不同品种水稻纹枯病菌遗传多样性及致病力分化

Genetic Diversity and Virulence Variation of Rice Sheath Blight Pathogen ( Rhizoctonia solani AG-1 IA) from Different Rice Varieties

运用RAPD分子标记技术分析了从 6个水稻品种上采集的 4 0个水稻纹枯病菌菌株的遗传多样性 .筛选出的10条引物共扩增出 98条RAPD谱带 ,其中 81条具有多态性 ,多态率为 82 .6 5 % ,菌株间的遗传相似性系数 (以Nei’s基因一致度表示 )变幅为 0 .5 6 4 4～ 0 .930 7.用UPGMA法可以将供试菌株分成 4个RAPD聚类组群 (Ⅰ、Ⅱ、Ⅲ、Ⅳ ) ,相同寄主来源的菌株基本上聚集在同一组群内 ,表明同一寄主来源的菌株间具有较近的亲缘关系 .在温室条件下 ,致病力测定结果表明所有菌株对Tetep都有致病性 ,病情指数变幅在 0 .4 0～ 11.83之间 .分析结果表明 ,纹枯病菌群体存在丰富的遗传多样性 ,不同寄主上的水稻纹枯病菌群体间发生了很大的遗传分化 (FST=0 .6 32 ) ,这种遗传差异与寄主的选择作用有一定的关系 .RAPD聚类组群的划分和菌株的寄主来源有一定的相关性 。

Forty isolates of rice sheath blight pathogen ( Rhizoctonia solani AG-1 IA) from six rice varieties were analysed for genetic diversity by using random amplified polymorphic DNA (RAPD) technique. Of 98 RAPD bands that were amplified with 10 arbitrary decamer primers, 82.65% were polymorphic. Analysis of amplified polymorphic DNA fragments showed that Nei's genetic identity were 0.564 4～0.930 7, the tested isolates were classified as 4 RAPD groups(Ⅰ,Ⅱ,Ⅲ,Ⅳ), and the isolates from the same host were fallen into the same group by using UPGMA cluster analysis. The results of virulence test in greenhouse indicated that all isolates were virulent to rice variety Tetep, and the range of disease index varied from 0.40 to 11.83. It was suggested for genetic analysis that there was abundant genetic diversity existing in rice sheath blight fungal population, and that the genetic variation was very significant within populations from different rice varieties( F ST =0.632), and that host selection affected the population genetic structure of Rhizoctonia slani AG-1 IA. The RAPD cluster groups were in line to some extent with host origin of isolates, but virulence variation was not related to host origin of isolates and RAPD groups.