Histological investigation of the plant regeneration process in onion (Allium cepa L.) Calli

The plant regeneration process in onion (Allium cepa L.) calli was investigated histologically. In the plant regeneration process from the calli, embryo-like structures formed on the surface of the calli, that developed into plantlets. Several developmental stages of these embryo-like structures were recorded histologically. These embryo-like structures progressed from a globular embryo to a bipolar embryonic shoot and root apices which were connected with vascular bundles. On the other hand, the shoot-like structures, having abnormal, hyperhydrated appearance, seemingly formed via organogenesis. However, these shoot-like structures did not develop into shoots or plantlets. Therefore, it was concluded that the regeneration of the plantlets occurred through somatic embryogenesis.