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.