Identification of alien chromosomes through GISH and RFLP analysis and the potential for establishing potato lines with monosomic additions of tomato chromosomes.

To increase the potential for establishing a complete series of tomato chromosome addition-sbstitution lines in a potato background, six new BC1 progeny were produced. All of them originated from crosses between three different hexaploid potato (+) tomato fusion hybrids. Three different somatic hybrids, viz., C31-17-5, C31-17-24, and C31-17-51, were used as female parents, and four different tetraploids, viz., Katahdin, Frieslander, 6704-1, and AM66.42 were used as male parents. A characterisation of the genomes of the three fusion hybrids and the six BC1 progenies (6739, 2001, 2002, 2003, 2004, and 2005) through genomic in situ hybridization and restriction fragment length polymorphism (RFLP) analysis indicated that there was preferential tomato chromosome elimination in the fusion hybrids. Similar analyses of the six BC1 progeny indicated that a variable number of the alien tomato chromosomes (6-11) were present in individual plants. RFLP analysis using chromosome specific DNA probes indicated that BC1 progenies had retained all 12 tomato chromosomes, albeit in different individual plants. This means that the available BC1 progenies have the potential for establishing a complete series of tomato chromosome addition-substitution lines in a potato background.