Expression of genes responsible for ethylene production and wilting are differently regulated in carnation (Dianthus caryophyllus L.) petals

Carnation petals exhibit autocatalytic ethylene production and wilting duri ng senescence. The autocatalytic ethylene production is caused by the expre ssion of 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase g enes, whereas the wilting of petals is related to the expression of the cys teine proteinase (CPase) gene. So far, it has been believed that the ethyle ne production and wilting are regulated in concert in senescing carnation p etals, since the two events occurred closely in parallel with time. In the present study, we investigated the expression of these genes in petals of a transgenic carnation harboring a sense ACC oxidase transgene and in petals of carnation flowers treated with 1,1-dimethyl-4-(phenylsulfonyl)semicarba zide (DPSS). In petals of the transgenic carnation flowers, treatment with exogenous ethylene caused accumulation of the transcript for CPase and in-r olling (wilting), whereas it caused no or little accumulation of the transc ripts for ACC oxidase and ACC synthase and negligible ethylene production. In petals of the flowers treated with DPSS, the transcripts for ACC synthas e and ACC oxidase were accumulated, but no significant change in the level of the transcript for CPase was observed. These results suggest that the ex pression of ACC synthase and ACC oxidase genes, which leads to ethylene pro duction, is differentially regulated from the expression of CPase, which le ads to wilting, in carnation petals. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.