A dsRNA-degrading nuclease (dsRNase2)limits RNAi efficiency in the Asian corn borer (Ostrinia furnacalis)

• 作者: Yun-He Fan Hui-Fang Song Mureed Abbas Yan-Li Wang Tao Li En-Bo Ma Anastasia M.W.Cooper Kristopher Silver Kun Yan Zhu Jian-Zhen Zhang
• 来源期刊: 中国昆虫科学（英文版）
• 年，卷（期）: 2021,（6）
• 所属期刊栏目: Original articles
• 页码范围: 1677-1689
• 页数: 13页
• 语种: 英文
• DOI: 10.1111/1744-7917.12882

摘要

The efficiency of RNA interference (RNAi) varies substantially among dif-ferent insect species.Rapid degradation of double-stranded RNA (dsRNA) by dsRNA-degrading nucleases (dsRNases) has been implicated to cause low RNAi efficiency in several insect species.In this study,we identified four dsRNase genes (OfdsRNase1,Ofd-sRNase2,OfdsRNase3 and OfdsRNase4) from the Asian corn borer (Ostriniafurnacalis)transcriptome database.Bioinformatic analyses showed that each deduced protein se-quence contained endonuclease NS domains and signal peptides.Gene expression analysis revealed that OfdsRNase2 was exclusively expressed in the midgut of larvae.RNAi effi-ciency was investigated in 2-d-old fifth-instar larvae (high expression of dsRNase2) and 2-d-old pupae (low expression of dsRNase2) by feeding or injecting dsRNA targeting a marker gene that encodes the lethal giant larvae protein (OfLgl).Our results showed that Of Lgl only partially silenced the expression of OfLgl in pupae,but not in larvae,suggest-ing that OfdsRNase2 could contribute to lower RNAi efficiency in larval stages.This hy-pothesis was supported by our RNAi-of-RNAi experiment using a tissue culture technique where the silencing efficiency against the reporter gene,OfHex1,was significantly im-proved after knockdown of OfdsRNase2.When double luciferase assays were performed to evaluate the role of the four dsRNases in vitro,only OfdsRNase2 expressed in S2 cells significantly affected RNAi efficiency by degrading dsRNA.Taken together,our results suggested that the degradation of dsRNA by OfdsRNase2 in the midgut contributed to low RNAi efficiency in O.furnacalis larvae.