A Flower Senescence-Related mRNA from Carnation Shares Sequence Similarity with Fruit Ripening-Related mRNAs Involved in Ethylene Biosynthesis

The programmed senescence of carnation (Dianthus caryophyllus L. cv White Sim) flower petals is associated with an increase in the production of ethylene (1). This increase in ethylene plays a critical role in the initiation and regulation of the biochemical processes of senescence, including gene activation (1, 4, 5). The onset ofincreased ethylene production in aging petals is associated with the concomitant increases in both ACC2 synthase and EFE activities, which convert Sadenosyl-L-methionine to ACC and oxidize ACC to ethylene, respectively (1). Senescence of carnation petals is accompanied by the accumulation of specific mRNAs (4), several of which have recently been cloned. The increase in ethylene biosynthesis in senescing petals would indicate mRNAs encoding ACC synthase and EFE are likely among the population of senescence-related transcripts. Here we report the nucleotide sequence of a flower senescence-related cDNA (pSR 120) (Table I) from carnation. The sequence of pSR 120 is 1250 base pairs and contains an open reading frame of 321 amino acids (Fig. 1). The nucleotide and predicted protein sequences are highly homologous to ripening-related cDNAs from tomato (3) and avocado (6). The tomato clone, pTOM 13, was recently found to be involved in ethylene synthesis based on inhibition of ethylene production by antisense RNA (2). A lack of capacity to convert ACC to ethylene in these transgenic plants expressing antisense pTOM 13 led to the speculation pTOM 13 may encode the EFE.