid; Enzyme; Induction; Hypersensitivity; Hydrogen Peroxides; Carbon-nitrogen lyases; Ammonia-lyases; Cell death; Defense mechanism; Spermatophyta; Biological accumulation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.121.1.163

H2O2 from the oxidative burst, cell death, and defense responses such as the production ofphenylalanine ammonia lyase (PAL), salicylic acid (SA), and scopoletin were analyzed in cultured tobacco (Nicotiana tabacum) cells treated with three proteinaceous elicitors: two elicitins (alpha-megaspermin and beta-megaspermin) and one glycoprotein. These three proteins have been isolated from Phytophthora megasperma H20 and have been previously shown to be equally efficient in inducing a hypersensitive response (HR) upon infiltration into tobacco leaves. However, in cultured tobacco cells these elicitors exhibited strikingly different biological activities. Beta-Megaspermin was the only elicitor that caused cell death and induced a strong, biphasic H2O2 burst. Both elicitins stimulated PAL activity similarly and strongly, while the glycoprotein caused only a slight increase. Only elicitins induced SA accumulation and scopoletin consumption, and beta-megaspermin was more efficient. To assess the role of H2O2 in HR cell death and defense response expression in elicitin-treated cells, a gain and loss of function strategy was used. Our results indicated that H2O2 was neither necessary nor sufficient for HR cell death, PAL activation, or SA accumulation, and that extracellular H2O2 was not a direct cause of intracellular scopoletin consumption.