Modification of light quality improves the growth and medicinal quality of clonal plantlets derived from the herbal plant Gentiana

Abstract

Gentians are medicinal plants whose roots and rhizomes have been used as natural medicines for gastrointestinal problems. The active components are bitter compounds known as secoiridoid glycosides such as gentiopicrin and swertiamarin. Previously, procedures for the in vitro clonal culture of gentian plantlets were established. In this study, the effect of different wavelengths of light emitted by LED on plantlet growth and the concentrations of active components was investigated. We found that plantlet growth was promoted after irradiation with red light. Because a similar trend was observed in all gentian cultivars tested, the improved effect of red light on plantlet growth seemed to be a common characteristic of Gentiana species. We also found that both leaves and roots of the plantlets contained gentiopicrin and swertiamarin. Gentiana triflora ‘Maciry’ had the highest concentration of both compounds compared with several gentian lines and cultivars. Furthermore, the concentrations of roots were increased by far-red and blue light irradiation. These results suggest that modification of light quality by LED is an effective strategy for improving the growth and concentration of active components in gentian plantlets that can be used as a novel ingredient in natural medicine.