Characterization of NlHox3, an essential gene for embryonic development in Nilaparvata lugens

Abstract

Hox genes encode transcriptional regulatory proteins that control axial patterning in all bilaterians. The brown planthopper (BPH), Nilaparvata lugens (Hemiptera: Delphacidae), is a destructive insect pest of rice plants in Asian countries. During analysis of the N. lugens transcriptome, we identified a Hox3-like gene (NlHox3) that was highly and specifically expressed in the embryonic stage. We performed functional analysis on the gene to identify its roles in embryonic development and its potential use as a target in RNA interference (RNAi) based pest control. The sequence analysis showed that NlHox3 was homologous to the Hox3 gene and was most closely related with zen of Drosophila. There were no significant differences in oviposition between the treated and control females after injecting double-stranded RNA of NlHox3 (dsNlHox3) into newly emerged female adult BPHs; however, there was a significant difference in the hatchability of those eggs laid, which no egg from the treated group hatched normally. Injecting female adult BPHs with dsNlHox3 led to necrosis of these offspring embryos, with eye reversal and undeveloped organs, suggesting that NlHox3 was an essential gene for embryonic development and might be a potential target for RNAi-based control of this insect pest.

Alteration of insulin signaling to control insect pest by using transformed bacteria expressing dsRNA

“…In this regard, V‐ATPase gene expressed in the midgut of the corn rootworm, Diabrotica virgifera virgifera , has been selected and its RNAi results in mortality high enough to be used in developing a novel insecticide . To have a direct and detrimental effect on insect development, a morphogen (Hox gene) has been targeted by dsRNA, leading to significant embryonic mortality of the brown plant hopper, Nilaparvata lugens . To avoid any adverse effect on mammals, insect‐specific genes such as chitin synthase and ecdysone receptor have been targeted to develop dsRNA insecticide …”

“…4 To have a direct and detrimental effect on insect development, a morphogen (Hox gene) has been targeted by dsRNA, leading to significant embryonic mortality of the brown plant hopper, Nilaparvata lugens. 5 To avoid any adverse effect on mammals, insect-specific genes such as chitin synthase and ecdysone receptor have been targeted to develop dsRNA insecticide. [6][7][8] Delivery techniques of efficient dsRNAs to target insects, especially into their cytoplasm, have been investigated.…”

An Overview of Embryogenesis: External Morphology and Transcriptome Profiling in the Hemipteran Insect Nilaparvata lugens

“…Guided by functional analysis, the hub genes in each embryonic stage were identified (Supplementary Figure S3), which laid the foundations for future studies of N. lugens embryonic development. Moreover, previous studies have suggested parental RNAi was a new pest control strategy (Ren et al, 2018) and lasted for seven generations in Sitobion avenae (Abdellatef et al, 2015). Thus, these hub genes in each embryonic stage, combining with parental RNAi, may be used for controlling crop pests such as N. lugens.…”

“…Parental RNAi was conducted according to the previously described method (Bucher et al, 2002;Ren et al, 2018). dsRNA synthesis (approximate 250 bp) was carried out following the manipulation with the T7 RiboMAX Express TM RNAi System (Promega, United States).…”

“…Since embryogenesis is the fundamental process for insect development, we try to identify "hub" genes during embryogenesis that could be potentially used for BPH management based on RNA interference (RNAi) technologies. Although cuticular genes (Pan et al, 2018) and a Hox3-like gene (NlHox3) (Ren et al, 2018) were involved in N. lugens embryonic development, overviews of morphological data and embryonic transcriptomes are little known in the hemipteran rice planthoppers, especially in N. lugens.…”