A number of 151695 wheat expression sequence tags (ESTs) that originated from GenBank/dbEST from July 14, 2003 to August 24, 2004 were used to search for simple sequence repeats (SSRs) with motif 2―5 bp, and 2038 simple sequence repeats (EST-SSRs), which accounted for 1.34% of EST database, were identified. Based on these SSR sequences, 249 EST-SSR primer pairs and 166 amplified clear bands in various wheat cultivars were designed. These EST-SSR markers can be used as new molecular markers in wheat and related species. Using Chinese Spring nulli-tetrasomic lines, 93 EST-SSR primer pairs and 193 EST-SSR loci were located on 19 wheat chromosomes except for 4A and 4B. Forty-three loci were mapped on 11 chromosomes of the genetic frame- work map previously constructed using recombinant inbred lines.
CHEN Haimei LI Linzhi WEI Xianyun LI Sishen LEI Tiandong HU Haizhou WANG Honggang ZHANG Xiansheng
为加速分子标记在翦股颖中的应用,利用GenBank中翦股颖EST数据信息,展开了翦股颖EST-SSR信息分析和标记开发研究。在16992条翦股颖EST序列中,共发现微卫星序列254条,占整个EST总数的1.49%。EST序列总长为12717kb,平均每50.07kb含有1个SSR。EST-SSR分布特征分析表明,在所有SSR中,六核苷酸基序最多(37.80%),三核苷酸基序(31.10%)次之;六核苷酸基序以TGCGGC/ACGCCG出现频率最高(3.15%),TCCAGC/AGGTCG次之(2.36%);三核苷酸基序以CAG/GTC出现频率最高(10.63%),其次分别为GCA/CGT(3.54%)、GAT/CTA(2.36%)和AAG/TTC(2.36%)。根据这些含有SSR的EST序列,利用Pri mer 5.0软件,设计了77对EST-SSR引物,并选择其中15对引物进行合成。15对引物在翦股颖中均有PCR扩增条带。利用这些引物,选用8个翦股颖品种进行多态性研究,其中9对EST-SSR引物有多态性,共检测到23个多态性位点,平均每对引物产生2.56个多态性位点。
