Encapsulation of nodal segments of Allamanda cathartica for short-term storage and germplasm exchange

Synthetic seed has the potential to be used as a cost-effective tool for propagation and storage of germplasm. In the present study, synthetic seeds were produced by encapsulating nodal segments of Allamanda cathartica in calcium alginate gel. The best gel complex was achieved using 3% sodium alginate and 100 mM calcium chloride (CaCl2·2H2O). Maximum conversion response of encapsulated nodal segments into plantlets was obtained on Murashige and Skoog (MS) medium with 3.0 μM meta-Topolin (mT) and 0.5 μM alpha-naphthalene acetic acid (NAA). Encapsulated nodal segments could be stored at low temperature (4 °C) up to 6 weeks with a survival frequency of 85%. The regenerated shoots rooted on half-strength MS medium containing 0.5 µM indole-3-butyric acid (IBA). Plantlets with adequate root and shoot systems were hardened off successfully with 90% success rate. Inter Simple Sequence Repeat (ISSR) markers were used to evaluate genetic stability among synthetic seed derived plantlets. The repeated high regeneration of plants from alginate-coated axillary buds and apparently good viability of the synseeds after four weeks of storage indicate that this is a viable strategy for the exchange of A. cathartica genetic resources. Synseed technology enhances the efforts of micropropagation and helps in the maintenance of rare, endangered and elite genotypes. Allamanda cathartica possesses high global market value due to the presence of phytoconstituent in leaves and roots of the plant. Plant has ornamental properties for its attractive funnel shaped yellow coloured flowers. Genetic stability of the regenerated plantlets were analyzed using PCR-based molecular markers.