Correlation analysis of mandarin fish (Siniperca chuatsi) growth hormone gene polymorphisms and growth traits

Screening of trait-associated molecular markers can be used to enhance the efficiency of selective breeding. Previously, we produced the first high-density genetic linkage map for the mandarin fish (Siniperca chuatsi) and identified 11 quantitative-trait loci significantly associated with growth, of which one is located within the growth hormone (GH) gene. To investigate the GH gene polymorphisms and their correlation with growth, the complete sequence was cloned and 32 single-nucleotide polymorphisms (SNPs) and one simple-sequence repeat (SSR) were identified. Of which, eight SNPs (G1-G8) and the SSR (GH-AG) were selected for genotyping and correlation analysis with growth traits in a random population. The results showed that the four novel polymorphic loci (G1, G2, G3 and GH-AG) were significantly correlated with growth traits of mandarin fish (P<0.05). Of these, G1, G3 and GH-AG showed highly significant correlations with multiple growth traits (P<0.01) and the combined SNP analysis showed that G1-G3 formed four effective diplotypes (D1-D4), among which D1 was highly significantly greater than D4 (P<0.01) for some important growth traits. In conclusion, our results show that the four polymorphic loci G1-G3 and GH-AG within the mandarin fish GH gene are significantly correlated with growth traits and could be used as candidate molecular markers for selective breeding of superior varieties of mandarin fish.