Y Chromosome Molecular Genetic Diversity Analysis In Water Buffalo, Yak And Horse

The water buffalo is employed as an important draught animal in China. At present, studies of the origin and evolution of buffalo are involved in archaeology, morphology and molecular genetics. Tremendous progress has been made in studying mt DNA for maternal origin, but research on molecular genetic diversity of Y chromosome still needed for paternal origin. In this dissertation, in order to obtain more reliable buffalo Y-specific microsatellite(Y-STR) polymorphic markers, 42 pairs of the bovine Y-STR markers were used to screen 196 male samples representing 10 local Chinese buffalo breeds.Yak, an ancient cattle in China, has played an indispensable role in animal husbandry in the Tibetan ethnic group areas, which are important natural, ecological, and economic resources. In addition, different yak breeds are an important part of gene pool of bovinae domestic animals, which have an irreplaceable ecological status. Studies on genetic diversity of yaks are great of significance, but studies on the Y chromosome are still limited. In this dissertation, in order to acquire reliable yak Y-specific microsatellite(Y-STR) polymorphic markers, eight pairs of the bovine Y-STRs were used to screen the Y-STR in 108 male yaks of two Chinese Qinghai plateau yak populations and Datong yak.China has the most abundant genetic resources and the world’s largest number of horse. However, researches on molecular genetic diversity of the Y chromosome in Chinese horse were rare and there were no Y-SNPs found at present. Analysis of the genetic diversity of local horse will provide a scientific basis of breeding and make contribution to build up the database of horse genetic condition. In this dissertation, four pairs of horse Y-SNP primers were used to analysis the molecular genetic diversity of the 13 local Chinese horse breeds.The main results of Y chrosome genetic diversity analysis in buffalo, yak and horse are as follows:1. Screening Y-STRs and genetic diversity analysis in buffalo(1) In this study, 42 pairs of the bovine Y-STR markers were screened in Chinese buffalo, 35 buffalo Y specific microsatellite loci were found, including 12 polymorphic markers(UMN0108, UMN2008, UMN0705, UMN0907, UMN1113, INRA126, BC1.2, UMN2713, UMN2908, PBR1F1, UMN2001, INRA189). Otherwise, sevenpairs markers(UMN2303, UMN2405, UMN0929, UMN0803, UMN0301, UMN1307, UMN1514)were non-Y specific microsatellites.(2) Fluorescence genotyping results showed that three markers(INRA189, PBR1F1, and UMN2001) were polymorphic which proved that the conventional genotyping methods are certainly reliability.(3) Ten Chinese buffalo breeds have high genetic variability. The Cluster analysis showed that the Chinese buffalo have two paternal origin.2. Y-STRs screening and genetic diversity analysis in yak(1) In this study, eight Y-STR markers were screened in Chinese Qinghai plateau yak. Five markers(BM861,BYM-1,INRA126,UMN0307, and UMN0103)were non-Y specific microsatellite, one marker(INRA124) has no amplification product, two markers(INRA189 and UMN2404) were polymorphic.(2) Fluorescence genotyping results showed that two markers(INRA189 and UMN2404) were polymorphic. UMN2404 was first proved could be used for the Y chromosome genetic research on yak.(3) Two Chinese Qinghai plateau yak populations and Datong yak have a very low genetic diversity.3. Screening Y-SNP and genetic diversity analysis in horse(1)Three Y-SNPs(Y-45701/997,G→T mutation;Y-50869,T→A mutation;Y-45288,T indel)were first found in Chinese local horse.(2)At three Y-SNPs loci, Chinese local horses have low polymorphic compared with European and American horse. Horses from northwestern China revealed high Y chromosome diversity.