Abstract
RNA interference (RNAi) is a promising next generation technology for the development of species-specific pest management. The key to successful RNAi based-plant protection is dependent in part on data-driven target gene selection, a challenging task due to the absence of laboratory strains and the seasonality of most pest species. In this study, we aimed to identify novel target genes by performing a knowledge-based approach in order to expand the spectrum of known potent RNAi targets. Recently, the protein-coding genes ncm, Rop, RPII-140, and dre4 have been identified as sensitive RNAi targets for pest control. Based on these potent RNAi targets, we constructed an interaction network and analyzed a selection of 30 genes in the model beetle Tribolium castaneum via injection of dsRNA synthesized by in vitro transcription. Nineteen of these targets induced significant mortality of over 70%, including six that caused 100% lethality. Orthologs of active T. castaneum RNAi targets were verified in the economically important coleopteran pests Diabrotica virgifera virgifera and Brassicogethes aeneus. Knockdown of D. v. virgifera genes coding for transcription factor Spt5, Spt6, and RNA polymerase II subunit RPII-33 caused over 90% mortality in larval feeding assays. Injection of dsRNA constructs targeting RPII-215 or the pre-mRNA-processing factor Prp19 into adult B. aeneus resulted in high lethality rates of 93 and 87%, respectively. In summary, the demonstrated knowledge-based approaches increased the probability of identifying novel lethal RNAi target genes from 2% (whole genome) to 36% (transcription- and splicing-related genes). In addition, performing RNAi pre-screening in a model insect increased also the probability of the identification essential genes in the difficult-to-work-with pest species D. v. virgifera and B. aeneus.
Highlights
The world population is expected to reach ∼ 10 billion people in 2050, necessitating a substantial crop yield increase to meet the global food demand (Johnson and Jones, 2017; Rohr et al, 2019)
We evaluated if the newly discovered RNA interference (RNAi) targets could be leveraged to the economically important pest species, the Western Corn Rootworm (WCR) D. v. virgifera, a devastating pest of maize in the US Corn Belt, and the pollen beetle B. aeneus, a key pest of oilseed rape. For both of these difficult-to-work with agricultural pest insects we identified novel RNAi target genes that caused more than 90% mortality, suggesting that these genes may be considered as potential RNAi target for RNA-based management
Insecticidal RNAi target genes have been identified in key biological systems of the insect physiology like digestion, defense mechanisms, vesicular trafficking, and detoxification (Mao et al, 2007; Bautista et al, 2009; Kim et al, 2015; Kola et al, 2015; Head et al, 2017; Knorr et al, 2018; Cooper et al, 2019)
Summary
The world population is expected to reach ∼ 10 billion people in 2050, necessitating a substantial crop yield increase to meet the global food demand (Johnson and Jones, 2017; Rohr et al, 2019). An area where significant productivity gains can be made is the reduction of crop losses associated with insect pests, which is estimated at ca. The primary solution for insect control, the use of chemical pesticides, is facing. Novel Pest Control RNAi Targets challenges like resistance development and growing concerns of undesirable effects on the environment or non-target organisms. Modified (GM) crops expressing insecticidal Bacillus thuringiensis (Bt) proteins provided a technology improvement on pest management that reduced the dependence on chemical insecticides (Phipps and Park, 2002; James, 2009; Areal and Riesgo, 2015). Wide adoption of Bt trait technology has resulted in field-evolved resistance (Tabashnik et al, 2009, 2013). New pest control strategies to overcome these obstacles are urgently required
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