Screening,Identification And Biocontrol Mechanism Of Antagonistic Fungi Against Sclerotinia Sclerotiorum

Sclerotinia sclerotiorum(Lib.de Bary)is one of the main diseases causing Sclerotinia stem rot in rapeseed.At present,biological control has become one of the main effective ways to control this disease.In order to better prevent and control the sclerotial disease of rapeseed and provide relevant experimental basis for its development and prevention preparation,in this dissertation,the isolation,screening,identification and the biological control mechanism of antagonistic microorganisms against S.sclerotiorum,and obtained the following main experimental results:1.Isolation,screening and biological characteristics of sclerotia disease of rapeFrom the soil collected from the nongcui garden and greenhouses of Anhui Agricultural University,8 strains of antagonistic fungi were isolated and screened out.Among them,3 strains of antagonistic fungi had better inhibitory effect on the bacteria,and they were used to biocontrol fungi Y-1,Y-2 and Y-3 respectively.The inhibition rates of biocontrol fungi Y-1,Y-2 and Y-3 on S.sclerotiorum were 79.53%,72.09% and 76.74%,respectively.The biological characteristics of biocontrol fungi Y-1,Y-2 and Y-3 were studied.The experimental results showed that the optimal temperature of biocontrol fungus Y-1 was 35?.The optimum temperature of biocontrol fungus Y-2 is 25?.The optimum temperature of biocontrol fungus Y-3 is 25~30?.The optimal p H values of biocontrol fungi Y-1,Y-2 and Y-3 are 7,and they can utilize a variety of carbon and nitrogen sources.2.Identification of biocontrol fungi Y-1,Y-2 and Y-3Through morphological identification and 18 S r DNA sequence alignment,antifungal fungus Y-1 was preliminarily identified as Aspergillus.the biocontrol fungus Y-2 preliminary identification of sorghum attached aureus(Epicoccum sorghinum).the biocontrol fungus Y-3 was preliminarily identified as Fusarium oxysporum.3.Antagonistic scope of biocontrol fungi Y-1,Y-2 and Y-3The confrontation culture tests of the biocontrol fungus Y-1,Y-2 and Y-3 respectively with 10 kinds of pathogenic fungi such as apple anthrax fungus(Colletotrichum gloeosporioides),tomato early blight fungus(Alternaria solani),rice sheath blight fungus(Thanatephorus cucumeris),wheat scab fungus(Fusarium graminearum)and wheat sheath blight fungus(Rhizoctonia cerealis)were conducted,and the experimental results show that the biocontrol fungus Y-1,Y-2 and Y-3 all had inhibitory effects on 10 kinds of plant pathogenic fungi,with different inhibitory effects.Among them,biocontrol fungus Y-1,Y-2 and Y-3 have the best inhibitory effect on wheat sheath blight fungus.4.The inhibitory effect of fermentation broth of biocontrol fungi Y-1,Y-2 and Y-3 on the mycelium growth of S.sclerotiorumThe metabolic fluid of biocontrol fungus Y-1 has a certain inhibitory effect on S.sclerotiorum.The higher the concentration of metabolic fluid is,the better the inhibitory effect is.The metabolic fluid of biocontrol fungus Y-2 had no inhibitory effect on S.sclerotiorum at different concentrations.The metabolic fluid of biocontrol fungus Y-3 had the best inhibitory effect on S.sclerotiorum.Under different concentration conditions,it had inhibitory effect on S.sclerotiorum,and the inhibitory effect was obvious.5.Inhibitory effect and thermal stability of biocontrol fungus proteins Y-1 and Y-3 on S.sclerotiorumThe proteins extracted from the metabolites of biocontrol fungus Y-1 and Y-3 had inhibitory effect on S.sclerotiorum.The inhibition rate of biocontrol fungus Y-1 protein against biocontrol fungus Y-1 was 93.02%,and that of biocontrol fungus Y-3 protein against biocontrol fungus Y-3 was 92.44%.Moreover,after the protein was heated in the water bath at 95? for 30 min,it still had an inhibitory effect on S.sclerotiorum.Therefore,it can be concluded that the proteins extracted from biocontrol fungus Y-1 and Y-3 are heat-stable proteins.6.Effect experiment of biocontrol fungus Y-1 and Y-3 on S.sclerotiorum of oilseed rapeThe control effect of biocontrol fungus Y-1 protein on Sclerotinia stem rot in isolated leaves reached 83.49%,and the control effect of biocontrol fungus Y-3 protein on isolated leaves of intragytes reached 100%.The control effect of biocontrol fungus Y-1 protein on Sclerotinia stem rot on potted plants was 85.71%,and the control effect of biocontrol fungus Y-3 protein on potted plants was 91.61%.