Abstract: Unpollinated ovule-derived calli of a sugar beet (Beta vulgaris) line 1804/6 were subcultured for three months on a MS medium containing 1.0 mg/L 2,4-D, 0.5mg/L 6-BA. Good yield of protoplasts was obtained by treating calli with a mixture containing 2.0% cellulase Onozuka R-10, 0.05% Pectolyase Y-23, 0.5% snailase, 3mmol/L MES, 0.5% bovine serum albumin and 0.2% potassium dextransulfate prepared in CPW 9M. After purified by washing and centrifugation, protoplasts were cultured in a modified MS medium containing 0.5mg/L 2,4-D, 0.25mg/L 6-BA, 250mg/L casein hydrolysate, 200mg/L yeast extract, 10000mg/L sucrose, 90000mg/L glucose, and 0.3% agarose at a denisity of 4×104–1×105 /ml. Sequential divisions gave rise to the development of proembryo. By the eighth day many proembryo-like structures were easily seen, and they developed into globular embryos after 15 days and became core compact and turned into heart-shaped embryos in the following days. Phytohormone combination was one of the factors influencing the direct embryogenesis, and osmotic pressure might also play a role in this respect.

Key words: ugar beet, Protoplast, Direct embryogenesis