Molecular Cloning of the Porcine HTRA3 Gene and Association of a SNP with Litter Size Traits.

HtrA serine peptidase 3 (HTRA3) is an important reproduction-related gene. In this study, we cloned the full-length coding sequence of the porcine HTRA3 gene using RT-PCR. Sequence analysis of this gene revealed that the pig HTRA3 gene encodes a protein of 453 amino acids, which has high homology with the HTRA3 protein of five species: water buffalo (96 %), killer whale (96 %), sperm whale (96 %), Yangtze River dolphin (96 %) and smalleared galago (93 %). Phylogenetic analysis revealed that the pig HTRA3 gene has a closer genetic relationship with the HTRA3 gene of cattle. PCR-HpaIIRFLP was established to detect the GU373693:c.1140 G>A substitution of the porcine HTRA3 gene coding sequence, and eight pig breeds displayed obvious genotype and allele frequency differences at this mutation locus. Association of this SNP with litter size traits was assessed in Large White (N = 200) and Landrace (N = 200) pig populations, and the results demonstrated that this polymorphic locus was significantly associated with the litter size of all parities in Large White and Landrace sows (P < 0.05). Therefore, the HTRA3 gene could be a useful candidate for increasing the litter size in pigs. These data serve as a foundation for further insight into this novel porcine gene.