中文摘要：

利用蒺藜苜蓿（Medicago truncatula）EST数据库开发新的EST—SSRs标记，分析EST-SSRs的分布特征。利用SSRIT软件对NCBI上公布的285285条蒺藜苜蓿EST序列进行SSR序列的检测，共检测出6688个SSR序列，分布于6512个EST中，占整个EST数据库的2．28％。其中二核苷酸重复基元出现的频率最高，占总EST—SSRs的34．4％（2301条），其次是三核苷酸重复基元，占29．6％（1982条）．4～6核苷酸重复基元所占比例均较小。利用Primer Premier5．0随机设计100对EST—SSRs引物，PCR扩增结果表明，85对引物在蒺藜苜蓿RIL群体亲本A17和A20上有清晰的扩增条带，占合成引物总数的85％，在RIL-8群体中检测到29个EST—SSRs引物有多态性，占可扩增引物的34．1％。本研究开发了85个蒺藜苜蓿EST-SSRs新标记。

英文摘要：

New EST-SSRs markers by EST database of Medicago truncatula were developed and the distribution characteristic of EST-SSRs was analyzed. 6 688 of 285 285 EST sequences of M. truncatula from the National Center for Biotechnology Information （NCBI） were detected by SSRIT software, which accounted for 2.28%. Among them, 2 301 dinucleotide repeat elements, accounting for 34.4%, had the highest frequency and followed by 1 982 trinucleotide repeats, which accounted for 29. 6% of the total EST-SSRs. The ratio of four to six nucleotide repeat elements was comparatively lower. Selecting 100 primer pairs randomly, 85 primer pairs showed clear amplification belts, accounting for 85% of designed primers and 29 primer pairs showed polymorphisms, accounting for 34.1% of primers available. Besides, 85 new M. truncatula EST-SSR markers have been developed.