Glucosylation of flavonoids in petals of Petunia hybrida

During the biosynthesis of anthocyanins in Petunia hybrida, the 3-hydroxyl group is glucosylated. Their supposed biosynthetic precursors, the dihydroflavonols, are glucosylated at the 7 or 4′ positions. The question arose of whether these glucosides or the aglucones act as a substrate in anthocyanin...

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Bibliographic Details
Published in:Planta 1981-12, Vol.153 (5), p.459-461
Main Authors: Schram, A.W, Timmerman, A.W, Vlaming, P. de, Jonsson, L.M.V, Bennink, G.J.H
Format: Article
Language:English
Subjects:
anthocyanin
Biosynthesis
dihydroquercetin-glucosides
Evaporation
Flavonoids
Flowering
Flowers
Glucosides
Hydrolysis
Petals
Petunia hybrida
plant biochemistry
plant physiology
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Summary:During the biosynthesis of anthocyanins in Petunia hybrida, the 3-hydroxyl group is glucosylated. Their supposed biosynthetic precursors, the dihydroflavonols, are glucosylated at the 7 or 4′ positions. The question arose of whether these glucosides or the aglucones act as a substrate in anthocyanin synthesis. Using isolated flower buds of white flowering mutants that were blocked in an earlier step of biosynthesis, it was found that anthocyanin-3-glucosides and dihydroquercetin-7-glucoside were synthesized if dihydroquercetin, dihydroquercetin-7-glucoside, or dihydroquercetin-4′-glucoside were used as precursors in these experiments. Intracellular dihydroquercetin-glucosides were not used as a substrate for anthocyanin synthesis. The results are explained by deglucosylation of dihydroquercetin-glucosides during uptake by isolated flower limbs. Dihydroquercetin-7-glucoside, formed intracellularly, is not available as a precursor for anthocyanins. We conclude that the aglucone form of dihydroquercetin acts as a substrate in anthocyanin biosynthesis.
ISSN:0032-0935
1432-2048
DOI:10.1007/BF00394986