Elimination of Solanum phureja nucleolar chromosomes in S. tuberosum + S. phureja somatic hybrids.
The karyotype of the dihaploid SVP1 line of S. tuberosum (2n=2x=24) showed two nucleolar chromosomes with differently sized satellites. The diploid SVP5 line (2n=2x=24) and tetraploid regenerants of S. phureja had larger but similar satellites. Somatic hybrids between the diploid lines of these potato species with genome combinations 4 tub + 2 ph (plants 1-3), 2 tub + 4 ph (plants 4-7) and 4 tub + 4 ph (plant 8) had lost 2 phureja nucleolar chromosomes if 4 phureja genomes were present. One phureja nucleolar chromosome of plants 1-3 and both of plants 5 and 7 had rearranged satellites. Elimination of the two nucleolar chromosomes occurred preferentially, was under genetic control, and probably took place during early callus development. NOR activity resulting in rear-rangements between NORs may have caused the elimination.
Department of Genetics, Biological Centre, University of Groningen, P.O. Box 14, NL-9750, AA Haren, The Netherlands.
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Pijnacker
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Ferwerda
K J
KJ
Puite
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Roest