Somatic embryogenesis of Panax ginseng in liquid cultures: a role for polyamines and their metabolic pathways

A callus with embryogenic capacity was generated from root sections of Pana x ginseng and used as an inoculum source for embryogenic liquid cultures in a three-step process: - a suspension culture of cell aggregates in the pre sence of an auxin/cytokinin mixture, - an induction medium containing auxin only (for 5 to 30 days), - a regeneration medium containing cytokinin only (for one month). Up to 25 embryos were recovered per 2.5 g of aggregates i n these conditions. Incorporation of polyamines or their precursors arginin e and ornithine into either the induction or regeneration media increased t he number of embryos produced by up to 4 times. Inhibitors of both biosynth esis and biodegradation of polyamines reduced the number of embryos. These results support earlier findings of the role of polyamines in the process o f somatic embryogenesis. The success of these liquid cultures opens up the possibility of producing somatic embryos of Panax ginseng in bioreactors.