葡萄生单轴霉重寄生菌F3的鉴定及防治效果测定

为明确从生长异常的葡萄霜霉层上分离获得的菌株F3对葡萄生单轴霉Plasmopara viticola的重寄生作用及对葡萄霜霉病的防治效果,通过光学和扫描电子显微镜观察菌株F3对葡萄生单轴霉的重寄生作用,并对菌株F3进行形态特征观察及28S rDNA序列分析,采用孢子囊萌发抑制和离体叶片点样法测定该菌株对葡萄霜霉病的防治效果。结果表明,菌株F3对葡萄生单轴霉表现出覆盖、缠绕的重寄生现象。结合形态特征与序列分析结果将该菌株最终鉴定为层生镰刀菌Fusarium proliferatum。菌株F3分生孢子悬浮液及其无菌发酵液对葡萄霜霉菌孢子囊萌发具有显著的抑制作用,抑制率分别为86.8%和83.1%;经菌株F3分生孢子悬浮液预防处理后的离体葡萄叶片发病率为10.9%,显著低于对照的发病率98.8%,防治效果达88.9%;菌株F3分生孢子悬浮液与葡萄霜霉病菌孢子囊混合后点样接种处理的叶片发病率为50.0%,也显著低于对照,防治效果为49.1%;而治疗处理的叶片发病率与对照间无显著差异。表明层生镰刀菌对葡萄生单轴霉具有重寄生作用,且对葡萄霜霉病具有较强的预防控制作用。

Identification of the mycoparasitic strain F3 on Plasmopara viticola and its control effect on grape downy mildew

To clarify the hyperparasitic role of the strain F3 obtained from abnormal lesions of grape downy mildew in suppression of Plasmopara viticola and its control effect on grape downy mildew, the hyperparasitism of strain F3 on P. viticola was observed under light and scanning electron microscopes. Strain F3 was identified based on its morphology and the sequence of 28S rDNA. Control tests were performed by using an inhibition assay of sporangial germination of P. viticola and a drop inoculation method on detached grape leaves. The results showed that the hyperparasitism of strain F3 on P. viticola could be observed with the evidence of either hyphal coverage of or coiling around its sporangiophores, and the strain F3 was identified as Fusarium proliferatum based on morphological characteristics and sequence analysis. The germination of P. viticola sporangia was strongly inhibited by the spore suspension and sterile filtrate of strain F3, with the inhibition rates of 86.8% and 83.1%, respectively. In the preventive control treatments, the incidence of leaves treated with the spore suspension of strain F3 in vitro was 10.9%, which was significantly lower than that of the control (98.8%), and the control efficiency reached 88.9%. Control effects could also be obtained by the simultaneous inoculation, and the inci-dence and control efficacy were 50.0% and 49.1%, respectively. In the curative assays, however, no control effects could be observed. The results demonstrated that strain F3 showed a hyperparasitic effect on P. viticola, and strong protection control on grape downy mildew.