Molecular Cloning And Functional Study Of E74 And E78 From Nilapparvata Lugens(St(?)l)

The brown planthopper(Nilaparvata lugens St(?)l)are highly productive and important migratory pests in many rice-growing areas of Asia.Brown planthopper,as a kind of specialized insect,seriously harms the yield of rice crops.E74 gene in brown planthopper and homologous Ets in mammals are members of the Ets(E26 transformation-specific)transcription factor family.The E74 gene affects insect pupation and ovarian development,and is involved in the regulation of vitellogenesis and expression of Vg gene.The E78 gene in brown planthopper is a member of the nuclear hormone receptor superfamily.The E78 gene regulates reproductive organ development,stem cell function,gamete development and survival.It is also important for normal egg production and maternal control of early embryogenesis.Studies have shown that Nl E74 gene,as a kind of early transcription factor,may activate the expression of Nl E78 gene.Both the Nl E74 and Nl E78 genes are regulators in the ecdysis pathway.In this study,the full length of brown planthopper Nl E74 and Nl E78 were obtained by cloning,and phylogenetic tree was constructed for genetic analysis.Moreover,biological information analysis was carried out to predict the existence of Ets family transcription factor domain in Nl E74 amino acid sequence,and relatively conservative Nuclear Receptor Ligand-binding domain(NR-LBD)and zinc finger domain in Nl E78 amino acid sequence.q RT-PCR showed the temporal and spatial expression characteristics of Nl E74 and Nl E78 genes,and it was found that the expression levels were higher in brown planthopper nymphs of the fifth instar and in female ovaries.In RNAi interference experiments,it was found that after the expression of Nl E74,Nl E78 and NlβFTZ-F1 were down-regulated in the fourth and fifth nymphs,the proportion of nymphs ’molting failure from the fourth to the fifth instar and molting failure from the fifth instar to the adult increased,leading to a decrease in the emergence rate of brown planthappers.After RNAi interference,the ovaries of brown planthopper developed slowly and the number of eggs was reduced.Through the Co-Immunoprecipitation(Co-IP)experiment,it was found that E78 protein interacts with the downstream regulator E93 of the ecdysis signaling pathway.Immunofluorescence technique was used to localize the cells,and E78 and E93 genes were found to be expressed in the nucleus.After the Nl E74 and Nl E78 genes were down-regulated by RNAi interference,transcriptome data of the samples were analyzed,and it was found that most of the genes with different expression were related to the cuticular proteins of Nilaparvata lugensis.The results of this study indicated that Nl E74 and Nl E78 genes have effects on the signal transduction of juvenile hormone and molting hormone,which is of great significance for the rapid control of target insect pests.