Association of Single Nucleotide Polymorphisms in Exon 6 Region of BMPRIB Gene with Litter Size Traits in Sheep

Abstract

The objective of this study was to investigate polymorphisms of BMPRIB (bone morphogenetic protein type IB receptor) gene and its effect on litter size traits in sheep. Three populations including 101 Small Tailed Han sheep, 79 Poll Dorset and 81 hybrids (Poll DorsetxSmall Tailed Han sheep) were used to detect the polymorphisms in exon 6 region of sheep BMPRIB gene. A fragment of approximately 190bp was amplified by one pair of primers, the polymorphism was revealed from the analysis of three populations by the technique of PCR -SSCP, and a mutation from A to G at 746 of the coding region was confirmed by sequencing in several individual. Statistical results indicated the distribution of allele B (with a A→G mutation) and A (without mutation) or genotype AA, AB and BB frequencies differed in three populations. BB genotype (44.55%) and B allele (66.34%) frequencies of Small Tailed Han sheep were higher than those of the others. Analysis of variance showed that the polymorphism of BMPRIB gene was associated with positive effect on litter size traits. The means of genotype BB and AB were about 1.04 and 0.74 more than genotype AA for litter size (p<0.05). Analysis of BMPRIB genotype effects on litter size in three populations indicates the existence of genotype BB or B allele increases the litter size. It suggested that the polymorphism in exon 6 (at 746 in the coding region) of sheep BMPRIB gene may be used as a marker for early selection of prolificacy in sheep.