Double phase culture system mediated enhanced protocol for shoot proliferation of Vanilla andamanica Rolfe. - an endemic wild relative of commercial Vanilla from the Andaman and Nicobar Islands

Abstract

A liquid overlay culture system in micropropagation improved shoot proliferation in many species. In the present investigation, we have developed an enhanced shoot proliferation protocol using the double phase culture system (DPS) for Vanilla andamanica, an endemic species of the Andaman and Nicobar Islands recognized under the vulnerable category by the IUCN. In vitro generated nodal explants were used for shoot proliferation experiments and were tested in Murashige and Skoog medium augmented with various cytokinins (BAP, KIN, 2iP) and auxins (IBA, NAA, IAA) to produce a maximum of 3.24 ± 0.08 shoots per explant in 5 µM BAP and 5.23±0.67 roots per shoot in basal MS medium. A remarkable increase in shoot regeneration was observed when the nodal explant was cultured on DPS system with optimum cytokinin (5 µM BAP). On evaluation of the influence of DPS and conventional single-phase systems (SPS), (solid medium) exhibits an improved multiplication rate on a DPS with optimal BAP (5µM) with an average of 8.66 ± 0.17 shoots per explant, which represents a 2-fold increase over the rate of SPS + 5 µM BAP. The plantlets were rooted at 100% frequency in half-strength MS medium devoid of auxins and acclimatized with 100% success. A double-phase mediated enhanced shoot proliferating procedure could be employed for large scale multiplication and commercial breeding trials for better results with regard to V. andamanica.