Control of western corn rootwormviaRNAi traits in maize: lethal and sublethal effects ofSec23dsRNA

Abstract

Background RNA interference (RNAi) triggered by maize plants expressing RNA hairpins against specific western corn rootworm (WCR) transcripts have proven to be effective at controlling this pest. To provide robust crop protection, mRNA transcripts targeted by double‐stranded RNA must be sensitive to knockdown and encode essential proteins. Results Using WCR adult feeding assays, we identified Sec23 as a highly lethal RNAi target. Sec23 encodes a coatomer protein, a component of the coat protein (COPII) complex that mediates ER‐Golgi transport. The lethality detected in WCR adults was also observed in early instar larvae, the life stage causing most of the crop damage, suggesting that WCR adults can serve as an alternative to larvae for dsRNA screening. Surprisingly, over 85% transcript inhibition resulted in less than 40% protein knockdown, suggesting that complete protein knockdown is not necessary for Sec23 RNAi‐mediated mortality. The efficacy of Sec23 dsRNA for rootworm control was confirmed in planta; T0 maize events carrying rootworm Sec23 hairpin transgenes showed high levels of root protection in greenhouse assays. A reduction in larval survival and weight were observed in the offspring of WCR females exposed to Sec23 dsRNA LC25 in diet bioassays. Conclusion We describe Sec23 as RNAi target for in planta rootworm control. High mortality in exposed adult and larvae and moderate sublethal effects in the offspring of females exposed to Sec23 dsRNA LC25, suggest the potential for field application of this RNAi trait and the need to factor in responses to sublethal exposure into insect resistance management programs. © 2019 Society of Chemical Industry

Double-Stranded RNA Technology to Control Insect Pests: Current Status and Challenges

“…Other genes have also demonstrated plant protection against D. v. virgifera, including the vacuolar proton pump, V-ATPase A (Baum et al, 2007), the septate junction proteins snakeskin (ssj1) and mesh (ssj2) (Hu et al, 2016), Troponin I (Fishilevich et al, 2019), SNARE binding protein Ras opposite/Sec1, RNA polymerase II subunit RpII140, FACT complex protein dre4/spt16 (Knorr et al, 2018), and Sec23 subunit of the coat protein complex II (COPII) (Vélez et al, 2019). HIGS in other insects has been explored with a high degree of variability in the response (Yu et al, 2016;Zhang et al, 2017).…”

Nudivirus Sequences Identified from the Southern and Western Corn Rootworms (Coleoptera: Chrysomelidae)

“…New transgenic lines have been developed that use a combination of gut-active Bt-derived proteins and silencing RNAs to silence essential rootworm genes through RNA interference (RNAi) [8][9][10]. While promising, there are indications that WCR will also readily develop resistance and cross-resistance to RNAi corn varieties, and care must be taken to preserve their efficacy after deployment [11,12]. Given the significant losses resulting from rootworm damage, and limitations associated with current management techniques, new tools to suppress rootworm populations are urgently needed.…”

De Novo Assembly of the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Psyllidae) Transcriptome across Developmental Stages

“…The success of RNAi-based strategies in future pest management will rely on the identification of essential target genes that confer lethal phenotypic effects upon knockdown [ 28 ]. Generally, functional genes involved in insect development, metamorphosis, or key metabolic processes may be suitable RNAi targets as part of control strategies of insects [ 15 , 16 , 17 , 18 , 29 , 30 , 31 , 32 , 33 ]. Previous studies have shown that trehalase plays pivotal roles in various physiological processes, including energy metabolism [ 34 ], chitin synthesis during molting [ 35 ], and diapause [ 36 ].…”