Study On Genetic Diversity In 6 Native Sheep Breeds In China Using MtDNA Marker

The genetic diversity of 283 sheep of six indigenous sheep breeds in China was analyzed using mtDNA marker based on the requirement of project assignment. The sheep breeds include Bayinbuluke sheep with short and fat tail from Bayinbuluke district of Hejing county, Cele Black sheep with short and thin tail from Cele county in North Kunlun Mountain, Kalakuer sheep with fat rump from Kule county.Keerkezi sheep with short and fat tail from Kezilesukeerke Prefecture and Yecheng sheep with short and fat tail from Yecheng Prefecture of Xinjiang, and Qinghai Black Tibetan sheep with long and fat tail from Qinghai province in China. The study was based on PCR-SSCP and subsequent clone sequencing protocols. Six pairs of primers for the PCR-SSCP of sheep mtDNA were designed by author (OV4, OV5, OV6, OV7, OV8 and OV9) and other primer pairs to amplify the D-Loop region designed byHiendleder (1998a) and Gunjun (OV2 and OV3) were also used in this study. The main The 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 indegenous sheep genetic resources. The results were as following:1. Comparison of the mtDNA sequences showed the replacement substitutions of base pairs in D-Loop between the hyplotypes A, B and C. AH the substitutions are transitions alone.2. PCR-SSCP and dendrograms of D-Loop proved that the hyplotype C also existin othersheep breeds of China.3. Two nonsymonymous mutations were found in ND2 and Cytb as of Asn¹⁴⁶³⁴ —? Ser¹⁴⁶³⁴ and Met⁴²⁰⁸—?Thr⁴²⁰⁸.Apart from these, 7 symonymous mutations were found in all sheep mtDNA sequences.4. Length variation in insertion or deletion of base pair or tandemly repeated sequence in D-Loop was found in six sheep breeds.5. An insertion of a base pair (c) in the six sheep breeds (between 16343 and 16344) was detected compared to the published sheep mtDNA complete sequence in the GenBank.6. Hyplotypes A, B and C were basically in the same linkage in six sheepsheep breeds with a few exceptions.7. Phylogenetic trees of NJ, UPGM and amaximum likelihood estimation support the classification of three hyplotypes in six sheep breeds in China and Bayinbuluke sheep and Kalakuer sheep had a closer relationship compared to others.