Requirements for efficient plantlet regeneration using cotyledonary nodal explants of purple coral tree (Erythrina fusca Lour.)

There are over hundred species in the genus Erythrina which are of practical importance in multiple ways. The requirements for Erythrina plantlet regeneration in vitro were rarely studied. Surface-sterilized seeds of purple coral tree (Erythrina fusca Lour.) exhibited a high germination rate (80%) in vitro. The cotyledonary nodes from the one-month-old purple coral tree seedlings grown in vitro were used as explants. About 70% of the cotyledonary nodal explants exhibited shoot regeneration when the explants were cultured vertically with the cut ends inserted into basal Murashige and Skoog (MS) medium compared to only 10% of those placed lying horizontally on the surface of the medium. Supplementation of the basal MS medium with 1 mg L−1 of BAP, 1 mg L−1 kinetin and 1 mg L−1 TDZ resulted in the greatest shoot elongation and the highest number of shoots developed from the cotyledonary nodal explants. The regenerated shoots were able to root (100%) on basal MS medium while supplementation with 2 mg L−1 of either NAA or IBA was inhibitory to root elongation. This is the first study on plantlet regeneration of purple coral tree which seems to have more complex requirements for shoot regeneration in vitro than those reported for the other three Erythrina species. Since only 30% of the rooted in vitro shoots survived during acclimatization following a previously published protocol for acclimatization of another plant, it is recommended that future studies are to investigate the requirements of higher plantlet survival for the rooted in vitro shoots of purple coral tree.