Analysis Of The Sequence Evolution Of MtDNA Gene And Population Geneitc Structure In South West Horse Breeds

The genetic diversity of 147 horses of eight horse breeds was analyzed. The horse breeds were collected from Ceheng country of Guizhou province (Guizhou horse, n=30), Debao district of Guangxi province (Debao horse, n=34), Qiubei country of Yunnan province (Qiubei horse, n=30) , Wenshan country of Yunnan province (Wenshan horse, n=18), Dali district of Yunnan province (Dali horse, n=10), Ningqiang district of Shanxi province (Ningqiang horse, n=20), Shandong province (Jianchang horse, n=2) And the shelted pony (n=3) from Jinan zoo as a control. The study was based on PCR-SSCP and subsequent clone sequencing protocols. Three pairs of primers for the PCR-SSCP of horse mtDNA were designed by author (MT2,MT3,MT5) and other primers (MT1,MT4 ) were designed by Stephen Paul Harrison. The main thesis objective of this study was to address the genetic variation within population and between populations which could provide baseline information for conservation and utilization of the South West Horse genetic resources. The results were as following:1. The amplified products of 3 pairs of primers were polymorphic. In MT2 and MT4, there were existed two haplotypes and the frequency of haplotype B was higher than A. We detected four haplotypes in MT3 and haplotype A is prevalent.2. In ND4 and ND4L sites, the average percent value of G+C was 42.3%～47.1%, the bias of nucleotide composition is not prominence, but the bias of the frequency of codon usage is prominence3. Nucleotide diversity was high in all of South west horses (0.00467～0.00737), Dali horse'Pi was lowest (Pi=0.00467); Qiubei horse'was highest (Pi =0.00737). The genetic distance among horse breeds was nearest; coefficient of similarity was high.4. Nst of South west horses is among -0.35665～0.01694.5. Independence of Qiubei horse was highest among horse breeds and they can be viewed as a MU independently; Average number of nucleotide differences of Dali horse was lowest among horse breeds and signified the breed seldom inlet gene of others breeds, so they should be protected.