Regeneration of plants from tobacco protoplasts and some factors affecting the plant differentiation.

Protoplasts were isolated from the cell suspension culture derived from leaf and stem calli of tobacco (Nicotiana tabacum cv. Ko Hsin No. 1) haploid pollen-plants. After 12 hr in the liquid culture medium, the protoplasts became oval-shaped, and produced a new cell wall. The first division of the newly formed cells was completed after 24 hr in culture. After 4 weeks in culture, the yellowish calli reached 1 mm in size were then transferred to an auxophyton. 18 days later, the calli became 3-4 mm in size. After the calli were transferred to a differentiation culture medium, shoots and roots soon turned up. Regeneration of whole plants was obtained thereafter. The division and differentiation of regenerated cells were affected not only by the calli originated from different organs and their, age, but also by the basic components of the differentiation culture medium and the type of cytokinin used.