Cloning and characterization of a cDNA encoding sucrose synthase associated with flower opening through early senescence in carnation (Dianthus caryophyllus L.)

Flower opening in carnations (Dianthus caryophyllus L.) is the result of the enlargement of petal cells, which requires sugar metabolism. A cDNA encoding sucrose synthase (DcSUS1) was isolated from carnation petals as a candidate gene acting in the initial step of sugar metabolism in petal cells. DcSUS1 transcripts were detected abundantly in floral tissues of flowering carnation plants; the transcripts accumulated most in the petals and style followed by the ovary, whereas only small accumulation were found in stems, leaves, and calyces. Moreover, nearly constant accumulation of DcSUS1 transcripts was found in the petals during flower opening, fully open, and early senescence periods, whereas decreasing accumulation was detected in petals when senescence progressed. These findings suggested the involvement of DcSUS1 expression in petal cell growth during the opening of carnation flowers.