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1	Author	K. Stich, T. Eidenberger, F. W. Urst, G. Forkm	Requires cookie*
	Title	Flavonol Synthase Activity and the Regulation of Flavonol and Anthocyanin Biosynthesis during Flower Development in Dianthus caryophyllus L. (Carnation)
	Abstract	Flavonol synthase (FLS) was demonstrated in crude extracts from flower buds o f Dianthus caryophyllus (carnation). The enzyme catalyzed the conversion o f dihydrokaempferol and dihydroquercetin to kaempferol and quercetin, respectively. The reaction required 2-oxoglutarate, ferrous ion and ascorbate as co-factors and had a pH optimum at about 7.4. The demonstration o f FLS activity allowed comparative studies on flavonol and anthocyanin biosynthesis during bud and flower developm ent. Besides FLS the flavonoid enzymes chal cone synthase (CHS), flavanone 3-hydroxylase (FH T) and dihydroflavonol 4-reductase (D F R) were measured. D F R is specifically involved in anthocyanin synthesis, while CHS and FHT provide dihydroflavonol, the com m on substrate for both FLS and D F R . Maximum ex pression o f CHS, FHT and FLS activity was already observed in small buds, whereas D FR activity started to increase much later and reached its highest level in opened flowers. A sub stantial correlation was observed between the time courses o f FLS and D F R activity and the accumulation o f flavonols and anthocyanins, respectively. The com petition o f FLS and D F R for dihydroflavonols was found to be largely circumvented by different substrate specificities and by the sequential expression o f the two enzymes. Both flavonols and anthocyanins are obviously not, or only to some extent, subject to degradation.
	Reference	Z. Naturforsch. 47c, 553 (1992); received February 17/April 21 1992
	Published	1992
	Keywords	Anthocyanins, Flavonoid Enzymes, Flavonols, Flower D evelopm ent, Dianthus caryophyllus
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	TEI-XML for	default:Reihe_C/47/ZNC-1992-47c-0553.pdf
	Identifier	ZNC-1992-47c-0553
	Volume	47