Screening And Identification Of Antagonistic Strains Against Sunflower Sclerotinia Pathogenic Fungus

This paper introduces the pathogenesis of the sunflower sclerotinia,the harm of sunflower sclerotinia pathogenic fungus,and the research progress of the anti-fungus effect of sunflower sclerotinia at home and abroad.This paper mainly studies the isolation of the fungus disease pathogen from the sunflower gathered from the Inner Mongolia sunflower withdrawn,and identification of the ITS gene area sequence to insure the pathogenic fungus species.Antagonistic strains against sunflower sclerotinia were isolated from Inner Mongolia,Qinghai and Jiuquan region by tablet confrontation experiment,and some effective antagonistic strains were analyzed by different screening analysis experiments to testify the anti-fungus effect of them.Sclerotium fungus disease pathogen was identified as Sclerotinia sclerotiorum.The 16 antagonistic strains were isolated from the samples,which isolated from the 142 strains from the 3 different regional soil samples.The 16 antagonistic strains were researched by 16 S rRNA gene sequencing.Choosing 3 representative strains,which have strong anti-fungus activity to study the sunflower vitro blade anti-fungus effect experiment,sunflower potted plant anti-fungus experiment,the physiological and biochemical characteristics experiments,determination of growth curve and anti-fungus activity of the crude extract,which the result shows that the anti-fungus control efficiency of the strain Z9,ZX6 and NKZ is 69.27%,53.56% and 80.42% respectively in the sunflower vitro blade anti-fungus effect experiment,and the anti-fungus control efficiency of the strain Z9,ZX6 and NKZ is 66.00%,57.75% and 74.93% respectively in the sunflower potted plant anti-fungus experiment,and detecting the anti-fungus activity of the crude extract of these 3 strains by tablet confrontation experiment.Three strains,designed Z9,ZX6 and NKZ,showed 16 S rRNA gene sequence similarities of 99.61%,100.00% and 99.93% to their most closely related species respectively.Based on the results of morphological characteristics,physiological and biochemical characteristics,it was confirmed that the Streptomyces albidoflavus was proposed for strain Z9,the Streptomyces cinnamonensis was proposed for strain ZX6 and the Bacillus velezensis was proposed for strain NKZ.Choosing these 7 effective antagonistic strains,which have strong anti-fungus activity to research the seed husk infection experiment and seed germination experiment to verify the anti-fungus effect of these 7 effective antagonistic strains,which the result shows that the incidence of seed husk infection of the original microbial fermentation of the strain Z9,ZX6,NKZ,NM63,JQ134,J7 and J33 is 30.00%,37.78%,24.44%,14.07%,14.44%,26.67% and 31.85% respectively and the promotion rate of the fermentation filtrate of the strain Z9,ZX6,NKZ,NM63,JQ134,J7 and J33 is 21.33%,16.12%,26.32%,40.87%,44.60%,45.96% and 46.59% respectively in the seed germination experiment,as well as use these 7 strains to make the microbial composite fermentation agent to prevent and control the fungus disease in the sunflower potted plant experiment.The anti-fungus efffect of strain ratio for Z9:ZX6:NKZ:NM63:JQ134:J7:J33 equal to 1:1:1:1:1:1:1 is 79.45%,and the strain ratio for Z9:ZX6:NKZ:NM63:JQ134:J7:J33 equal to 1:1:2:2:2:2:2 is 83.08% respectively in the sunflower potted plant experiment.These antagonistic strains have these advantages,which have simple culture condition,easy to save and safe to the environmental protection.Therefore,these antagonistic strains have a good applicaion potential.