Novel SNPs of the ABCG۲ Gene and Their Associations with Milk Production Traits in Iranian Holstein Bulls

ABCG۲ (ATP binding cassette subfamily G member ۲) gene, located on chromosome ۶ encodes the ABCG۲ protein that transports various xenobiotics, cytostatic drugs across the plasma membrane as well as cholesterol into milk. A single nucleotide change (A/C) in base ۸۶ of exon ۱۴ is capable of encoding a substitution of tyrosine with serine in the ABCG۲ gene and increase milk yield while decreasing milk fat and protein concentrations. The major aim followed in this research was to study Single Nucleotide Polymorphisms (SNPs) of ABCG۲ gene and their association with milk production traits in Iranian Holstein bulls. Genomic DNA of ۱۰۵ ified bulls was extracted from semen samples using highly Pure PCR template preparation kit. Primers were designed through Oligo software (Version ۵.۰) and utilized in PCR. Then the PCR fragments were sequenced. The A/C substitution in base number ۸۶ of exon ۱۴ was observed with ۲% frequency which affected protein percentage (P< ۰.۰۵). Some SNPs were detected for the first time in intron ۱۳, exon and intron ۱۴ in comparison with sequences in the NCBI database. A deletion mutation in base number ۲۰ (T/-) and a missense mutation in base number ۶۷ (A/G) of exon ۱۴ that cause the substitution of serine with glycine were discovered which were significantly associated with protein yield and fat percentage, respectively (P< ۰.۰۵). Furthermore, significant association was observed between fat percentage and mutations in base numbers ۴,۱۳۳ (T/C) and ۴,۱۳۷ (T/G) of intron ۱۳ (P< ۰.۰۵). Substitutions in base numbers ۲ (T/C) and ۵۵ (G/C) of intron ۱۴ resulted in a significant effect on fat yield and fat percentage (P< ۰.۰۵).

Keywords:

ABCG۲ gene , Holstein bulls , Milk production traits , Polymorphism