Abstract: Seventy eight strains of Xanthomonas oryzae pv. oryzae collected mostly from North, Northeast and a few from Center and South China have been assessed the RFLP types for analyzing the population structure and genetic diversity by using two probes, pJEL 101 and pBSavrXa 10. Genomic DNA from each strain of X. o. pv. oryzae was digested to completion by enzymes EcoR I or BamH I for blots probed with pJEL101 or pBSavrXa10. Sixteen RFLP types were identified respectively. Fourteen RFLP types were found in strains of pathotypes 1, 2 and 6, which were from North and Northeast China(using pJEL 101).Among them differed only at one or 3-4 banding positions. In comparison between those with RFLP types of strains from Guangdong and Yunnan provinces were distinct from one another at 7 or 8 positions varied. Cluster analysis based on RFLP banding showed six groupings at 85% similarity. The majority of strains from pathotypes 1, 2 and 6 were grouped in clusters 1. A few strains, LN43, GD1358 and YN5 were grouped in clusters 4, 5 and 6. respectively. The genetic diversities of the population of strains tested was 0.77 (for pJEL101 ) and 0.83 (for pBSavrXa10) respectively. Genetic diversities for each pathotypes tested as a subpopulation has been also calculated. The preliminary analysis here showed that the genetic diversity of X.o. pv. oryzae in China was various. It will be necessary to assess more strains collected from South, Center and Southwest China for analyzing the population constructure and genetic relationship of X.o. pv. oryzae in China systematically.

Key words: bacterial blight, genetic diversity, population structure, RFLP type, strains

摘要： 用两个DNA探针pJEL101和pBSavrxa10，测定了78个来自18个地区的水稻白叶枯病菌系的RFLP型，其中主要来自华北、东北和少数来自华中、华南，以分析其群体结构和遗传多样性。各菌系的基因组DNA分别用限制性内切酶EcoR I和BamH I酶切探针pJEL101或pBSavrxa10。通过分子杂交，分别鉴定出16种RFLP型。病原型1、2和6的多数来自华北和东北菌系表现14种RFLP型。它们之间多数只有一带之差，或有3～4个带位不同。然而，它们与来自广东和云南的菌系相比，差别较大，有7～8条带位不同。根据参试菌系的RFLP带型分簇（Cluster），如以彼此之间的带位相似率达85%为界，可分为6簇，多数病原型1、2和6的菌系为簇1，少数几个菌系，LN43、GD1358和YN5分别为簇4、5和6。参试的菌系群体遗传变异为0.77（pJEL101）和0.83（pBSavrxa10）。也分析了亚群体的各病原型内的遗传变异，初步分析表明中国的水稻白叶枯病菌系的遗传变异多种多样。但尚需测试更多的来自华南；华中和西南地区的菌系，方能较系统地分析全国菌系的群体结构及其遗传关系。

关键词: 水稻白叶枯病, 遗传多样性, 群体结构, RFLP型, 菌系