Variation of chlorophyll and essential oils in photomixotrophic cell cultures of Coleonema album (Thunb.)

Callus cultures of Coleonema album were grown under different light regimes and in the presence of different concentrations of phytoeffectors and gelling agents. Both an increased photonic fluence and photoperiod stimulated the accumulation of chlorophyll (max 450 mg per kg wet weight) and of volatile monoterpenes. The application of different light sources showed that chlorophyll and terpene biosynthesis (max 130 mg per kg wet weight) were stably correlated during 11 subcultivations. Phytoeffector concentrations modulated some of the light effects: Formation of chlorophyll and aliphatic esters occurred in a broad range of phytoeffector conditions, while volatile terpenes were restricted to a narrow window. Increased concentrations of agar or gellan gum (≤12 g L^-1 decreased growth and increased concentrations of chlorophyll and volatiles. Photomixotrophic cells are discussed as an in vitro system to study the control of oligoisoprenoid formation in higher plants.