Genetic control of the conversion of dihydroflavonols into flavonols and anthocyanins in flowers of Petunia hybrida

Abstract

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 An1, An2, An6, or An9 and homozygous recessive for F1 accumulate dihydroflavonols in comparable amounts. The synthesis of dihydromyricetin is blocked in an1an1 mutants, which indicates a regulating effect of the gene An1 on the gene Hfl. Similar mutants, but dominant for F1, accumulate flavonols (kaempferol and quercetin) instead of dihydroflavonols. Myricetin is accumulated in minor amounts and not at all in an1an1 mutant. Furthermore, the synthesis of this flavonol is not controlled by the gene F1. The synthesis of cyanidin (derivatives) is greatly reduced when flavonols are synthesized (F1 dominant). In mutants dominant for Ht1 and Hf1 and thus able to synthesize cyanidin (derivatives) and delphinidin (derivatives), predominantly delphinidin (derivatives) are synthesized. The results indicate that kaempferol (derivatives), quercetin (derivatives), and delphinidin (derivatives) are the main endproducts of flavonoid biosynthesis in Petunia hybrida.

Selective Accumulation of Delphinidin Derivatives in Tobacco Using a Putative Flavonoid 3′,5′-Hydroxylase cDNA fromCampanula medium

“…In petunia, dihydromyricetin, a product of 3?,5?-hydroxylases, is the best substrate for DFR but a poor substrate for FLS. [22][23][24] Therefore, if this situation is comparable for tobacco in the same family as petunia, e‹cient 3?,5?-hydroxylation in Ka1-transgenic tobacco is likely to increase anthocyanins instead of ‰avonols. Similarly, the slight increase in the total anthocyanin contents in the AK14-transgenic tobacco can probably be attributed to poor 3?,5?-hydroxylation by the AK14 product.…”

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

“…Synthesis and isolation of ('4C)-dihydroquercetin 14 ( C)-Dlhydroquercetin was prepared by feeding '4C-labelled acetate to excised flowerbuds of the dihydroquercetin accumulating petunia mutant W78.25 buds were surface sterilized and dissected as described by KHO et al (31). The corollas were incubated in a petri dish (90• mm) with 10 ml petunia culture medium (31) 14 containing 1 mCi sodium (1-C)-acetate and 1 mCi sodium (2-'nC)-acetate.…”

A Research Strategy to Understand the Mechanisms that Govern Flower Color Pattern Formation

“…In such studies, we often observe the accumulation of compounds upstream of the inhibited step in the pigment biosynthetic pathway, so that the inhibited step is detectable based on the variation in composition (Gerates et al 1982). Among anthocyanin-related compounds, flavones, flavonol and cinnamic acid derivatives are contained in plant tissues as glycosides at similar levels to anthocyanins and their biosynthetic relationship is shown in Fig.…”