Studies On Fungicidal Activity Of Endophytic Fungus In Euonymus Japonicus

The plant endophyte can metabolize many interesting secondary metabolites with novel structure and distinctive activities, which is an important source of new molecular skeleton and drugs, and has good prospects in the agricultural and medical application. The fermentation product of the strain 2QR1 isolated from the root of Euonymus japonicus, has strong fungicidial activity on various plant pathogens. The isolation and identification of active components of the strain 2QR1 have been carried out in this paper. The main results are as follows:1. Taking different separating culture mediums, 21strains of endophytic fungus was separated from the roots, stalks or leaves of Euonymus japonicus. The results of bioassay test indicated that the strain 2QR1 had a certain degree fungicidial activity.2. The fungicidal activity of the strain 2QR1 has been studied. The bioassay results of fungicidal activities showed that the EC50 value of ethyl acetate extract of the fermentation broths of the strain 2QR1 against Bipolaris sorokiniana,Fusarium graminearum,Glomerella cingulata,Exserohilum turcicum,Fulvia fulva,Alternaria longipe and Fusarium solani in inhibiting the mycelium growth test was 53.6,63.1,63.3,98.2,106.5,115.9 and 166.3μg/mL respectively, and the EC50 value against Exserohilum turcicum,Alternaria longipes,Bipolaris sorokiniana and Fusarium solani in inhibiting spore germinations test was 94.8,139.1,146.6 and 180.1μg/mL respectively. At the concentration of 500μg/mL, the inhibition zone diameter of ethyl acetate extract of the fermentation broths of the strain 2QR1 was all more than 16mm against Bacillus subtilis, Bacillus cereus and Staphylococcu aureus. The results of pot test indicated that ethyl acetate extract of fermentation broths had 61.9% protective efficacy and 81.6% therapeutic efficacy against wheat powdery mildew at the concentration of 2000μg/mL.3. The compound B9 was separated from the ethyl acetate extract of fermentation broths by open silica gel column and HPLC. Based on the data of spectral (MS, ¹H NMR, ¹³C NMR), and compared with related literatures, B9 was identified as asterric acid. In inhibiting spore germination test, the value of EC50 of B9 against Exserohilum turcicum, Alternaria longipes, Bipolaris sorokiniana and Fusarium solani was 0.8, 1.4, 3.3 and 5.0μg/mL respectively.4. By means of observation on aerial mycelium, macroconidia,microconidioa and colony morphology characteristics of the strain 2QR1, compared with related classify system, the strain 2QR1 was preliminarily identified as Aspergillum sp..