INDUCTION OF ANTHOCYANIN SYNTHESIS AND RELATED ENZYME-ACTIVITIES IN CELL-CULTURES OF CENTAUREA-CYANUS BY UV-LIGHT IRRADIATION

In cell suspension cultures of Centaurea cyanus, anthocyanin was synthesized by continuous ultraviolet (UV) and white light irradiation. The activities of three enzymes, phenylalanine ammonia-lyase (PAL) involved in general phenylpropanoid metabolism, chalcone synthase (CHS) and chalcone-flavanone isomerase (CHFI) related to flavonoid biosynthesis, were also induced and/or increased by light irradiation. After illumination, anthocyanin accumulation was initiated at 20 hr and reached a maximum at 72 hr. The activities of PAL and CHFI increased immediately, whereas CHS activity was induced with a lag time of 6 hr after light irradiation was started. The activities of three enzymes reached maxima prior to a maximum anthocyanin accumulation. Each maximum activity was recorded at 20 hr (PAL), 36 hr (CHS) and 40 hr (CHFI) respectively. The maximum activity of CHS was very low compared to the other two enzymes and PAL and CHFI activities were detected even in the dark. In the case of short period irradiation, anthocyanin accumulation closely correlated with CHS activity rather than PAL and CHFI activity. These results show that chalcone synthase has an important role in the regulation of anthocyanin synthesis in Centaurea cell cultures.