Association analysis on KISS1 gene polymorphism with reproductive traits in Nubian goats

【Objective】Clarifying the relationship between transfer inhibin gene(KISS1) polymorphism and reproductive traits(litter size, birth weight and weaning weight) in Nubian goats, so as to provide reference basis for further molecular marker assisted selection breeding of goats.【Method】In this study, the SNP sites of KISS1 gene in Nubian goats were screened by DNA mixing pool and Sanger sequencing. Then 355 Nubian goats were genotyped by MTA-Seq sequencing. The association between SNP sites of KISS1 gene and lambing phenotypic traits of Nubian goats was analyzed by SAS 9.2 general linear model(GLM).【Result】The results showed that two SNP of g.1341600A>G and g.1341674C> G were found in KISS1 gene intron. Population genetic analysis showed that the g. 1341600A>G locus was moderately polymorphic(0.25<P<0.50), and the test showed that the g.1341600A>G locus was in Hardy-Weinberg equilibrium(P_HWE> 0.05), while the g.1341674C>G site was low polymorphism(PIC<0.25), and test showed that the g.1341600A>G locus was not in Hardy-Weinberg equilibrium(P_HWE<0.05).Association analysis showed that at g.1341600A>G locus, the first, second and total parity litter size of GG and AG genotypes were higher than those of AA genotypes and reached significant level at the first parity litter size(P<0.05, the same below). At g.1341674C>G locus, the first, third and total parity litter size of CC genotypes were higher than those of GG genotypes and reached significant level at the first parity litter size.At g.1341674C>G locus, the first, third parity and total parity birth weight of GG genotypes were higher than those of CC genotypes, and reached significant level at the third parity birth weight.There was no significant difference among different genotypes of Nubian goats in diverse parities birth weight at g.1341600A>G(P>0.05, the same below). There was no significant difference among different genotypes of Nubian goats in diverse parities weaning weight at g.1341600A>G and g. 1341674C>G. The results of linkage disequilibrium and haplotype analysis showed that g. 1341600 C>G locus and g. 1341674C>G locus could form linkage disequilibrium module, and the frequencies of GC, AC and AG were 0.645, 0.265 and 0.090, respectively. The correlation analysis between haplotype combination and reproductive traitsshowed that there was a significant correlation between haplotype combination and the first parity litter size, and the litter size of AACC was significantly lower than those of other genotypes.【Conclusion】There are two SNP loci in KISS1 gene intron (g. 1341600A>G and g. 1341674C>G), which are related to their reproductive traits in Nubian goats. The A allele of g.1341600A>G and the C allele of g.1341674C>G can be used as potential molecular markers for Nubian goat breeding, and the AACC combination ewes of KISS1 gene should be eliminated in the breeding process in the future.