Isolation And Antagonistic Analysis Of Bacteria And Fungi From Sclerosphere Of Sclerotinia Sclerotiorum

In 90% of Sclerotinia sclerotiorum's life cycle time, it survives as the form of sclerotia in the soil, so soil environment has an important effect on Sclerotinia sclerotiorum. There are abundant of soil microbial communities among the soli, what kind of soil microbial biomass exist in sclerosphere of Sclerotinia sclerotiorum sclerotia, and wheaher the antagonism exist between the two, have an important significance on the the state of Sclerotinia sclerotiorum sclerotia's survival.Define soil adhesion in the epidermis of sclerosphere, which groups of microbes exist around sclerotia, whether antagonism exist between Sclerotinia and those microbes, those mentioned above has a decisive effect for the survival state of Sclerotinia sclerotiorum sclerotia. After applying the field, Coniothyrium minitans survive to long-term as the form of spores in the soil which also rely on the soil as the natural habitats. Therefore, soil microbial communities impact on the parasitism of Coniothyrium, so, soil microbial communities is also of great Significance of the theoretical value on Coniothyrium parasitic for Sclerotinia sclerotiorum sclerotia.First, isolated soil fungal and soil bacterial in sclerosphere, the two populations were significantly higher than the microbial populations of bulk soil. Soil microbial populations of sclerotia divided by soil microbial populations of unsclerotiasphere is W, define W as the effect value of sclerotiasphere. The results show that:W range is 1.43-249.59.Then, by vitro antagonistic tests between the microbial and the Sclerotinia sclerotiorum, the result showed:the 33 fungal isolates,10 isolates (numbered as:A1,B,C2,D0,E,E0,E1,F,F1and SDD) on the antagonistic role of Sclerotinia sclerotiorum, the 66 bacterial isolates,7 isolates (numbered as:a0,e1,e2,h,f1,x-a and x-f) on the antagonistic role of Sclerotinia sclerotiorum. The results also show that:These fungi and bacteria on minitans isolates have different degrees of antagonism.Parasitism of C. minitans mixed with antagonistic strains on sclerotia of S. sclerotiorum shows that:all antagonistic strains can impact the effect of biocontrol agent (BCA) of Sclerotinia sclerotiorum, fungal strains A1,C2,D0,E0,F,F1 and SDD, bacteria straina0,h,e1,e2,f1,x-a and x-f can reduce effect of biocontrol agent (BCA) of Sclerotinia sclerotiorum. Bacterial strains ao can be parasitic on Sclerotinia sclerotia.Excised leaves experiments show that:all antagonistic strains have different effect levels of biological control of Sclerotinia sclerotiorum, on the leaf blade,in which antagonistic strains A1,B,and SDD, a0,h,e1,and e2, mixed with C. minitans can reduce the infection to the leaves by Sclerotinia sclerotiorum.By morphological identification and molecular biology:the stains A1 and B were identified as Penicillium spp. The stains C2,F1 and SDD were identified as Fusarium spp. The stains D0,E0 and F were identified as Trichoderma spp. The stains E and E1 were identified as Aspergillus spp. The stains a0 and h were identified as Paenibacillus spp. The stains e1,e2 and f1 were identified as Bacillus subtilis.The stains x-a and x-f were identified as Pseudomonas spp.The results show that:field application of C. minitans will be affected by the soil microorganisms, and it is the most important impact factor on the reduced effectiveness of biological control to Sclerotinia sclerotiorum in field.