| Beauveria bassiana is an important material for pest biological control,and Bombyx mori is an important model insect for studying the immune response mechanism of insects.In-depth study of the immune response mechanism of insects against Beauveria bassiana infection is of great significance for improving the control effect of Beauveria bassiana against pests from the perspective of immunosuppression.In this study,three strains of Beauveria bassiana strains with high,medium and low virulence to Bombyx moris were first screened,and the Bombyx mori immunity induced by the three strains with different virulences under surface infection and in vivo injection was further studied The main research results of the expression differences of response genes are as follows:1.Screening of Beauveria bassiana with different pathogenicity under body surface infection mode:Using the method of water inoculation,the pathogenicity of 18 Beauveria bassiana strains on third-instar larvae of Bombyx mori was studied.Bb38 was selected as the highly virulent strain infecting Bombyx mori,Bb2393 was the virulent strain infecting Bombyx mori,Bb2943 is a low-virulence strain that infects Bombyx moris.The half-lethal time was 3.595 d,4.511 d,and 7.46 d respectively;the half-lethal concentrations were 104.275 spores/ml,105.2309 spores/ml,and 107.0134 spores/ml,respectively.2.Screening of Beauveria bassiana with different pathogenicity under in vivo injection method:The pathogenicity of 18 strains of Beauveria bassiana strains on third-instar larvae of Bombyx mori was studied by inoculation with spore suspension.Bb38 was selected as the highly virulent strain infecting Bombyx moris,Bb2393 was the virulent strain infecting Bombyx moris,and Bb2943 was the low virulent strain infecting Bombyx moris.The half-lethal time was 31.825 h,39.638 h,65.659 h.3.Differences in the expression of Bombyx mori immune-related genes induced by different virulence strains under body surface infection methods:The genes expressed in the low-virulence-infection group sl,the toxic-infection-infection group sm,and the high-virulence-infection group sh were compared with the control group dz,and the number of DEGs was compared and analyzed.The significantly different expressed genes were 2697,1323,924;the GO function of DEGs is significantly enriched.There are 32 GO function classifications in the three experimental groups;the Pathway of DEGs is significantly enriched.There are 15 pathway pathways in the three groups.DEGs are neutral and immune In response to the genetic differences,5 immune response up-regulated genes and 4down-regulated immune genes were co-expressed.4.Differences in the expression of Bombyx mori immune-related genes induced by different virulence strains in vivo:The genes expressed in the low toxicity group zl,the toxic group infection zm and the high toxicity group zm were compared with the control group dz,and the number of DEGs was compared and analyzed.The significant differential expression genes were 2535,1282,1499;the GO function of DEGs is significantly enriched,there are 34 GO function classifications in the three groups of experimental groups;the Pathway of DEGs is significantly enriched,there are 15 pathways in the three groups,and the DEGs are Gene differences related to immune response,7 immune response up-regulated genes and 2 down-regulated immune genes co-expressed.5.Analysis of the influence of infection mode on the expression of the Bombyx mori immune genes:Highly virulent strains were used to infect Bombyx moris.They were infected by water immersion method(sh)and injection method(zh),and compared with the expression genes of the control group(dz).The DEGs were compared and analyzed.Number,significantly differentially expressed genes are 924 and 1499 respectively;the GO function of DEGs is significantly enriched,the GO function classifications in both experimental groups are 32 and 34;the Pathway of DEGs is significantly enriched,and the pathways are all 18;the differences in genes related to immune response in DEGs found that 10 genes were co-expressed,of which 6 genes were up-regulated and 4 genes were down-regulated.6.Expression of several immune genes of Bombyx mori at different times after infection:Fluorescence quantitative method was used to measure the expression analysis of several immune genes of Bombyx mori after infection.Five up-regulated genes peptidoglycan recognition protein,cecropin,serine protease,cytochrome P450 class 4,serine protease inhibitor and two The down-regulated gene superoxide dismutase,Cu-Zn family,and lysozymes in the Bombyx mori were infected by Beauveria bassiana during 8--24 h.The relative expression level was stable,and there was a certain regularity,indicating that the Bombyx mori was When infected by Beauveria bassiana with different virulences,under other conditions constant,the virulence of the infected fungi has a certain relationship with the differential expression of immune genes in the Bombyx mori. |
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