Protoplast Fusion Induced by Polyethylene Glycol (PEG)

Abstract

The fusion of protoplasts from different plants to form somatic hybrid cells and the subsequent regeneration of plants from the callus tissue produced from the proliferation of the fusion product was an extremely important achievement. The ultimate aim of this work is to produce hybrids which cannot be produced by normal sexual means. However, isolated protoplasts will not aggregate and fuse easily in the absence of an inducing agent. Several chemicals have been used successfully to induce fusion but the most successful and the one most widely used at the present time is polyethylene glycol (PEG). The effects of PEG are not specific and it will promote the aggregation and fusion of protoplasts from the same or different species. The process of aggregation and fusion can be best observed when the two protoplast populations are quite different in appearance, for example when one contains anthocyanin in the vacuole (some strains of Daucus carota cell cultures) and the other contains a number of green chloroplasts (Nicotiana tabacum mesophyll cells). Here the hybrid cells will contain both the visible markers and the process of mixing can be observed with ease.