Preliminary Investigations on Agrobacterium-mediated Transformation of Somatic Embryos in Quercus variabilis

This study was conducted to establish a transformation system by using somatic embryogenesis in Quercus variabilis somatic embryos induced by immature zygotic embryos were used as transformation recipients. A strain of Agrobacterium tumefaciens(EHA105) harbouring a pCAMBIA1301 plasmid containing hpt II and β-glucuronidase(GUS) genes was used in the study. Several factors influencing genetic transformation were assayed. The results showed that the suitable antibiotic concentrations were 300 mg/L cephalosporin and 30 mg/L hygromycin. Transformation efficiencies were up to 91.7% with 15 days pre-culture time, to 100% with the concentrations of OD₆₀₀=0.5 A. tumefaciens and 200 μmol/L acetosyringone. After 4 weeks of selective culture in hygromycin-added medium, histochemical and PCR molecular analysis confirmed the presence of GUS reporter gene in the somatic embryos.