Association analysis of BMP7 gene SNP loci with reproductive performance in Kele pig

【Objective】The study aimed to identify the association between single nucleotide polymorphisms（SNP） loci of bone morphogenetic protein 7 gene（BMP7）and the reproductive performance of Kele pig，to explore molecular marker-assisted selection for reproductive traits in Kele pig，and to provide reference for accelerating the improvement of reproductive performance and the breed improvement process of Kele pig.【Method】A total of 150 healthy multiparous Kele sows were selected as the study subjects. SNP loci of the BMP7 gene were screened and identified using the Sanger sequencing method，and the population genetic parameters for each SNP locus were calculated. The association between SNP loci and 6 reproductive traits of Kele pigs，including total litter size，litter weight at birth，average birth weight， number of weaned piglets，litter weight at weaning，and average weaning weight，was analyzed using the general linear model（GLM）in SPSS 22.0.【Result】Five SNPs loci were identified in the BMP7 gene of Kele pigs：g.57602289C>T （exon No. 2），g.57602334C>T（exon No. 2），g.57602404C>T（intron No. 2），g.57602418C>T（intron No. 2）and g.57602561G>T（intron No. 2），all of which exhibited 3 genotypes. The dominant genotypes for the 5 SNP loci were CT，CT，CT，CT and GT respectively，with corresponding polymorphism information content（PIC）ranging from 0.358 to 0.375，all exhibiting moderate polymorphism（0.25P_HWE>0.05），and strong linkage disequilibrium［LD coefficient（D'）>0.800，correlation coefficient（R²）> 0.330］was observed among all SNP loci. The results of the association analysis showed that individuals with the TT genotype at the 3 loci，g.57602289C>T，g.57602334C>T and g.57602418C>T，had significantly higher litter weight at birth compared to those with the CC genotype（P<0.05）. The number of weaned piglets in TT genotype individuals was extremely significantly higher than in those with the CC and CT genotypes（P<0.01，the same below）. The total litter size with the TT genotype individuals at the g.57602404C>T locus was extremely significantly higher than that of individuals with the CC genotype. The total litter size with the TT genotype at the g.57602561G>T locus was extremely significantly higher than that of individuals with the GG genotype. Additionally，individuals with the H2H2 and H3H3 diplotypes showed higher total litter size，litter weight at birth，number of weaned piglets，and weaning litter weight compared to other diplotypes，with H2H2 individuals demonstrating a particularly notable advantage in the number of weaned piglets and litter weight at birth.【Conclusion】Five SNPs loci identified in the BMP7 gene of Kele pigs are strongly associated with their reproductive performance. BMP7 gene can be considered a candidate gene for reproductive traits of Kele pigs， and the diplotype H2H2 can serve as a reference for reproductive traits molecular marker-assisted selection.