RNAi-screening of potentially lethal gene targets in white-backed planthopper (Sogatella furcifera) via a spray-induced and nanocarrier-delivered gene silencing system

Authors: MA - Guizhou University; LIU - Guizhou University; ZHAO - Guizhou University; LUO - Guizhou University; FENG - Guizhou University; ZHOU - Guizhou University; ZHANG - Guizhou University; GONG - Guizhou University; HE - Guizhou University; Hull, Joe; DEWER, YOUSSEF - Agricultural Research Center Of Egypt; HE - Guizhou University; HE - Guizhou University

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2023
Publication Date: 1/3/2024
Citation: Ma, Liu, Zhao, Luo, Feng, Zhou, Zhang, Gong, He, Hull, J.J., Dewer, Y., He, He 2024. RNAi-screening of potentially lethal gene targets in white-backed planthopper (Sogatella furcifera) via a spray-induced and nanocarrier-delivered gene silencing system. Journal of Agricultural and Food Chemistry. 72:1007-1016. https://doi.org/10.1021/acs.jafc.3c05659.
DOI: https://doi.org/10.1021/acs.jafc.3c05659

Interpretive Summary: RNA interference (RNAi), a cellular mechanism for regulating gene expression, has been developed as a tool for assessing in vivo gene functionality and, more recently, has been proposed as an alternative to chemical-based insect pest management. Despite this interest, wide-spread adoption of the technique has been limited by inefficient delivery of the RNAi triggering agents [e.g. double-stranded RNAs (dsRNAs) that are homologous to the target genes] and identification of suitable candidate genes. The utilization of sprayable formulations that incorporate nanoparticles as dsRNA carriers/protectants has shown promise as an efficient delivery system for some species. Similarly, a number of essential genes that are typically well-conserved across species have been reported to be ideal target genes. However, although these genes may be structurally conserved, they are not always functionally conserved, especially in agricultural pests. Consequently, the utility of these genes as RNAi targets needs to be empirically determined. Using sprayable dsRNAs encapsulated by a specific class of nanoparticles, the role of eleven conserved genes in insect growth and development was evaluated in the white-backed planthopper, a common pest of rice. Although targeted knockdown of the eleven genes induced negative effects in treated planthoppers, the most pronounced effects (high mortality and impaired shedding of the insect exoskeleton) were observed with genes encoding a member of the heat shock protein 70 family and a protein phosphatase. These targets and the sprayable delivery system provide insights that can be further developed for larger scale planthopper control.

Technical Abstract: RNA interference (RNAi) is a widespread post-transcriptional silencing mechanism that targets homologous mRNA sequences for specific degradation. RNAi-based pest management control is target-specific and considered sustainable biopesticide. However, the specific genes targeted and the efficiency of the delivery methods can vary widely across species. In this study, a spray-induced and nanocarrier-delivered gene silencing (SI-NDGS) system that incorporated gene specific dsRNAs targeting conserved genes was used to evaluate phenotypic effects in the white backed planthopper (WBPH). At two days post-spraying, transcript levels for all target genes were significantly reduced and knockdown of two gene orthologs, hsc70-3 and PP-a, resulted in elevated mortality (> 60%) and impaired ecdysis. These results highlight the utility of the SI-NDGS system for identifying genes involved in WBPH growth and development potentially exploitable as high mortality target genes to develop as an alternative method for WBPH control.