Identification of Novel Polymorphisms in Porcine Ring Finger Protein 4 and Matrix Metalloproteinase 9 Genes and Association Analysis with Litter Size Traits

Reproduction trait plays an important role in pig production. Identification of molecular markers that are linked to litter size may contribute to the genetic development of porcine reproduction traits. In this study, porcine ring finger protein 4 （pRNF4） and Matrix metalloproteinase 9 （pMMP-9） were selected as candidate genes on the basis of their physiological roles in reproduction. Two single-nucleotide polymorphisms （416C〉T in pRNF4 and - 1257G〉A in pMMP-9） that could be detected by PCR restriction fragment length polymorphism （PCR-RFLP） were discovered and tested for statistical associations with litter size traits in three populations. For 416C〉T, TT genotype was associated with a significantly higher （p〈0.05） number of live births than those recorded for CC sows and the additive effect was significant （p〈0.05） in Qingping and Min Pigs populations in later parities. For -1257G〉A, inconsistent results were found in three populations. The results suggested that T allele in pRNF4 gene might confer a high prolificacy in breeding and further studies were needed to confLrm the results.