Lipid Synthesis Ability Of Binodoxys Communis And Its Regulation On Lipid Metabolism Of Host Aphis Gossypii

Aphis gossypii is an important pest of cotton,and Binodoxys communis is the dominant parasitic wasp of cotton aphid,which can effectively control the population of cotton aphid.Most parasitic wasps lack the ability to synthesize lipids,which need to be obtained by regulating host metabolism.It has not been reported whether B.communis has the ability to synthesize lipids and how to regulate and utilize the host to satisfy its own growth and development.In this study,transcriptome sequencing,fluorescence quantitative PCR,LC-MS/MS and targeted lipid metabolic flux techniques were used to qualitatively and quantitatively analyze the genes and metabolites of B.communis.The ability of lipid synthesis and accumulation of A.gossypii was studied systematically,and its effect on the lipid synthesis pathway of host A.gossypii was clarified,and the utilization ways and ways of metabolites of B.communis to A.gossypii were preliminarily elucidated in order to clarify the ways of lipid regulation and utilization of host by parasitoids,so as to lay a foundation for studying the interaction between parasitoids and hosts and revealing the co-evolution of parasitoids and host insects.The main research results are as follows:1.The dynamic changes of gene expression and metabolites of lipid synthesis pathway in different developmental stages of B.communis were clarified.Dynamic monitoring of glycolysis,tricarboxylic acid cycle,and glycerol and glycerophospholipid metabolism through combined analysis of transcriptome and metabolome in different developmental stages of B.communis.Compared with the 3-day larvae,the expressions of g6pi,fbpa and gapdh involved in glycolysis were all down-regulated in the 5-day larvae,and no differences in the expressions of acc and fas were detected,and the carbohydrate metabolism decreased.However,gpat1,pap and dgat1 in the G3P pathway were all significantly up-regulated,and the corresponding glyceride content was also significantly increased.Compared with 1-day adults,the content of triglyceride and diglyceride decreased significantly in 3-day male and female adults,and only the tgl gene responsible for decomposing lipids was highly expressed.Results showed that the larvae of B.communis did not have the ability to convert carbohydrates into fats,but had the ability to synthesize triglycerides;no signs of lipid synthesis were detected in the adult stages.2.The gene response of sucrose induction to lipid synthesis of B.communis was confirmed.Compared with the control group,the expression of pepck,pp X1,pp X2 and fas decreased significantly in female adults of B.communis induced by sucrose.Sucrose treatment did not promote the lipid synthesis of parasitoids.It is completely different from the transcriptional strategy change of A.gossypii to activate lipid synthesis after sucrose induction.In GO and KOG analysis,the metabolic process of B.communis and lipid synthesis was weaker than that of cotton aphid.It was preliminarily concluded that the adults of B.communis could not use sucrose or carbohydrates to participate in glycolysis and a series of lipid synthesis processes.3.The regulation of host lipid metabolism pathway gene expression by B.communis was clarified.In order to confirm how the B.communis regulates the host to complete its own growth and development under the condition of weak lipid synthesis ability.In this study,we focused on the fatty acid synthesis pathway,the glyceride synthesis pathway,the glycolysis pathway and the amino acid metabolism pathway contained 36 genes related to the lipid synthesis of A.gossypii,and the real-time fluorescence quantitative PCR technology was used to study the transcription changes of these genes in the body of the parasitical cotton aphid.The results showed that A.gossypii parasitized by B.communis,2glycolysis pathway genes,5 fatty acid synthesis pathway genes,6 glyceride synthesis pathway genes and 5 amino acid metabolism pathway key genes were all significantly up-regulated.Among them,the expression of glycerol kinase in the glyceride synthesis pathway decreased significantly,and there was no significant change in the expression of other genes.4.The regulation and utilization pathway of B.communis on the metabolism of cotton aphid and the lipid synthesis ability of parasitoid wasp larvae were clarified.Based on the targeted lipid metabolic flux test of ¹³C,the ¹³C flow rates of glycolysis,tricarboxylic acid cycle and pentose phosphate pathway in the unparasitized A.gossypii,parasitized A.gossypii and larvae of B.communis were detected.It was found that the metabolic ability of the three pathways of parasitized A.gossypii was stronger than that of unparasitized A.gossypii,and F6P,GAP,succinate,malate,citrate,G6P and 6PG were all up-regulated.¹³C was found in the metabolic species of parasitic bee larvae.However,¹³C-labeled DHAP and GAP were not detected in larvae,and the content of these two metabolites was very low in quantitative detection.The glycolysis pathway was blocked,the de novo synthesis of fatty acids was blocked,and the lactic acid content increased significantly,resulting in a very low level of carbohydrate utilization.It was confirmed that the metabolism and utilization of the A.gossypii was regulated and utilized by the B.communis,and it was clear that the larvae of the B.communis do not have the ability to convert carbohydrates into fatty acids and triglycerides,and the larvae depended on the regulation of the host to complete their own energy metabolism.