Flavonoid biosynthesis in pink-flowered cultivars derived from 'William Sim' carnation (Dianthus caryophyllus)

Analyses for anthocyanin concentration and flavonoid composition of flowers of two white, four light-pink, four deep-pink, and three red cultivars der ived from 'William Sim' carnation revealed that anthocyanin content increas ed from the light - pink - flowered cultivars, to the deep-pink-flowered cu ltivars, and to the red - flowered cultivars. Simultaneously, examination o f gene expression of enzymes involved in anthocyanin biosynthesis showed th at transcriptional levels of dihydroflavonol 4-reductase gene (DFR) and ant hocyanidin synthase gene (ANS) in the deep-pink-flowered cultivars were cor respondingly lower in the red-flowered cultivars, whereas those of ANS was much lower in the light - pink - flowered cultivars except in 'Lolyta'. In light - pink - flowered cultivars, transcripts of flavanone 3-hydroxylase g ene (F3H) in 'Lolyta' and ANS in 'Dusty' were undetectable on the Northern blots, but both transcripts were detected on reverse transcription - polyme rase chain reaction (RT-PCR). Low anthocyanin accumulation in pink-flowered cultivars seems to be regulated at different steps in anthocyanin biosynth esis.