Identification and functional analysis of dsRNase genes in drosophila suzukii

Authors: YOON, JUNE-SUN - Oregon State University; AHN, SEUNG-JOON - Mississippi State University; FLINN, CHRISTINA - Oregon State University; MARTIN, ROBERT - Oregon State University; Choi, Man-Yeon

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2021
Publication Date: 6/21/2021
Citation: Yoon, J., Ahn, S., Flinn, C.M., Martin, R.R., Choi, M.Y. 2021. Identification and functional analysis of dsRNase genes in drosophila suzukii. Archives of Insect Biochemistry and Physiology. 107(4). Article e21822. https://doi.org/10.1002/arch.21822.
DOI: https://doi.org/10.1002/arch.21822

Interpretive Summary: The spotted-wing drosophila (SWD) is a serious economic pest species. SWD exhibits a wide host range in its introduced and native areas, infesting most small fruits in Asia, Europe, and North America. The fly spreads to additional subtropical areas, including South America, Australia, and Africa. The current control for SWD has primarily relied on conventional chemical insecticides despite carrying many potential negative effects. Recent research has sought alternative control methods to reduce insecticide inputs, but they still cannot fully protect small fruits from the fly damage. Recently, application of RNAi has presented itself as a for SWD control. New biological alternative for SWD control. The oral delivery of double stranded RNA (dsRNA) is considered as a practical approach in the field, but its efficacy is limited due to the dsRNA degradation in the gut of the insect. In this study, we identified two dsRNase genes, named dsRNase1 and dsRNase2, in the SWD gut, and investigated the gene expression profiles in various SWD tissues and during the life stages. The research results are a step towards improving RNAi feeding application for SWD control.

Technical Abstract: RNAi efficiency on insects is different from order to order and species to species; Coleopteran species are relatively more amenable to RNAi than other species. One of the major factors is the presence of dsRNA-degrading enzymes, called dsRNases, in saliva, gut, or hemolymph in insect, which degrade the introduced double-stranded RNA (dsRNA), resulting in the low efficacy of RNAi. In this study, we report a dsRNA-degrading activity in the gut homogenates of the spotted-wing drosophila, Drosophila suzukii, measured by ex vivo assay. Then, we identified two dsRNase genes in D. suzukii, named dsRNase1 and dsRNase2. In silico analysis shows that their gene structures are similar to those of Drosophila melanogaster. Both dsRNases are highly expressed in gut tissues compared to the rest of the body. Heterologous expression in Sf9 cells obtained the dsRNA degrading activity for both dsRNases with stronger activity in dsRNase1 than dsRNase2. Both genes were highly expressed during larval and adult stages but not in egg and pupal stages, suggesting the dsRNases protect foreign RNA molecules received from the feeding periods. dsRNase1 was expressed relatively highly in adults, whereas dsRNase2 showed more expression in early larvae.