EFFICIENT CALLUS INDUCTION AND PLANT-REGENERATION VIA SOMATIC EMBRYOGENESIS FROM IMMATURE LEAF-DERIVED PROTOPLASTS OF GROUNDNUT (ARACHIS-HYPOGAEA L)

High yields of protoplasts were obtained from immature leaves of asept ically grown plants of Arachis hypogaea using an enzyme solution conta ining cellulase 2.0% (w/v) and Macerozyme 1.0% (w/v) in 0.6 M mannitol . Isolated protoplasts were cultured in Kao's medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP). The protoplasts started to divide after 3-5 days of culture. Sustaine d divisions resulted in mass production of cell colonies and mini call i in 4 weeks. After 4 weeks, protoplast colonies were transferred to t he Murashige and Skoog (MS) medium supplemented with a-naphthalene ace tic acid (NAA) and BAP. Colonies proliferated into actively growing ca lli. Further attempts to regenerate plants from such calli were not su ccessful. However, protoclones differentiated roots on the same medium . Alternative methods for plant regeneration from protoplast derived c allus cultures were tried through somatic embryogenesis. Protoplast-de rived calli treated with 2,4-D and BAP formed somatic embryos. Somatic embryogenesis began in the proembryo stage and proceeded from globula r to dicotyledonary stage. Embryos were then transferred onto hormone- free MS medium for germination. Five to ten percent of these embryoids germinated and grew to plantlets. Regenerated plants were transferred to plastic cups and grown to maturity.