En-masse production of elite clones of Dendrobium crepidatum: A threatened, medicinal orchid used in Traditional Chinese Medicine (TCM)

Orchids are one of the promising medicinal plant families of which Dendrobium crepidatum. Lindl & Paxton figures out prominently because of its multi directional medicinal attributes. In the present report, in vitro regeneration protocol has been developed from the nodal segments of D. crepidatum, to cater sustainable commercial exploitation and conservation needs. Thidiazuron (TDZ) at 3 mg/l singly resulted in the response frequency of 55% which could be increased to 97% by incorporating NAA at 0.5 mg/l and TDZ at 2 mg/l in combination in the medium. Shoot induction rate was further enhanced with the use of polyamines and at 0.8 mM putrescine along with 2 mg/l TDZ and 0.5 mg/l NAA in the medium 11.8 shoots/explant could be obtained. Highest rooting frequency of the shoots was achieved in medium containing 2 mg/l IBA. Genetic stability of the acclimatized plants was assessed using Start Codon Targeted (SCoT) polymorphism and inters simple sequence repeats (ISSR). SCoT revealed a total variability of 10% within the micropropagated plants whereas the cumulative ISSR and SCoT data revealed 6.25% clonal variability indicating high genetic fidelity amongst the regenerates. A comprehensive higher yield of the secondary metabolites along with significant higher antioxidant potentials as compared to the mother plant was revealed using DPPH and FRAP assays. An increased regeneration frequency with a comparative higher yield of secondary metabolite and genetic stability reported in the present communication ensure the ingenuity of this clonal propagation protocol developed for D. crepidatum which can be further utilized in the sustainable commercial utilization and conservation of other medicinally important orchid species.