Isolation, characterization, inheritance and linkage of microsatellite DNAmarkers in white spruce (Picea glauca) and their usefulness in other spruce species

Microsatellite DNA/simple-sequence-repeat (SSR) loci were identified, isola ted and characterized in white spruce (Picea glauca) by screening both a no n-enriched partial genomic library and a partial genomic library enriched f or (AG/TC)(n)-containing clones. Inheritance and linkage of polymorphic SSR loci were determined in F-1 progeny of four controlled crosses. We also as sessed the compatibility and usefulness of the P. glauca microsatellite DNA markers in five other Picea species. Twenty-four microsatellites were iden tified by sequencing 32 clones selected from screens of 5400 clones from th e two libraries. The (AG/TC), microsatellites were the most abundant in the non-enriched library. Eight microsatellite DNA loci were of the single-cop y type, and six of these were polymorphic. A total of 87 alleles were detec ted at the six polymorphic SSR loci in 32 P. glauca individuals drawn from several populations. The number of alleles found at these six SSR loci rang ed from 2 to 22, with an average of 14.5 alleles per locus, and the observe d heterozygosity ranged from 0.48 to 0.91, with a mean of 0.66 per locus. P arents of the controlled crosses were polymorphic for five of the six polym orphic SSR loci. Microsatellite DNA variants at each of these five SSR loci followed a single-locus, codominant, Mendelian inheritance pattern. Joint two-locus segregation tests indicated complete linkage between PGL13 and PG L14, and no linkage between any of the remaining SSR loci. Each of the 32 P . glauca individuals examined had unique single or two-locus genotypes. Wit h the exception of non-amplification of PGL12 in P. sitchensis, P. mariana, and P. abies and the monomorphic nature of PGL7 in P. mariana, primer pair s for all six polymorphic SSR loci successfully amplified specific fragment s from genomic DNA and resolved polymorphic microsatellites of comparable s izes in P. engelmanni, P. sitchensis, P. mariana, P. rubens, and P. abies. The closely related species P. mariana and P. rubens, and P. glauca and P. sitchensiss could be distinguished by the PGL12 SSR marker. The microsatell ite DNA markers developed and reported here could be used for assisting var ious genetics, breeding, biotechnology, tree forensics, genome mapping, con servation, restoration, and sustainable forest management programs in spruc e species.