Optimization of direct somatic embryogenesis from mature zygotic embryos of Panax ginseng C. A.!Meyer

Culture conditions were optimized for somatic embryogenesis of Panax ginseng. The highest frequency of embryo formation was obtained when tissues were excised from the middle region of the cotyledon segments of zygotic embryos. Only treatment with light could stimulate the formation of single-type somatic embryos, whereas multiple-type somatic embryos and calli were observed under dark conditions. The highest production of somatic embryos was found with an NH4+:NO3- ratio of 21:39. Among the tested media (MS, B5, and; SH), maximum formation of somatic embryos was obtained when cotyledon explants were cultured on an 1% agar MS medium supplemented with 5% sucrose. Regenerated ginseng plantlets were transferred to an autoclaved soil mixture in the greenhouse. These transformants showed no detectable variations in their morphology or growth characteristics compared with the donor plant.