Anthocyanin Formation in the Petals of Hibiscus mutabilis L

Lehrstuhl für Pflanzenphysiologie, Ruhr-Universität Bochum, D-4630 Bochum. Bundesrepublik Deutschland Z. Naturforsch. 44c, 357—360 (1989); received January 9, 1989 Dedicated to Professor Achim Trebst on the occasion o f his 60th birthday Anthocyanin, L-a-Aminooxy-ß-phenylpropionic Acid, Phenylalanine Ammonia-Lyase, Hibiscus mutabilis When opening in the morning flowers of Hibiscus mutabilis L. appear white or ivory. The flower colour changes to red by late afternoon due to the accumulation of the anthocyanin cyanidin-3-sambubioside. At the onset, and during the rapid phase of pigment accumulation, phenylalanine ammonia-lyase (PAL) activity in the petals increases rapidly to seven times its initial level and then decreases while the flower senesces. In excised petals, the PAL inhibitor L-aaminooxy-ß-phenylpropionic acid (AOPP) suppresses pigment formation and causes the accumu­ lation of phenylalanine. Anthocyanin synthesis depends, therefore, on the de novo production of cinnamic acid.