1. Mamestra brassicae Multiple Nucleopolyhedroviruses Prevents Pupation of Helicoverpa armigera by Regulating Juvenile Hormone Titer.
- Author
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Yang, Yanqing, Dai, Jinping, Zhang, Guozhi, Singh, Deepali, Zhang, Xiaoxia, and Liang, Zhenpu
- Subjects
JUVENILE hormones ,HELICOVERPA armigera ,NUCLEOPOLYHEDROVIRUSES ,GENE expression ,INSECT metamorphosis ,LARVAE ,PLASMODIOPHORA brassicae - Abstract
Simple Summary: Baculovirus infection can prevent the pupation of insects. However, the molecular mechanism of baculovirus preventing the pupation of larvae by regulating the Juvenile hormone (JH) pathway is still unclear. In this study, we examined the interactive relationship of Mamestra brassicae multiple nucleopolyhedroviruses (MbMNPV) and Helicoverpa armigera (H. armigera). We found that MbMNPV infection caused an increased JH titer and inhibited the expression levels of juvenile hormone esterase (JHE) and juvenile hormone epoxide hydrolase (JHEH). Our studies further proved that the JH is mainly degraded by JHE in H. armigera larvae. Knocking down of HaJHE promoted MbMNPV replication. These findings suggest that the infection of H. armigera larvae by MbMNPV leads to an increased JH titer by inhibiting the expression of JHE, which prevents pupation of H. armigera and promotes MbMNPV replication. Baculovirus infection can prevent the pupation of insects. Juvenile hormone (JH) plays a vital role in regulating insect molting and metamorphosis. However, the molecular mechanism of baculovirus preventing the pupation of larvae by regulating the Juvenile hormone (JH) pathway is still unclear. In this study, we found that the Mamestra brassicae multiple nucleopolyhedroviruses (MbMNPV) infection prolonged the larval stage of fourth instar Helicoverpa armigera (H. armigera) by 0.52 d and caused an increase in JH titer. To identify the genes that contribute to the JH increase in H. armigera-MbMNPV interaction, we analyzed mRNA expression profiles of the fat bodies of H. armigera infected by MbMNPV. A total of 3637 differentially expressed mRNAs (DE-mRNAs) were filtered out through RNA-seq analysis. These DE-mRNAs were mainly enriched in Spliceosome, Ribosome biogenesis in eukaryotes, Aminoacyl-tRNA biosynthesis, Mismatch repair, and RNA degradation signaling pathway, which are related to the virus infection. Real-time PCR was used to verify the RNA sequencing results. To find out which genes caused the increase in JH titer, we analyzed all the DE-mRNAs in the transcriptome and found that the JHE and JHEH genes, which were related to JH degradation pathway, were down-regulated. JHE and JHEH genes in the larvae of MbMNPV-infected group were significantly down-regulated compared with the control group by RT-qPCR. We further proved that the JH is degraded by JHE in H. armigera larvae by RNAi, ELISA, RT-qPCR and bioassay, while the hydrolysis of JH by JHEH in H. armigera larvae can almost be ignored. Knocking down of HaJHE promoted the expression of the JH receptor gene Met and the downstream gene Kr-h1, and the replication of MbMNPV. This study clarified that JH is mainly degraded by JHE in H. armigera larvae. The MbMNPV infection of H. armigera larvae leads to the increase of JH titer by inhibiting the expression of JHE. The increase in JH titer promotes the expression of the JH receptor gene Met and the downstream gene Kr-h1, which prevents the pupation of H. armigera, and promotes MbMNPV replication. This study provides new insights into H. armigera and MbMNPV interaction mechanisms. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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