Morphological features, inter simple sequence repeat ( ISSR ) polymorphism and pathogenicity on three hosts,were observed to analyze 15 Corynespora cassiicola strains obtained from cucumber plantations in Qing county, Hebei. A total of 92 polymorphic sites were generated from 16 primers by ISSR technique. Dendrogram was derived and it showed the genetic relationships among 15 Corynespora cassiicola isolates. The strains were divided into two clusters,and the similarity coefficient of the strains was 0.82. By means of potted test and morphological characteristics , it was indicated that the morphologies of these strains were diverse; and all isolates had significant differences in the average disease indexes. The population differentiation of Corynespora cassiicola had obvious correlation with the pathogenicity and morphological characteristics of these strains. The strains of cluster I were collected in 2009 and had cylindrical conidia, and pathogenicity was significantly greater than that of strains in clusterll. It was primarily indicated the pathogen in 2009 differentiated into another population under the effect of environment and hosts.%本研究对15株河北青县黄瓜棒孢叶斑病病原菌多主棒孢菌Corynespora cassiicola的形态学特征、分子类群及在不同寄主上致病力分化的相互关系进行综合研究.由16对ISSR随机引物对15株供试菌株进行ISSR标记分析,得到92个多态性位点,所有菌株划分为2个分子类群,遗传相似性系数为0.82.结合形态特征的比较和致病力鉴定结果,发现多主棒孢菌的显微特征和培养性状丰富；所有菌株对黄瓜致病力较强,而在番茄和茄子上的致病力存在显著的差异.ISSR分子类群同菌株的致病力和显微特征具有显著的相关性,分子类群Ⅰ的菌株多为2009年采集的,以圆柱形孢子为主,对3个寄主的致病力显著高于类群Ⅱ的菌株.
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