Genome-wide Association Study Of Hair Length Trait In Tianzhu White Yak (Bos Grunniens) Based On 2b-RAD

Tianzhu white yak(Bos grunniens)has a high utilization value because of its white coat color.Besides producing meat,wool,villus,milk and other products,it is also regarded as a landscape animal in the plateau.The hair length of the white yak is one of the important factors affecting its landscape value.In this study,we used 2b-RAD sequencing and general linear model and variance component model to conduct genome-wide association analysis,polymorphic loci and candidate genes related to the hair length of the white yak were screened out,and candidate genes were verified by real-time quantitative PCR.The study aimed at identifying key SNPs and genes affecting the target trait and providing theoretical support for the breeding of longhaired white yak.The main research results are as follows:1.A total of 78732 polymorphic markers were obtained by 2b-RAD sequencing,which was filtered according to the integrity > 80%,the minimum allele frequency(MAF)> 0.01.2.Forty-three candidate SNP loci and eight genes were obtained by means of genome-wide association analysis: FER gene on chromosome 2,DKK1 gene on chromosome 6,MST1 gene on chromosome 7,ZFP36L1 and PDGFG gene on chromosome 12,FGF5 and LEF1 gene on chromosome 24,BMP6 gene on chromosome 26.3.RT-qPCR analysis showed that the expression levels of FGF5 and DKK1 gene in normal yaks’ skin tissue were significantly higher than those in long-haired yaks(P < 0.01),while the expression levels of BMP6 gene were significantly lower than those in long-haired yaks(P < 0.05).LEF1,FER,MST1,ZFP36L1 and PDGFD gene expression levels showed no significant difference(P>0.05).