Study On The Genetic Diversity, Origion And Divergence By Using Mitochondrial DNA Sequences Of 6 Chinese Domestic Goat Breeds In Sichuan, Chongqing And Guizhou Province

In this study,the complete sequence of mitochondrial DNA(mtDNA)control region(CR,D-loop) was sequenced of 66 individuals from 7 domestic goat breeds(including 1 introduced breed-Boer goat)in Sichuan,Chongqing and Guizhou province.Based on goat's mtDNA whole sequnence and Capra goats' D-loop sequnences,the genetic variety,origion and divergence of these goats were analyzed by using DNAMAN,BioEdit,ClustalW,MEGA3.1,DNASP,Arlequin2.0 and Network4.1 softwares.The results showed that:1.The goat complete sequence length of mtDNA D-loop CR was 1,212 bp or 1,213bp.The length difference was one insertion/deletionin on 1075 site.There were 116 polymorphic sites,with 83 parsimony informative polymorphic sites and 33 singleton polymorphic sites.Only 1 polymorphic site with three variants was found in our study.The largest number of site variants was in the sequence from 300bp to 700bp,and then from 1000bp to 1100bp.The base composition of D-loop complete sequence in the tested breeds was A+T(about 55.7%)＞C+G(about 44.3%).The number of transition was larger than that of transvertion.A total of 50 haplotypes were found,and the range of haplotype diversity and nucleotide diversity were 0.9167-1.0000 and 0.004125-0.023157,respectively.The results indicate that the goat genetic diversity in Sichuan,Chongqing and Guizhou province is very abundant.2.The population genetic structure was studied by using AMOVA.The results showed that the variation was only 3.82%among groups,whereas 96.18%within breeds.There was no significant difference was found between breeds.The results indicate that 6 tested goat breeds have no significant heredity differentiation.3.Three NJ trees of the 6 goat breeds were formed based on matrix D_a,Dxy and Fst.The result showed that the NJ tree based on matrix Dxy was the best.First,Nanjiang goat and Chuandong White goat was custered together,and then were Banjiao goat,Chengdu Grey goat,Guizhou White goat,Qianbei Grey goat and Boer goat.4.There were 2 differenent lineages(A and B)in the tested goat breeds,by using phylogenetic and divergent goat mtDNA median network analysis.The results indicate that goat breeds in Sichuan, Chongqing and Guizhou province were origioned from two differenent ancestors.5.The mean pairwise difference and nucleotide diversity between haplotypes from the Chinese goats are 5.000000 and 0.007976,whereas those from the five Asian countries(i.e.India,Pakistan,Mongolia, Malaysia and Laos)are 3.338235 and 0.006940,respectively.Our preliminary study indicated that mtDNA lineage B of goats was probably originated from China.