Antagonistic Effects Of Bacillus Amyloliquefaciens HR-2 On Rice Blast Fungus And Rape Sclerotia

Rice blast and sclerotinia disease seriously affect the yield and quality of rice and rapeseed in my country.With the emergence of disadvantages of traditional control methods,it is particularly important to seek an environmentally friendly and efficient new fungicide.In this experiment,a Bacillus amyloliquefaciens strain HR-2 with broad-spectrum antifungal activity was isolated from Hunan.Through antagonism and pot experiments,the antagonistic effect of this strain on rice blast fungus and rape sclerotia was determined.The development of biocontrol preparations for rice blast and rape sclerotium disease provides a scientific basis and lays the foundation for field prevention and control.The main research contents and results are as follows:1.The collected samples were separated and screened by the plate dilution method,and a Bacillus strain HR-2 with broad-spectrum antifungal activity was obtained.The inhibitory rates of this strain against Magnaporthe oryzae and Sclerotinia sclerotiorum were 82.34%and 72.32%,respectively,combined with morphological observation,Gram staining,16S r RNA,gyr A and tuf gene sequence alignment analysis,identified it as Bacillus amyloliquefaciens.2.Carry out rice pot and rape detached leaf experiments,and carry out field trials on the efficacy of rape sclerotia disease.The results of the rice pot experiment showed that the 10times dilution of strain HR-2 had a control effect of 61.69%against rice blast,which was equivalent to the positive control 50 mg/L azoxystrobin,and there was no significant difference between the treatments;The test results of detached leaves of rape show that the HR-2 stock solution and 10 times dilution of the rape leaf surface can effectively inhibit the infection and growth of sclerotinia hyphae on the leaves,and the HR-2 stock solution has the most significant control effect,The diameter of the diseased spot of Rapeseed sclerotiorum is0 cm;The field efficacy test further verified the control effect of HR-2 strain on rape sclerotia,and the results showed that the minimum disease index of rape sclerotia when sprayed with HR-2 stock solution and 3/3 boscalid mixture was 1.56?0.13 e.The highest control effect is64.33%,followed by HR-2 stock solution treatment,and the control effect is 64.17%.There is no significant difference between the two.3.With the help of hydrochloric acid precipitation and LC-MS technology,the antibacterial active substances in the crude extract of HR-2 strain are separated and purified.The test results showed that phenol,naringenin,lauric diethanola Mide,dinitolmide and neosperidin dihydrochalcone,selected from 24 monomer compounds,were effective against rice blast fungus and rapeseed.Sclerotinia sclerotiorum has different degrees of antagonism.The 5 monomer compounds were further mixed in equal amounts to carry out drug susceptibility tests.The results showed that as the concentration of the mixture increased,the antagonistic effect showed an increasing trend.Finally,a preliminary analysis of the metabolic pathways was carried out,and the results showed that the differential metabolites were significantly enriched in the nitrogen metabolism pathway and the arginine and proline pathways.4.Using plate counting method and UV spectrophotometer OD₆₀₀nm to explore bismerthiazol,boscalid,fludioxonil,triadimefon,azoxystrobin,tebuconazole,propiconazole,benziothiazolinone,thiosen copper and dimethomorph The influence of 10 chemical fungicides on the growth of biocontrol strain HR-2.The preliminary screening results showed that 100 mg/L of 5 chemical fungicides,tebuconazole,propiconazole,benziothiazolinone,thiosen copper and dimethomorph,were shaken with the HR-2 strain for 24 hours,and the growth of the strain was inhibited.The strain is inactive.The remaining 5 chemical fungicides with good compatibility were further screened.The results showed that the three chemical fungicides of boscalid,fludioxonil and azoxystrobin at different concentrations were shaken with the HR-2 strain at 36 h and 48 h,there was no significant difference between each concentration and CK,the growth of the strain was not affected,and the bacteria and drugs had good compatibility...