Analysis of molecular mechanism of long-lasting carnations

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1.Analysis of ethylene production in the long-lasting carnation 'White Candle'In senescing carnation (Dianthus caryophyllus L.) flowers, ethylene is produced from the gynoecium, and acts as a diffusible signal received by petals to induce autocatalytic ethylene production in the petals. We discovered cv. ‘White Candle (WC)' as a long-lasting cultivar, of which cut flowers produce ethylene only in trace amounts and have a long vase life. The low ethylene production in these flowers was due to low ethylene production in the gynoecium, accompanied by low accumulation of ACC synthase (DC-ACS1) transcripts. These findings further support the importance of ethylene production from the gynoecium in the senescence of carnation flowers.2.Cloning and characterization of a cDNA for a novel carnation cysteine proteinaseThe wilting of carnation petals is caused by degradation of cell components, which leads to cell death during senescence of petals, mediated by some hydrolytic enzymes such as cysteine proteinase (CPase, DC-CP1), lipase and so on. We isolated a cDNA for a novel cysteine proteinase (DC-CP2) from carnation and compared its expression to that of DC-CP1 in senescing carnation petals. Furthermore, we isolated and characterized the nucleotide sequences of promoter region of both DC-CP1 and DC-CP2 genes.3.Analysis of wilting and fading in senescing carnation petalsWe categorized senescence of carnation flowers was into two types ; the first is 'wilting' which is induced by the action of ethylene and the second is 'fading' which occurs independent on ethylene. We revealed that a cysteine proteinase (DC-CP1) and its inhibitor (DC-CPIn) were up-regulated in carnation petals undergoing wilting as well as fading.