The Inhibition Of Phytopathogenic Fungi And Mechanism Of Essential Oil Extracted From Asarum Heterotropoides Fr.Schmidt Var.mandshuricum (Maxim.) Kitag

The inhibition tests of the extracts from Asarum heterotropoides Fr. Schmidt var. mandshuricum(Maxim.) Kitag. shown that the essential oil (EO) was effective component among the others ones andthe inhibition was evaluated compared to the common fungicides,Metalaxyl (MT) and Nongkang120(NK) aginst phytopathogen.The mechanism of inhibition was analyzed,which contributed to the basisof the potential plant-derived fungicide developed from A.heterotropoides var. mandshuricum.Involved by the 16 phytopathogenic fungi,the mycelia growth rate tests of EO were demonstrated effective on the EO-amended medium at the concentration of 500μg/ml.The inhibition rates of 14 of the all cultures phytopathogen were more than 50%;and the spores germination inhibition rates of Alternaria humicola and Pestalozzia sp. were 72.5% and 72.85%,which suggested that EO was a broad-spectrum component. Phytopathogen by A. humicola, A. longipes Phytophthora cactorum,Pestalozzia sp. and Colletotrichum gloeosporioides Penz.,EC₅₀ of EO were tested on the EO-amended medium. All the values of EC₅₀ were ranged from 59.70μg/mL to 410.20μg/mL.EC₅₀ to Phytophthora cactorum was 59.70μg/mL.Thus, EO was regarded as an effective component more than NK(EC₅₀), and less than MT(EC₅₀).By Scanning Electron Microscope (SEM), inhibition of EO on A.humicola was observed.The spores of A. humicola cann't germinate when they were inoculated on the EO-amended medium at concentration of 320μg/mL and the shape of the spores were deformed.The selective permeability of hyphal membrane were measured by electrical conductivity.The values of the cultures transferred onto the EO-amended medium for 2, 5, 10 h were 5.318 6.362 and 8.982μS/cm, respectively .which implyed that EO was effective a little more than ME (P<0.05) and no significant difference to NK.The mechanism of EO was the osmosis of hyphal membrane caused inclusion leakage.By the 3,5-dinitrosalicylic acid (DNS) method,the rates of the reducing sugar absorption of the treated mycelia (-0.63%) were totally different from that of the control (9.95%), which demonstrated that EO could affect the reducing sugar absorption seriously.By biochemic method, the results of the activity of succinate dehydrogenase (SDH) showed that the SDH activities of EO-treated mycelia have decreased by 1.2 times after EO permeated into the cells,...