Flavonoid biosynthesis in white-flowered Sim carnations (Dianthus caryophyllus)

Analysis of flavonoid composition and gene expression of enzymes involved i n anthocyanin synthesis in flowers of four acyanic and one cyanic cultivar of Sim carnation showed that the acyanic flower cultivars are divided into three types. The first includes two normal white cultivars, 'U Conn Sim' an d 'White Sim'; the second includes a nearly pure white cultivar, 'Kaly'; an d the third includes a nearly pure white cultivar,'White Mind'. 'U Conn Sim ' and 'White Sim' accumulated flavonol glycosides and lacked anthocyanins. The transcription of the several genes of enzymes involved in flavonoid bio synthesis were reduced at a later flowering stage than the cyanic cultivar, especially the genes encoding dihydroflavonol 4-reductase and anthocyanidi n synthase. 'Kaly' accumulated flavanone glycosides and a small amount of f lavonol and flavone glycosides by blocking the transcription of the gene en coding flavanone 3-hydroxylase, in addition to the transcriptional reductio n of the genes for flavonoid biosynthesis at a later flowering stage. Altho ugh 'White Mind' contains little flavonoid, the position of the block on fl avonoid biosynthesis in 'White Mind' is not known. (C) 2000 Elsevier Scienc e B.V. All rights reserved.