A liquid culture system for plantlet conversion and slow growth storage of encapsulated shoot tips of Justicia adhatoda L.

Abstract

The present article demonstrates the applicability of liquid medium in propagation and short-term storage of synthetic seed of Justicia adhatoda L., a medicinally important plant used in many ayurvedic drugs. Shoot tips and nodal segments excised from shoots regenerated on meta-topolin (mT) containing medium were encapsulated in 3% Na-alginate and 100 mM CaCl2.2 H2O for the preparation of artificial seeds. Irrespective of media composition, shoot tips performed better than nodal segments with respect to shoot emergence from alginate beads and further conversion into plantlets in a single step. Morphogenic responses of encapsulated shoot tips in liquid as well as on agar-solidified medium were evaluated and maximum plantlet conversion was observed on PGR-free MS liquid medium. Encapsulated shoot tips were stored for 60 days using slow-growth storage approaches which were induced by a reduction of sucrose concentration (1%) in the medium and reducing MS medium strength to half. After storage, more than 50% synthetic seeds were converted into plantlets when transferred to a regrowth medium. This slow-growth approach may be applied for the short-term storage of synthetic seeds for a reasonable period that is sufficient for the exchange of germplasm for distant places.