ORGANOGENESIS FROM MATURE PECAN COTYLEDONS AND EMBRYONIC AXES

The regenerative capacity of mature pecan [Carya illinoinensis (Wangen h.) K. Koch] embryonic tissues was demonstrated after pretreating matu re nuts to eliminate associated endogenous contaminants. Cultured coty ledon segments were induced to form adventitious roots in a medium wit h 50 muM NAA. A regeneration medium with 20 mum BA and 5 muM IBA stimu lated prolific axillary shoot production from the embryonic axis witho ut causing cotyledon abscission. Cotyledon retention was essential for shoot initiation and long-term development. Eighty-five percent of th e shoots emerging from embryonic axes formed at the cotyledonary nodes . Thirty percent of the microshoots rooted on an auxin-free medium aft er preculture in a medium with 20 muM IBA. TDZ (25 muM) stimulated cal lus production from the cotyledonary nodes and radicles. Adventitious buds emerged on the callus surface and internally in callus. Chemical names used: alpha-naphthaleneacetic acid (NAA); 6-benzylaminopurine (B A); indole-3-butyric acid (IBA); N-phenyl-N'-1,2,3-thidiazol-5-ylurea (TDZ).