Applications of protoplast technology

Abstract Somatic hybridization of plants involves four discrete stages; protoplast isolation, protoplast fusion, the regeneration of plants from selected tissues, and analysis of regenerated plants. As virtually any combination of protoplasts can be induced to undergo fusion, somatic hybridization provides a means to circumvent sexual barriers to plant breeding. It not only provides a method for generating hybrids between sexually incompatible plants, but also facilitates the genetic modification of vegetatively propagated crops, sterile or subfertile species, and plants with naturally long life cycles. Fusion treatment results in the production of heterokaryons and homokaryons, while some protoplasts remain unfused. Heterokaryons are the fusion products relevant to plant genetic manipulation. They contain the nuclei of the two genera, species, or varieties, initially in a mixed cytoplasm. Heterokaryons may develop into hybrid cells. Like unfused plant cells, somatic hybrid cells are totipotent and are therefore capable of developing, via embryogenesis or organogenesis, into plants.