In vitro propagation and conservation of Swertia bimaculata Hook.f. & Thoms.

Swertia bimaculata Hook.f. & Thoms., a less bitter species of the genus Swertia, is phytochemically important for its bioactive compounds (xanthones). Flower buds and immature capsules were collected from in vivo donor plants from South Sikkim during the month of September 2009. Three to five per cent (3-5%) seeds within the intact or split capsule germinated aseptically in full strength Murashige and Skoog’s (MS) medium with low concentration of either benzylaminopurine (BA; 2.22 μM) or kinetin (Kn; 2.32 μM). In vitro grown shoot tips were used as primary explants. Shoot multiplication was obtained on half-strength MS medium (BM) with 3% (w/v) sucrose and with different combinations and concentration of BA (2.22-4.44 μM), Kn (2.32-4.65 μM) and 1-napthalene acetic acid (NAA; 0.54 μM). However, the best response with 15.6 shoots per explants was obtained on BM with 2.22 μM BA, 2.32 μM Kn and 0.54 μM NAA. The number of shoots was further increased to 20.6 on addition of 10 mM KNO3 in the medium. About 100% healthy root induction on isolated shoots was achieved on BM devoid of any plant growth regulator (PGR) within 5 wk. Complete rooted plantlets were successfully hardened and transplanted in the soil with 80-90% survival rate. Meiotic study from flower buds of donor plants and mitotic chromosome study from regenerated plants revealed n=13 bivalents and 2n=26 chromosomes respectively. The protocol of in vitro propagation and chromosomal database developed for the first time in an unexplored S. bimaculata is highly efficient, repeatable and can be used for conservation of germplasm.