银杏EST序列中微卫星的分布特征

本文利用从NCBI下载的21 590条银杏EST序列,分析了银杏(表达序列标签微卫星)EST-SSR在银杏EST序列的分布和比较了在不同长度EST序列中的SSR特性.在剔除冗余和低质量序列后,得到总长为5 708.385 kb的无冗余EST序列7 961条,发现了405个EST序列(5.09%)含有475个SSR,长度400-1000 bp的EST序列含SSR位点数为445个,占SSR总数的93.68%.二核苷酸和三核苷酸基元类型是银杏EST-SSR的主要类型,分别占SSR总数的73.89%和24.00%,最常见的SSR基元是:(AT)_n、(AG)_n、(AC)_n、(AAG)_n和(AAT)_n.通过对银杏EST序列中SSR位点信息的发掘分析,为有针对性地设计EST-SSR引物,开发银杏EST-SSR分子标记奠定基础.

Characteristics of EST-SSR Distribution in Ginkgo ESTs

In this study,we analyzed the distribution of EST-SSR in ginkgo EST database and compared the characters of EST-SSRs derived from the ginkgo expressed sequence tags (ESTs) in different length based on the 21 590ginkgo ESTs online downloaded in the NCBI database.7 961 non-redundant EST sequences that totaled 5 708.385 kb length were acquired posterior to removing some redundant and poor quality,EST sequences.It was found out that 475 SSRs distributed in 405 EST sequences which accounted for 5.09% of the 7961 non-redundant ESTs,and 445 SSRs in the range of 400 bp to 1000 bp length were identified which accounted for 93.68% of the total number of acquired SSRs.Dinucleotide and trinucleotide would be the major repeat types,which accounted for 73.89% and 24.00% of the total number of acquired SSRs,resepectively,and the motifs of (AT)_n,(AG)_n,(AC)_n,(AAG)_n and (AAT)_n might be the most frequent motifs.This research might lay the foundation for designing the targeted EST-SSR primers and developing EST-SSR molecular markers by mining the information of EST-SSR loci in ginkgo EST sequence data.