SOMATIC EMBRYOGENESIS AND ORGANOGENESIS INDUCED ON THE IMMATURE ZYGOTIC EMBRYO OF SUNFLOWER (HELIANTHUS-ANNUUS L) CULTIVATED IN-VITRO - ROLE OF THE SUGAR

Immature zygotic embryos of sunflower constitute an experimental syste m where the change of a single key factor (sucrose concentration) cond itions the in vitro morphogenesis to either organogenesis (87 mM sucro se) or somatic embryogenesis (350 mM sucrose). Experiments with a vari ety 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 embr yogenesis, but not organogenesis, to occur. The nature of the sugar us ed, though, was less important.