Induction of callus and somatic embryogenesis from cotyledon explants of Parkia biglobosa (Jacq.) Benth

To explore the potential for in vitro rapid regeneration of Parkia biglobosa , an endangered multipurpose woody angiosperm, cotyledon explants obtained from 7-day old aseptically germinated seedlings were cultured on Murashige and Skoog (MS) basal medium supplemented with 0.4-1.0 mg/L naphthalene acetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-D). Cotyledon explants were placed either with the abaxial surface facing up or down on the media. Induced calli were subcultured on media containing 0.8 mg/L Kinetin combined with different concentrations (0.2, 0.6 and 1.0 mg/L) of 2,4-D. Unlike in NAA, successful calli induction was observed in all concentrations of 2,4-D investigated. Callus production was only at the cut edges and on the abaxial surface of the explants. Induced calli turned friable, more nodular and with small protuberances on media containing 0.8 mg/L Kinetin combined with either 0.2 mg/L or 0.6 mg/L 2,4-D. The protuberances eventually developed into somatic embryos in an auxin-free suspension culture medium. The developed protocol established the potential to produce plantlets from cotyledon explants through somatic embryogenesis. It also offers itself as a highly efficient method for mass clonal propagation and conservation of P. biglobosa.