Detection Of SSR Markers Associated With Skeletal Growth Traits Of Japanese Flounder (Paralichthys Olivaceus)

The Japanese flounder is marine precious economical fishes in China, the artificialcultivation of Japanese flounder began from the1990s, nowadays it has been the mostimportant breeding species throughout the north and FuJian coastal areas. Despite this,most of the production is carried out using unselected breed. The broodstock mainlycome from wild fish captured in the sea or under several generations cultured. Theoffspring take on slow growth rate, poor resistance to disease and weak ability of adapto intensive breeding. Therefore the development of genetic improvement study and thecultivation of excellent family of Japanese flounder of good economic traits such as fastgrowth have very important meaning to protect the natural resource and meet thecurrent needs of aquaculture industry.Samples were obtained from BeiDaiHe center lab station of the Chinese Academyof Fishery Science, based on mito-gynogenetic diploid families of Japanese flounder,which were precious genetic research materials especially for its high purity andobvious character segregation. Skeletal traits are quantitative traits that can besignificantly influenced by genetic factors rather than little environment effects.Detection of SSRs associated with skeletal growth traits was very important forMolecular assisted selection （MAS）. The experimental population were62doublehaploids （DHs） Japanese flounder.106pairs of primer, which amplified clear bandswith nearly free degradation, good polymorphism and segregation in offsprings werescreened from primers that were designed according to Paralichthys olivaceusmicrosatellite sequences in GenBank, NCBI. Skeletal growth traits were obtained fromX-ray films. Statistical product and service solutions （SPSS） software was used toanalyze the genetic parameters of growth traits including body weight （BW）, bodylength （BL）, body height （BH）, rib length （RL）, dorsal rib length （DRL）, ventral riblength （VRL）, ventral fin pterygiophore length （VFPL）, dorsal fin pterygiophore length （DFPL） and vertebra height （VH）, aiming at providing essential data for selectivebreeding and detection of quantitative trait loci （QTL） for growth in Paralichthysolivaceus. The results showed:1. According to the measured skeletal quantitative data from X-ray films of62DHsJapanese flounder, the correlation coefficient of BW with BL is0.797, correlationcoefficient of BW with BH is0.939, correlation coefficient of BL with BH is0.799. Thephenotypic correlation between all the skeletal growth traits reached the extremesignificance level （P<0.01）. All the phenotypic traits were suited for selection ofrepresentative traits.2. The regression equation to estimate the BW（Y） is Y（体重）=–1674.681+10.781X₁（体长）+141.589X₂（体高）（R²=0.887）；the regression equation to estimate the BH（Y） is Y（体高）=0.043+1.142X₁（肋骨长）+0.517X₂（腹鳍担骨长）+0.878X₃（背鳍担骨长）（R²=0.974）；theregression equation to estimate the RL（Y） is Y（肋骨长）=–0.014+1.033X₁（背肋长）+0.893X2（腹肋长）+1.490X₃（脊椎骨高）（R²=0.995）. The correlation between the forcasted value andmeasured value were0.887,0.974and0.995, all reaching the extremely significancelevel at0.01level. The BW（Y） of adult DH Japanese flounder showed obvious linearcorrelation with its BL（X1） and BH（X₂）. The BH（Y） of adult DH Japanese floundershowed obvious linear correlation with its RL（X₁）, VFPL（X₂） and DFPL（X₃）. The RL（Y）of adult DH Japanese flounder showed obvious linear correlation with its DRL（X₁）,VRL（X₂） and VH（X₃）.3. The results of microsatellite analysis showed that22microsatellite markers weresignificantly correlated with nine skeletal growth traits（P<0.05）, which including3SSRs that significantly correlated with BW（P<0.05）,11SSRs that significantlycorrelated with BL（P<0.05）,9SSRs that significantly correlated with BH（P<0.05）,10SSRs that significantly correlated with RL（P<0.05）,7SSRs that significantly correlatedwith DRL（P<0.05）,11SSRs that significantly correlated with VRL（P<0.05）,5SSRsthat significantly correlated with DFPL（P<0.05）,13SSRs that significantly correlatedwith VFPL（P<0.05）,8SSRs that significantly correlated with VH（P<0.05）.4. Five microsatellite markers that were significantly correlated with skeletal deformity:Poli13-2TUF, Poli34TUF, Poli144TUF, Poli278TUF and Po15, were obtained bymicrosatellite analysis of21skeletal deformed Japanese flounder （P<0.05）. Amongthese five markers, Poli13-2TUF, Poli34TUF, Poli144TUF and Po15were all located in10th linkage map. SSR and EST-SSR molecular marker screening and linkage location analysis can be carried out in10th linkage map.Overview, X-ray skeletal growth traits were first used to analyze the correlationbetween the microsatellite markers and the body length, body height, rib length, dorsalrib length, ventral rib length, dorsal fin pterygiophore length, ventral fin pterygiophorelength and the vertebra height. The obtained22microsatellite markers providedimportant and essential data for molecular marker-assisted selection.