黄瓜种传镰刀菌种类的鉴定及其致病性研究

Study on identification of cucumber seedborne Fusarium species and testing of their pathogenicity

为明确我国主栽黄瓜品种的种子中携带镰刀菌的种类及其危害,对来自我国黄瓜主产区21个黄瓜品种的种子进行种传镰刀菌检测,从种胚和种子外部分离得到镰刀菌分离物9个,采用形态学及分子生物学的方法进行鉴定,并研究其对黄瓜种子发芽和幼苗致病性的影响。结果表明:9个分离物中,4个分离物为尖孢镰刀菌(Fusarium oxysporum),4个分离物为串珠镰刀菌(F.moniliforme),1个分离物为再育镰刀菌(F.proliferatum)。4个尖孢镰刀菌分离物对黄瓜种子发芽均有显著影响,发芽指数、活力指数、根长和鲜重等指标均显著降低,且能导致黄瓜幼苗出现典型的枯萎症状,经柯赫氏法则检验证明其具有致病性。其他分离物对黄瓜种子发芽也有一定的抑制作用,但没有致病性。

In order to study the seedborne Fusarium species and their harmness of cucumber seeds of popularly planted varieties,cucumber seeds of twenty-one varieties from cucumber-growing regions in China were collected for Fusarium detection. Nine Fusarium isolates were isolated from seed embryos and seed surface. The isolates were identified using morphology and DNA sequencing analysis. Effects on seed germination and pathogenicity of these Fusarium isolates were determined. Results showed that the nine Fusarium isolates belong to three species,i, e. Fusarium oxysporum （4 isolates）,F, moniliforme （4 isolates） and F. prolifertum （1 isolate）. The four F. oxysporum isolates had significant effect on seed germination,compared to the control treatment. The values of the germination index, the seedling vigor index,root length and fresh weight of seedlings decreased significantly in the treatment of F. oxysporum. Results also showed that the isolates of F. oxysporum were pathogenic to seedlings of cucumber and caused typical wilt symptoms on leaves,fulfilling Koch＇s postulates. All the other five isolates of Fusarium had suppressive effect on seed germination of cucumber, but they were not pathogenic to cucumber seedlings. To our knowledge, this is the first report of the seedborne F. oxysporum pathogenic to cucumber seedlings in China,