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

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...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1991-10, Vol.97 (2), p.545-550
Main Authors: Voisine, R. (Universite Laval, Quebec, Canada), Vezina, L.P, Willemot, C
Format: Article
Language:English
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
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Summary: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
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.97.2.545