Investigation Molecular Basis of Teb Color in Tongcheng Pig

Two end black (teb) is noteworthy as a source of phenotypic variation commonly seen in several Chinese indigenous breeds, including Tongcheng, Dongshan, Shaziling, Ganxi and Jinhua pig. To uncover the genetic basis underlying this color variation, a segregated population was established between Tongcheng and Duroc breeds, in which 21 backcross pigs with solid black color and their relevant founder pigs were genotyped by PorcineSNP 60K BeadChips (Illumina, USA). As a result, linkage analysis for genomic wide in these 33 pigs revealed 7 candidate regions, respectively locating on Chromosome 1, 9, 11 and 15 with a total of 174 Mb. Using the sliding window consisting of 9 adjacent SNPs, we conducted relative heterozygosity analysis in an independent date set, which contained 45 Tongcheng pigs and 23 Laiwu pigs, a solid black breed in China. Comparing with Laiwu pigs, 3 selective sweeps were identified in Tongcheng pig: one in the chromosome 1 ranging from 254452722-254822229 bp with 9.08 times decreased heterozygosity, while other two sweeps located in the chromosome 11 separately spanned from 42072670- 52764664 bp and 53920963- 54896945 bp with 14.73 and 49.87 times of reduction. In these 3 sweep regions, the Ednrb and Trpm6 were interesting for their association with melanogenesis regulation, and further work will focus on investigation variation of these two genes with teb color.