An efficient in vitro propagation protocol for rapidly producing Cannabis sativa plantlets from young leaf tissue was developed. Using gas chromatography-flame ionization detection (GC‐FID), high THC yielding elite female clone of a drug-type Cannabis variety (MX) was screened and its vegetatively propagated clones were used for micropropagation. Calli were induced from leaf explant on Murashige and Skoog medium supplemented with different concentrations (0.5, 1.0, 1.5, and 2.0 µM) of indole- 3-acetic acid (IAA), indole- 3- butyric acid (IBA), naphthalene acetic acid (NAA), and 2,4-dichlorophenoxy–acetic acid (2,4-D) in combination with 1.0 µM of thidiazuron (TDZ) for the production of callus. The optimum callus growth and maintenance was in 0.5 µM NAA plus 1.0 µM TDZ. The two-month-old calli were subcultured to MS media containing different concentrations of cytokinins (BAP, KN, TDZ). The rate of shoot induction and proliferation was highest in 0.5 µM TDZ. Of the various auxins (IAA, IBA, and NAA) tested, regenerated shoots rooted best on half strength MS medium (1/2 – MS) supplemented with 2.5 µM IBA. The rooted plantlets were successfully established in soil and grown to maturity with no gross variations in morphology and cannabinoids content at a survival rate of 95 % in the indoor growroom.

Inter-simple sequence repeat (ISSR) markers were used to evaluate the genetic stability of the micropropagated plants of Cannabis sativa over 30 passages in culture and hardening in soil for 8 months. A total of 15 ISSR primers resulted in 115 distinct and reproducible bands. All the ISSR profiles from micropropagated plants were monomorphic and comparable to mother plants, confirming the genetic stability among clones and mother plants. Chemical analysis of cannabinoids, using gas chromatography/flame ionization detection (GC/FID), was done to further confirm whether the qualitative and quantitative differences in the major secondary metabolites exist between the mother plant and micropropagated plants. Six major cannabinoids – Δ ⁹-THC, THCV, CBD, CBC, CBG, and CBN – were identified and compared with the mother plant. Our results clearly showed a similar cannabinoid profile and insignificant differences in THC content between the two types of plants. These results suggest that the micropropagation protocol developed by us for rapid in vitro multiplication is appropriate and applicable for clonal mass propagation of C. sativa.