Polymorphisms in the bovine hemoglobin-beta gene provide evidence for gene-flow between wild species of Bos (Bibos) and domestic cattle in Southeast Asia.

The electrophoretic variation in bovine hemoglobin-beta (HBB) is one of the most investigated genetic markers. The presence of a unique HBB variant, HBB(X), in Southeast Asian cattle has been reputed as a sign of gene-flow from wild bovine species. In this study, we analyzed the DNA sequences of HBB genes in domestic and wild bovine species to verify this belief. Isoelectric focusing of HBB chain revealed that the HBB(X) in domestic cattle had dimorphism and was separated into HBB(X1) and HBB(X2). The HBB(X1) had the same DNA sequence of the common HBB variant in gayal (Bos gaurus frontalis), while some of the HBB(X2) were identical with that of Cambodian banteng (Bos javanicus birmanicus). As a result, we confirmed that the bovine HBB variants can be a good indicator of introgression between wild and domestic cattle. The HBB(X1) was always predominant to HBB(X2) in the continental populations, suggesting that the gaur had contributed to the gene pool of domestic cattle in this region much more than the banteng. On the other hand, the mitochondrial DNA analysis could not detect gene-flow from wild species. Autosomal markers that can trace the phylogeny between alleles are suitable for the assessment of bovine interspecific introgression.