| The leptin gene(LEP) encodes a protein that greatly affects the regulation of reproduction, body weight, and energy balance in mammals. Five goat breeds were included in this study, which consist of Nanjiang yellow goat (n=267), Jianyang Daer goat (n=36), Meigu goat (n=37), Tibet goat (n=41), and Chuannan black goat (n=30). Our research detected the single nucleotide polymorphisms (SNP) of LEP gene, and analyzed the associations between LEP genetic variants and growth traits in Nanjiang Yellow goat. The main results of this study were as following:1. Six novel SNP of LEP gene were detected in the five goat breeds (g.117T>C, g.1642G>A, g.2883G>A, g.3053T>C, g.3190G>A, and g.3314T>C). The frequencies of major alleles ranged from 0.583 to 0.987, resulting in the significant difference between genotype distributions. The observed and expected heterozygosity ranged from 0.026 to 0.533 and 0.026 to 0.497, respectively. The PIC ranged from 0.025 to 0.370, indicating that the SNPs in caprine LEP gene of the studied population were moderate polymorphism. There is a large selection potential of these SNPs. Chi squared (χ2) test showed that all of the six SNPs were in Hardy-Weinberg equilibrium in the studied population (P> 0.05).2. Fifteen-five haplotypes of LEP gene were identified in the five goat breeds. The frequencies of the six common haplotypes ranged from 0.083 to 0.244. The linkage disequilibrium plot showed that an obvious linkage disequilibrium (LD) block was revealed only in the two cultured breeds (NJ and JY).3. Statistical analysis revealed that all of the six SNPs of LEP gene were associated with growth traits. The TT homozygotes at g.117T>C locus had higher body weight and longer chest circumference at 24 months than CC individuals (P<0.05). The individuals with GG genotypes at g.1642G>A and g.2883G>A loci showed higher body weight at birth (2.38±0.03 kg,2.43±0.05 kg), body weight at 2 months (10.59 ±0.16 kg,10.71±0.26 kg) than the A-bearing genotypes (AA or GA, P< 0.05). There were only one association detected among genotypes at the loci (g.3053T>C and g.3190G>A) in the BL-24. At the locus of g.3314T>C, a higher BWT was associated g.3190G>A) in the BL-24. At the locus of g.3314T>C, a higher BWT was associated with TT homozygotes, while longer BL-6 and BH-6 were observed in the animals with CC genotype (P< 0.05).4. The Association analysis shows that the individuals with H2H3 genotype had highest BWT and WT-2, and the individuals with H1H5 genotype had highest the other all growth traits.5. Our findings indicated that the LEP gene might be the important candidate gene influencing growth traits of goat. The genetic variations of LEP gene showed a relation with the growth traits in Nanjiang Yellow goat, and these genetic markers may be useful for future marker-assisted selection programs. |
