Single-Nucleotide Polymorphisms Identified within Exon 2 of Fertility-Associated Bone Morphogenetic Protein (BMP15) Gene in Three Romanian Sheep Breeds

The improvement of the reproductive traits of animals is of great interest for livestock production. Due to its positive impact on the sheep industry's profitability, prolificacy is one of the most economically significant biological traits, showing variation between and within breeds of domestic sheep (Ovis aries). Different mutations in BMPR-1B, BMP15 and GDF9 genes coding for the transforming growth factor-beta (TGF beta) superfamily have been shown to influence the ovulation rate and litter size. Numerous single-nucleotide polymorphisms (SNPs) in the bone morphogenetic protein 15 (BMP15) gene have been linked to ewe fecundity. Using targeted PCR amplification and Sanger sequencing, we were able to identify heterozygous SNPs in exon 2 of BMP15 in three sheep breeds reared in Romania: Tsigai, Cluj Merino and Tsurcana. The sequence analysis revealed three previously documented mutations, namely the missense mutation c.755T>C (L252P), which is predicted to change the tertiary structure of the BMP15 protein, and two silent mutations, c.747T>C (P249P) and c.1047G>A (V349V). In addition, we also identified one novel silent mutation, c.825G>A (S275S). Based on our findings and publicly available data, we indicate four putative mutational hotspots within exon 2 of BMP15 that could be considered for improving the indigenous sheep breeds through targeted gene editing and SNP genotyping strategies.