The Function Of JNK-mediated Spodoptera Exigua Midgut Immune Defense Serratia Marcescens PS-1

Spodoptera exigua is a kind of agricultural pest with increasing danger,which has great potential for explosive pests.For this trend,the experiment was conducted with S.exigua as the object,focusing on exploring the immune defense of the midgut of S.exigua.In this study,the first instar larvae of 5th instar of S.exigua were used as experimental materials and treated with Serratia marcescens PS-1.The i TRAQ technique was used to treat the proteins in the intestine of S.exigua on days 1,2 and 3 after treatment.Samples were tested for relative quantitation of proteins.Among the differential proteins screened out,the expression of JNK was significantly upregulated,and the JNK signaling pathway plays an important role in regulating insect stress response and immune defense.JNK(c-Jun N-terminal kinase)is a kinase that binds to and phosphorylates c-Jun.The transcriptome sequence of the S.exigua JNK gene is obtained by RT-PCR.Analysis of JNK gene expression in S.exigua using q RT-PCR.Using RNAi technology to interfere with the JNK gene of S.exigua to study its immune defense function in the midgut.The S.exigua was induced by PS-1 and q RT-PCR was performed to verify the relevant antimicrobial peptide genes and signaling pathway genes in the intestine of S.exigua.The main results are as follows:1.The Unigene sequence of the JNK gene transcriptome of S.exigua was obtained by RT-PCR.Its c DNA sequence is 1914 bp in length and has been phylogenetically and homologously analyzed with other species.2.The expression pattern of JNK gene of S.exigua was analyzed.The results of q RT-PCR showed that JNK gene was expressed in different tissues of S.exigua at different stages.The relative expression level of JNK in S.exigua larvae changed greatly,but in the adult stage,the expression level was higher.Expression levels in blood cells of the beet armyworm larvae are higher than in the midgut,fat body,and epidermis;JNK expression is extremely high after induction by S.marcescens PS-1.3.Relative quantification of protein in the intestine protein samples of S.exigua using i TRAQ technology.Based on the differentially expressed proteins,11 differential proteins such as JNK,PGRP-LC,Cecropin A2,and Lysozyme 1B were selected.q RT-PCR results showed that both viable S.marcescens PS-1 and E.coli DH5? could induce high expression of these genes in S.exigua.However,the heat-inactivated S.marcescens PS-1 and E.coli DH5? can only induce high expression of some genes,such as C-type Lectin,Defensin and so on.4.Study on the Immune Defense Function of JNK Gene of S.exigua using RNAi Technique.q RT-PCR results showed that significant RNAi effects were observed in the hemolymph,midgut and fat bodies of S.exigua.However,no obvious RNAi effect has appeared in the epidermis.After injection of ds JNK for 48 h,the expression levels of antimicrobial peptides Cecropin A2,Lebocin 2 and Moricin were significantly down-regulated in blood cells,while the expressions of antimicrobial peptides Cecropin A2,Lebocin 2,Lysozyme 1B and Moricin were significantly down-regulated in the midgut.It is speculated that the JNK gene regulates these antibacterial peptides.In summary,based on i TRAQ data,the dynamic expression of 11 differentially expressed proteins in the intestine of S.exigua was detected at the m RNA level.The RNAi technology was used to investigate the expression of JNK-regulated antibacterial peptide genes Cecropin A2 and Moricin in the haemolymph and midgut of the beet armyworm.