Abstract:Protoplasts from mustard seedling cotyledons were suspended in Nitsch medium and cultured at 26℃ under low intensity illumination. When colonies were observed in the cultures, fresh medium (3% sucrose replaced mannitol) was added by equalvolume. When protoplasts developed into small callus the cultures were transfered to modified MS agar medium, in which some of them produced roots while an others gave rise to green spots. Shoot-differentiation experiment is in progress.