Acceleration of Membrane Senescence in Cut Carnation Flowers by Treatment with Ethylene

The lipid microviscosity of microsomal membranes from senescing cut carnation (Dianthus caryophyllus L. cv. White Sim) flowers rises with advancing senescence. The increase in membrane microviscosity is initiated within 3 to 4 days of cutting the flowers and coincides temporally with petal-inrolling denoting the climacteric-like rise in ethylene production. Treatment of young cut flowers with aminoethoxyvinylglycine prevented the appearance of petal-inrolling and delayed the rise in membrane microviscosity until day 9 after cutting. When freshly cut flowers or aminoethoxyvinylglycine-treated flowers were exposed to exogenous ethylene (1 microliter per liter), the microviscosity of microsomal membranes rose sharply within 24 hours, and inrolling of petals was clearly evident. Thus, treatment with ethylene accelerates membrane rigidification. Silver thiosulphate, a potent anti-ethylene agent, delayed the rise in microsomal membrane microviscosity even when the flowers were exposed to exogenous ethylene. Membrane rigidification in both naturally senescing and ethylene-treated flowers was accompanied by an increased sterol:phospholipid ratio reflecting the selective loss of membrane phospholipid that accompanies senescence. The results collectively indicate that the climacteric-like surge in ethylene production during senescence of carnation flowers facilitates physical changes in membrane lipids that presumably lead to loss of membrane function.