Abstract: Abundance and distribution of microsatellite (simple sequence repeats, SSR) with repeated unit lengths of 1-6 base pairs in protein coding region of whole genome in rice blast fungus, Magnaporthe grisea was examined. The result showed that 3 240 SSRs (longer than 15 bp, 80% matches) were found within 2 387 genes. Among 4 732 annotated genes up to now, SSRs were found in 861 genes. Tri and hexa nucleotide repeats prevailed in protein coding exons of the genome, whereas, mono , di , tetra and penta nucleotide repeats were rare. The genes in which SSRs were most frequently found related to cellular regulation, and their position in genes varied among genes. SSRs were rarely conserved between genes with related sequences, suggesting high instability or a recent origin. The preferred location of SSR within the open reading frames of genes related to cellular regulation(transcription, signaling transduction) together with their instability suggested that SSR could have an important role in speciation. The instability of SSR distribution within protein coding regions suggested that analysis of polymorphism and functional role of these SSRs could benefit the functional genomics of M. grisea.

Key words: Magnaporthe grisea, genome, simple sequence repeat, distribution, protein coding region, functional genomics

摘要： 在对稻瘟病菌基因组中SSR分布进行了系统分析的基础上，对由1～6个碱基为重复单元的SSR在基因的蛋白质编码区中的分布进行了分析。结果表明，该病原菌的2 378个基因的编码区中共分布有3 240个SSR序列（标准是15 bp以上，匹配值为80％）。在已经有注释的4 732个基因中，861个基因的编码区中有SSR。编码区中的SSR以三碱基重复和六碱基重复为主，其他类型的SSR则很少在编码区中出现。SSR在这些基因中很少有保守性，表明这些基因的高度变异，或者起源是较晚的。含有SSR的基因多为转录蛋白、信号传导的细胞调节基因这一现象表明，SSR在物种形成过程中有重要作用。利用基因编码区中丰富的SSR序列信息及其变化带来的功能变化的信息，将可以在该菌功能基因组的研究中发挥十分重要的作用。

关键词: 稻瘟病菌, 基因组, 微卫星序列, 分布, 蛋白质编码区, 功能基因组学