Effect of Genetic Variations within the I-mfa Gene on the Growth Traits of Chinese Cattle.

I-mfa (inhibitor of the MyoD family a) is a transcription modulator that binds to MyoD family members and inhibits their transcriptional activities. It is highly expressed in the sclerotome and plays an important role in the patterning of the somite early in development. In this study, the polymorphisms of the bovine I-mfa gene were detected by polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) and DNA pool sequencing methods in 541 individuals from three Chinese cattle breeds. The results showed that P3 locus had two novel complete linked single nucleotide polymorphisms (NC_007324.4:g.12284A>G and g.12331T>C), resulting in a missense mutation p.S(AGC)113G(GGC) and a synonymous mutation p.H(CAT)128H(CAC), respectively. P4 locus had a novel SNP (NC_007324.4: g.16432C>A), which resulted in a nonsense mutation p.C(TGC)241X(TGA). The statistical analyses indicated that the three SNPs, are associated with the phenotypic traits in Luxi (LX), Qinchuan (QC), and Jiaxian (JX) cattle population (P < 0.05 or P < 0.01). The mutant-type variants were superior for growth traits; the heterozygote diplotype was associated with higher growth traits compared to wild-type homozygote. Our results provide evidence that polymorphisms in the I-mfa gene are associated with growth traits and may be used for marker-assisted selection in beef cattle breeding program.