Effects of spermidine, proline and carbohydrate sources on somatic embryogenesis from main root transverse thin cell layers of Vietnamese ginseng (Panax vietnamensis Ha et. Grushv.)

Abstract

The in vitro main roots transverse thin cell layers of Vietnamese ginseng (Panax vietnamensis Ha et. Grushv.) were cultured on Murashige and Skoog (MS) medium supplemented with 1.0 mg.l^-1 2,4- dichlorophenoxyacetic acid (2,4-D), 0.2 mg.l^-1 kinetin and 0.5 mg.l^-1 naphthaleneacetic acid (NAA), 30 g.l^-1 sucrose and 8.5 g.l^-1 agar to establish embryogenic culture. The effects of exogenous spermidine and proline on enhancement of somatic embryogenesis was investigated. The results show that spermidine (0.1 mM) and proline (300 mg.l^-1) resulted in a high frequency of somatic embryogenesis (93.3% and 86.7%, respectively). To further optimize a culture medium for induction of embryo formation of P. vietnamensis, three carbohydrate sources (sucrose, glucose and fructose) at 10 to 60 g.l^-1 were tested. Among them, glucose and fructose were not suitable for somatic embryogenesis in this species while sucrose at 50 g.l^-1 produced the highest embryogenic frequency (86.7%) number of embryos per responding explant (167). This study confirmed the importance of spermidine, proline and osmotic potential provided by sucrose in enhancement of somatic embryogenesis.

Key words: Panax vietnamensis, somatic embryos, spermidine, proline, carbohydrate.