Effects Of Two Entomopathogenic Fungi On Antioxidant Effect And Detoxification Metabolism Of Aphis Citricola Vander Goot

Aphis citricola Vander Goot is a common pest of fruit trees,which seriously damages apple,apricot,pear and other Rosaceae fruit trees.It infects new shoots or young buds and leaves by adults and nymphs,and spreads a variety of plant viruses to cause a lot of losses in orchards.In this study,Beauveria bassiana ZJU435 and Metarhizium anisopliae CQMa421 were used as materials to systematically analyze the lethal efficiency of different concentrations on A.citricola,and 1×108 spores/mL was selected as the best control concentration.The activities of antioxidant enzymes and detoxification enzymes were determined by 1×108 spores/mL,B.bassiana ZJU435 and M.anisopliae CQMa421 at 24 h after infection,and the transcriptome sequencing was conducted.Based on this,the related genes of immune and detoxification were identified and analyzed.This study can provide a theoretical basis for further study on the pathogenic mechanism of entomopathogenic fungi infecting A.citricola.The main results are as follows:1.Toxicity determination of two entomopathogenic fungi to A.citricolaThe lethal effects of B.bassiana ZJU435 and M.anisopliae CQMa421 with spore concentrations of 1×109 spores/mL,1×108 spores/mL,1×107 spores/mL and 1 × 106 spores/mL on A.citricola were determined.The results showed that the cumulative mortality of A.citricola treated with 1×109 spores/mL M.anisopliae CQMa421 for 9 days was 90%.The cumulative mortality after treatment with 1×108 spores/mL was 80%.After treatment with 1×109 spores/mL and 1×108 spores/mL of B.bassiana ZJU435 for 9 days,the cumulative mortality was 98%.Therefore,1×108 spores/mL B.bassiana ZJU435 and M.anisopliae CQMa421 were the best concentration to control A.citricola.2.Effects of two entomopathogenic fungi on A.citricolaThe antioxidant enzyme activity and detoxification enzyme activity of B.bassiana ZJU435 and M.anisopliae CQMa421 against A.citricola were determined.The results showed that there were differences in enzyme activities in A.citricola at different times.After 12 h of treatment,SOD,POD,CAT and CarE in A.citricola infected by B.bassiana ZJU435 increased,and GSTs and P450s were not significantly different from the control.After 24 h treatment,SOD and CAT tended to be stable,POD increased first and then decreased,GSTs and P450s continued to rise.The SOD,POD and CAT in A.citricola infected by M.anisopliae CQMa421 increased,and CarE,GSTs and P450s tended to be stable.With the increase of time,SOD and CAT tended to be stable,CAT increased first and then remained unchanged,POD,GSTs and P450s continued to rise.The results showed that GSTs and P450s may play a major role in detoxification metabolism of A.citricola.3.Transcriptome analysis of two entomopathogenic fungi infecting A.citricola after 24 hTranscriptome sequencing of A.citricola.The sequencing results showed that a total of 412060044 clean reads were obtained from the aphids infected with B.bassiana ZJU435 and M.anisopliae CQMa421 after 24 h.The number of unigenes assembled was 111432,the number of Transcriptions was 162528,the average length was 780.27 bp,and the N50 length was 1173 bp.Among them,there were 37661 differentially significant genes after 24 h of infection with B.bassiana ZJU435,including 29228 up-regulated genes and 8433 down-regulated genes.After M.anisopliae CQMa421 infection,there were 5508 differentially significant genes between the control groups,including 5370 up-regulated genes and 138 down-regulated genes.The obtained Unigenes were subjected to BLASTX alignment analysis by SwissProt,NR,KEGG,KOG and Pfam databases,and all annotations were successful.Eighteen P450 genes and seven GSTs genes were screened and identified.Homologous sequence alignment showed that A.citricola and Acyrthosiphon pisum had the highest sequence similarity.4.Expression analysis of immune genes and detoxification genes of A.citricolaThe results of qRT-PCR analysis of immune and detoxification related genes showed that 14 CYPs genes were significantly up-regulated,4 GSTs genes were significantly up-regulated,and 16 immune genes were significantly up-regulated after 24 h of B.bassiana ZJU435 infection.After M anisopliae CQMa421 infection for 24 h,four CYPs genes were significantly up-regulated,three GSTs genes were significantly up-regulated,and seven immune genes were significantly up-regulated.The number and expression of detoxification genes and immune genes in A.citricola infected by B.bassiana ZJU435 were higher than those infected by M.anisopliae CQMa421.In this thesis,the effects of two entomopathogenic fungi on the control of Aphis citricola were studied from the aspects of indoor virulence determination,enzyme activity determination,transcriptome sequencing and detoxification,and the relative expression level of immune-related genes,as well as the detoxification metabolism of Aphis citricola after infection.It provides a theoretical basis for its prevention and control at the molecular level and provides a basis for green prevention and control.