The primary objective of this study was to investigate the genetic differences in Phytophthora capsici isolates with different sensitivities to metalaxyl. Seventeen field isolates from Hexian, etc, Anhui Province (15 isolates), Nanjing, Jiangsu Province (1 isolate) , Qionglai, Sichuan Province (1 isolate) and 3 laboratory-induced metalaxyl-resist-ant isolates were analyzed for their genetic diversities using random amplified polymorphic DNA (RAPD) marker. Ten pairs of primers were used to amplify. 30 fragments, of which all fragments were polymorphic. Twenty isolates were divided into 4 groups (genotypes) indicating that there was a certain genetic diversity in P. capsici RAPD analysis revealed that there was genetic variations between the sensitive and laboratory-induced metalaxyl-resistant isolates. However, no correlation was found between the groups defined by RAPD analysis and the groups defined by metalaxyl sensitivity.%为研究不同地区及对甲霜灵不同敏感程度的辣椒疫霉菌株间的遗传差异,采用RAPD分子标记对分离自安徽省和县等(15株)、江苏省南京市(1株)、四川省邛崃市(1株)的17个菌株及经甲霜灵处理筛选得到的3个抗性突变菌株进行了RAPD指纹分析.结果显示10对引物共扩增出30个比较清晰的条带,且均为多态性条带；当以遗传相似系数0.7为阀值时,可以将供试的20个菌株分为4个遗传聚类组,说明辣椒疫霉具有一定的遗传多样性.同时,RAPD分析结果还表明,经甲霜灵处理所筛选得到的抗性突变株与野生型敏感亲本之间存在一定的遗传变异,但是辣椒疫霉菌株对甲霜灵的敏感程度与RAPD的聚类分组没有相关性.
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