Effect of seaweeds extract and plant growth regulators on high-frequency in vitro regeneration and ex-vitro rooting of Ceropegia maculata Bedd.: an endemic species of Southern Western Ghats

Indirect organogenesis system was used to develop a successful protocol for in vitro plant regeneration of Ceropegia maculata. Organogenesis was attained through callus derived from internode and leaf explants of 6 months old mature plants. Organogenic callus were induced from internode and leaf explants on MS medium fortified with 2,4-D at 0.5 mg L−1 (97.0%) and 0.7 mg L−1 (93.3%), respectively. Callus proliferation was achieved on 0.5 mg L−1 2,4-D with 0.5 mg L−1 NAA combination from both the explants. Adventitious shoot regeneration from callus was attained on MS medium augmented with TDZ 0.5 mg L−1 from internode and leaf derived callus (92.6% and 92.3%), respectively. In vitro rooting was observed on medium fortified with IBA 0.5 mg L−1 (5.93 shoot per roots). Callus derived shoots (about 4 cm) shifted to MS medium augmented with different concentration (10–30%) of Ulva lactuca, Caulerpa scalpelliformis and Sargassum wightii seaweed extracts, produced maximum shoot elongation (14.56 cm in length and 12.26 cm in length) from both internode and leaf explant derived shoots. Prolific rooting (7.33 root per shoot) was observed on the medium augmented with 20% S. wightii extract. Ex vitro rooting on in vitro derived shoots with IBA 100 mg L−1 produced maximum number of roots (10.36) and root length (7.33 cm) and grew normally. All the plantlets were successfully hardened and acclimatized upon transferred to the greenhouse condition, with the survival rate of 95%. This in vitro plant regeneration protocol can be used for mass vegetative propagation, conservation, plant genetic transformation, and gene function investigations in C. maculata.