Flavonoid biosynthesis in white-¯owered Sim carnations (Dianthus caryophyllus)

Abstract Analysis of¯avonoid composition and gene expression of enzymes involved in anthocyanin synthesis in¯owers of four acyanic and one cyanic cultivar of Sim carnation showed that the acyanic¯ower cultivars are divided into three types. The ®rst includes two normal white cultivars, U Conn Sim' and`White Sim'; the second includes a nearly pure white cultivar,`Kaly'; and the third includes a nearly pure white cultivar,`White Mind'.`U Conn Sim' and`White Sim' accumulated¯avonol glycosides and lacked anthocyanins. The transcription of the several genes of enzymes involved in¯avonoid biosynthesis were reduced at a later¯owering stage than the cyanic cultivar, especially the genes encoding dihydro¯avonol 4-reductase and anthocyanidin synthase. Kaly' accumulated¯avanone glycosides and a small amount of¯avonol and¯avone glycosides by blocking the transcription of the gene encoding¯avanone 3-hydroxylase, in addition to the transcriptional reduction of the genes for¯avonoid biosynthesis at a later¯owering stage. Although White Mind' contains little¯avonoid, the position of the block on¯avonoid biosynthesis in`White Mind' is not known.