Wolters, A.M.A., Department of Genetics, Wageningen Agricultural University, Dreijenlaan 2, Wageningen, NL-6703 HA, Netherlands
Schoenmakers, H.C.H., Department of Genetics, Wageningen Agricultural University, Dreijenlaan 2, Wageningen, NL-6703 HA, Netherlands
van der Meulen-Muisers, J.J.M., Department of Genetics, Wageningen Agricultural University, Dreijenlaan 2, Wageningen, NL-6703 HA, Netherlands
van der Knaap, E., Department of Genetics, Wageningen Agricultural University, Dreijenlaan 2, Wageningen, NL-6703 HA, Netherlands
Derks, E.H.M., Centre for Plant Breeding and Reproduction Research CPRO, P.O. Box 16, Wageningen, NL-6700 AA, Netherlands
Koornneef, M., Department of Genetics, Wageningen Agricultural University, Dreijenlaan 2, Wageningen, NL-6703 HA, Netherlands
Zelcer, A., Division of Genetics and Plant Breeding, Institute of Field and Garden Crops, Volcani Centre, Agricultural Research Organization, Bet-Dagan, 50250, Israel

This paper describes the analysis of the elimination of potato DNA from potato-tomato somatic cell hybrids. The hybrids were obtained by fusion of protoplasts of a cytoplasmic albino tomato genotype with leaf mesophyll protoplasts of a potato genotype carrying the β-glucuronidase (GUS) gene of Escherichia coli. The potato protoplasts were either isolated from unirradiated plants or from plants irradiated with 50 or 500 Gy of γ-rays. Green calli were selected as putative fusion products. The hybridity of these calli was confirmed by isoenzyme analysis. All of the green calli tested contained a potato-specific chloroplast DNA restriction fragment, and most of the calli analysed were positive for β-glucuronidase activity. In 72 of the hybrid calli we determined the percentage of potato nuclear DNA using species-specific probes. All of the tested green calli contained a considerable amount of potato genomic DNA, irrespective of the dose of irradiation of the potato parent. The limited degree of potato DNA elimination and the absence of true cybrids are discussed. © 1991 Springer-Verlag.