Screening of Single Nucleotide Polymophisms (SNPs) Related with Growth in Growth Hormone Secretagogue Receptor Gene (GHSR) of Nile Tilapia (Oreochromis niloticus)
Abstract： PCR amplification and direct sequencing were used for single nucleotide polymophisms (SNPs) searching from growth hormone secretagogue receptor gene (GHSR) of the 2 populations of Nile tilapia (Oreochromis niloticus) (i.e., Fast-growing population and Base population). Snapshot method was used for genotyping of SNPs, and the correlation between genotypes of SNPs and growth traits of tilapia were analyzed using general linear model (GLM) in the offsprings of the 2 populations. Five SNPs loci (S1 (A-409G), S2 (G-424T), S3 (T-553A), S4 (T-1114A) and S5 (A-1168C)) were found in GHSR gene, and they were located in 5′ flanking region. The results showed that individuals with genotype AA or AT at S4 site had significantly higher body length, body height, head length, caudal peduncle length, caudal peduncle depth, and larger body weight than the individuals with genotype TT (P＜0.05). The dominant genotype frequency of S4 site in the generation of Fast-growing population and Base population was AT (55%) and TT (75.94%), respectively. The 5 SNPs sites composed 7 diplotypes (D1~7). The body weight, body length, body height, head length and caudal peduncle depth of individuals with diplotypes D3 and D5 were significantly larger or higher than that of the individuals with diplotypes D4 and D7 (P＜0.05). The growth traits of individuals with diplotypes D1 (except for body width), D2 (except for body width and the shank length) and D6 (except for body height) had no significant difference compared with individuals with the other diplotypes. The dominant diplotypes in the generation of Fast-growing population and Base population were diplotypes D3 (46.25%) and D4 (35.44%), respectively. In conclusion, the genotypes AA and AT at S4 site, diplotypes D3 and D5 of GHSR gene were closely related to fast growth rate in Nile tilapia, which can be used as candidate molecular markers for tilapia breeding.
