Carlsberg Research Communications

, 49:503

Biosynthesis of proanthocyanidins in barley: Genetic control of the conversion of dihydroquercetin to catechin and procyanidins

Authors

  • Klaus Nyegaard Kristiansen
    • Department of PhysiologyCarlsberg Laboratory
    • Institute of GeneticsUniversity of Copenhagen
Article

DOI: 10.1007/BF02907552

Cite this article as:
Kristiansen, K.N. Carlsberg Res. Commun. (1984) 49: 503. doi:10.1007/BF02907552

Abstract

The conversion of dihydroquercetin to catechin and procyanidin was studied in maturing wild type barley (Hordeum vulgare L., cv. Nordal) seeds and proanthocyanidin free mutants blocked in four different genes,ant 13, ant 17, ant 18 andant 19. In the wild type barley grown under controlled conditions, maximal rate of synthesis of catechin, procyanidin B3 and procyanidin C2 occurred 8–16 days after flowering. Dihydroquercetin was radioactively labelled by feeding (1-14C)-acetate and (2-14C)-acetate to flowerbuds of a petunia mutant accumulating this flavonoid. When fed to pericarp-testa tissue of wild type barley labelled catechin, procyanidin B3 and procyanidin C2 were synthesized establishing dihydroquercetin as a precursor of these compounds. In addition labelled 2,3-trans-3,4-cis-leucocyanidin was synthesized indicating that this compound is an intermediate. The leucocyanidin was identified by co-chromatography with an authentic standard prepared chemically by reduction of dihydroquercetin with NaBH4. The major product of this reduction, however, was the 2,3-trans-3,4-trans-leucocyanidin. Only mutantant 18-102 accumulated dihydroquercetin in the seeds. Feeding (14C)-dihydroquercetin to pericarp-testa tissue from the mutants revealed thatant 17-139 was capable of synthesizing significant amounts of labelled catechin and procyanidin, whereasant 13-101,ant 13-152,ant 18-102 andant 19-109 synthesized none or only very small amounts of these compounds. It is concluded that (i)ant 18 controls the reduction of dihydroquercetin to 2,3-trans-3,4-cis-leucocyanidin, (ii)ant 19 controls the reduction of the leucocyanidin to catechin, and (iii)ant 13 andant 17 control unidentified steps prior to dihydroquercetin.

Keywords

Flavonoid biosynthesis leucocyanidin isomers ant mutants genetic control high pressure liquid chromatography 1H NMR mass spectroscopy

Abbreviations

BAW

n-butanol-acetic acid-water

BW

n-butanol-water

CAW

chloroform-acetic acid-water

H NMR

proton nuclear magnetic resonance

HOAc

acetic acid

HPLC

high pressure liquid chromatography

MS

massspectroscopy

sBAWC

s-butanol-acetic acid-water-chloroform

3,4-cis-diol

(2R,3S,4S)-3,4,5,7,3′,4′-hexahydroxyflavan

3,4-trans-diol

(2R,3S,4R)-3,4,5,7,3′,4′-hexahydroxyflavan

TLC

thin layer chromatography

UV

ultra violet

WsB

water saturated s-butanol

Copyright information

© Carlsberg Laboratory 1984