Question

Fusion product of protoplasts of different plants is called

• A. Synkaryon
• B. Heterokaryon
• C. Parthenospore
• D. None of the above

Answer 1

Answer: (B)

Heterokaryon

In 1969, an altogether new approach was proposed to raise hybrids which could not be produced through the conventional methods of hybridization because of sexual incompatibility. This technique involves the fusion of isolated protoplasts. Since only somatic cell protoplasts have been employed for this purpose, the technique is described as parasexual hybridization. It involves three steps (i) Isolation of protoplast (ii) Fusion of isolated protoplasts (iii) culture of hybrid protoplasts to regenerate whole plants. Polyethylene glycol (PEG) is commonly used for fusion of protoplasts. PEG treatment brings about rapid aggregation of the protoplasts which is a prelude to fusion. Fusion may occur between two or more protoplasts. The fusion of two dissimilar protoplasts results in the formation of a heterokaryon. Upon culture, the nuclei in the heterokaryon may fuse to establish a true hybrid cell.