鱼腥草内生放线菌的分离及杀菌活性研究

Separation and Fungicidal Activity Research of Endophytic Actinomycetes from Houttuynia cordata

[目的]探索鱼腥草内生放线菌的杀菌生物活性。[方法]以新鲜鱼腥草为材料,从其根、茎和叶部共分离得到7株内生放线菌。采用抑制菌丝生长速率法和抑制孢子萌发法对7株内生菌发酵产物进行杀菌活性筛选。[结果]这7株内生放线菌均具有一定抑制活性。其中,编号为K3和K15的2株内生菌发酵液对玉米纹枯病菌、玉米小斑病菌、黄瓜枯萎病菌和禾谷镰刀菌等4种植物病原真菌均有较强抑菌活性,其抑制率均在70%以上,对玉米小班病菌孢子萌发的抑制率在90%以上。进一步研究K15和K3菌株的抑菌活性可知,K15和K3菌株发酵液对玉米小斑病菌的孢子萌发的EC50值分别为3.71和14.97 mg/ml;盆栽和田间试验结果均表明K15和K3菌株发酵液对小麦白粉病有较好的防治效果,对小麦白粉病的盆栽保护和治疗效果均高于70%,田间防治效果分别为77.46%和66.55%。[结论]K15和K3菌株发酵产物具有广谱的杀菌活性,特别对小麦白粉病菌有很好的田间防治效果。

[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.