3-卤苯基芳香胺去甲斑蝥素衍生物对油菜菌核病菌的抑菌机理

为探究斑蝥素衍生物对核盘菌Sclerotinia sclerotiorum (Lib.) de Bary的抑菌活性和抑菌机理，测定了5 种3-卤苯基芳香胺取代去甲斑蝥素 ( BY 、 BY-1 、 BY-2 、 BY-3 和 BY-4 ) 对核盘菌的菌丝生长和菌核形成的影响，采用离体叶片法测定了其对油菜菌核病的相对防效；并通过测定斑蝥素衍生物处理菌体后菌丝形态、菌体相对电导率、丙二醛含量、还原糖和可溶性蛋白含量、几丁质酶活性及草酸含量等分析斑蝥素衍生物的抑菌机理。结果显示:5种斑蝥素衍生物对核盘菌均有显著的抑制作用， BY 、 BY-1 、 BY-2 、 BY-3 和 BY-4 的EC₅₀值分别为37.6、8.78、6.45、12.2和50.4 μg/mL。其中， BY-2 对核盘菌菌核形成的抑制作用最强，在12.5 μg/mL时的抑制率达86.52%；在100 μg/mL时其对离体叶片上油菜菌核病的相对防效达到97.71%。表明在苯环C-3’位引入氯原子可以显著提高化合物对油菜菌核病菌的抑菌活性。用斑蝥素衍生物处理核盘菌后，菌丝体表面粗糙，或脱水枯萎，或畸形膨大；细胞膜通透性增加，菌体内还原糖和可溶性蛋白含量降低，几丁质酶活性提高，草酸含量显著降低。表明斑蝥素衍生物能够有效抑制油菜菌核病菌，为生物源杀菌剂的开发提供了理论依据。

Inhibitory mechanism of cantharidin derivatives against Sclerotinia sclerotiorum

In order to investigate the antifungal activities and the inhibitory mechanism of cantharidin derivatives against Sclerotinia sclerotiorum, the inhibitory effects of five halogenated aromatic amines( BY , BY-1 , BY-2 , BY-3 and BY-4 ) on the mycelial growth and the sclerotia formation of S. sclerotiorum were determined. The relative control efficacy against Sclerotinia rot on detached leaves of rapeseed and the antifungal mechanism of cantharidin derivatives were analyzed by measuring the mycelial morphology, the mycelial relative conductivity, the malondialdehyde content, the reduction of sugar content and soluble protein content, the activity of chitinase and the content of oxalic acid in the hypha treated with cantharidin derivatives. The results showed that five cantharidin derivatives significantly inhibited the mycelial growth of S. sclerotiorum, and the EC₅₀ values of BY , BY-1 , BY-2 , BY-3 and BY-4 were 37.6, 8.78, 6.45, 12.2 and 50.4 μg/mL, respectively. The inhibitory effect of the derivative BY-2 on sclerotia formation was the strongest. And the inhibition rate was 86.52% at the concentration of 12.5 μg/mL. The treatment of the detached rapeseed leaves with the derivative BY-2 (100 μg/mL) afforded 97.71% relative control efficacy. These results indicated that the introduction of a chlorine atom at the C-3′ site of benzene ring could significantly improve the inhibitory activity of cantharidin against S. sclerotiorum. After the hypha was treated with cantharidin derivatives, the surface of mycelia turned rough, or dehydrated and shriveled, or deformed and expanded. The cell membrane permeability was increased, and the reducing sugar content and soluble protein content were decreased. Furthermore, the chitinase activity was also increased, and oxalic acid content was significantly decreased. Above all, the results showed that the cantharidin derivatives could effectively prevent and cure Sclerotinia stem rot, and provided theoretical basis for the development of biological fungicide.