Fig. 2.

Protoplast fusion. a Fungal cell walls are digested with cell wall degrading enzymes, exposing protoplasts (b). c Polyethylene glycol (PEG) facilitates fusion of protoplasts, which may belong to different strains or species, as represented by red or blue chromosomes. d Fused protoplasts form heterokaryons and may progress partway or completely through the parasexual cycle, resulting in diploid or recombined haploid hybrids. e Applications of fungal heterokaryons or hybrids resulting from protoplast fusion include genetic analyses, fermentation, pharmaceutical production, bioremediation, and biocontrol