Phytochemistry Vol. 49, No. 7, pp. 1929-1934, 1998

Plasmid constructions containing rolA, rolB and rolC genes, isolated earlier from the TL-DNA of Agrobacterium rhizogenes were used to transform a cell culture (strain 1c) of Panax ginseng. The levels of ginsenosides were measured in the resulting transgenic tissues to evaluate the possible role of rol genes in ginsenoside formation. The ginsenoside content of the hairy root culture of P. ginseng, transformed by wild type A4 plasmid DNA and containing all rol loci, was higher than that of the control 1c culture (5.12-8.92 mg g.1 dry wt), being in the range of 13.23-21.27 mg g.1 dry wt. Ginseng tissue, transgenic for the rolA gene appeared to lose the ability to synthesize ginsenosides since only a trace amount of Re ginse- noside was found in 1c-rolA tissue. 1c-rolB cultures contained at least five times lower ginsenoside levels compared to the initial 1c culture. The ginsenoside content of rolC transgenic roots was about three times higher than that of the respective control. Taking into account the di.erences in cell di.erentiation levels in tissues transformed by rol genes, we compared the ginsenoside levels in rolC roots and tumours. It was found that ginsenoside production in tissues with di.erent levels of di.erentiation is nearly the same. We have concluded that the plant oncogene rolC is responsible for increased ginsenoside formation in ginseng hairy root cultures.