Use of Protoplasts on Plant Breeding: Cytoplasmic Aspects

Somatic hybridization has renewed the interest for cytoplasmic genetics in higher plants by offering the possibility of manipulating chloroplast and mitochondrial genomes (reviewed by galun and Aviv, 1986; Pelletier, 1986). Moreover, these manipulations may have a direct application in plant breeding. In this perspective we shall try to discuss three main questions which could be asked by breeders to cell biologists, using examples chosen in the Nicotiana and Brassica genera. These questions are: 1) is it possible to increase the genetic diversity of cytoplasms in a given species? 2) Are cell fusion techniques the best tools for modifying organelle composition of a cytoplasm or for transferring as quickly as possible a given cytoplasm into several nuclear backgrounds? 3) If these new cytoplasmic combinations are viable, have they the required qualities to be included in the production of cultivated varieties?