Genome-Wide Association Study Of Porcine Leukocyte Function Trait CD4+in A Large White×Minzhu F2Design Population

With the development of pig production and persistent breeding, more benefit from pig production has been obtained. But with the improvement of growth rate, the risk of pig breeding and plagued by disease, which cause great economic losses each year, is increasing. So, the improvement of disease resistance has been the major aim for pig breeding in recent year.In the current study, a porcine Large White×Minzhu F2design population was used to detect the SNPs associated with leukocyte function trait CD4+significantly. A total of294F2individuals were obtained and Illumina PorcineSNP60BeadChip technology was used to genotype each animal. The blood sample of each animal was collected on240±7d and CD4+was detected using Flow Cytometry. Data were analyzed in a three step Genome-wide Rapid Association using the Mixed Model and Regression-Genomic Control (GRAMMAR-GC) method. A total of five SNPs (two with genome-wide significant and three with chromosome-wide significant) associated with CD4+were detected in this GWAS. These SNPs were located in the interval of2.3Mb (2.0-4.3Mb) on SSC13. The SATB homeobox1(SATBI) gene was mapped to this interaval. For its function to T cell differentiation and maturity, the SATBI gene could be a good candidate gene for CD4+for further research. A real-time fluorescent quantitative PCR method was used to detect the expression levels between the high (>18%) and low group (<7%) for CD4+in spleen and lymph tissue. No significant different gene expression was discovered between the two extremely groups. To search for causative mutations, we sequenced the entire coding region of the SATBI gene using two DNAs pools of Large White Duroc and Minzhu. Two synonymous mutations of g.23527T>C in Exon5and g.45814C>T in Exon7and one nonsynonmous mutation of g.45830G>A) in Exon7were found. The nonsynonymous mutation g.45830G>A shown significant association with CD4+(P<0.05). These results indicated that the SATB1gene could be a good candidate gene and the nonsynonymous mutation g.45830G>A could be as a candidate causative mutation for further investigation for leukocyte function trait CD4+for pig breeding.