To further utilize the EST-SSR resources of ginseng. 4988 ESTs of Panax quinquefolium L in the database of NCBI were downloaded and analyzed , which had a length of 2616. 042 kb on total. Among them, there were 313 ESTa sequences containing 349 EST-SSR, which amounted to 7. 00 ％ of the all ESTs sequence population. The average length and diatribution distance of the EST- SSRs were about 24.4 and 7.5 kb, respectively. Among the different motifs ranging from 1 to 6 bp, trinucleotide repeats were most abundant. it was 34. 09 ％ , followed by dinucleotide repeats and mononucleotide repeats,which were 32. 09 ％ and 21. 78 ％ . Among all identified motif types. A/ T had the high EST frequency ( 20. 9 ％ ) , followed by AT/TA , which was 16. 9 ％ . The results indicated that , the SSR sequence had higher frequency from EST database of Pauax quinquefolium L . the type abundant and the polymorphism to be high . According to the EST of Panax quinquefolium L. .building EST-SSR marker is a effective way .%为了进一步利用现有的西洋参EST-SSR资源,从NCBI公共数据库中下载了4988条西洋参EST,全长为2616.042 kb.含SSR的E ST序列313条,共349个SSR,平均每相隔7.5 kb出现1个SSR.SSR出现的频率和平均长度分别为7.00%和24.4 bp.在1～6 bp的重复基元中,三核苷酸重复基元出现频率最高,为34.09%;其次为二核苷酸重复基元和单核苷酸重复基元,分别为32.09%和21.78%.出现最多的重复基元为A/T(20.9%),其次是AT/TA(16.9%).结果显示,西洋参的EST数据库中SSR序列出现频率较高,类型较丰富、多态性较高,根据西洋参EST建立其EST-SSR标记是一条简便而又有效的途径.
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