Isolation and growth of protoplasts from cell suspensions of Pinus contorta dougl. ex loud.

Cell suspensions were initiated from embryo derived calli of Pinus contorta. Some of these cell lines could be maintained in culture for at least one year without reduced growth.A high yield of protoplasts was obtained from the cell suspensions. The protoplasts started to divide after two days and cell clusters could be observed after about two weeks. The growth phase of the cell suspensions was very important for the division of protoplasts. Only protoplasts isolated from suspensions in an actively dividing phase were able to divide with a high frequency and to give rise to cell clusters.