Molecular Characterization and a Duplicated 31-Bp Indel Within the LDB2 Gene and Its Associations with Production Performance in Chickens

Many studies have shown that the LDB2 gene plays a regulatory role in retinal development and the cell cycle, but its biological role remains unclear. In this study, a 31-bp indel in the LDB2 gene was found for the first time on the basis of 2797 individuals from 10 different breeds, which led to different genotypes among individuals (II, ID and DD). Among these genotypes, DD was the most dominant. Association analysis of an F-2 resource population crossed with the Gushi (GS) chicken and Anka chicken showed that the DD genotype conferred a significantly greater semi-evisceration weight (SEW, 1108.665 g +/- 6.263), evisceration weight (EW, 927.455 g +/- 5.424), carcass weight (CW, 1197.306 g +/- 6.443), breast muscle weight (BMW, 71.05 g +/- 0.574), and leg muscle weight (LMW, 100.303 g +/- 0.677) than the ID genotype (SEW, 1059.079 g +/- 16.86; EW, 879.459 g +/- 14.446; CW, 1141.821 g +/- 17.176; BMW, 67.164 g +/- 1.523; and LMW, 96.163 g +/- 1.823). In addition, LDB2 gene expression in different breeds was significantly higher in the breast muscles and leg muscles than in other tissues. The expression level in the breast muscle differed significantly among stages of GS chicken development, with the highest expression observed at 6 weeks. The expression levels in the pectoral muscles differed significantly among Ross 308 genotypes. In summary, we studied the relationships between a 31-bp indel in the LDB2 gene and economic traits in chickens. The indel was significantly correlated with multiple growth and carcass traits in the F-2 resource population and affected the expression of the LDB2 gene in muscle tissue. In short, our study revealed that the LDB2 gene 31-bp indel can be used as a potential genetic marker for molecular breeding.