A new insight into cattle's maternal origin in six Asian countries.

The domestication of cattle fuelled the development of agricultural society in the history of human being. The evolution and genetic relationship of cattle can be elucidated by investigating the variation of mitochondrial DNA (mtDNA) D-loop sequence. In this study, we built a cattle phylogeny with a pool of 856 individual D-loop sequences, of which 264 Chinese cattle D-loop sequences were obtained in this study (141 ones were first analyzed, and 123 were first submitted) and the rest sequences of cattle from six Asian countries (Japan, Korea, Mongolia, Nepal, India and China) were retrieved from GenBank. Our results indicated that cattle from six Asian countries fell into three clades, Bos taurus (taurine), Bos indicus (zebu) and yak. Four main haplogroups T1A, T2, T3 (including T3A and T3B) and T5 were found in taurine, and two haplogroups I1 and I2 in zebu. Furthermore, we found that I1 and I2 haplogroups were separated by four variable sites rather than five ones and four haplogroups or sub-haplogroups of T1A, T3A, T3B and T5 were found for the first time in these Asian cattle. These data brought us a new insight into cattle's genetic structure in these six Asian countries. The geographical distribution of haplogroups was also outlined to provide systematic information on cattle genetic resources.