Identification of polymorphic loci in the deiodinase 2 gene and their associations with head dimensions in geese.

Objective This study was conducted to clone and compare the molecular characteristics of the deiodinase 2 (DIO2) gene between Sichuan White geese and Landes geese, and to analyze the association between polymorphisms of the DIO2 gene and head dimensions in Tianfu meat geese. Methods The coding sequence of the DIO2 gene was cloned by polymerase chain reaction (PCR) and vector ligation and aligned by DNAMAN software. A total of 350 Tianfu meat geese were used to genotype the polymorphisms of the DIO2 gene and measure the head dimensions. Association analysis between the polymorphisms of the DIO2 gene and head dimensions was carried out. Results An 840-bp coding sequence of the DIO2 gene was obtained and comparison analysis identified four polymorphic loci between Sichuan White geese and Landes geese. Further analysis showed that the dominant alleles for the four polymorphic loci were G, G, A, and T and the frequency of the heterozygous genotype was higher than that of the homozygous genotype in Tianfu meat geese. Compared to that in the population of non-knob geese of Tianfu meat geese, the head dimensions in the population of knob geese were significantly higher except for nostril height. However, in the non-knob geese, beak width 1 (BW1), beak width 2 (BW2), nostril length (NL), cranial width 1 (CW1), and maxillary length (ML) had significant differences among different genotypes or haplotypes/diplotypes. Conclusion These results suggested that polymorphisms of the DIO2 gene could be considered molecular markers to select larger heads of geese in the population of non-knob geese.