Technical Abstract: Source, Description, and PCR Primers: The source, description, and PCR primers were previously reported by Lang and Plante (1994). PCR conditions: PCR samples contained 50 ng DNA, 15 mM MgC12, 50 mM KCL, 10 mM Tris-HCL (pH8.3), 30 uM dCTP, dGTP and dTTP, 3 uM dATP, .1 uCi [alpha 32P] dATP (3000 Ci/umole), .4 uM for each of two primers, and .35 unit Taq polymerase. The PCR protocol was: initial denaturation, 94 degrees for 3 min followed by 30 cycles of 1 min at 94 degrees, 30 sec at the annealing temperature (Table 1) and 1 min at 72 degrees. The final extension at 72 degrees was for 4 min. Alleles: Number and size of alleles were initially reported by Lang and Plante (1994). The number and size of the alleles listed in Table 1 were observed in the parents and grandparents (n=52) of the USDA/MARC reference families. PCR products were analyzed and scored according to Bishop et al. (1994). Fourteen markers followed Mendelian inheritance patterns, while SRC159 followed a sex-linked inheritance pattern. Chromosomal location: Location of marker loci (Table 1) was determined by linkage analysis according to Kappes et al. (1997). Marker location within each respective linkage group can be viewed at http://sol.marc.usda.gov/.