Protoplast-fusion-derived Solanum cybrids: application and phylogenetic limitations.

We established interspecific Solanum cybrids in order to study the intrageneric nuclear-organelle compatibility and the introgression of advantageous plasmone-coded breeding traits into potato. Cybridization was performed by the donor-recipient protoplast-fusion procedure. We found that the plastomes of S. chacoense, S. brevidens, and S. etuberosum could be transferred into the cybrids having S. tuberosum nuclear genomes; chondriome components were likewise transferred from the former species into these cybrids. The combination with S. chacoense as organelle donor and potato as recipient resulted in green fertile plants with potato morphology. By using S. etuberosum as an organelle donor and potato as recipient, male-sterile cybrid plants, most of them having pigmentation abnormalities, were obtained. The combination of S. brevidens with potato resulted in palegreen (almost albino) regenerants. The latter albino plantlets had both the chloroplast DNA and the mitochondrial DNA of the donor (S. brevidens) and did not survive the transfer into the greenhouse. An immediately applicative result of this study is the de novo establishment of male-sterile plants in a potato cultivar. Such plants should be useful as seed parents in the production of hybrid, true-potato seeds.