cell cultures: Present and future aspects.

cell cultures have been used to produce plant secondary metabolites, as well as in biosynthetic studies. Shikonin, a representative secondary metabolite of , was first produced industrially by dedifferentiated cell cultures in the 1980s. This culture system has since been used in research on various plant secondary metabolites. Other boraginaceaeous plant species, including , , and , have been shown to produce shikonin, and studies have assessed shikonin regulation, including transgene expression, in these plants. This review summarizes current knowledge of shikonin production by cell and hairy root cultures, including the historical aspect of large-scale production, and discusses future biochemical and biological research using this species.