Single Nucleotide Polymorphisms in the Leptin-a Gene and Associations with Growth Traits in the Golden Pompano, Trachinotus blochii

Leptin is a multifunctional protein involved in processes such as body weight (BWT) regulation, food intake, and appetite regulation. In this study, we isolated and cloned the full-length leptin-a gene from the golden pompano, Trachinotus blochii. A search for polymorphisms, as well as association analyses between these polymorphisms and 10 growth traits were performed. A total of 10 polymorphisms, consisting of five single nucleotide polymorphisms (SNPs) in intron 1 (C203T, G252A, C380G, G383C, and G587A), one mutation in exon 2 (T775A), one mutation in exon 3 (G1239A), and three SNPs in the 3-untranslated region (G1424A, T1653A, and A1654T) were identified and genotyped in 150 individuals. The C203T and C380G polymorphisms, as well as the G1424A and T1653A polymorphisms, showed complete linkage. Association analyses revealed that the T775A polymorphism was significantly associated with BWT, body height (BWH), body length, and overall length (OL), and genotype TT had negative effects on growth traits. Additionally, the SNP G1239A was significantly associated with BWT, BWH, OL, and head length, with the GA genotype showing positive effects on growth traits. The results indicate that polymorphisms in the leptin-a gene loci can be used as a selection criterion to improve growth traits in golden pompano.