我国玉米灰斑病菌遗传多样性的ISSR分析

为明确我国发生的玉米灰斑病菌地理差异及遗传结构,利用简单序列重复区间(ISSR)对玉米灰斑病菌遗传多样性进行了分析,并利用尾孢菌特异引物对分离自四川、云南、湖北、贵州等西南地区的16个玉米灰斑病菌菌株进行了分子鉴定。结果显示,通过ISSR标记筛选出10个扩增多态性好且稳定的通用引物,共扩增出81条DNA条带,均为多态性条带,扩增片段大小在200~2 000 bp之间,菌株遗传相似系数为0.19~1.00。在遗传相似系数为0.19时,供试菌株被聚为2大类群,来自西南地区和东北地区的菌株各自聚为一组,在DNA水平上表现出明显差异,认为是2类不同的致病类群。分子鉴定结果显示引起西南各地区玉米灰斑病的主要致病菌均为玉米尾孢菌Cercospora zeina。表明我国玉米灰斑病菌存在丰富的遗传多样性,ISSR标记可揭示出玉米灰斑病菌株间的亲缘关系及遗传差异性,可用于其遗传多样性研究。

Genetic diversity analysis of Cercospora spp. by ISSR in China

In order to understand the biological variation and genetic structure among different geographic regions of Cercospora causing maize gray leaf spot in China, genetic diversity of 29 isolates of Cercospora, isolated from different geographic regions in China, were analyzed by inter-simple sequence repeats (ISSR). The results showed that a total of 81 bands were amplified using 10 primers, ranged from 200-2 000 bp, and all of them were polymorphic. And the coefficient ranged from 0.19-1.00. At similar level of 0.19, all isolates were clustered into two distinct groups. Strains from maize collected from southwest and northeast clustered into two different groups. There was significant genetic differentiation between the two groups, indicating there were two Cercospora species causing gray leaf spot. Cercospora species were indentified using the species-specific primers. The results showed that 16 strains of the gray leaf spot pathogens belonged to Cercos pora zeina. ISSR analysis revealed the phylogenetic relationship and genetic differentiation of the Cercospora isolates tested in this study, and demonstrated relatively abundant genetic diversity of Cercospora in China.