Establishment of hairy root lines and analysis of gentiopicroside in the medicinal plant Gentiana macrophylla

Abstract

The leaf explants from the eight-week-old Gentiana macrophylla Pall sterile seedlings were precultured for three days on Murashige and Skoog (MS) agar medium with 1 mg/l of 6-benzyladenine, and then incubated in MS liquid medium containing Agrobacterium rhizogenes R1000 for 2 h with shaking. After 10 days of culture on hormone-free MS agar medium with 500 mg/l cefotaxime under illumination of 300 μmol/(m2 s) with a 16-h photoperiod at 24°C, up to 18.3% of the infected explants produced typical hairy roots (HRs). Finally, three stable HR lines with no morphologically visible differences were obtained. The HR lines could vigorously grow and propagate on/in hormone-free half-strength MS solid/liquid medium. Moreover, they changed from white to green when moved from darkness to the light and spontaneously produced calli, which were able later to produce adventitious buds. PCR analysis revealed that three HR lines, which were undergone to continuous subculturing over two years, still contained the rolC gene from the A. rhizogenes Ri plasmid. HPLC revealed the HR line possessing a certain capacity of synthesizing gentiopicroside (0.11 mg/g dry wt).