Abstract
Min pigs, a prominent local breed from Northeast China, have diverged into two distinct breeds, Ermin (EM) pigs and Hebao (HB) pigs, through prolonged natural and artificial selection. Although these two breeds exhibit distinct differences in body size, the genetic mechanisms underlying this variation remain poorly understood. In this study, we performed whole-genome resequencing and transcriptome analysis on EM and HB pigs to elucidate the genetic basis of body size variation in Min pigs through genome-wide selection signal analysis and the identification of differentially expressed genes (DEGs). The analysis of genetic diversity and population genetic structure across 14 pig breeds revealed that, compared with other breeds, Min pigs present relatively high genetic diversity and a unique genetic structure. Notably, EM pigs exhibited significant genetic differentiation from HB pigs. Integrated analysis of whole-genome resequencing and transcriptome data revealed candidate genes associated with body size variation in Min pigs, including ENPP1, ENPP3, SPP1, CLU, ITGA11, ITGB1, IQGAP2, BMP7, and F2RL2. These genes are enriched primarily in pathways related to ECM-receptor interactions; pantothenate and CoA biosynthesis; starch and sucrose metabolism; nicotinate and nicotinamide metabolism; pyrimidine metabolism; nucleotide metabolism; cellular responses to lipids; biomineral tissue development; biomineralization; and other pathways related to cell signaling, metabolic responses, lipid deposition, and skeletal development. Notably, ITGB1 on chromosome 10 showed strong positive selection in EM pigs, with an SNP locus exhibiting a significant G/A allele frequency difference between EM pigs (G = 52.94%, A = 47.06%) and HB pigs (G = 0%, A = 100%). Our findings suggest that Min pigs potentially modulate lipid metabolism efficiency in adipose tissue through variations in the expression of the ITGB1 gene, potentially contributing to body size differences. These results provide new insights into the genetic mechanisms underlying body size variation in domestic pigs and serve as a valuable reference for identifying and breeding pig breeds with distinct body sizes.