Plant regeneration from protoplasts of Gentiana by embedding protoplasts in gellan gum

A protoplast-to-plant system was developed in Gentiana using a gellan gum-embedding culture. Viable protoplasts could be routinely isolated from in vitro-grown plantlets, and they were embedded in 0.2% gellan gum-solidified B5 medium containing 2 mg l^-1 NAA, 0.1 mg l^-1 TDZ, 0.1 M sucrose and 0.4 M mannitol. Weekly addition of fresh liquid medium was essential for preventing cell browning. Colony growth was promoted by lowering mannitol concentration of the culture media after one month, and visible colonies were produced after 2 months of culture. Shoot regeneration from protoplast-derived calluses was stimulated by 1 to 10 mg l^-1 TDZ in combination with 0.1 mg l^-1 NAA. Protoplast-derived plants were recovered following rooting of the shoots in plant growth regulator-free medium and they were successfully transferred to soil.Abbreviations BA benzylaminopurine - FDA fluorescein diacetate - FW fresh weight - MES 2-N-morpholinoethane sulfonic acid - NAA -naphthaleneacetic acid - TDZ N-1,2,3-thiadiazol-5-yl-N-phenylurea (also called thidiazuron)