Characteristics of the inhibitory action of 1,1-dimethyl-4-(phenylsulfonyl)semicarbazide (DPSS) on ethylene production in carnation (Dianthus caryophyllus L.) flowers

1,1-Dimethyl-4-(phenylsulfonyl)semicarbazide (DPSS) inhibited ethylene prod uction in carnation flowers during natural senescence, but did not inhibit the ethylene production induced by exogenous ethylene in carnation flowers, by indole-3-acetic acid (IAA) in mungbean hypocotyl segments and by woundi ng in winter squash mesocarp tissue. These findings suggested that DPSS doe s not directly inhibit ethylene biosynthesis from L-methionine to ethylene via S-adenosyl-L-methionine and 1-aminocyclopropane-1-carboxylate. During n atural senescence of carnation flowers, abscisic acid (ABA) was accumulated in the pistil and petals 2 days before the onset of ethylene production in the flower, and the ABA content remained elevated until the onset of ethyl ene production. Application of exogenous ABA to cut flowers from the cut st em end caused a rapid increase in the ABA content in flower tissues and pro moted ethylene production in the flowers. These results were in agreement w ith the previous proposal that ABA plays a crucial role in the induction of ethylene production during natural senescence in carnation flowers. DPSS p revented the accumulation of ABA in both the pistil and petals, suggesting that DPSS exerted its inhibitory action on ethylene production in naturally -senescing carnation flowers through the effect on the ABA-related process.