A SNP at the exon 1 of the Lipoprotein lipase (LPL) gene is associated with milk traits in the Mediterranean River buffalo

Lipoprotein lipase is a key enzyme for the lipid metabolism playing a fundamental role in the composition of fat in adipose tissue as well as in milk. LPL gene was poorly investigated in dairy ruminants, and it has been never studied in river buffalo. Aims of this work were to explore the genetic diversity of LPL (from exon 1 to 4) in this species; to characterize the gene promoter; and to achieve an association study with milk traits. Genomic DNA of 14 individual samples of Mediterranean Italian breed was amplified and sequenced. Thirteen consensus sequences for transcription factors were found. C/EBPα and Oct-1 are the main regulatory motifs together with LP-α, although a deeper investigation is necessary to elucidate the role of the latter element, which in buffalo (and ruminants in general) is lacking the downstream cis-acting motifs (LP-β) compared to human. A total of 11 SNPs have been detected. The SNP g.107A>G was the only polymorphism found at exon level, therefore a genotyping was achieved by PCR-RFLP in a population of 523 Mediterranean buffaloes. The allele frequency was 0.63 and 0.37 respectively for the G and A allele. This SNP was significantly associated with n3-PUFA (P<0.03; 306 individual milk samples), with the GG genotype showing the highest value (+8.25% and +7.14% compared with AA and AG, respectively). The AA and GG genotypes showed higher values also for the milk yield compared with AG, but the estimated difference only approached the level of significance (P=0.07). This study is among the first reports that show an association between milk fatty acids and LPL genotype in ruminants, and it adds further knowledge in the study of genes involved in the regulation of milk fatty acids composition in river buffalo.