Characterization Of The Sequence Of Cyt B Gene & D-loop Region Of Tiger MtDNA And Their Significance In Subspecies Identification

A sequence of 381bp in D-loop region of 13 Amur tiger mtDNA were cloned and sequenced. 2 sequences of Amur tiger D-loop region and 32 sequences of cyt b gene of 4 tiger subspecies in GenBank were also combined to our data in the analysis of characteristics of the two regions for evaluating their significance of subspecies identification. The result showed that 79 polymorphic sites forming 9 haplotypes were found within the 381bp region in D-loop; Two types of sequences were discovered in D-loop region of Amur tiger, Short Sequence that is highly homologous to other species, and Long Sequence that contains a 22bp insertion. The homology among 11 Short Sequences is 99.5%~100%, whilst that among 4 Long Sequences is 98.5%~99.2%. The homology between is Short Sequence and Long Sequence is75.5-81.6%. It indicated that the Long and Short sequence should be considered respectively when they become candidates for identifying subspecies; This region in D-loop is not suitable for phylogenetic analysis in case of their extremely large divergence. In the 32 full length cyt b sequences, 14 polymorphic sites forming 10 haplotypes were found, occupying 1.23% of the whole sequence. The homology among individuals is between 99.3 ~ 100%, averagely 99.6%, neither insertion nor deletion is found. All subspecies have their specific base at certain sites. These results showed that cyt b gene is very suitable for identifying subspecies of tiger. We proposed specific haplotypes on cyt b gene for specifically identifying Amur tiger, Bengal tiger, Indo-China tiger and Sumatran tiger.