Abstract: IS PCR and rep PCR were used to analyze the genetic diversity in a population of 128 strains of Xanthomonas oryzae pv. oryzae collected mostly from Center, South and Southwest China. Genomic DNA from 114 strains was amplified with four specific primers, J3, ERIC, REP and BOX by PCR and revealed 20, 12, 6 and 5 haplotypes, respectively. The genetic diversities of the population of strains tested were 0.82 (for J3), 0.49 (for ERIC), 0.35 (for REP) and 0.30 (for BOX), respectively. Dendrograms were generated from the data sets obtained by using UPGMA analysis. All strains tested were similar to each other at a level of 70% similarity, six and five clusters were grouped using primers J3 and ERIC, respectively. The strains classified into Chinese pathotypes 0-Ⅴ and Ⅶ were grouped in Cluster 1 for primer J3; Strains from pathotypes 0-Ⅶ, and a new pathotype were grouped in Cluster 1 for primer ERIC. One hundred and twenty eight strains were classified into different pathotypes by assessing on the five differential varieties. Most of strains were classified into pathotypes Ⅳ, Ⅱ and 0. A new pathotype was identified based on its reaction pattern different from all the seven Chinese pathotype.

Key words: rice, bacterial blight, pathotype, genetic diversity

摘要： 用IS-PCR和rep-PCR法结合传统病理学分析了128个主要采自我国华中、华南和西南地区的水稻白叶枯病菌（Xanthomonas oryzae pv. oryzae）的群体遗传多样性。用4个专化引物J3、ERIC、REP和BOX对114个菌系基因组DNA进行PCR扩增反应，4个引物分别呈现20、12、6和5种谱型，遗传多样性值分别为0.82、0.49、0.35和0.30。以彼此间带位相似率达70%为界，用UPGMA聚类分析法，可将114个病原菌分为6簇（J3）和5簇（ERIC）。引物J3的簇1中包括0~Ⅴ、Ⅶ 7个病原型，ERIC引物的簇1中包括0~Ⅶ 和新型9个病原型。将128个病原菌在我国5个鉴别品种上测定以进行病原型分群，参试菌系多数属于Ⅳ型、Ⅱ型和0型，并出现了一群系列反应型不同于所有病原型的新类型。

关键词: 水稻, 白叶枯病, 病原型, 遗传多样性