Genetic Transformation of Panax ginseng (C.A. Meyer) for Increased Production of Ginsenosides
Panax ginseng C.A. Meyer is a herbaceous plant belonging to the family Araliaceae. It grows wild in Eastern Asia and is cultivated in northern China, Korea, and Japan. The root has been used as a drug since ancient times, and various pharmacological effec
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1 Introduction Panax ginseng C.A. Meyer is a herbaceous plant belonging to the family Araliaceae. It grows wild in Eastern Asia and is cultivated in northern China, Korea, and Japan. The root has been used as a drug since ancient times, and various pharmacological effects have been ascribed to ginsenosides (triterpene saponins; Shibata et al. 1985; Yamamura et al. 1989); it has been used for instance, as an astringent and tonic, for antistress, anticancer, as an aphrodisiac, etc. However, the root is very expensive because field cultivation is laborious and requires a long period (5-7 years). This problem might be circumvented by the establishment of rapidly growing tissue cultures. Extensive studies have been conducted on various in vitro aspects of Pan ax species, and the literature reviewed (see Choi 1988; Shoyama et al. 1995). Many investigators have also examined the culture of Agrobacterium rhizogenes-transformed roots (hairy roots) as a means for the production of secondary metabolites (Saito et al. 1992; Sauerwein et al. 1992; see also Bajaj 1995). A key feature of hairy root culture is the high-level productivity of secondary metabolites because the roots can grow rapidly in defined hormonefree media without any decrease in the productivity of specific secondary metabolites, and the productivity is very stable in comparison with that in other tissue cultures supplemented with phytohormones (Hamill et al. 1987). Some investigators have studied the Agrobacterium rhizogenes-transformed roots of Panax ginseng so far (Table 1). This chapter deals with the Agrobacterium rhizogenes-transformed ginseng root (hairy root). The production of ginsenosides (Fig. 1) by the transformed root, and the application of the transformed root for the biotransformation of exogenous substrates are discussed.
lPharmaco Science Research Laboratories, Shiseido Research Center, 1050 Nippa-cho, Kohokuku, Yokohama 223, Japan
Biotechnology in Agriculture and Forestry, Vol. 38 Plant Protoplasts and Genetic Engineering VII (ed. by y'P.S. Bajaj) © Springer-Verlag Berlin Heidelberg 1996
Coculture
Coculture
Calli
A-4
A-4
Direct infection
Root and stem (I-year-old) Calli
ATCCI5834
31/32 days
20.1/30 days
Direct infection
Stem
A-4
6.2/3 weeks
Growth rate (fold/period)
Induced roots
Coculture
Direct infection
Root and stem (I-year-old) Calli
ATCCI5834
A-4
Method
Agrobacterium Plant rhizogenes material
Induction of transformed roots
Ginsenosides (0.36-0.95% dry wt.) Ginsenosides (0.47--0.82% dry wt.) Adenosine (0.0$-0.22% dry wt.) Guanosine (0.01--0.05% dry wt.) Ginsenosides (1.7-2.2% dry wt.) Glucoside of digitoxigenin (by bioconversion) Glucosides of phenylpro-pionic acid (by bioconversion)
Ginsenosides
Product
Table 1. Summary of the studies of A. rhizogenes-transformed roots of Panax ginseng
Inomata et al. (1993)
Yoshikawa and Furuya (1987) Ko et al. (1989)
Yokoyama et al. (1987)
Reference
Higher ability of giucosylation Kawaguchi et al. (1990) than any other cell cultures Higher ability of giucosylation Yo
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