Direct somatic embryogenesis on leaf explants of Oncidium Gower Ramsey andsubsequent plant regeneration

Segments taken from young leaves of an orchid (Oncidium Cower Ramsey) produ ced clusters of somatic embryos directly from epidermal and mesophyll cells of leaf tips and wound surfaces without an intervening callus within 1 mon th when cultured on a Gelrite(TM)-gelled 1/2-MS basal medium supplemented w ith a low dosage (0.3-1 mg/l) of thidiazuron. Subculturing of these embryo clusters produced more embryos and subsequent plantlet formation on the sam e medium. The high-frequency embryogenesis of these leaf cells in this orch id is strong evidence of their totipotency, and further modification of the protocol for plant formation could be useful for the mass propagation and transformation of selected elite lines.