RECOMBINATION OF SOLANUM-BREVIDENS CHROMOSOMES IN THE 2ND BACKCROSS GENERATION FROM A SOMATIC HYBRID WITH SOLANUM-TUBEROSUM

Solanum brevidens synteny groups were examined with 47 widely-distribu ted RFLP markers in 17 BC2 progeny from six fertile BC1 plants. The BC 1 plants were derived from a single S. brevidens + S. tuberosum somati c hybrid backcrossed with S. tuberosum (potato). Probes which were lin ked in potato and tomato were also found to be syntenic along each of the 12 S. brevidens chromosomes. More than half of the S. brevidens sy nteny groups had lost one or more S. brevidens-specific RFLPs in the B C2, suggesting that recombination had occurred. For 8 of the 12 S. bre videns RFLP synteny groups, the frequency of recombinant chromosomes e xceeded that of intact parental chromosomes. Using the RFLP data, 161 RAPD markers were tentatively located throughout the S. brevidens geno me. Further analyses with 39 of these 161 RAPD markers generally showe d that RAPD and RFLP results were comparable, but some inconsistencies were noted with 14 of the 39 RAPD markers. The extent of marker loss and the high frequency of synteny groups which were marked by a single S. brevidens-specific RFLP marker suggest that the S. brevidens chrom osomes have some pairing affinity with potato chromosomes. This intera ction should facilitate the transfer of novel disease-resistance trait s into potato breeding lines. One plant was recovered with the chromos ome number of S. tuberosum (2n=48) that carried a single S. brevidens RFLP marker, suggesting transfer of this S. brevidens marker into the genome of S. tuberosum.