DIRECT SOMATIC EMBRYOGENESIS AND REGENERATION OF PLANTS FROM SEEDLING EXPLANTS OF PEANUT (ARACHIS-HYPOGAEA) - PROMOTIVE ROLE OF THIDIAZURON

An efficient procedure has been developed for inducing direct somatic embryogenesis, organogenesis, and regeneration of plants from tissue cultures of peanut (Arachis hypogaea L.). Thin transverse sections of the cotyledons and juvenile leaves were cultured on Murashige and Skoog medium supplemented with N6-benzylaminopurine (BAP) or a substituted phenylurea, thidiazuron (TDZ). Somatic embryos or shoot buds differentiated from cut surfaces of the cotyledons and midrib region of the leaves. The application of BAP induced differentiation of shoot buds whereas the treatment with TDZ resulted in the production of somatic embryos. Somatic embryos developed into plants after subculturing on a basal medium. Agar-solidified medium was found to be superior to the liquid medium for the development of embryos and shoot buds. The procedure of TDZ-induced somatic embryogenesis and plant regeneration was successfully applied to three genotypes of peanut. A distinct feature of this study is the induction of the morphogenic competence in cultures of seedling explants of peanut that so far have remained recalcitrant to somatic embryogenesis in vitro.