蒺藜苜蓿EST-SSRs分布特征及标记的开发

Distribution characteristics and marker exploitation of EST-SSRs in Medicago truncatula

利用蒺藜苜蓿(Medicagotruncatula)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285 285条蒺藜苜蓿EST序列进行SSR序列的检测,共检测出6 688个SSR序列,分布于6 512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%(2 301条),其次是三核苷酸重复基元,占29.6%(1 982条),4～6核苷酸重复基元所占比例均较小。利用Pri mer Premier 5.0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。

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.