CopE and TLR6 RNAi-mediated Tomato Resistance to Western Flower Thrips

The western flower thrips (WFT; Frankliniella occidentalis) is a mesophyll cell feeder that damages many crops. Management of WFT is complex due to factors such as high fecundity, short reproduction time, ability to feed on a broad range of host plants, and broad pesticide resistance. These challenges have driven research into developing alternative pest control approaches for WFT. This study analyzed the feasibility of a biological control-based strategy to manage WFT using RNA interference (RNAi)-mediated silencing of WFT endogenous genes. For the delivery of RNAi, we developed transgenic tomato lines expressing double-stranded RNA (dsRNA) of coatomer protein subunit epsilon (CopE) and Toll-like receptor 6 (TLR6) from WFT. These genes are involved in critical biological processes of WFT, and their dsRNA can be lethal to these insects when ingested orally. Adult WFT that fed on the transgenic dsRNA-expressing tomato flower stalk showed increased mortality compared with insects that fed on wild-type samples. In addition, WFT that fed on TLR6 and CopE transgenic tomato RNAi lines showed reduced levels of endogenous CopE and TLR6 transcripts, suggesting that their mortality was likely due to RNAi-mediated silencing of these genes. Thus, our findings demonstrate that transgenic tomato plants expressing dsRNA of TLR6 and CopE can be lethal to F. occidentalis, suggesting that these genes may be deployed to control insecticide-resistant WFT.