Plant regeneration through somatic embryogenesis and shoot organogenesis from immature zygotic embryos of Sapium sebiferum Roxb.

•This is the first report of the plant regeneration from IZEs of S. sebiferium.•Mechanical damage significantly improved the primary SEs induction.•A 1.0 mg l −1 IAA was an optimal concentration for somatic embryogenesis.•The SEs at early contyledonary stage were suitable for SSEs induction.•Direct shoot organogenesis occurred best on MS medium with 1.0 mg l−1 6-BA.

Sapium sebiferium Roxb. is a highly valued ornamental plant species in tropical and subtropical regions. Here we present an efficient protocol for plant regeneration from immature zygotic embryos (IZEs) of S. sebiferium through direct somatic embryogenesis and shoot organogenesis for the first time. The results showed that mechanical damage, plant growth regulators (PGRs) and light regimes had great influence on in vitro morphogenesis. High frequency of somatic embryogenesis was obtained when the mechanical damaged IZEs were cultured on the Murashige and Skoog (MS) medium containing 1.0 mg l−1 indole-3-acetic acid (IAA) under continuous darkness for two weeks followed by a light/dark photoperiod cycle for four weeks. The induction frequency of somatic embryogenesis was up to 90.0%. Somatic embryos (SEs) at early cotyledonary stage showed highest proliferation frequency (81.7%) and 80.0% of secondary somatic embryos (SSEs) germinated on plant growth regulators (PGRs)-free MS medium. For direct shoot induction pathway, the best shoot regeneration rate (63.3%) was obtained on the medium supplemented with 1.0 mg l−1 6-benzyladenine (6-BA). The plantlets derived from two ways were successfully acclimatized in the greenhouse with more than 90% survival rate. This study will be beneficial for the rescue of immature embryo, inheritance of heterosis as well as the genetic improvement of S. sebiferium.