An Efficient Plant Regeneration Using Leaf Explant for Osbeckia octandra (L.) DC; A Valuable Medicinal and Ornamental Plant

Abstract

Osbeckia octandra (Heen Bovitiya), which is one of the most valuable ayurvedic medicinal and ornamental plants in Sri Lanka is now threatened due to overexploitation in its natural habitat. In order to preserve this economically important plant species, a highly efficient in vitro clonal propagation system using leaf explants was developed in this study. The effects of three different concentrations of plant growth regulators: (6-benzylaminopurine (BAP), 1-naphthaleneacetic acid (NAA) and kinetin) and incubation conditions on plant regeneration were investigated. The plant growth parameters were analyzed in 15 biological replicates using one- way or two-way ANOVA. The present study revealed that the highest number of shoots per leaf explant with 92.4% shoot induction rate was achieved when young mature leaf explants were inoculated on Murashige and Skoog (MS) medium supplemented with 3 mg/L BAP and 0.5 mg/L NAA under dark conditions. When micro shoots were separated and subcultured on hormone-free MS medium with high sugar content (4%), shoots multiplied rapidly and a vigorous root system was developed under light conditions. The in vitro grown plantlets were successfully acclimatized and 89% of the regenerated plantlets survived. Our novel clonal propagation system will open new avenues for large- scale multiplication and improvement of medicinal and ornamental characteristics of this valuable species using biotechnological tools.