黑龙江省葫芦科白粉病菌RAPD分析

2010年采集黑龙江省不同生态区不同设施内的甜瓜、黄瓜、南瓜、西瓜等瓜类白粉病菌菌株17份，采用国际通用的瓜类白粉病菌生理小种鉴别寄主对17份白粉病菌进行了生理小种鉴定。根据13个鉴别寄主的抗感反应，初步确定黑龙江省葫芦科作物白粉病菌存在3个生理小种，即单囊壳白粉菌Podosphaera xanthii的生理小种1和生理小种N1号及一个新生理小种，其中生理小种1为优势小种。通过对13份白粉病菌的RAPD分析，从119个随机引物中筛选出10个条带清晰而且重复性好的引物，扩增得到157个位点，其中多态性位点为138个，多态性位点频率为97.89%，表明黑龙江省葫芦科作物白粉菌具有丰富的遗传多样性。利用NTSYS-PC软件进行数据分析，结果表明13个菌株之间遗传相似系数的变化幅度为0.52－0.75。根据遗传相似系数用类平均法（UPGMA）对其聚类，以遗传相似系数0.60为阈值，供试菌株可区分为4个类群。同是生理小种1的菌株部分聚到了同一类，新生理小种与部分生理小种1菌株聚到同一类，同是生理小种N1的两个菌株未聚到同一类；相同地理来源或相同寄主来源的白粉菌也未聚到一类。初步确定葫芦科白粉病菌致病性与DNA多态性不形成对应关系，菌株的遗传多样性与菌株地理来源、寄主来源及设施类型亦无明显的直接关系。

RAPD analysis of cucurbit powdery mildew fungus in Heilongjiang Province

17 samples of powdery mildew were collected and separated from diseased melon, cucumber, pumpkin and watermelon in greenhouses or open field in various ecological regions of Heilongjiang Province in 2010. They were investigated for physiological races by using standard differential hosts of powdery mildew. Based on their resistant or susceptible types on 13 differential hosts, three races on Cucurbitaceae were preliminarily confirmed, including races 1, race N1 and a new one of Podosphaera xanthii in Heilongjiang Province. Race 1 was dominant in Heilongjiang. Thirteen isolates of powdery mildew were evaluated by using random amplified polymorphic DNA (RAPD) with 10 primers selected from 119 random primers. A total of 157 bands were amplified, including 138 polymorphic bands with 97.89% polymorphic band frequency. The RAPD amplifying results show that high genetic diversity existed among the isolates of P. xanthii on Cucurbitaceae in Heilongjiang. After analysis by software NTSYS-PC, the similarity coefficient of the 13 isolates varied from 0.52 to 0.57. The UPGM dendrogram divided the 13 isolates into 4 groups at the similarity coefficient of 0.60. The isolates of race 1 were partly clustered into the same group, and the new race was clustered into the same group with partial race 1 isolates; two isolates of race N1 were not clustered into the same group with partial race 1 isolates. The isolates originated from the same geographic regions or hosts were also not clustered into the same group. It is indicated that no obvious association was found between DNA polymorphism and pathogen races in biological tests on cucurbits. Meanwhile, no association was found between the results of RAPD analysis and any other parameter analysis such as geographic regions, greenhouse types or host origins.