关键词：
黄瓜;多主棒孢菌;ISSR;聚类分析;遗传距离
摘 要：
多主棒孢菌(Corynespora cassiicola)是危害黄瓜、番茄、橡胶等作物的重要病原真菌。研究不同地区、相同或不同寄主棒孢菌的遗传多样性,对了解多主棒孢菌的遗传分化和病害防治具有重要意义。本研究从天津、山西、河南、河北、山东、辽宁等黄瓜主产区共采集、分离纯化得到32个黄瓜多主棒孢菌菌株,对其生物学培养特征以及ISSR遗传变异进行了分析。菌株培养特征表明,在供试32个菌株中,Ⅰ型菌株有24个(5-28号),占75%,其菌落黑褐色,边缘浅绿,菌丝生长旺盛,PDA培养基上产孢量较少;Ⅱ型菌株4个(1-4号),占12.5%,菌落黑色,粉末状,PDA培养基上可大量产孢;Ⅲ型菌株4个(29-32号),占12.5%,菌落浅灰色或灰白色,菌丝疏松,基物浅粉色,PDA培养基上产孢量极少。其中Ⅰ型菌株占75%,为病菌优势小种。对该32个菌株和2个番茄寄主分离的多主棒孢菌株多样性进行了ISSR指纹分析,23条ISSR引物共扩增获得204个位点,其中194个为多态位点,占95.10%。32个黄瓜寄主的菌株间遗传变异较大,两两间的遗传相似系数在0.627 5~0.995 1之间。UPGMA聚类分析表明,在遗传相似系数为0.65时,将34个菌株分为4个组,每组包含的菌株数分别为26、5、1、2。聚类分析结果显示,来源于黄瓜和番茄寄主上的菌株遗传分化较大,在相似系数为0.31时可以明显分为两簇。从多态性分析及聚类结果看,病菌分化与地理来源无明显的相关性,但与寄主来源可能存在相关性。该研究充分说明黄瓜棒孢叶斑病菌基因组在SSR区域具有丰富的遗传多态性,为黄瓜棒孢叶斑病抗病育种以及综合防治提供了重要的理论参考,并可以为多主棒孢菌的分类鉴定及系统发育研究提供依据。
译 名：
ISSR Fingerprinting Analysis of Corynespora cassiicola Genome of Cucumber
作 者：
Li Shuju;Wang Huizhe;Yang Ruihuan;Deng Qiang;Cao Mingming;Tianjin Kernel Cucumber Research Institute;
关键词：
Cucumber,Corynespora cassiicola,ISSR,Clustering analysis,Genetic distance
摘 要：
Corynespora cassii cola is an important fungus pathogen harming cucumber, tomato, rubber and other crops. Assessing the genetic diversity of Corynespora cassiicola isolates from different eco-geographical regions and host plants is crucial important for understanding the evolution of this fungal pathogen and its control. 32 C.cassiicola isolates were sampled from main cucumber growing counties of Tianjin, Shanxi, Henan, Hebei,Shandong, and Liaoning Province in China. In the research culturing features and genetic variation based on ISSR marker were studied. According to culturing feature on PDA medium, the tested isolates could be classified into 3types, typeⅠ isolates that accounted for 75.0% were the most, followed by typeⅡ(12.5%) and typeⅢ(12.5%). The colony of type Ⅰ strains were dark brown, light green edge, mycelia growth, spore production in PDA medium less;typeⅡ strain colonies were black powder, being able to produce a large number of spores in PDA medium, and type Ⅲ strain colonies were light gray or pale, loose hyphae, base pale pink, rarely spores in PDA medium. We detected DNA polymorphism of 32 C. cassiicola isolates from cucumber host and 2 isolates from tomato host plants of different regions using inter simple sequence repeat(ISSR) markers. Total 204 scorable bands were generated with 23 ISSR primers, among them 194 were polymorphic loci(95.10%). Genetic distance of 32 cucumber host isolates based on ISSR markers ranged from 0.627 5 to 0.995 1, which showed that the genetic diversity was high among the 32 tested isolates. UPMGA(Unweighted Pair Group Method with Arithmetic Mean) analysis indicated that the dendrogram consisted of four groups, including 26, 5, 1 and 2 isolates for each group, respectively. As the genetic similarity coefficient was 0.31, genetic difference was identified between the isolates from cucumber host and tomato host by cluster and principal component analyses,which can distinguish different isolates of corynespora cassiicola from cucumber and tomato host. ISSR analysis indicated that the genetic variation of 34 isolates should be great but be not related to geographic regions, whereas the definite correlations between the genetic similarity and host region existed obviously, which indicated that the ISSR loci in C. cassiicola genome were rich in polymorphism. Our research might provide an important basis for resistant breeding, prevention and control of this disease in productio as well as for the classification and identification of C. cassiicola and its phylogenetic research.
