A MICROSATELLITE MAP OF WHEAT

Hexaploid bread wheat (Triticum aestivum L. em. Thell) is one of the w orld's most important crop plants and displays a very low level of int raspecific polymorphism. We report the development of highly polymorph ic microsatellite markers using procedures optimized for the large whe at genome. The isolation of microsatellite-containing clones from hypo methylated regions of the wheat genome increased the proportion of use ful markers almost twofold. The majority (80%) of primer sets develope d are genome specific and detect only a single locus in one of the thr ee genomes of bread wheat (A, B, or D). Only 20% of the markers detect more than one locus. A total of 279 loci amplified by 230 primer sets were placed onto a genetic framework map composed of RFLPs previously mapped in the reference population of the International Triticeae Map ping Initiative (ITMI) Opata 85 x W7984. Sixty-five microsatellites we re mapped at a LOD >2.5, and 214 microsatellites were assigned to the most likely intervals. Ninety-three loci were mapped to the A genome, 115 to the B genome, and 71 to the D genome. The markers are randomly distributed along the linkage map, with clustering in several centrome ric regions.