Plant regeneration from cell suspension-derived protoplasts of Populus x beijingensis

A protocol for plant regeneration from cell suspension-derived protoplasts of Populus x beijingensis is described. Protoplasts were isolated from cell suspension cultures 6 d after subculture and further cultured in liquid NH4NO3-free Murashige and Skoog (MS) medium supplemented with 0.6 M glucose, 9.05 mu M 2,4-dichlorophenoxyacetic acid, and 0.89 mu M 6-benzyladenine at a density of 2 x 10(5) protoplasts per milliliter. The initial plating efficiency and final plating efficiency recorded after 10 and 30 d reached 33.7 and 1.07%, respectively. The proliferated calli transferred to regeneration medium supplemented with 2.22 mu M 6-benzyladenine and 0.54 mu M alpha-naphthaleneacetic acid gave the highest rate of shoot formation (44.4%). All protoplast-derived shoots were able to form roots on half-strength MS medium supplemented with 2.46 mu M indole-3-butyric acid.