Selection of Fused Protoplasts - After the fusion treatment as above, the protoplast population consists of a mixture of parental types, homokaryons and heterokaryons, of which heterokaryons (potential source of future hybrids) often make only 0. 5%-10%. Efforts have been made to select the heterokaryons or the calli derived from them. Following methods have been used for selection:

(i) The hybrids Nicotiana glauca X N. longsdorfii could- grow on a medium (Nagata and Takebe, 1971), on which none of the parents could grow.