P. de Vlaming

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Petunia hybrida mutants, homozygous recessive for one of the genes An1, An2, An6, or An9 do not show anthocyanin synthesis in in vitro complementation experiments per se (see also Kho et al. 1977). Extracts of flowers of these mutants all provoke anthocyanin synthesis in isolated petals of an an3an3 mutant. Mutants homozygous recessive for one of the genes(More)
In Petunia hybrida four complementary genes are present, each having, if homozygous recessive a blueing effect on the flower colour. These genes have no qualitative or quantitative effect on anthocyanins and flavonols. In mutants homozygous recessive for one (or more) of the Ph genes the pH of aqueous flower limb homogenates is increased. It is assumed that(More)
An anthocyanin 5-O-glucosyltransferase from flowers of Petunia hybrida was purified about 30-fold. Using uridine 5′-diphosphoglucose as glucose donor (Km 0.22 mM), the enzyme glucosylated the 3-(p-coumaroyl)-rutinoside derivatives of delphinidin and petunidin (Km 3 μM), isolated from pollen of Petunia. Delphinidin 3-rutinoside, cyanidin 3-rutinoside and(More)
White flowers of the Petunia hybrida line W43 accumulate glucosides of 4-coumaric acid and caffeic acid and are able to synthesize anthocyanins from exogeneously supplied naringenin, suggesting that W43 is blocked in a biosynthetic step preceding the formation of naringenin. The cultivar Red Star contains a similar mutation as W43; the genetic background of(More)
In flower extracts of defined genotypes of Petunia hybrida, an enzyme activity was demonstrated which catalyses the hydroxylation of naringenin and dihydrokaempferol in the 3′-position. Similar to the flavonoid 3′-hydroxylases of other plants, the enzyme activity was found to be localized in the microsomal fraction and the reaction required NADPH as(More)
The genes An2, Rt and An1 are located in chromosome VI and closely linked. Pollination of the triple recessive line W127 (an2an2rtrtan1) with irradiated pollen of the triple dominant line M1 (An2An2RtRtAn1An1) led to the recovery of at least 3.3% induced an2 recessives. Karyotype analysis and genetic data showed that these mutants all contained a deletion(More)
Full coloured Petunia hybrida flowers lose their colour and become completely white if the gene Fa is dominant. This gene is only expressed in mutants with the pH gene Ph4 homozygous recessive. It is shown by genetical experiments that the fading is restricted to the 3-rutinosido(p-coumaroyl)-5glucoside glycosylation pattern of anthocyanins. The(More)
The relation between four methylation genes (Mt1, Mt2, Mf1 and Mf2) in flowers of Petunia hybrida and anthocyanin-methyltransferase activity was investigated in vitro. All genes controlled methyltransferase activity. This activity was measured with cyanidinnd petunidin-derivatives as substrates. A cross provided evidence that the Mf-genes regulate(More)
Chemogenetic investigations and precursor experiments on flowers of Petunia hybrida suggest that recessive alleles of the gene An3 block the biosynthetic pathway of flavonols and anthocyanins between the flavanone and dihydroflavonol step. In confirmation of this hypothesis, activity of the enzyme flavanone 3-hydroxylase, which catalyses the conversion of(More)
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(More)