中文摘要：

用随机扩增多态性DNA（RAPD）技术，对采自广东、广西的香蕉和粉蕉上的30个香蕉枯萎病菌（Fusarium oxysporum fsp．cubense）菌株和3个其它尖孢镰刀菌专化型的菌株进行比较及聚类分析。在遗传相似系数0．67时，可将供试菌株划分为3个RAPD群（RGs），其中香蕉枯萎病菌4号生理小种（FOC4）共15个菌株属于RGⅠ，1号生理小种（FOC1）共15个菌株属于RGⅡ，供试的其它尖孢镰刀菌专化型的3个菌株则属于RGⅢ。这说明香蕉枯萎病菌和供试3个其它专化型菌株与致病性间存在明显的相关性。1号生理小种内菌株间的遗传分化大于4号生理小种内菌株间的遗传分化。从90条RAPD随机引物中筛选出2条引物可产生4号生理小种的RAPD标记2个。将这2个RAPD标记电泳切胶回收、克隆及测序，并根据这2个特异片段序列设计SCAR上下游特异引物，通过对30个菌株的PCR扩增检验，其中一个RAPD标记成功地转化为SCAR标记，初步建立了以此为基础的4号生理小种快速检测技术，其检测灵敏度为2ng新鲜菌丝。对采自不同地区的显症样品、吸芽、室内接种未显症的香蕉苗以及发病的香蕉植株不同部位进行检测，能够准确灵敏地鉴定出4号生理小种，从而为香蕉枯萎病菌的快速检测及防治奠定了基础。同时，快速检测结果发现，田间发病植株果柄的各部位及果实内并没有枯萎病菌的存在。

英文摘要：

Thirty strains of Fusarium oxysporum f. sp. cubense （FOC） were isolated from banana or Plantain banana in Guangdong and Guangxi Province. Random amplified polymorphic DNA （RAPD） clustering analysis of the 30 strains and the 3 other strains （F. oxysporum f. sp. lyscopersici, F. oxysporum f. sp. niveum, F. oxysporum f. sp. momodicae） showed that these 33 strains could be divided into three RAPD groups （RGs）. RG I and RG 11 included all strains of Race 4 and Race 1, respectively, and RG 11 included the three others. A total of 90 random primers were selected to perform random amplified polymorphic DNA （RAPD） analysis and two of them could amplify Race 4-specific DNA fragments. The study demonstrated that there was significant correlation between the RAPD groups and the fusarium wilt pathogenic types. The diversity level of Race 1 was greater than that of Race 4. Based on cloning and sequencing of these RAPD marker fragments, the sequence characterized amplified region （SCAR） primers were designed and used for amplifying the 30 FOC strains, the SCAR marker was successfully set for Race 4. This method could amplify target segment from minimal 2 ng of fresh mycelinm. Specificity and sensitivity analysis showed that the SCAR marker could specially and steadily detect different samples. Our results demonstrated that F. oxysporum did not exist in fruit stem and fruit of the diseased plants. This study provide a useful method for identifying banana fusarium wilt.