Identification and functional analysis of dsRNases in spotted‐wing drosophila, Drosophila suzukii

Abstract

RNAi efficiency in insects is different from species to species; some species in Coleoptera are relatively more amenable to RNA interference (RNAi) than other species.One of the major factors is the presence of dsRNAdegrading enzymes, called dsRNases, in saliva, gut, or hemolymph in insects, which degrade the double-stranded RNA (dsRNA) introduced, resulting in the low efficacy of RNAi. In this study, we report a dsRNA-degrading activity in the gut homogenates from the spotted-wing drosophila, Drosophila suzukii, by ex vivo assay. Then, we identified two Drosophila suzukii dsRNase genes, named DrosudsRNase1 and DrosudsRNase2. In silico analysis shows that the gene structures are similar to dsRNases found in other insects.When dsRNases expressed in Sf9 cells were compared for their dsRNA degrading activities, dsRNase1 was more vital than dsRNase2. Both dsRNases were expressed highly and exclusively in the gut compared to the rest of body. Also, they were highly expressed during larval and adult stages but not in embryonic and pupal stages, suggesting the dsRNases protect foreign RNA molecules received during the feeding periods. DsRNase1 was expressed at a higher level in adults, whereas dsRNase2 showed more expression in early larvae. Our study on the tissue and development-This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Effective delivery and selective insecticidal activity of double-stranded RNA via complexation with diblock copolymer varies with polymer block composition

“…The entropically favourable complexation, due to the associated release of counterions, has previously been demonstrated through the use of agarose gel electrophoresis (Cohen electrophoresis following ex vivo vha26 dsRNA degradation was used to highlight the protective properties of both the homopolymer and diblock copolymers against D. suzukii gut enzymes, of both adult ies and L3 larvae. As described by Yoon et al, late-stage D. suzukii L3 larvae (and pupae) express lower levels of dsRNases, in comparison to early-stage L1 or L2 larvae and the adult ies (Yoon et al 2021). Hence, samples were incubated with L3 larvae gut enzymes for 24 h, rather than the shorter 30 min for adult gut enzymes.…”

Identification of the Extracellular Nuclease Influencing Soaking RNA Interference Efficiency in Bursaphelenchus xylophilus

“…This provides an important basis for the follow-up research, but it still cannot rule out the possible degradation function of other extracellular nucleases such as BxyNuc4 . A phylogenetic analysis showed high similarity among the BxyNuc6 and the nucleases that have been reported to degrade dsRNA in insects [ 20 , 22 , 29 , 30 , 31 ]. Whether the BxyNuc6 also has the function of degrading dsRNA needs to be further verified with a protein function study.…”

“…When ingested, dsRNA should avoid dsRNase degradation and move from intestinal or hemolymph lumen to tissues to effectively exert its inhibitory effect. In recent years, many studies have suggested that extracellular nuclease is the important factor leading to low RNAi efficiency in insects, such as Ostrinia furnacalis [ 21 ] and Drosophila suzukii [ 22 ]. When silencing the extracellular nuclease or inhibiting the activity of enzymes, RNAi efficiency is significantly improved.…”

RNAi Targets in Agricultural Pest Insects: Advancements, Knowledge Gaps, and IPM

“…In vivo co-targeting of dsRNases together with other vital genes has been demonstrated to significantly reduce gene expression and insect performance, compared to targeting only the vital gene, in insects of the orders Coleoptera (Almeida Garcia et al, 2017;Spit et al, 2017;Prentice et al, 2019;Peng et al, 2020a), Hemiptera (Luo et al, 2017;Chung et al, 2018;Kaur et al, 2020;Sharma et al, 2021), and Diptera (Tayler et al, 2019;Giesbrecht et al, 2020). Additional studies also suggest that inadequate oral RNAi is due to the presence of dsRNases in an even greater diversity of insect taxa (Song et al, 2017;Ghodke et al, 2019;Cooper et al, 2020;Fan et al, 2020;Peng et al, 2020b;Yoon et al, 2021).…”