High-frequency in vitro propagation and assessment of genetic uniformity and micro-morphological characterization of Origanum majorana L. –A highly traded aromatic herb

Abstract

Origanum majorana (L.) (family Lamiaceae) is a multipurpose medicinal plant with high demand across the pharmaceutical, cosmetic, food, beverage, and perfume industries that has raised concern for its mass propagation through in vitro culture techniques. The present report describes an effective in vitro propagation system for an aromatic medicinal plant Origanum majorana L. The Murashige and Skoog's (MS) medium supplemented with 1.0 mg L-1 6-benzylaminopurine (BAP) initiated a maximum of 4.4 ± 0.22 micro-shoots from the nodal segment explants. The regenerated shoots were further proliferated (98.0 ± 0.22 shoots per explant/culture vessel) on MS medium augmented with 0.5 mg L-1 BAP and 0.25 mg L-1 α-naphthalene acetic acid (NAA). Individual shootlets were rooted on a half-strength MS medium with 1.0 mg L-1 indole-3 butyric acid (IBA) (4.8 ± 0.20 roots/shoots). The rooted plantlets were transplanted into eco-friendly paper cups containing soilrite®: manure; sand (2:1:1) and maintained in the greenhouse for hardening. Inter simple sequence repeats (ISSR) molecular markers were utilized to investigate the somaclonal variations between in vitro developed plants and the mother plant of O. majorana. The band patterns of regenerated plantlets have shown genetic uniformity with the donor plant. The foliar micro-morphological features under in vitro and ex vitro conditions were compared with the mother plant and elucidated morphologically stable plantlets development through gradual acclimatization. This is the foremost report on ISSR molecular marker-based genetic fidelity studies and foliar micro-morphological evaluation of micropropagated plants of O. majorana.