Genetic mapping and QTLs analysis of growth traits in olive flound-er(Paralichthys olivaceus)

Using a population including 92 F₁ individuals obtained from the cross olive flounder from Japan ×olive flounder from Korea as the segregating population, genetic linkage maps of flounder were constructed using the SSR marker by joinmap4.0 software .A total of 221 SSR markers were fixed to the genetic linkage map. 178 SSR markers were linked to 22 linkage groups in female map and 194 SSR markers are linked to23 linkage groups in male map. The lengths of the female and male maps are 599.0 cM and 693.4 cM and covered 76.27% and 78.82% of the genome, respectively. Principal component analysis was handled with three sets of data, overall length, weight and body depth.1 set of data that can explain 89.6% of the three traits was obtained, which was named growth-trait, GT of flounder. Based on the linkage maps, trait- marker regression and complexity interval mapping were analyzed to fix QTLs related to growth traits by WinQTLCart 2.5 software, the experiential LOD-value of 2.5 was the threshold value of existing QTLs. Three QTLs related to growth traits were obtained from this research , qGT-f4,qGT-m20 and qGT-f20, and the variance explained by the three loci were 27.60%, 13.74%, 10.27%, respectively. Twenty-two SSR markers related to growth traits (P<0.05) were obtained from trait- marker regression analyzing. The variance explained by single SSR, ranged from 3.70% to 11.26%. The six markers, scaffold558_51720, scaffold558_26183, scaffold903_69232, scaffold485_47120, scaffold1262_77386 and scaffold809_65154 were highly significantly ( P< 0.01) correlated with growth traits, and the variance explained by the six were 10.42%,7.31%,10.07%,10.07%,8.39%,11.26% respectively.