REGENERATION OF CERATOZAMIA-EURYPHYLLIDIA (CYCADALES, GYMNOSPERMAE) PLANTS FROM EMBRYOGENIC LEAF CULTURES DERIVED FROM MATURE PHASE TREES

Embryogenic cultures were induced from pinnae removed from young leaf flushes of mature-phase trees of the endangered cycad species, Ceratoz amia euryphylidia. Induction media consisted of B5 major salts, Murash ige and Skoog minor salts and organics, 400 mg l(-1) glutamine, 100 mg l(-1) asparagine, 100 mg l(-1) arginine, 60 g l(-1) sucrose, 2 g l(-1 ) gellan gum, 4.65-13.94 mu M kinetin and 4.52-9.05 mu M 2,4-dichlorop henoxyacetic acid. Cultures were maintained in darkness. Embryogenic c ultures were comprised of precotyledonary somatic embryos that prolife rated by somatic polyembryogenesis following subculture onto medium wi thout plant growth regulators. Somatic embryo development and maturati on occurred spontaneously from proliferating cultures on medium withou t plant growth regulators. Somatic embryos were monocotyledonous and m ature somatic embryos germinated on semisolid medium without growth re gulators. Subsequent development, which included the elongation of the first leaves, occurred only after subculture onto semisolid medium wi thout plant growth regulators containing 0.5% (wt/vol) activated charc oal and under low light intensity. The time period from explanting to plant recovery was approximately 3 years.