Exogenous application of chitosan, a potent biotic elicitor enhances micropropagation efficiency of Cymbidium aloifolium (L.) Sw., an orchid of medicinal and horticultural importance

Cymbidium aloifolium (L.) Sw., an orchid renowned for its horticultural and medicinal importance. It is extensively exploited for its horticultural appeal and usage in traditional medicines. In vitro-raised plants of C. aloifolium were raised through seeds. Different media viz., Murashinge and Skoog (MS), Knudson (KC) and Mitra medium supplemented with different concentrations of chitosan (1-5 mg/l) were used for asymbiotic seed germination. The highest germination percentage of 96.04% was observed for the seeds grown in Mitra medium supplemented with 3 mg/l chitosan. Further, the growth and development of regenerants were found to be more pronounced in MS medium supplemented with 5 mg/l of chitosan wherein the highest average numbers of multiple shoots (41.7) and root s (24.1) were recorded. A prominent increase of 4.12-fold in multiple shoots, 2.88- fold in leaf number, 4.02- fold in leaf length, 2.64-fold in root number, 2.85- fold in root length and high acclimatizing ability (87%) were observed in the chitosan-treated regenerants of C. aloifolium. Mass scale propagation of C. aloifolium was obtained in MS medium supplemented with chitosan using axillary buds as secondary explants from the in vitro- raised plants. They were subjected to the assessment of clonal fidelity using 3 types of molecular markers viz., Start Codon Targeted polymorphism (SCoT), Directed Amplification of Minisatellite-region DNA (DAMD), and Inter-Simple Sequence Repeat (ISSR). The analysis unveiled high genetic monomorphism (86.87%) and low genetic polymorphism (13.13%) amongst the in vitro-raised plantlets. The present study enumerates an efficient utilization of chitosan as a potent bio stimulant that enhances the rate of seed germination and multiplication of shoots and roots with genetically stable plantlets.