Identification of IGFBP2 gene polymorphism and association of genotypes with performance traits in Large White Yorkshire pigs.

Abstract

Pig promises distinct qualities like early maturity, high fecundity, produces piglets between eight to twelve in each farrowing and high feed conversion efficiency that make piggery a low-cost profitable enterprise. The objective of this study was to evaluate the genetic diversity in Large White Yorkshire pigs based on variations in Insulin like growth factor binding protein 2 (IGFBP2) gene which is involved in regulation of embryonic development and association of variants with economic traits. Blood samples were collected from 100 pigs and polymorphism was explored in IGFBP2 gene using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique. A 245 bp fragment in intron 2 of IGFBP2 gene was amplified using PCR. Amplified PCR products of IGFBP2 gene were digested using MspI restriction enzymes. In this study, polymorphic patterns were revealed for the IGFBP2 gene. Two types of genotypes i.e. CC (55 and 190 bp) and CT (55, 190 and 245 bp) were observed for the targeted loci of intron 2 of IGFBP2 gene. The CC genotype was found to have higher genotype frequency as 0.88. Frequencies of 'C' and 'T' alleles were 0.94 and 0.06 in Large White Yorkshire pigs. Results of the Chi-square test showed that the targeted locus of IGFBP2 gene was in Hardy-Weinberg equilibrium (p < 0.05) in the screened pig population. CT genotyped pigs farrowed one more piglet than CC and litter weight at birth was also one kilogram more in CT as compared to the homozygous CC genotyped pigs. A total of 13 samples of intron 2 region of IGFBP2 gene were sequenced and on comparison of sequencing results with reference sequence of Duroc cross (BV727778), a single nucleotide polymorphism (SNP) i.e. T278C was found and there was change in nucleotide at one position i.e. A171G (Transition). In conclusion, CT genotypes of the IGFBP2 gene may be selected further for propagation through breeding programmes in Large White Yorkshire pigs for higher litter size and litter weight at birth.