Induction of senescence-like deterioration of microsomal membranes from cauliflower by free radicals generated during gamma irradiation

• Published in: Plant physiology (Bethesda) Vol. 97; no. 2; pp. 545 - 550
• Main Authors: Voisine, R. (Universite Laval, Quebec, Canada), Vezina, L.P, Willemot, C
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.10.1991
• Subjects: Biological and medical sciences; BRASSICA OLERACEA; Cauliflower; Cell membranes; CONTAMINANTES; DETERIORATION; DETERIORO; endoplasmic reticulum; ENVEJECIMIENTO; Florets; Free radicals; Fundamental and applied biological sciences. Psychology; gamma radiation; Irradiation; lipid peroxidation; Lipids; MEMBRANA; MEMBRANE; microsomes; Nonesterified fatty acids; ORGANITE CELLULAIRE; ORGANULOS CITOPLASMATICOS; Phosphates; Phospholipids; Plant physiology and development; Plants; POLLUANT; RADIACION GAMMA; RAYONNEMENT GAMMA; Senescence and abscission; Vegetative apparatus, growth and morphogenesis. Senescence; VIEILLISSEMENT; Gamma irradiation; Senescence; Brassica oleracea; Vegetable crop; Cruciferae; Dicotyledones; Angiospermae; Plasma membrane; Isolation; Lipids; Spermatophyta; Free radical
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.97.2.545

Membrane deterioration differs in aging and senescent tissues. Involvement of free radicals in the process is generally recognized. Little is known about the physiological effects of gamma irradiation on plant tissues. Degradation of microsomal membranes by the action of free radicals, generated in vivo by gamma rays, was investigated. Cauliflower florets (Brassica oleracea L., Botrytis group) were exposed to 2 or 4 kiloGray of gamma radiation. Membrane deterioration was assessed during 8-day storage at 13 degrees C. Some senescence was indicated in nonirradiated controls by a parallel depletion of lipid phosphate and protein. Irradiation caused an immediate increase in tissue electrolyte leakage and a small increase in the free fatty acid content of membranes. In irradiated samples, leakage of electrolytes and the ratios of sterol to phospholipid and of free fatty acid to phospholipid increased with storage. During this period, membrane protein was progressively lost and the lipid phosphate-to-protein ratio increased markedly. Polyunsaturated fatty acids were selectively depleted from the free fatty acid fraction for all treatments, suggesting lipoxygenase activity. No change in lipid saturation was observed in the polar lipid fraction. The results suggest an enzyme-catalyzed senescence-like membrane deterioration, probably induced by chemical deesterification of phospholipids by free radicals generated during irradiation