Enhancing RNAi Efficiency to Decipher the Functional Response of Potential Genes in Bemisia tabaci AsiaII-1 (Gennadius) Through dsRNA Feeding Assays

Abstract

Whitefly Bemisia tabaci is a global invasive pest that causes substantial losses to agricultural crops worldwide either by direct feeding or vectoring numerous plant viruses. Management with insecticides remains a big challenge due to its rapid resistance development potential as well as the impact of these chemicals on nontarget organisms. Thus, in search of alternate and novel pest management strategies RNA interference (RNAi) has come up as potential future tool in this direction. The present study targets nine potential genes (Aquaporin (AQP), Calcitonin (CAL), CyclophilinB (CYCP), Knottin-1 (k-1), Heat shock proteins (Hsp20, Hsp40 and Hsp70), SWItch/Sucrose Non-fermentable (SNF7) and inhibitor of apoptosis (IAP) of whitefly that have been implicated to play a role in various vital physiological functions and virus transmission. The RNAi mediated knockdown efficiency of these genes has been improved through the conjugation of respective target gene dsRNA with CQD (carbon quantum dots) nanoparticles or simultaneous knockdown of dsRNA specific gut nucleases. The studies revealed that feeding of dsRNA (40 µg/ml sucrose diet) of the target gene(s) either conjugated with CQD or along with dsRNA against dsRNase (dsdsRNase) (40 µg/ml sucrose diet) enhanced the RNAi efficiency by 24-89% compared to whiteflies fed with naked dsRNA of the same target gene. The studies provide insights about the functional role of various genes in whitefly, which can possibly be exploited for the management of this pest in the future.

Strategies for enhancing the efficiency of RNA interference in insects

“…A slightly different strategy was used in sweet potato whitefly ( Bemisia tabaci ). Researchers mixed dsRNAs specific to endonucleases in the gut with target gene dsRNAs with the result that suppression of the target transcripts and mortality increased by 4‐ to 10‐fold 30 . In addition, Ae.…”

“…Recent studies have provided insights into strategies for enhancing RNAi efficiency in insect pests even further by manipulating the structure of dsRNA molecules, 27 targeting multiple transcripts using a single dsRNA construct, 28 adding repeats of the same dsRNA sequence, 29 mixing dsRNAs, 30 or using other small RNA species (reviewed in Flynt 31 ). Studies have shown that adding additional gene targeting sequences 28 or adding repeats of the same targeting sequence 29 to a dsRNA enhances the toxicity of dsRNAs to two-spotted spider mite (Tetranychus urticae) or P. xylostella, respectively, in feeding assays.…”

“…Researchers mixed dsRNAs specific to endonucleases in the gut with target gene dsRNAs with the result that suppression of the target transcripts and mortality increased by 4-to 10-fold. 30 In addition, Ae. aegypti larvae were treated with long dsRNAs and paperclip dsRNAs (pcRNA) in which the dsRNA sequence folded back on itself, creating one half of a paperclip shape.…”

Whitefly endosymbionts: IPM opportunity or tilting at windmills?

“…Still, incremental improvements in the field continue to being made. For example, use of carbon quantum dots conjugated to dsRNA and additional knockdown of gut nucleases that are responsible for degradation of dsRNA have recently been explored (Kaur et al 2020 ). Looking ahead, a COVID-19-fueled explosion of RNA research, especially on the topic of RNA delivery, will undoubtfully have a profound impact on RNA use in the fields outside human medicine (Coccia 2021 ; Cheng et al 2020 ; Miao et al 2019 ; Pardi et al 2018 ).…”

Optimizing Efficient RNAi-Mediated Control of Hemipteran Pests (Psyllids, Leafhoppers, Whitefly): Modified Pyrimidines in dsRNA Triggers

“…RNAi-based studies in whiteflies show significant knockdown of a wide set of gene targets, with reviews by Kaur et al (2020) [119], Luo et al (2017) [24] and others (e.g., and references therein: [120][121][122][123][124][125][126][127][128]. The earliest RNAi in whitefly, B. tabaci, used dsRNA's of actin, BtSnap and chickadee [129].…”