Genetics analyses to three breeds of sheep in Xinjiang with EST-SSR polymorphic.

A total of 3295 EST sequences from NCBI were mined to develop EST-SSR makers.Using SSRHunter software,two hundred and nine SSR motifs were identified from 196 ESTs and the frequency of EST-SSRs was 6.3%.The dinucleotide repeat motif was the most abundant SSR,accounting for 71.8%,followed by tri-,hexa-,penta-and tetra-nucleotide repeats by 9.1%,8.1%,5.7%and 5.3%,respectively.Among the dinucleotide repeats,AC/TG was the most abundant type.A total of 22 EST-SSR primer pairs were designed and tested with genomic DNA of Chinese Merino sheep and 18 of which could show clear PCR products by electrophoresis.Five of these primers revealed a moderate to high polymorphism information content(PIC)in Chinese Merino sheep,Duolang sheep and Romney Marsh sheep and the PIC value ranged from 0.5030 to 0.7583.These EST-SSR markers can be used for further studies on the relationship between micro-satellite loci and wool traits of sheep.Duolang sheep and Romney Marsh sheep's genetic relationship was closest.