High-frequency somatic embryogenesis from small suspension-cultured clusters of cells of an interspecific hybrid of Oryza

Suspension cultures in which cell clusters were small and had a high capacity for somatic embryogenesis (about 60%) were established from immature panicles of F-1 plants from a cross between Oryza sativa and Oryza latifolia The cells were subcultured at seven-day intervals in a modified N6 medium. The cell clusters were quite small (approximately 30-200 mu m in diameter) after culture for two months in this medium. When small clusters of cells were transferred to N6 medium, that had been diluted with an equal volume of water and supplemented with alpha-naphthalenacetic acid (53 nM), 4-pyridylurea (2.2 mu M) and sucrose (30 g l(-1)), somatic embryogenesis occurred at high frequency (about 60%). The system established in the present work is useful for biochemical and molecular biological research of the somatic embryogenesis in the Gramineae.