Genetic polymorphism of the ovine MAP3K5 gene and its association with body size traits in Hu sheep of China

As an excellent local sheep breed in China, Hu sheep have the characteristics of producing more lambs and good motherhood. The purpose of this study was to identify the polymorphism of the mitogen-activated protein kinase 5 (MAP3K5) gene and determine whether it was associated with the body size traits (body height, body length, chest circumference, and cannon circumference) in Hu sheep. The polymorphism of MAP3K5 was identified by using PCR amplification, followed by Sanger sequencing, and KASPar (Kompetitive Allele Specific PCR) technology was used for genotyping subsequently. The results of the association analysis showed that MAP3K5 (g.205261 A > G) was significantly associated with body height at 80, 100, 140, 160, and 180 d; body length at 80 and 160 d; chest circumference at 100, 140, 160, and 180 d; and cannon circumference at 100 and 120 d, respectively. The results of qRT-PCR showed that the expression level of MAP3K5 in the heart was significantly higher (P < 0.05) than in the other 10 tissues. In summary, the MAP3K5 mutation loci may be used as a candidate molecular marker for the body size traits of Hu sheep.