In vitro flowering and effective micropropagation protocol were studied in Swertia chirayita, an important medicinal plant using axillary bud explants. The Murashige and Skoog's medium (MS) supplemented with benzyl amino purine (BAP) 1.0 mg L−1 and adenine sulfate 70.0 mg L−1 was found optimum for production of multiple shoots. In the present study, incubation of flowering cultures on BAP supplemented medium (during shoot multiplication) was found necessary for flowering (6 weeks). However, concentrations of auxins-like IBA (0–2.0 mg/L) were ineffective to form reproductive buds. Subculture duration, photoperiod, and carbon source type do have influence on the in vitro flowering. The mature purple flowers were observed when the cultures were maintained in the same medium. This is the very first report that describes in vitro flowering system to overcome problems associated with flower growth and development as well as lay foundation for fruit and seed production in vitro in Swertia chirayita.

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Enhanced in vitro caulogenesis has been tested in Swertia chirayita on MS supplemented with BAP, IAA, IBA, NAA and additives like adenine sulfate and d-glutamine with 2.5% sucrose. The best in vitro caulogenesis was observed in MS fortified with 4.43 μM BAP in combination with IAA (0.8 μM) that resulted increase in shoot multiplication rate. The multiplication and elongation of shoots were further enhanced by the addition of adenine sulfate (0.007%) that resulted in the further increase in multiplication fold. The addition of adenine sulfate reduced the use of other cytokinins with different auxins reported in the previous studies on Swertia chirayita. The study suggests adenine sulfate as a primary assimilable reduced nitrogen source for enhancing the shoot multiplication and elongation in Swertia chirayita. RAPD markers were employed to check the genetic variation among the clonal stock that resulted in 97% similarity.

An efficient in vitro regeneration protocol for medicinally important herb

Six populations of Pinus gerardiana from the states of Himachal Pradesh representing the natural range of distribution were evaluated for genetic diversity using the RAPD markers. Fifteen random decamer primers, selected from thirty-five primers initially screened, were used to assess variation. A total of 149 amplified products were generated out of which 111 amplicons were polymorphic. All selected primers produced polymorphic amplification products, however, the extent of polymorphism varied with each primer. The value of similarity coefficient had a very narrow range from 0.53 to 0.67. The genetic distance varied from 0.32 to 0.44 between populations. The UPGMA dendrogram revealed the clustering of six populations of P. gerardiana in two clusters. First cluster consisted of four populations i.e. Lawrang, Respa, Speelo-1 and Speelo. The second cluster consisted of two populations i.e. Ampa and Kanam having a similarity coefficient of 0.66. The populations of the P. gerardiana showed high homogeneity and a very low amount of genetic divergence as evident by the very narrow range of the similarity coefficient and genetic distance. The average percent polymorphism is also very low in this species.