Separation and Fungicidal Activity Research of Endophytic Actinomycetes from Houttuynia cordata

[Objective]The aim was to research fungicidal activity of endophytic actinomycetes from Houttuynia cordata.[Method]Seven strains of endophytic actinomycetes were isolated from root,stem and leaf of Houttuynia cordata.By the method of growth rate and spore germination,bactericidal activity screening were carried out with 7 strains of endophytic bacteria fermentation products.[Result]The results showed that all fermentation filtrates of the endophytes exhibited antibiotic activity to some target pathogenic fungus, in which the antibiotic activity of strain K3 and K15 against target fungus were strong.The fermentation filtrate of endophytic actinomycete K3 and K15 exhibited strongly antibiotic activity to Fusarium oxysporum,Thanatephorus cucumeris,Cochliobolus heterostrophus and Fusarium moniliforme in vitro,the inhibited rate of mycelia growth against these target pathogenic fungus were all above 70%,and the inhibited rate of spore germination against Cochliobolus heterostrophus were above 90%.The fungicidal activities of fermentation filtrate K15 and K3 were further studied and the results showed that the value of EC50 inhibiting spore germination against Cochliobolus heterostrophus were 3.71 and 14.97 mg/ml.The results of pot and field experiments showed that the fermentation filtrate of strain K15 and K3 exhibited control effect against wheat powdery mildew,the protective effects and curative effects of the fermentation filtrate against wheat powdery were above 70% on potted wheat plants,the control effects were 77.46% and 66.55% in field experiment,respectively.[Conclusion]The fermentation filtrates of K15 and K3 exhibited broad spectrum of bactericidal activity,and had better field control effect against wheat powdery mildw.