| Genetic linkage maps were constructed for turbot (Scophthalmus maximus L.) using microsatellite markers in an F1 family and quantitative trait loci(QTL) associated with the growth of turbot were detected and located in the maps.1. In present study, by construction the microsatellite enrichment libraries and colony hybridization, microsatellites were isolated for the turbot (Scophthalmus maximus L.) covering the whole genome in a large scale. By 14 different probes detection, 952 clones were sequenced and after cluster analysis, 753 individual positive clones were finally obtained. Using Vector NTI Suite 8.0 (Invitrogen) and tandem repeats finder (TRF) software, a total of 1004 tandem repeat sequences were found , including 831 microsatellites and 173 minisatellites, which accounted for 82.77% and 17.23% of total repeat sequences respectively. The results of analyzing the different nucleotide unit crossing the whole genome of turbot were also represented. It showed that: the di-nucleotide unit was the dominant repeat unit among the six repeat unit types, whose number was the most abundant, and the repeat unit cumulative length was the largest as well, while the penta-nucleotide type was disadvantage in the whole repeat unit types. The CV (Coefficient of Variation) was introduced to evaluate the ability of the repeated variation of microsatellites. The AGG (126.11) motif was the most variable repeat unit type in this research with a CV value 126.11, but the average CV of di-nucleotides was the most common type among the six repeat unit types as the basis of origin and evolution of repeat sequences. In this study, a negative correlation between the length of repeat units and the average copy number was detected (r = -0.5, P= 0.072).2. Six hundred and fifty-three primer pairs were designed and 284 primer pairs with high polymorphisms were screened, which were developed from the SSR-enriched libraries. The genetic linkage map of turbot was performed using an F1 family, and the map was constructed using 158 microsatellite markers among all the polymorphic markers. Of these segregating markers, 125 were mapped to the female framework map and 10 (8.0%) markers showed a significant distortion from the expected 1:1 ratio (P<0.01). final female linkage map consisted of 30 linkage groups spanning 919.1 cM with an average distance of 12.9 cM. And 118 were assigned to 22 linkage groups in male map, and 13 (11.0%) markers showed a significant distortion from the expected 1:1 ratio (P<0.01). The total length of the male map was 721.7 cM with an average distance of 9.9 cM. By using two kinds of methods to estimate the genome length, the average estimate length was 1695.0 cM for female and 1137.3 cM for male with coverage of 35.5%and 48.2% respectively. In Turbot, the female map was 49.0% larger than the male map, which may reflect sex-specific recombination rates in Turbot.In addition, only one possible QTL for the turbot standard length associated with the growth of Turbot was detected and located in the female and male maps. The QTL in related to the growth clustered on linkage group would be very useful for improving this trait by molecular marker-assisted selection.
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