Genetic control of flavone synthase II activity in flowers of Gerbera hybrids

In flower extracts of defined genotypes of Gerbera hybrids an enzyme activi ty was demonstrated which catalyses the introduction of a double bound betw een the C atoms 2 and 3 of the flavanones naringenin and eriodictyol. The p roducts formed were the corresponding flavones, apigenin and luteolin. Simi lar to flavone synthases II from other plant species, the enzyme activity o f this cytochrome P450-dependent monooxygenase was found to be localized in the microsomal fraction. The reaction required NADPH as cofactor and had a pH-optimum of about 7.5. Flavone synthase II activity was detectable only in flower extracts of genotypes with dominant wild-type alleles at the locu s Fns, but not in lines with recessive alleles (fns fns). The results estab lish for the first time a correlation between a gene and the enzyme activit y of flavone synthase II. (C) 1998 Published by Elsevier Science Ltd. All r ights reserved.