PULSE TREATMENTS OF PENICILLIN-G AND STREPTOMYCIN MINIMIZE INTERNAL INFECTIONS AND HAVE POST TREATMENT EFFECTS ON THE MORPHOGENESIS OF GINSENG ROOT CULTURE

This study was initiated to determine whether antibiotic pulse treatme nts (APT) could effectively eliminate internal. infections of ginseng (Panax ginseng) root explants containing vascular tissue, and subseque ntly have post-treatment effects on changing explant behaviors in call us induction and organogenesis or somatic embryogenesis. For contamina tion control, a treatment of 40 min with an antibiotic solution consis ting of 1000 mg/l of penicillin-G and 1000 mg/l of streptomycin immedi ately following Na-hypochlorite sterilisation significantly decreased contamination rate. Extending treatment time to 2-3 h further lowered the contamination rate to 30-40%. On the other hand, explants treated with antibiotics for 20 min or less were all contaminated. APT also ha d post-treatment effects; it delayed callus induction for 1-12 months depending on pulse duration and stimulated the generation of more hard and darker looking than fragile- and lighter looking callus. The indu ced callus proliferated at a depressed rate, increasing subculture int ervals from 1 to several weeks, and not until after five subcultures d id it fully recover. The regeneration ability of the recovered callus was also affected by APT: the regeneration of adventitious roots was p romoted, whereas somatic embryos were not observed.