Abstract
This study aimed to investigate the associations between single-nucleotide polymorphisms (SNPs) and haplotypes in the exon 13 and the intronic regions of the yak
IGF1R
gene and growth traits, with the goal of identifying molecular markers related to growth performance. A total of 400 3-year-old female yaks from the Qinghai Plateau were used as the experimental population. DNA sequencing was employed to detect and genotype SNPs in the
IGF1R
gene. Haploview 3.32 software was used for linkage disequilibrium and haplotype analysis, and the associations between different genotypes and haplotype combinations with growth traits, including body weight, body height, body length, chest circumference, and cannon bone circumference, were evaluated. One SNP (g.7383084C>T) was identified in exon 13, and three SNPs (g.7383136G>A, g.7383137C>T and g.7383177G>A) were identified in intron 13. Haplotype and linkage disequilibrium analyses revealed weak linkage among the four loci, and six haplotypes were identified, among which Hap2 was the dominant one. Association analysis of growth traits indicated that g.7383084C>T, g.7383136G>A, g.7383137C>T, and g.7383177G>A loci were significantly or highly significantly associated with body height and body length in plateau yaks. The advantageous genotypes were CC and CT for g.7383084C>T, GA for g.7383136G>A, CT for g.7383137C>T, and GG for g.7383177G>A. Genotype combination analysis showed that all five common diplotypes were significantly associated with some growth traits, with H
2
H
6
being the optimal haplotype combination. These results suggest that polymorphisms in the exon 13 and intronic regions of the
IGF1R
gene in Qinghai Plateau yaks can serve as molecular markers. The significant associations with growth traits provide data-based support for their direct application in the genetic improvement and efficient breeding of yaks.