Carotenoid accumulation confers distinct colouration to plant tissues, with effects on plant response to light and as well as health benefits for consumers of plant products. The carotenoid pathway is controlled by flux of metabolites, rate-limiting enzyme steps, feed-back inhibition, and the strength of sink organelles, the plastids, in the cell. In apple (Malus × domestica Borkh), fruit carot...

A key step in the biosynthesis of flavonoids is the hydroxylation of (2s)-flavanones in the 3 position to form the respective dihydroflavonols. The reaction is catalyzed by F30H, a soluble fraction enzyme requiring 2-oxoglutarate, oxygen, Fez+, and ascorbate for full activity (Heller and Forkmann, 1988). By using genetic mutants that lack F 3 0 H activity, cDNA clones have been identified that ...