Protoplast fusion

Abstract

When protoplasts are isolated the only barrier between the cytoplasm and the external environment is the plasma membrane. The lack of the cell wall allows the plasma membrane of two or more protoplasts to come into intimate contact, something which is not possible under normal circumstances. When two protoplast plasma membranes come into contact, under certain conditions they will stick together rather like two soap bubbles. Later, again like two soap bubbles, if given on appropriate stimulus they will fuse together forming a single sphere surrounded by a single membrane [1,2]. Whilst studying mechanically isolated protoplasts, Kuster [3] was able to see occasional spontaneous fusion. However, with the development of enzymic methods for producing large numbers of isolated protoplasts great interest has now developed in the use of protoplast fusion (hybridization) as a possible plant breeding tool. Although positive results in this area leading to agronomically improved plants have been very scarce many people still believe that protoplast fusion offers a useful tool to plant breeders to make crosses between sexually incompatible species for transfer of nuclear or cytoplasmic characters. Protoplant fusion can be used to make crosses within species (intraspecific), between species (interspecific), within genera (intrageneric) and between genera (intergeneric).