Changes of Gentiopicroside Synthesis during Somatic Embryogenesis in Gentiana macrophylla

In vitro plant regeneration of Gentiana macrophylla Pall. and determination of gentiopicroside content during somatic embryogenesis are described in the present work. The highest percentage of embryogenic callus formation was observed in Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.0 mg/L 6-benzylaminopurine (BA). Calli were subcultured on MS medium containing 1.0 mg/L 2,4-D, 1.0 mg/L BA and 500 mg/L lactalbumin hydrolysate (LH) at intervals of 25 days. A higher frequency of somatic embryo maturation was achieved on MS medium containing 135 vitamins (MB) supplemented with different concentrations of 1-naphthaleneacetic acid (NAA) and BA than with a combination of NAA and kinetin (KT). Addition of AgNO3 improved maturation of somatic embryos while thidiazuron (TDZ) promoted vitrification. The gentiopicroside contents of embryogenic calli and globular-, heart-, torpedo-, and cotyledon-shaped embryoids were determined by high-performance liquid chromatography (HPLC). Gentiopicroside was not detectable in embryogenic calli, but in all types of somatic embryos. The highest gentiopicroside content was observed in cotyledon-shaped embryoids, reaching more than 12 mg/g dry weight.