Polymorphism Of CSN3?ACACA Genes And Its Association With Milk Production Traits In Chinese Holstein Cattle

Two candidate genes associated with milk production traits.the CSN3(kappa casein)and ACACA(acetyl coenzyme A carboxylase alpha)genes.were selected to study in Chinese Holstein cattle.The method of direct sequencing of PCR products was used to determine genotype.The genetic polymorphism parameters were calculated by POPGENE software,HAPLOVIEW3.32 software was used to analyze linkage disequilibrium and haplotype of the SNPs in candidate genes.Correlation analysis was performed by SPSS software on gene polymorphisms and milk production traits.The aim of this study was to screen molecular markers that have important influence on milk production traits in Chinese Holstein cattle.The results will help for determining the major genes that affecting milk production traits,providing theoretical basis for marker assisted breeding and improving milk production traits in Chinese Holstein cattle.The results show that:1.A total of 4 SNPs loci were detected by amplification of CSN3 gene in Chinese Holstein cattle: g.463G>A,g.1012A>C,g.2015T>A and g.2396G>T.except g.2396G>T,other 3 SNPs loci were closely associated with milk production traits in Chinese Holstein cattle.g.463G>A can most significantly affect the rate of milk fat(P<0.01),and significantly affect the rate of milk protein(P<0.05).g.1012A>C can most significantly affect the milk fat percentage(P<0.01).g.2015T>A can most significantly affect the milk fat and milk protein rate(P<0.01).The diplotype association analysis showed that,H14H14(ACAG-ACAG)in milk fat rate was significantly higher than the other.Because the kappa casein encoded by CSN3 gene is the main component of milk protein,different genotypes in SNP loci of CSN3 gene will show differential expression,that ultimately affect milk production traits.2.A total of 2 SNPs loci were detected by amplification of ACACA gene in Chinese Holstein cattle: g.43569T>C,g.43617T>G.Both SNPs loci were closely associated with lactation traits in Chinese Holstein Cattle.Specifically,g.43569T>C can most significantly affect the rate of milk protein and lactose(P<0.01),significantly affect the rate of milk fat(P<0.05).g.43617T>G significantly affected the rate of milk protein and lactose(P<0.05).The diplotype correlation analysis showed that H1H1(CG-CG)in the milk fat rate was most significantly higher than the others,significantly higher than the other diplotypes in rate of lactose.Because the ACACA gene plays important roles in fatty acid synthesis in mammary tissue,different genotypes in SNP loci of ACACA gene will show differential expression,that ultimately affect the lactation traits.3.Therefore,the CSN3 and ACACA genes can be used as candidate genes that affect milk production traits for marker assisted selection,and provide scientific basis for the breeding of Chinese Holstein cattle.