Somatic embryogenesis in cocoa (Theobroma cacao L.) and mulberry (Morus alba L.)

In woody species such as cocoa and mulberry, the development of somatic embryogenesis protocols constitutes a necessary and useful tool for the propagation, improvement and in vitro conservation of plant genetic resources. In the species Theobroma cacao, cotyledons and flower buds were used as explants. Experiments were performed for differentiation, maturation and conversion of somatic embryos to plants. A histological characterization of the somatic embryogenesis process was also carried out. Somatic embryos were obtained from staminoids in differentiation media with kinetin (9.32 mu M) and NAA (2.69 mu M) in the clone 'UF-613' and 'Pound-7'. These were observed in globular, heart-shaped, torpedo and cotyledonal stages. Somatic embryo maturation was achieved in DKW medium with 6% sucrose. The conversion rate of somatic embryos was 20.8% for 'UF-613' and 31.8% for 'Pound-7'. In Morus alba 'Acorazonada' different types of explants and culture media were evaluated to obtain callus and embryogenic structures. A 94% formation of embryogenic structures was achieved in calli from culture media with 4.54 mu M TDZ subcultured in cocoa differentiation media.