Expression and Regulation of Senescence-related Genes in Carnation Flowers with Low Ethylene Production during Senescence

Abstract

We investigated ethylene production, ethylene biosynthesis genes, and senescence-related genes in flowers of a carnation (Dianthus caryophyllus L.) cultivar ‘Miracle Symphony’ (MS) and lines 006-13 and 62-2, which have a longer vase life than flowers of ‘White Sim’ (WS). WS flowers showed typical symptoms of senescence, but flowers of MS, 006-13, and 62-2 did not show symptoms of senescence, although they showed differences in vase life and ethylene production by day 15. The flowers of 006-13 and 62-2 produced small amounts of ethylene as a result of the low expression of two ethylene biosynthesis genes, DcACS1 and DcACO1; those of MS produced extremely low levels of ethylene. By day 15, the flowers of 006-13 and 62-2 showed increased expression of some senescence-related genes (DcCP1, DcbGal, DcGST1, and DcLip) that were upregulated by exogenous ethylene, indicating that a low level of ethylene production could induce the senescence of petals. In contrast to the upregulation of these senescence-related genes, the expression of DcCPIn, which was downregulated by exogenous ethylene decreased in petals of MS, 006-13, and 62-2 during flower senescence and was the same in all three lines at day 15. The results suggest that extended vase life depends on reduced levels of ethylene production, ethylene biosynthesis gene expression, and senescence-related gene expression.