Characterization and association analysis with litter size traits of porcine matrix metalloproteinase-9 gene (pMMP-9).

The mammalian matrix metalloproteinase-9 (MMP-9), which might play a role in ovulation, uterus remodeling, embryo development, and implantation in mammals, is one of the potential functional candidate genes for porcine reproductive traits. In this study, the entire genomic sequence of porcine MMP-9 (pMMP-9) gene was established; it contains 13 exons and 12 introns. Real-time PCR analysis revealed that pMMP-9 is highly expressed in the Minzhu uterus before puberty and decreases significantly after sexual maturity (p < 0.05). Two single-nucleotide polymorphisms (A3011G and T5079C) that can be detected by PCR restriction fragment length polymorphism (PCR-RFLP) were discovered and tested for statistical associations with litter size traits in a crossbred population (Line DIV) derived from Landrace, Large White, Chinese Tongcheng and/or Chinese Meishan pigs. For A3011G, the GG genotype was associated with a significantly higher (p < 0.05) number of live births than those recorded for AA sows and the additive effect was significant (p < 0.05). The T5079C marker is not associated with litter size in this population. Further studies are needed to confirm the results of this study.