中国不同地区烟草寄生疫霉(Phytophthora parasitica var. nicotianae)菌株的随即多态性DNA扩增分析

来自中国云南、辽宁、山东3省的烟草寄生疫霉（Phytophthora parasitica var.nicotianae)菌株的致病性已被划分为3种致病类型组，即强致病性组、中致病性组和弱致性组。上述省是中国的烟草主产区，选自云南省的15个烟草寄生疫霉菌株、山东省的13个烟草寄生霉菌株和辽宁省的20个烟草寄生疫霉菌株，选择3个烟草栽培品种在温室内进行接种试验测定不同菌株的致病性分化。提取受试菌株的DNA，利用PCR技术对受试苗菌株的模板DNA进行随机多态性扩增分析，对扩增DNA片段谱带借助于UPGMA分析法构建遗传树，结果表明，受试菌株被划分为4个遗传聚类组，每个遗传聚类组内包括不同的烟草寄生疫霉致病性菌株，而且来自于不同烟区相同的致病性菌株和每种致病性的不同菌株皆不属于同一个遗传聚类组内。结果表明RAPD－PCR的遗传标记分析结果与不同致病性组的划分未有明显的区别。因此，随机多态性DNA图谱的相同与不同不能当作区分来自不同烟区的烟草寄生疫霉的致病性分化的分子检测的工具。

Random amplified polymorphic DNA analysis of China isolates of Phytophthora parasitica var.nicotianae from different districts

China isolates of Phytophthora parasitica var. nicotianae have been divided into three large pathogenic groups (PGS) (Hv(A), Iv(B), Wv(C)) which came from Yunnan, Shandong and Liaoning. These three districts belong to main tobacco regions in China: 15 isolates derived from Yunnan of the southwest, 13 isolates from Shandong of the east and 20 isolates from Liaoning of the northeast. PGS were determined through pathogenic assays in greenhouse studies with three tobacco cultivars. The isolates were analyzed by means of the random amplified polymorphic DNA (RAPD) method. All tested isolates could be differentiated into four cluster groups. Each cluster group contained different PGS isolates, while the same PGS isolates came from different tobacco regions or isolates of each PGS did not belong to the same cluster group. The conclusion shown that there was no significant different in RAPD pattern among highly virulence, intermediate virulence and weakly virulence groups in China. Therefore, the similarities and difference in banding patterns by RAPD could not be a useful molecular tool in identification and phytogenetic studies of the PGS of the same pathogen from the difference tobacco districts.