Enhanced Somatic Embryogenesis and Viable Synthetic Seeds in Picrorhiza scrophulariiflora Pannell: A Conservation Milestone

A novel protocol for somatic embryogenesis has been established using callus derived from various explants of Picrorhiza scrophulariiflora, which is highly valued and endangered due to its medicinal significance and is indigenous to the Eastern Himalayas. A wide range of callusing (8.11-100%) from different explants were noticed in WPM supplemented with either 2, 4-D or NAA alone (0.1-2.0 mg/l). The incorporation of Kn and BAP, at various concentrations alongside different levels of NAA did not enhance callus formation. Out of which, only the friable callus upon transfer to WPM medium with cytokinins such as Kn or BAP (0.1–2.0 mg/l), could produce embryogenic callus which later by supplementation with ABA (0.1-1.0 mg/l) for 2 weeks, produced 92% matured somatic embryos. Furthermore, in a medium containing WPM with Kn (0.5 mg/l) and GA3 (0.5 mg/l), around 73% of the well matured somatic embryos of this species were germinated. However, leaf derived friable callus were, invariably, found to be superior in all aspects when compare with other explants. The encapsulated somatic embryos when stored at 4°C showed as high as 100% of germination when kept up to 15 days, which however, gradually decreased as the storage time increased and thus as high as 20% viability were recorded when kept for 105 days. Afterwards, plantlets derived from somatic embryos were successfully acclimatized and transplanted to the field. Random amplified polymorphic DNA analysis indicated the genetic uniformity of the donor plants, somatic embryo derived plantlets and the synthetic seed derived plantlets. This was the first report of somatic embryogenesis of this medicinally important genus.