Functional characterization of five developmental signaling network genes in the white‐backed planthopper: Potential application for pest management

Abstract

BACKGROUND The white‐backed planthopper (WBPH, Sogatella furcifera) is a major rice pest that exhibits condition dependent wing dimorphisms – a macropterous (long wing) form and a brachypterous (short wing) form. Although, the gene cascade that regulates wing development and dimorphic differentiation has been largely defined, the utility of these genes as targets for pest control has yet to be fully explored. RESULTS Five genes typically associated with the developmental signaling network, armadillo (arm), apterous A (apA), scalloped (sd), dachs (d), and yorkie (yki) were identified from the WBPH genome and their roles in wing development assessed following RNA interference (RNAi)‐mediated knockdown. At 5 days‐post injection, transcript levels for all five targets were substantially decreased compared with the dsGFP control group. Among the treatment groups, those injected with dsSfarm had the most pronounced effects on transcript reduction, mortality (95 ± 3%), and incidence (45 ± 3%) of wing deformities, whereas those injected with dsSfyki had the lowest incidence (6.7 ± 4%). To assess the utility of topical RNAi for Sfarm, we used a spray‐based approach that complexed a large‐scale, bacteria‐based double‐stranded RNA (dsRNA) expression pipeline with star polycation (SPc) nanoparticles. Rice seedlings infested with third and fourth instar nymphs were sprayed with SPc–dsRNA formulations and RNAi phenotypic effects were assessed over time. At 2 days post‐spray, Sfarm transcript levels decreased by 86 ± 9.5% compared with dsGFP groups, and the subsequent incidences of mortality and wing defects were elevated in the treatment group. CONCLUSIONS This study characterized five genes in the WBPH developmental signaling cascade, assessed their impact on survival and wing development via RNAi, and developed a nanoparticle‐dsRNA spray approach for potential field control of WBPH. © 2023 Society of Chemical Industry.

RNA Interference-Screening of Potentially Lethal Gene Targets in the White-Backed Planthopper Sogatella furcifera via a Spray-Induced and Nanocarrier-Delivered Gene Silencing System

“…The fluorescence intensity of the dsRNA/SPc group was noticeably brighter than that of either the naked dsRNA or RNase-free water control groups, confirming that the SPc nanoparticles enhance cuticular penetration of the dsRNA. 7,9,28 The incorporation of detergent as an amphiphilic surfactant minimized the shedding of SPc/dsRNA droplets, which further facilitated cuticular penetration. The high mortality rate and increased incidence of atypical phenotypes associated with SI-NDGS utilization make it a promising approach in WBPH.…”

“…DsSfhsc70-3 (final concentration was 100 ng/ μL) was fluorescently labeled using a fluorescein RNA labeling mix (Roche Diagnostics, Germany) and then mixed with SPc at room temperature (23−25 °C) for 15 min at a mass ratio of 1:1.5. 7,28 The final concentrations were 50 and 75 ng/μL for dsSfhsc70-3 and SPc, respectively. The fifth instar nymphs were immobilized as described previously 7,28 and then placed on a 2% PBS agarose gel.…”

“…7,28 The final concentrations were 50 and 75 ng/μL for dsSfhsc70-3 and SPc, respectively. The fifth instar nymphs were immobilized as described previously 7,28 and then placed on a 2% PBS agarose gel. A 0.5 μL aliquot of each of the treatments (dsSfhsc70-3/SPc, dsSfhsc70-3, and RNase-free water without fluorescein) was applied to the nymphal notum using a pipet ranging from 0.1 to 2.5 μL (Eppendorf, Hamburg, Germany).…”

“…11 The SPc nanocarrier minimizes environmental degradation of the dsRNA by forming a protective envelope around the nucleic acid that also enhances cuticular penetration and by extension enhances RNAi efficiency. 7,12 SPc-dsRNA complexes rapidly penetrated the green peach aphid M. persicae and triggered RNAi-mediated knockdown of the wing development genes vestigial and ultrabithorax. 13 Moreover, an SPc-based dsRNA spray delivery system was recently successfully applied against the soybean aphid Aphis glycines 9 and the cotton aphid A. gossypii.…”

“…The application of RNAi to agricultural pests and pathogens for the purpose of controlling their population has involved multiple methods, including microinjection, host-induced gene silencing (HIGS), virus-induced gene silencing (VIGS), direct feeding via field application of the dsRNA, and spray-induced gene silencing (SIGS). Although each has its uses and limitations, the spray-induced and nanocarrier-delivered gene silencing (SI-NDGS) system is particularly well-adapted for controlling pest populations in field conditions and has been successfully used with insect pests such as the white-backed planthopper Sogatella furcifera , and the Myzus persicae . A first greenhouse application of bacteria-expressed and nanocarrier-delivered RNA pesticide for Myzus persicae control .…”