| Turbot, Scophthalmus maximus (L.)(Family Bothi-dae), is economicallyimportant in wild fsheries and has stimulated the development of aquaculture forseveral other species. Since turbot was introduced to China in1992, breeding andculture technology has been greatly advanced and commercialized. However, theflatfish farming industry remains limited to certain areas by environment constraint.So, Cultivating strains with good quality, resistance to thermal tress are the basis forsustainable development of aquaculture of this species. And basis on this background,our study take the strategy of traditional family selection and marker-assist selection(MAS). We validated and appraisal of performance in thermal tolerance family, usedmolecular markers (SSR and SNP) analyze correlation with thermal resistibility, andbreeding selection of UTT (Upper Thermal Tolerance) fish by molecular marker, andexcavating the quantitative trait loci (QTL) related to thermal tolerance, and so on.The main results are as follows:1. The development of Turbot, Scophthalmus maximusL breeding work wasstudied in2007, Four imported turbot stocks were collected to construct56full-sib.Among these, we selected32good F1family which were come from differentcomponent groups, and the large scale high temperature project was start in2008.Through the growth and upper thermal tolerance traits of the test F1family, and theodd ratio of tolerance by bCOX regression analysis, we selected4family as hightolerance family, the mortality rate below25%. In2010, we selected fish form the F1tolerance family as parent, constructed12F2famil, which can subject the hightemperature. The result that mortality rate of F2family just10.25%; and non-breeding50.95%; and F1family was50.1%, the F2family tolerance was higher than F1, whenthey in the27℃condition. When they in the28℃condition, F2family the mortality rate just32.83%, was lower than F1in the27℃condition, then their mortality rate is50.1%. According to these analysis, we judged that the tolerance of F2family haveincreased1-2℃；and combined the result of the odds ration, we definite4family asthe F2high tolerance family.2. The present work refers to the correlative analysis between molecular markers(SSR and SNP) and the heat-resistance of turbot (Scophthalmus maximus L.). Fromthis project, we screened out some suitable microsatellite molecular markers for MAS.According to the candidate SSR and SNP loci, primers was designed to test and verify,129SSR and21SNP loci were validated, and were used to analyze correlation withheat-resistance. The results show that3SSR loci is significantly negative-correlatedwith trait, which is Sma-USC38,3/9CA15, HLJDLP33; and4SSR loci issignificantly positive-correlated with trait, which Saml-125INRA, Sam-USC86,L12144, Sma-USC81; of which Saml-125INRA, Sam-USC86has extremesignificance of0.333and0.544(P<0.01). And1SNP loci is extreme significance of0.328(P<0.01), positive-correlated. These markers and their differential bands couldbe used for molecular assistant selection of heat-resistant turbot.3. In this chapter, two associated with temperature resistance molecular markersSam-Usc27and saml-125INRA design breeding scheme, starting from moleculargenetic point of view, finally constructs a relatively clear genetic background of thethird generation of temperature resistant strains, and the temperature on theperformance of evaluation, genetic and genetic structure of three generation, theapplication of MAS in turbot breeding are discussed. The results showed that the twogeneration of temperature resistant strains of parental selection is effective use ofmolecular markers, after screening improves overall offspring temperature resistantperformance is significant; two pairs of primers in inheritance is relatively stable.4. WinQTLCart2.5software conducted to detect the quantitative trait loci (QTL)for thermal tolerance using interval mapping (CIM). Results showed that one QTLwere indentified for thermal tolerance on the linkage groups of C9(Sma-USC65)LOD=2.64, which explained14.1%.5. Response surface methodology (RSM) was used to determine the optimumprocessing conditions that give maximum specific growth rate (SGR) and food conversion rate (FCR). Temperature (17-25°C), salinity (19‰-40‰), and body size(10-500g) were the factors investigated. Experiments were designed according toBox-Behnken design with these three factors. The result shows that the coefficient ofdetermination (R2=0.9991for SGR and0.9817for FCR) and probability value(P<0.0001) shows significance for the regression model. In addition, interactionsbetween temperature-salinity, temperature-body size of fish, and temperature-bodysize of fish on the growth was significant (P<0.05), that of temperature-body size onfeed utilization was significant (P<0.05). The optimum conditions to obtain themaximum specific surface area of SGR and FCR were temperature20.88°C,salinity24.07‰, and body size263.81g, under which the maximal value reached3.69%day-1and0.869respectively. |
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