| Maize ear rot is an important disease in the corn production process and can cause serious yield losses.Fusarium oxysporum is one of the main pathogens of corn ear rot,and the fumonisin produced by it will contaminate corn and its products,and will also harm human and animal health.In this paper,the growth rates of different concentrations of pyraclostrobin on wild-type strains of Fusarium oxysporum,FUM1 overexpressing strains,FUM21 overexpressing strains,FUM21 different silencing efficiency strains,fumonisin toxigenic ability and FUM family in strains were studied.The influence of gene cluster expression;the effect of different nitrogen sources and carbon sources on the production of fumonisin by F.verticillioides of FUM21 overexpressing strain.The mechanism of pyraclostrobin inhibiting the production of fumonisin by F.verticillioides was preliminarily determined,which provided a reference for the prevention and control of corn ear rot and the inhibition of fumonisin production.Mainly achieved the following results:1.Pyraclostrobin can inhibits the production of fumonisin by Fusarium oxysporum.When the concentration of pyraclostrobin was 0.01 ?g/mL,0.05 ?g/mL,0.1 ?g/mL,0.5 ?g/mL,and 1?g/mL,the inhibition rates for fumonisin production were 30.67%,31.25%,and 44.89%,32.29%,22.57%,respectively,and the concentration of pyraclostrobin to 0.1?g/mL had the strongest inhibitory effect on fumonisin production by F.verticillioides.2.Pyraclostrobin can inhibit the expression of FUM1,FUM2,FUM6,FUM7,FUM8,FUM19 and FUM21 genes after treatment with F.verticillioides.The inhibitory rates of pyraclostrobin on the expression levels of F.verticillioides on FUM1,FUM2,FUM6,FUM7,FUM8,FUM19 and FUM21 were 73%,27.73%,40.21%,38.46%,36.51%,and 47.36%,respectively.66.94%,pyraclostrobin mainly affects the expression of FUM1 and FUM21 genes.3.Pyraclostrobin inhibits the growth,sporulation and fumonisin production of wild-type and FUM1 overexpressing strains and FUM21 overexpressing strains of F.verticillioides.After treatment with pyraclostrobin,the growth rates of FUM1 and FUM21 overexpressing strains were 1.03±0.01 cm/d and 0.97±0.02 cm/d,respectively.The sporulation of FUM1 and FUM21 overexpressing strains was 20.21±0.35 and 15.77±0.14,respectively,and the sporulation of wild type strain was 13.45±0.26,which was significantly lower than that of overexpressing strain.The inhibitory rates of pyraclostrobin on the toxigenic ability of FUM1 and FUM21 overexpressing strains were 43.84% and 36.63%,respectively.4.Pyraclostrobin inhibited the growth rate and sporulation of F.verticillioides on FUM21 silencing strain.The silencing efficiency of FUM21 treated with 0.1 ?g/mL pyraclostrobin was 19.32%,28.95%,42.98%,60.87%,78.14%,respectively.The growth rates of FUM21 silencing strains were 1.14±0.01 cm/d,0.93±0.06 cm/d,0.88±0.03 cm/d,0.79±0.05 cm/d,and 0.67±0.06cm/d,respectively,and the difference was not significant.The strains of FUM21 with different silencing efficiency inhibited the spore inhibition of strains with high silencing efficiency,and the sporulation yields were 19.33±0.04,15.67±0.08,11.25±0.04,9.37±0.11,8.13±0.02,respectively.When the silencing efficiency of FUM21 is higher than 42.98%,the sporulation ability is significantly decreased.The synthesis of fumonisin by different silencing efficiency strains was detected by HPLC-post-column derivatization.The silencing efficiency of FUM21 was 78.14%,and the fumonisin was 189.93 ?g/g,which was significantly lower than that of wild type.5.Different nitrogen and carbon sources affect the FUM21 overexpressing strain to produce fumonisin.When the nitrogen source is beef extract and the carbon source is mannitol,the FUM21 overexpression strain is promoted to produce fumonisin.When beef extract was used as nitrogen source,the amount of fumonisin produced by FUM21 overexpressing strain was 31.97±0.06 ?g/g,which was significantly higher than that of peptone,ammonium sulfate,glutamic acid and potassium nitrate as nitrogen source.The amount of toxin produced.When mannitol was used as a carbon source,the amount of fumonisin produced by FUM21 overexpressing strain was 28.97±0.13 ?g/g,which was significantly higher than that of soluble starch,maltose,fructose and glucose as carbon source fumonisin. |
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