Abstract: The DNA of 242 Magnaporthe grisea isolates from Mile County, Yunnan Province, which originated from monoculture and mixture fields, was extracted and amplified by rep PCR which primers were from palindromes Pot2 of Magnaporthe grisea. All isolates were amplified 2-28 DNA bands, the size was from 400 bp to 23 kb, but mainly from 5-10 kb and 80% bands were in 0.4-6.0 kb. Genetic structure of Magnaporthe grisea in different culture pattern fields by clustering analysis showed that there was relationship between complexity of isolates genetic lineages and culture patterns. There were more genetic lineages in mixture field than in monoculture one. The dominant lineages were not distinct in mixture field. In 80% similarity, the strains from glutinous rice in monoculture were divided into nine lineages, while strains from japonica in mixture were 15 lineages. The result proved that biodiversity might provide a convincing basis for the steady selection of rice variety to pathogen.

Key words: japonica rice, glutinous rice, variety diversity, Magnaporthe grisea, genetic lineage, monoculture, mixture culture

摘要： 利用稻瘟病菌的一段倒位重复序列Pot2设计的一对引物，采用repPCR分子指纹技术对来自云南省弥勒县粳稻种植区的水稻品种（净栽合系41、净栽黄壳糯、混栽合系41和黄壳糯）多样性田间242个稻瘟病单孢分离菌株的DNA进行扩增。结果显示所有供试菌株均扩增出2~28条谱带，扩增片段大小为400 bp~23 kb，但80%左右的片段集中在0.4~6.0 kb。将供试菌株扩增谱带进行聚类分析，比较了混栽与净栽田间病菌群体遗传结构的组成差异。结果表明，在粳稻种植区，水稻品种多样性种植有利于对稻瘟病菌的稳定性选择,在不同的遗传相似水平, 菌株遗传宗群复杂度与栽培方式有一定的相关性。混栽田间病菌遗传宗群较净栽田间复杂。在80％的相似水平上，净栽糯稻田间的稻瘟病菌被划为13个宗群，而混栽粳稻和黄壳糯田间由糯稻品种上分离的稻瘟病菌群体被划为20个宗群；净栽粳稻田间的稻瘟病菌可划为9个宗群，而混栽粳稻和糯稻田间由粳稻品种上分离的稻瘟病菌群体可划为15个宗群。

关键词: 粳稻, 糯稻, 品种多样性, 稻瘟病菌, 遗传宗群, 单一栽培, 混合栽培