Somatic embryogenesis and organogenesis induced on the immature zygotic embryo of sunflower (Helianthus annum L.) cultivated in vitro: role of the sugar

Summary Immature zygotic embryos of sunflower constitute an experimental system where the change of a single key factor (sucrose concentration) conditions the in vitro morphogenesis to either organogenesis (87 mM sucrose) or somatic embryogenesis (350 mM sucrose). Experiments with a variety of culture media differing in the sugar type and concentration, as well as osmotic pressure, indicate that a minimal threshold level of both, sugar supply and osmotic pressure, are required for somatic embryogenesis, but not organogenesis, to occur. The nature of the sugar used, though, was less important.Abbreviations IZE immature zygotic embryo