Somatic embryogenesis and plant regeneration from immature embryo cultures of onion (Allium cepa L.)

Somatic embryos were obtained and plants regenerated from immature embryos of onion following culture on embryogenic induction media. Highest rates of somatic embrogenesis resulted from 0.5- to 1.5-mm immature embryos cultured on media containing 5 mg/l of picloram. Somatic embryos formed either directly on the surface of embryos or developed from compact cultures. The production of somatic embryos was significantly affected by the addition of auxin, embryo size and cultivar. The potential of somatic embryogenic cultures for plantlet regeneration has been maintained for over 1 year in some lines. Three types of immature-embryo-derived cultures were characterized by histology. Some cultures were morphologically similar to immature-embryo-derived embryogenic cultures of other monocotyledonous species. Cultures such as these have proven to be useful target tissues in transformation studies.