Éditeur(s) : HAL CCSD SpringerLink
Résumé : Trinucleotide microsatellites have proven to be the markers of choice in human genetic analysis because they are easier to genotype than dinucleotides. Their development can be more time-consuming due to their lower abundance in the genome. We isolated trinucleotide microsatellites in Norway spruce (Picea abies K.) using an enrichment procedure for the genomic-library construction. Here we report on the characterisation of 85 ATC microsatellite-containing clones, from which 39 markers were developed. Many of the clones showed the occurrence of tandem repeats of higher order than the trinucleotide ones, often resembling minisatellite repeats. The sequencing of a sample of the alleles at one of the loci revealed size homoplasy due to base substitutions within the microsatellite region. The presence of ATC motifs within repetitive sequence families was observed. We found a significant relationship between the level of polymorphism and the length of the microsatellite. The levels of variability for ATC trinucleotide markers were lower than those for dinucleotides, both when tested on all loci in a set of six individuals and on a subset of loci in four natural populations. This difference is most likely attributable to lower mutation rates for trinucleotide than for dinucleotide loci. The availability of markers with different mutation rates allows one to select the proper marker set to investigate population processes on different time scales.
Theoretical and Applied Genetics

hal-01032029
https://hal.archives-ouvertes.fr/hal-01032029
DOI : 10.1007/s00122-002-0986-1

Éditeur(s) : HAL CCSD SpringerLink
Résumé : The development of microsatellite markers can be a time-consuming process, especially in species such as conifers where many microsatellites have been shown to be associated with the repetitive fraction of the genome and to produce complex banding patterns following electrophoresis. Therefore, procedures to eliminate this fraction from further processing are sought. In this paper, we report on the development of 53 dinucleotide SSR markers in Norway spruce, 35 of which (66%) produce simple, polymorphic patterns. This high efficiency is obtained by introducing a dot-blot selection against high copy number sequences, performed on the microsatellite-containing clones. The resulting markers turned out to be polymorphic and useful for population genetic studies and for linkage mapping. Seven additional markers that were not subject to the dot-blot selection are also presented.
Theoretical and Applied Genetics

hal-01031865
https://hal.archives-ouvertes.fr/hal-01031865
DOI : 10.1007/s00122-001-0843-7

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : Four populations of Norway spruce (Picea abies Karst.) were screened using nine nuclear microsatellite markers (three trinucleotides and six dinucleotides) and four chloroplast markers (all mononucleotides). Marker classes were compared for their variability, mutation rate and ability to detect differentiation between stands. Dinucleotide markers proved to be the most variable group and chloroplast stretches the least variable, with differences in mutation rate between the former and the latter spanning over two orders of magnitude. Variability correlated to the number of repeats but not to the absolute length of the microsatellite region. The different marker classes were combined with two different measures of genetic distance in order to investigate the performance of markers and evolutionary models for the study of genetic variation in natural populations of Norway spruce. Weir and Cockeram's F$_{rm ST}$ generally performed better in this clear-cut, four-population model study. Chloroplast haplotypes turned out to be the most sensitive marker system, being able to differentiate populations and to detect differences in genetic variability between sub-regions.
ISSN: 1286-4560

hal-01032048
https://hal.archives-ouvertes.fr/hal-01032048
DOI : 10.1051/forest:2006029