Genetic clonal fidelity assessment of rhizome-derived micropropagated Acorus calamus L. – A medicinally important plant by random amplified polymorphic DNA and inter-simple sequence repeat markers

Background: Acorus calamus – a critical medicinal plant, is overexploited, leading to population reduction. Establishing an efficient in vitro protocol is essential for the large-scale production of genetically identical plants. Objectives: Development of fast and reliable in vitro regeneration protocol for A. calamus and clonal fidelity assessment of the regenerants using molecular markers. Materials and Methods: Plants were regenerated on Murashige and Skoog medium with different concentrations of growth regulators in two phases – shooting and rooting. Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were employed to evaluate the genetic stability of in vitro clones. Results: 6 Benzylaminopurine (BAP) at 1.6 and 2.4 mgL⁻¹ was effective for shoot induction, while root induction was superior in indole-3-butyric acid-incorporated medium at 2.5 mgL⁻. Thirteen RAPD and 16 ISSR primers produced 59 and 96 clear, unambiguous, and reproducible bands, respectively. Both the markers revealed a high monomorphism of 96.79% and 95.63% among the regenerants. Nei's genetic distance analysis disclosed a close genetic association (0.000–0.068) among the genotypes. Conclusion: ISSR was better than RAPD markers in clonal fidelity assessment of the regenerants. The in vitro protocol developed is reliable and suitable for the rapid propagation of true-to-type A. calamus plants.