Protoplast Technology in Genome Manipulation of Potato Through Somatic Cell Fusion

Abstract

Protoplast fusion has been developed as a method for plant breeding. Especially promising results in somatic genome manipulation through protoplast technology have been obtained with the plant families Brassicaceae, Rutaceae, and Solanaceae. The fusion of protoplasts derived from diverse origins generates a hybrid cell, where the protoplasm, organelles, and genetic material from both of the partner cells are combined. This fusion product is called a heterokaryon or a heterokaryocyte. The fusion of isolated protoplasts from somatic cells and regeneration of hybrid plants from the fusion products (somatic hybrids) allow combining of complete genomes of two desirable parents, irrespective of their taxonomic relationship. Usually, protoplast fusion can be classified as symmetric and asymmetric hybridization. Symmetric fusion incorporates the whole genomes of both parents, particularly nuclear ones, whereas asymmetric fusion allows partial genome transfer from a donor cell to a recipient. In asymmetric fusion, the donor cells are usually subjected to irradiation or ultraviolet treatment before fusion. In comparison to other techniques of chromosomal and genetic engineering, somatic genome hybridization has a unique potential to transfer simultaneously both nuclear and cytoplasmic genes. It overcomes gene segregation and enables the transfer of both mono- and polygenic traits among sexually incompatible species. The technique of cell fusion has already been applied to produce a large number of intergeneric, intertribal, or interfamily symmetric and asymmetric somatic hybrids by several research teams and private companies. Procedures for protoplast fusion of potato to produce symmetric somatic hybrids are included, along with detailed lists of materials and descriptions of techniques.