|| We have developed a highly saturated linkage map in peach using 3 separate crosses (Sc x B, NJ Pillar x KV 77119, and Lovell x Nemared) : one segregating for morphological characters, one segregating for fruit quality traits, and one that contains important rootstock characters. Linkage maps were created for each cross using RFLP, RAPD, and AFLP markers. In the fruit quality cross, with the analysis of 2 years of field data, we have identified 12 QTL that influence soluble solids, pH, cold tolerance, maturity, and fruit size. In the rootstock cross, we have identified tightly linked markers to 2 loci controlling resistance to Meloidogyne spp. root-knot nematodes. In both maps, identified markers are being converted to sequence tagged sites (STS) for use in marker assisted selection. Anchor loci present in 2 or 3 of the maps were used to join the equivalent linkage groups from each map resulting in a combined linkage map for peach. We are also constructing physical maps for several genomic regions controlling traits of interest, to convert genetic map distances to physical distances. Probes specific to individual "combined" linkage groups, are being used to determine their respective chromosomal assignments by in situ hybridization as well.