甘蓝枯萎病病原菌的鉴定

 采用温室接种致病性测定、形态学观察和分子鉴定方法对甘蓝枯萎病病原进行了研究。从北京市延庆县9个甘蓝生产基地采集甘蓝枯萎病病样96份,分离获得来自甘蓝病株根、短缩茎、叶片等器官的30个真菌分离物。经过致病性试验证实,分离物GLW3和GLW8为甘蓝枯萎病病原菌。经形态学鉴定,GLW3为尖孢镰刀菌(Fusarium oxysporum),GLW8为轮枝样镰刀菌(Fusarium verticillioides)。利用镰刀菌的核糖体DNA(rDNA)内转录间隔区(internal transcribed spacer,ITS)的保守性和变异性,分别采用真菌通用引物和镰刀菌属及轮枝样镰刀菌特异性引物对GLW3和GLW8进行PCR扩增,并将测序结果在GenBank中进行同源性比对分析,分子鉴定与形态学鉴定结果一致。轮枝样镰刀菌作为甘蓝枯萎病的病原菌系首次报道。

Identification on pathogen of cabbage wilt disease

The pathogens of cabbage wilt disease were identified on the basis of pathogenicity testing, as well as morphological characters and molecular identification. Ninety-six diseased cabbage samples were collected from nine villages of cabbage production area in Yanqing county, Beijing. Thirty isolates of possible pathogenic fungi were isolated from roots, stems and leaves of infected cabbage plants. Bases on the pathogenicity experiment, the results showed that GLW3 and GLW8 were the pathogens of cabbage wilt disease. The morphological identification showed that GLW3 remained with Fusarium oxysporum and GLW8 was identified as Fusarium verticillioides. By using of conservation and variability of the internal transcribed spacer (ITS) of Fusarium ribosome DNA, the ITS sequences of the isolates GLW3 and GLW8 were amplyfied by PCR technique with universal primers of fungi and specific primers of Fusarium genus and F. verticillioides, respectively, those sequences were analyzed by comparing with that in GenBank. The molecular identification indicated the same results with morphology identification. Fusarium verticillioides was first reported as the pathogen of cabbage wilt disease.