CHARACTERIZATION OF MICROSATELLITE MARKERS IN EASTERN WHITE-PINE

An enrichment cloning method was evaluated for the isolation of micros atellite loci from eastern white pine and the resulting markers were e xamined for polymorphisms. A 200-fold enrichment was achieved for high ly abundant (AC)(n) repeats, but for much less abundant (ACAG)(n) repe ats an enrichment of only 20-fold was obtained. Using a single set of PCR conditions, 19 microsatellite loci were identified from 77 primer pairs evaluated. Genotyping of 16 (AC)(n) loci in 16 unrelated white p ines from the north-central United States revealed an average of 5.4 a lleles per locus and an average observed heterozygosity of 0.515. Five loci were scored among megagametophytes from a single pine to obtain a haploid genotype of the segregating female meiotic products. All loc i segregated according to Mendelian expectations and linkage was estab lished for two of the loci. It was concluded that (AC)(n) loci are hig hly variable in this species and that SSR (simple sequence repeat) mar kers can be efficiently developed for genome mapping and population ge netics studies.