Gene Pyramiding For Sheep Carcass Traits Based On EST-SSR Markers

In order to develop new EST-SSR markers to enrich ovine molecular markers and select polymorphic markers which correlate with economic trait to establish the multi-gene pyramiding method for the best genotype groups in allusion to different trait, ovine specific tissues EST were mined to develop EST-SSR markers. Afterwards, association analysis between EST-SSR markers and traits was carried out in order to find traits associative loci. Using e-PCR accomplished the chromosome locations and gene ontology annotations for polymorphic loci. In addition, the linkage relationships among traits associative loci were analyzed to acquire independent loci which were used for gene pyramiding. Finally, cluster analysis executed based on traits similarity to classify genotypes groups and find the best combination for different trait. The results are as follows:1.17 primer pairs of EST-SSR markers showed high polymorphism and 12 of them were relevant with wool or reproductive traits.16 polymorphic loci were successfully positioned on bovine 13 pair chromosomes using e-PCR.2. Chromosomes NJ clustering figure between cattle and sheep was drawn on the basis of similarity coefficient calculated by positioning markers. Finally,16 EST-SSR markers were successfully positioned on ovine chromosomes. The gene ontology annotation had performed and 9 loci were highly homologous with known gene.3.12 traits associative loci turned out to be independence based on the value of r2 and D' between two of them. A total of 7 groups and corresponding best genotypes combination were obtained on the basis of traits similarity among genotypes.The development of microsatellite markers based on EST is efficient though their polymorphisms were low and have high genetic effects with traits. It is feasible to position EST-SSR markers on ovine chromosomes by e-PCR. The best genotype groups in allusion to different trait was obtained through cluster analysis based on traits similarity among genotypes and it not only can be used for economic trait selection breeding programs, but also are helpful to animal breeding of gene pyramiding.