Intron polymorphisms of MAGI-1 and ACSF2 and effects on their expression in different goose breeds

The goose is one of the most important waterfowl, having lowing laying rate. Previous studies have shown the SNPs in the introns of MAGI-1 (Record-106975) and ACSF2 (Record-106582) significantly associated with egg production in geese. However, the mechanism of those SNPs influencing egg production remains unclear. In this study, the three goose breeds (Yangzhou geese, Zhedong white geese, and Carlos geese) with obviously different egg production were selected, and the allele frequency distribution and functions of those SNPs were investigated. The results suggested that the allele frequency distribution of ACSF2 was significantly different among the three goose breeds (χc² = 92.377, Pc = 2.29 × 10^-22), with the C allele appearing at frequencies of 0.29 in the Yangzhou geese and 0.94 in the Carlos geese. In contrast, the allele frequencies of MAGI-1 were not significantly different among the different goose breeds. Quantitative Reverse Transcription PCR (qRT-PCR) showed that the expression of MAGI-1 with the AG genotype individuals was significantly higher than those of the AA and GG genotype. For ACSF2, the CC genotype had significantly higher expression than both the AC genotype and the AA genotype. The luciferase reporter analysis revealed that the site-directed mutation ACSF2 (A>C) significantly drove the expression activity. Further analysis suggested that the mutation altered the binding site of the transcription factor BARHL2. Binding of BARHL2 to the ACSF2 intron was confirmed by electrophoretic mobility shift assay (EMSA) analysis. Thus, our findings revealed the A>C mutation of ACSF2 (Record-106582) could promote the expression by regulating the binding of BARHL2, resulting in differences in egg performance, which provided molecular insights into the effect of the polymorphism in ACSF2 on egg performance in geese.