Ngoc Linh ginseng (Panax vietnamensis Ha et Grushv.), an endemic medicinal plant of Vietnam, is restricted to a certain ecological area. In cell culture for biomass of gingseng production, the residual growth regulators might affect the safety of products and the health of users. Hairy roots that derive from using the in vitro techniques in combination with gene transfer techniques can resolve these problems. In this study, the authors investigated the effects of Agrobacterium concentrations (00600 = 0.3, 0.5, 0.7, 0.9), infection times (10, 20, 30 minutes and 16 hours), Acetosyringone concentrations (50, 100, 150 and 200 mM) and explant sources (leaves, stems, roots, callus, roots and embryos) to efficiency of gene transfer. Bacterial concentration for treatment with OD600 of 0.5 showed the highest temporary expression of Gus (59 percent) with longer infection time, the efficiency of gene transfer was higher but the vitality of transgenic explants was decreased, the duration of 20 mins was suitable for infection. Acetosyringone concentration of 100 mM was found to be better than others (Gus expression level was 61 percent)
Gus expression in various sources of explants was different, the highest level was found in callus while root explants were unsuitable for this study. Root samples proved unsuitable material in this study. After 8 weeks of culture on selective medium, the authors were recorded initially effective gene transfer with the formation of hairy roots from callus, thin cell layers ofrhizome, somatic embryo and stems.