基于公共数据库的西瓜EST-SSR信息分析与标记开发

EST-SSR Information Analysis and Markers Development in Watermelon Based on Public Databases

为了给西瓜遗传基础研究提供新的共显性分子标记,对公共数据中的8 619条西瓜EST序列进行处理和分析,获得202个EST-SSR,分布在191条EST序列中,出现频率为2.31%,分布密度为1/19.1 kb。其优势重复基序为二核苷酸和三核苷酸（68.8%）,在二核苷酸基序中以AG/TG类型为最多（46%）;在三核苷酸基序中,以AAG类型为最多（43%）。基序重复次数以4次（17.8%）、7次（15.3%）和11次（14.9%）为最多。长度主要分布在20~30 bp（76%）。利用上述EST-SSR序列设计获得24对引物在西瓜白化致死近等基因系中进行验证,结果获得了16对有效的扩增引物,占总设计引物对数的66.7%。结果表明：利用公共数据库中的EST序列开发西瓜EST-SSR标记是一种有效的方法。

In order to explore a new co-dominant molecular markers to study the genetic basic research in watermelon.We analysed a total of 8 619 watermelon ESTs from GenBank and sought out 202 SSR contained in 191 EST sequences.The frequency of the SSRs was 2.31% and mean the distribution density was 1/19.1 kb in watermelon.The dominant repeat motifs were dinucleotide and trinucleotide.AG/TG was the most repeat type in dinucleotide（46%） and AAG was the most repeat type in trinucleotide（43%）.The most motif repeat times were 4（17.8%）,7（15.3%） and 11（14.9%）.The length was mainly distributed between 20 to 30 bp.We obtained 24 primer pairs from 202 EST-SSRs in watermelon.Then utilized albino lethal near-isogenic lines of watermelon for verify these primers.We obtained 16 effective amplified primer pairs,accouting for 66.7% of the total number of designed primer pairs.The results suggest that use of public EST databases to develop EST-SSR primers of watermelon are effective method.