牡丹EST资源的SSR信息分析

Analysis of SSR motifs in tree peony(Paeonia suffruticosa Andrews.) EST sequences

首先对NCBI数据库下载获得的2 204条牡丹EST序列进行比对,去冗余后得到1 658条牡丹EST序列,然后利用MISA软件对这些序列进行筛查,结果在其中901条EST序列中发掘出1 111个SSR,出现频率为67.00%,平均每1 004 bp出现1个SSR。在牡丹EST–SSR中,单核苷酸重复是最主要的重复类型(89.38%),其次是二核苷酸重复(6.67%)和三核苷酸重复(3.78%),四核苷酸重复和六核苷酸重复分布极少,没有五核苷酸重复。A/T是优势重复基元,占微卫星总数的87.76%。牡丹EST–SSR基元类型的重复次数主要集中在6～30次,其基元长度主要集中在26～31 bp。

The development of genomic SSR markers is a difficult and time-cost work.EST database has become a rich source for in silico identification of SSRs and provided a cost-effective,labor-efficient approach for SSR marker development.Firstly,2 204 ESTs of tree peony（Paeonia suffruticosa Andrews.） were downloaded from the database of NCBI and some redundant sequences were removed and 1 658 non-redundant ESTs were obtained.Subsequently,MISA,a web tool for SSR hunting,was used to analyze the SSR motifs in the EST sequences.The results showed that a total of 1 111 SSRs were detected which were distributed in 901 ESTs,with the frequency for the non-redundant ESTs being 67.00 %,the average distribution distance of the EST-SSRs were about 1 004 bp.Among the different SSRs motifs,mononucleotide repeats were most abundant（89.38%）,followed by dinucleotide（6.67%） and trinucleotide repeats（3.78%）.Distribution of hexanucleotide repeat and tetranucleotide repeat were very few,and there is no existence of pentanucleotide.A/T was the most frequent repeat motif and accounted for 87.76% in all SSRs.Among all SSRs,The repeated times of motifs mainly concentrated in 6 to 30,and the motifs length mainly concentrated in 26 to 31 bp.