Study on heteroplasmic variation and the effect of chicken mitochondrial ND2

NADH dehydrogenase subunit 2 gene (ND2) is one of the mitochondrial DNA (mtDNA) protein coding genes, which is a subunit of NADH dehydrogenase. The main purpose of this study was to investigate the variation/heteroplasmic sites of chicken ND2, and thus to evaluate the association with chicken growth traits, carcass traits, and serum biochemical indexes. Seventeen variants were detected in the ND2 gene by Sanger sequencing, which constructed 15 haplotypes; the haplotype diversity (hd) was 0.7692. Mt.A5703T and mt.T5727G in the ND2 gene had been detected as the heteroplasmic sites via the created restriction site restriction fragment length polymorphism (CRS-PCR-RFLP) method. Moreover, the study on distribution of two heteroplasmic variants in the Gushi chicken F2 resource population revealed that the heteroplasmic ratio of mt.A5703T and mt.T5727G was 9% and 40%, respectively. It showed that there was obvious heteroplasmic difference between two sites. Association analysis of the variation/heteroplasmy with the related traits in Gushi chicken F2 population showed that the mt.A5703T and mt.T5727G were significantly associated with the pectoral muscle fat content and the duodenum length, but no significance was found with body weight (BW). It was the first time to indicate that heteroplasmic variation had significant effect on growth traits, carcass parameters, and meat quality traits, which showed the potential importance of related variation.