Regulation of Senescence in Carnation (Dianthus caryophyllus) by Ethylene

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Abstract
Carnation (D. caryophyllus) flowers were exposed to 2 .mu.l/l ethylene and examined at intervals to determine the time course of wilting, decrease in water uptake and increase in ionic leakage in response to ethylene. A rapid decrease in water uptake was observed about 4 h after initiating treatment with ethylene. This was followed by wilting (in-rolling of petals) about 2 h later. CO2 inhibited the decline in water uptake and wilting and this is typical of most ethylene-induced responses. Ethylene did not affect closure of stomates. Ethylene enhanced ionic leakage, as measured by efflux of 36Cl from the vacuole. This was judged to coincide with the decrease in water uptake. Gassing flowers with propylene initiated autocatalytic ethylene production within 2.4 h. Since the increase in ethylene production by carnations preceded the increase in ionic leakage and the decline in water uptake by several hours, it is apparent that the change in ionic leakage does not lead to the initial increase in ethylene productions as reported in morning glory but may explain the autocatalytic phase of ethylene production.