| In this study, 32 families of large yellow croaker(Larimichthys crocea) which built in the fall of 2011 were used as experimental materials, the abilities for tolerant to high temperature(THT), low salinity(TLS) or exposure(TE) were compared between different families. Genetic parameters of growth-related traits were estimated for one-month and six-month old L. crocea. Furthermore, the genotype distribution of twenty-two microsatellite markers were investigated in an F1 family of L. crocea with 20-month old, and the correlation between growth-related traits and microsatellite markers were also analyzed using statistical method. The results as follows:1. The tolerance abilities of THT, TLS or TE of L. crocea different pedigrees juvenile were significant difference, according to the heating rate 1 ℃?h-1 for the THT treatment, which the range of upper thermal tolerance(UTT) was 16.90~66.46 ℃?h, an average of UTT was 45.67 ℃?h; The indicator of TLS was low-salt tolerance time(LTT), which it be calculated at low salinity 3 condition from salinity 25 directly. The range of LTT was 1.27~4.95 h, an average of LTT was 2.74 h; The survival rate of desiccation(SRD) was calculated on the process of which under the original breeding water after 5 min dry exposure(air temperature was 22.0 ℃), the result ranged from 4 to 84 %, and the average was 34 %. The abilities for tolerant to high temperature, low salinity or exposure were compared between 32 families of one-month old L. crocea. The heritabilities for THT, TLS and TE were 0.76 ± 0.16, 0.39 ± 0.39 and 0.72 ± 0.48, respectively. According to 5.0 % selection rate, among 1 high-temperature tolerance family, 3 high temperature sensitive families, 2 low-salt tolerance families, 3 low-salt sensitive families, 3 desiccation tolerance fimilies, and 3 desiccation sensitive families were obtained. All of these could be served as useful materials for further selective breeding and genetic research.2. The performance of growth were compared between 32 families for one-month and six-month old of L. crocea. Genetic parameters of two growth-related traits of L. crocea were also estimated. At one-month old stage, f505 grew fastest. At six-month old stage, f215 grew fastest. Estimated heritabilities for full length and body mass of L. crocea were 0.67±0.18 and 0.79±0.10 at one-month old, and 0.31±0.31 and 0.40±0.32 at six-month old, respectively.3. The estimated breeding values(EBV) of UTT, LTT, SRD and growth-related traits were got by using animal model. The selection method based on phenotypic value was compared with the selection method based on EBV. The results as follows, for THT, TLS, TE and growth-related traits, the seletiton efficiecy based on EBV was higher than that based on phenotypic value.4. Using a F1 full-sib family of L. crocea at twenty-month old as experimental material, it was analyzed for the genotype distribution of twenty-two microsatellite markers, and the correlation of growth-related traits. The genotype distribution of partly loci deviated from Mendel’s Laws severely, such as KPC43、LYC0124、LYC0134、LYC0212 and LYC0446, which suggested these loci might link with the adaptive gene, and LYC0446 may link with recessive homozygous lethal genes. We discovered that LYC0077 had a significant impact on body weight, body length and body height(P<0.05), and the allele A(165 bp) had positive effect and can be used as a molecular markers in selection breeding; LYC0015 and LYC0243 had a significant impact on body height(P<0.05), and no significant effect on body length and body weight, the allele C(110 bp) for LYC0015 and the allele A(160 bp) for LYC0243 have positive effect on growth-related traits. Three genotypes of these loci with favorably effect on growth-related traits were also determined, BC for LYC0015, AA for LYC0077 and AB for LYC0243 respectively. The best genotype combination(BC/AA/AB) for LYC0015, LYC0077 and LYC0243 were also selected according to body weight, which conformed to the Additive Effects Model. The results presented here provide a starting point for the eventual mapping of economically important genes and marker-assistant selection(MAS) in large yellow croaker. |
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