The effect of high pH and calcium on tobacco leaf protoplast fusion.

High frequencies of fusion were induced between isolated tobacco leaf protoplasts when they were incubated at 37 °C in the presence of 0.05 M CaCl2 in 0.4 m mannitol at pH 10.5. Subsequent to the fusion treatment the protoplasts were washed and cultured in a suitable medium and within two weeks, actively dividing cell colonies were observed. The fusion treatment had no irreversible, deleterious effects on the protoplasts.