A HIGH-RESOLUTION MAP OF THE VICINITY OF THE R1 LOCUS ON CHROMOSOME-VOF POTATO BASED ON RFLP AND AFLP MARKERS

The R1 allele confers on potato a race-specific resistance to Phytopht hora infestans. The corresponding genetic locus maps on chromosome V i n a region in which several other resistance genes are also located. A s part of a strategy for cloning R1, a high-resolution genetic map was constructed for the segment of chromosome V that is bordered by the R FLP loci GP21 and GP179 and includes the R1 locus. Bulked segregant an alysis and markers based on amplified fragment length polymorphisms (A FLP markers) were used to select molecular markers closely linked to R 1. Twentynine of approximately 3200 informative AFLP loci displayed li nkage to the R1 locus. Based on the genotypic analysis of 461 gametes, eight loci mapped within the GP21-GP179 interval. Two of those could not be seperated from R1 by recombination. For genotyping large number s of plants with respect to the flanking markers GP21 and GP179 PCR ba sed assays were also developed which allowed marker-assisted selection of plants with genotypes Rr and rr and of recombinant plants.