Genetically Modified Organism-Free RNA Interference: Exogenous Application of RNA Molecules in Plants

Abstract

3 Senior author. A.D. and K.P. conceived the idea and supervised the project; A.D., M.W., and E.D. wrote the sections on RNAi; A.D., E.D., and I.G. wrote the section on viruses and viroids; A.D. and K.P. wrote the sections on fungi and bacteria; A.D. and M.P. wrote the sections on insects and mites. [OPEN] Articles can be viewed without a subscription.

SIGS vs HIGS: a study on the efficacy of two dsRNA delivery strategies to silence Fusarium FgCYP51 genes in infected host and non‐host plants

“…The use of double-stranded (ds)RNA has promising potential for protecting plants from biotic stress by targeted gene silencing through RNA interference (RNAi) (e.g. Cai et al, 2018a;Dalakouras et al, 2019;Gaffar and Koch, 2019;Koch and Kogel, 2014;Majumdar et al, 2017;Zhang et al, 2017;Zotti et al, 2018). Through a mechanism called host-induced gene silencing (HIGS; Nowara et al, 2010) Arabidopsis thaliana and barley (Hordeum vulgare) plants are more resistant to Fusarium graminearum (Fg) infections when these plants express CYP3RNA, a 791 nucleotide (nt) long dsRNA targeting all three CYP51 genes (FgCYP51A, FgCYP51B, FgCYP51C) (Koch et al, 2013).…”

RNA-spray-mediated silencing ofFusarium graminearum AGOandDCLgenes improve barley disease resistance

“…Microbial pathogens and pests, unlike mammals, are amenable to environmental sRNAs, meaning that they can take up noncoding RNAs from the environment, and these RNAs maintain their RNAi activity (Winston et al 2007; Whangbo and Hunter 2008; McEwan et al 2012). This knowledge raises the possibility that plants can be protected from pathogens/pests by exogenously supplied RNA biopesticides (for review, see Mitter et al 2017; Cai et al 2018; Dubrovina and Kiselev 2019; Gaffar and Koch 2019; Dalakouras et al 2020). Possible agronomic application of environmental RNA is affirmed by the high sensitivity of Fg to dsRNAs and siRNAs (Koch et al, 2016).…”

RNA‐based biocontrol compounds: current status and perspectives to reach the market

“…However, the difficulty in genetic transformation of some crop species, expensive capital requirements and political/public concerns surrounding the cultivation and use of GM crops has favoured the need to develop sprayable dsRNA‐containing end‐use products (dsRNA‐EPs). Spray‐induced gene silencing (SIGS) and other exogenous applications (such as root or seed soaking, trunk injection, petiole absorption and mechanical inoculation) as alternatives to the GM plant approach silence target genes in a target organism without introducing heritable changes in the genome, hence do not fall within the restrictions currently defined by the EU regulation on Genetically modified organisms (GMOs). This of course excludes the scenario where the final product containing the dsRNA active ingredient is a GMO, as is the case when microbes are engineered to produce specific dsRNAs.…”

“…RNAi is based on natural sequence‐specific and evolutionarily conserved mechanisms in eukaryotes regulating gene expression at the transcriptional or post‐transcriptional level, thus providing a natural defence system that can target invading nucleic acids of hostile organisms and viruses. Deciphering the RNAi mechanisms has provided scientists with the ability to specifically silence target genes post‐transcriptionally, which could be endogenous plant genes, genes of plant pathogens (viruses and fungi) or genes of other plant pests (insects, mites, nematodes and weeds) . By using different types of RNAi triggers, such as hairpin‐structured RNAs (hpRNAs), artificial microRNAs (amiRNAs) and/or double‐stranded RNAs (dsRNAs), the function of these targets can be blocked.…”

“…Deciphering the RNAi mechanisms has provided scientists with the ability to specifically silence target genes post-transcriptionally, which could be endogenous plant genes, genes of plant pathogens (viruses and fungi) or genes of other plant pests (insects, mites, nematodes and weeds). 1 By using different types of RNAi triggers, such as hairpin-structured RNAs (hpRNAs), artificial microRNAs (amiR-NAs) and/or double-stranded RNAs (dsRNAs), the function of these targets can be blocked. Post-transcriptional RNAi mechanisms explore a sequence-dependent mode of action at the messenger RNA (mRNA) level to prevent the translation of the targeted mRNA into proteins by mRNA degradation or translational repression, hence leading to target gene silencing and subsequently the desired effect.…”