First interception of Verticillium albo atrum in Fangchenggang of Guangxi | 广西防城港首次截获苜蓿黄萎病菌

chinois. 从一批进境的美国苜蓿草样品中保湿分离得到了3株与苜蓿黄萎病菌（Verticillium albo-atrum）相似的目标菌VA1、VA2、VA3。该目标菌在PDA上生长迅速, 菌丝生长0.8～1.0mm/d,2～3d即可生成肉眼可见的菌落斑点; 菌落为白色圆形, 边缘规则呈圆形, 菌丝较致密, 气生菌丝较少, 菌落中心乳白色奶冻状; 培养4～5d即后产生气生典型轮枝状分生孢子梗, 7～8d后菌落中央表面因产生休眠菌丝开始变成黑褐色至黑色, 20d后菌落的表面和背面大部分均变黑色, 仍不产生微菌核和厚垣孢子。该目标菌的纯培养用V.albo-atrum特异引物Vaa1/Vaa2进行检测, PCR扩增后得到预期330bp的产物片段, 产物序列与V.albo-atrum相应序列的相似性为100%。 从而鉴定确认该目标菌为苜蓿黄萎病菌V.albo-atrum。

anglais. Three strains of the fungus, namely VA1, VA2 and VA3,were isolated from a batch of alfalfa samples, which were imported from USA and incubated under moist conditions, demonstrating the characters similar to V.albo-atrum. The strains grew rapidly on the PDA, with the colony growing at 0.8-1.0mm/d. After 2-3 days, the spot colony could be seen on the PDA. In addition, the colony had a regular and rounded margin with white compact mycelium and fewer aerial mycelia.The target fungus produced typical round aerial branched conidiophores after 4-5 days, and then became dark brown to black along with production of resting hyphae at the centre of the colony after 7-8 days, and the color of the surface and most of the back of the colony changed to black 20 days later, but still could not produce micro-sclerotia and chlamydospores. The pure cultures of the target germ were detected by the specific primers Vaa1/Vaa2.As expected, a 330 bp fragment was obtained by PCR amplification.The similarity between the product and corresponding sequence in V.albo-atrum was 100%. Therefore, it was confirmed that the target germ was V.albo-atrum.