Somatic Hybridization of Dihaploid Potato Protoplasts as a Tool for Potato Breeding*

Using electrofusion of protoplasts from different dihaploid potato breeding clones, 308 somatic hybrids, i.e. 16.7% of the totally regenerated plants, were obtained. The results indicate that factors such as ‘combining ability’ strongly influence hybrid formation in these intraspecific fusion experiments. Hybrid identification was predominantly carried out by isoenzyme analysis of the peroxidases and/or esterases in polyacrylamide-gradient gel electrophoresis. Further confirmation of the hybrid character was obtained by scoring phenotypic markers (petal colour, stem anthocyanin production, tuber characteristics, etc.) and, in some combinations, by evaluating tolerance against the herbicide metribuzin and nematode resistance against Globodera rostochiensis (Ro 1). The successful inheritance of metribuzin tolerance and nematode resistance confirm that monogenic dominant inherited traits are combined in the hybrids.