SOMATIC EMBRYOGENESIS AND PLANT-REGENERATION OF NEEM (AZADIRACHTA-INDICA JUSS,A.)

Somatic embryos were initiated with mature seeds of neem (Azadirachta indica A. Juss.) when cultured on Murashige and Skoog's medium supplem ented with thidiazuron (TDZ). Regeneration occurred via somatic embryo genesis: direct embryo formation and through an intermediary callus ph ase. TDZ was very effective and induced somatic embryogenesis across a wide range of concentrations (1-50 mu M). However, somatic embryogene sis was accompanied by callus formation at concentrations of 20 mu M a nd above. Cell suspension cultures were established with the TDZ-induc ed callus and groups of large cell clumps were formed within 2-3 weeks . Plants were regenerated from both directly formed somatic embryos an d somatic embryos derived from cell suspensions plated on semisolid me dium devoid of growth regulators. Regenerated plantlets continued to g row after transfer to a greenhouse environment and were similar phenot ypically to zygotic seedlings. This simple regeneration system may be beneficial for mass propagation of selected elite clones of neem.