title: Genetic control of chalcone-flavanone isomerase activity in Callistephus chinensis.
abstract: A mutant blocked in anthocyanin synthesis leads to an accumulation of 4,2',4',6'-tetrahydroxy-chalcone-2'-glucoside (isosalipurposide) in blossoms of Callistephus chinesis (L.) Nees, whereas in geno-types with the wild-type allele, higher oxidized flavonoids and anthocyanins are synthesized. Measurements of chalcone-flavanone isomerase activity of 18 lines of Callistephus chinensis showed a clear correlation between accumulation of chalcone in the recessive genotypes (ch ch) and deficiency of this enzyme activity. Both the chemogenetic and the enzymologic evidence lead to the following conclusions: 1. The first product of the synthesis of the flavonoid skeleton should be tetrahydroxychalcone.-2. The chalcone-flavanone isomerase catalyzes the formation of flavanone from chalcone in a stereospecific way and there-with furnishes the substrate for the further reactions in the flavonoid biosynthesis.
authors.affiliation: Institut für Biologie II, Lehrstuhl für Genetik der Universität Tübingen, Auf der Morgenstelle 28, D-7400, Tübingen, Federal Republic of Germany.
authors.forename: B
authors.initials: B
authors.lastname: Kuhn
authors.forename: G
authors.initials: G
authors.lastname: Forkmann
authors.forename: W
authors.initials: W
authors.lastname: Seyffert