小麦EST-SSR的分析及其引物的开发

Analysis and Exploitation of EST-SSRs in the Triticum aestivum

为开发出具有丰富多态性的、新型的小麦EST-SSR标记,利用已公布的1 071 367条小麦表达序列标签(expressed sequence tags,EST)序列,对≥24 bp的微卫星或简单重复序列进行了系统分析。结果表明,在所分析的小麦EST序列中,搜索到长度大于或等于24 bp,基序匹配值大于80%的SSR序列32 350个。在这些SSR中,单碱基SSR最多,数量达18 075个,占SSR总数的55.9%;其次为3核苷酸SSR,共6 106个,占SSR总数的18.7%,重复数大于30次以上的达444个,占所有3核苷酸SSR的7.2%。4核苷酸SSR数量最少,仅有696个,仅占SSR总数的2.2%。研究中收搜索到的6核苷酸SSR共1 562个,其基序组成可分为145类,优势基序为AGCCGC(达214个)。以上结果说明小麦EST序列中含有丰富的SSR,这非常有利于开发多态性较高的EST-SSR标记。

A total of 1 071 367 expressed sequence tags （ESTs） of Triticum aestivum was searched formono- to hexa-nucleotide simple sequence repeats （SSR or microsatellite） using software of ＂TandemRepeats Finder＂. And the type, size and frequency of these SSRs were determined. The results showedthat a total of 32 350 SSRs were found out in these ESTs with the criteria of SSR length ≥24 bp and80% matches. Considering all six classes of SSR, the most abundant microsatellite was mono-nucieotiderepeat, and the number of mono-nucleotide repeat SSR was 18 075, occupied 55.9% of total SSRs, followed by tri-nucleotide repeat, which number was 6 106, accounting for 18. 7% of all SSRs, and therewere A.A.A. tri-nucleotide repeat SSRs whose repeat number was more than 30, accounting for 7.2%. Theleast microsatellites were tetra-nucleotide, their number was 696, only accounting for 2. 2% of all SSRs.Especially, 1 562 hexa-nucleotide repeats SSRs were observed, and their motifs were also very abundance, with 145 types, and AGCCGC is the major motif, being 214. In this study, because the size ofall SSRs was more than or equal to 24 bp, these results would be useful for further molecular biologicalstudies and development of new EST-SSR molecular markers of T. aestivum.