Normalization of asparagus somatic embryogenesis using a maltose-containing medium

Abstract

Summary Embryogenic calli derived from internal buds were cultured and maintained on Murashige and Skoog (MS) medium containing 2 mg/L 2,4-D, 3 % sucrose and 0.2 % gellan gum. Normal somatic embryos were induced from the embryogenic calli by pretreating with ½MS liquid medium for 7 days, sieving through 600 μm stainless steel mesh and then partially desiccating on plant growth regulator-free MS medium containing a high concentration of gellan gum (1.0% w/v) for 1 week. Furthermore, use of maltose as a sugar and/or osmoticum in the embryo induction medium promoted development of normal somatic embryos. Using these methods, non-vitrified bipolor embryos were induced 30 days after transfer (approximately 1,500 embryos per 0.1 mL packed cell volume). The somatic embryos induced on maltose-containing medium exhibited a much higher germination rate (more than 80 %) with cold treatment (14 days at 4 °C) than that induced on sucrose-containing medium.