Microsatellite DNA markers in Populus tremuloides

Markers for eight new microsatellite DNA or simple sequence repeat (SSR) lo ci were developed and characterized in trembling aspen (Populus tremuloides ) from a partial genomic library. Informativeness of these microsatellite D NA markers was examined by determining polymorphisms in 38 P. tremuloides i ndividuals. Inheritance of selected markers was tested in progenies of cont rolled crosses. Six characterized SSR loci were of dinucleotide repeats (tw o perfect and four imperfect), and one each of trinucleotide and tetranucle otide repeats. The monomorphic SSR locus (PTR15) was of a compound imperfec t dinucleotide repeat. The primers of one highly polymorphic SSR locus (PTR 7) amplified two loci, and alleles could not be assigned to a specific locu s. At the other six polymorphic loci, 25 alleles were detected in 38 P. tre muloides individuals; the number of alleles ranged from 2 to 7, with an ave rage of 4.2 alleles per locus, and the observed heterozygosity ranged from 0.05 to 0.61, with an average of 0.36 per locus. The two perfect dinucleoti de and one trinucleotide microsatellite DNA loci were the most informative. Microsatellite DNA variants of four SSR loci characterized previously foll owed a single-locus Mendelian inheritance pattern, whereas those of PTR7 fr om the present study showed a two-locus Mendelian inheritance pattern in co ntrolled crosses. The microsatellite DNA markers developed and reported her e could be used for assisting various genetic, breeding, biotechnology, gen ome mapping, conservation, and sustainable forest management programs in po plars.