Direct somatic embryogenesis on leaf explants of Oncidium Gower Ramsey and subsequent plant regeneration.

Segments taken from young leaves of an orchid (Oncidium Gower Ramsey) produced clusters of somatic embryos directly from epidermal and mesophyll cells of leaf tips and wound surfaces without an intervening callus within 1 month when cultured on a GelriteTM-gelled 1/2-MS basal medium supplemented with a low dosage (0.3-1 mg/l) of thidiazuron. Subculturing of these embryo clusters produced more embryos and subsequent plantlet formation on the same medium. The high-frequency embryogenesis of these leaf cells in this orchid 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.