Systemic spreading of exogenous applied RNA biopesticides in the crop plant Hordeum vulgare

D Biedenkopf,T Will,T Knauer,A Koch,T Busche,L Jelonek,Alexandra Charlotte Ursula Furch

doi:10.1186/s41544-020-00052-3

Abstract

BackgroundSmall (s) RNA molecules are crucial factors in the communication between hosts and their interacting pathogens/pests that can modulate both host defense and microbial virulence/pathogenicity known as cross-kingdom RNA interference (ckRNAi). Consistent with this, sRNAs and their double-stranded (ds) RNA precursors have been adopted to control plant diseases through exogenously applied RNA biopesticides, known as spray-induced gene silencing (SIGS). While RNA spray proved to be effective, the mechanisms underlying the transfer and uptake of SIGS-associated RNAs are inadequately understood. Moreover, the use of the SIGS-technology as a biopesticide will require the systemic spreading of dsRNA/siRNA signals.ResultsThe integration of our findings strongly support the notion of long-distance spreading of SIGS-associated dsRNA and/or siRNA. In summary, our findings support the model that SIGS involves: (i) uptake of sprayed dsRNA by the plant (via stomata); (ii) transfer of apoplastic dsRNAs into the symplast (DCL processing into siRNAs); (iii) systemic translocation of siRNA or unprocessed dsRNA via the vascular system (phloem/xylem); (iv) uptake of apoplastic dsRNA or symplastic dsRNA/siRNA depending on the lifestyle/feeding behavior of the pathogen/pest.ConclusionsOur findings are significant contributions to our mechanistic understanding of RNA spray technology, as our previous data indicate that SIGS requires the processing of dsRNAs by the fungal RNAi machinery.

Highlights

Small (s) RNA molecules are crucial factors in the communication between hosts and their interacting pathogens/pests that can modulate both host defense and microbial virulence/pathogenicity known as crosskingdom RNA interference
Our results showed that transgenic Arabidopsis and barley (Hordeum vulgare) plants, expressing a 791 nucleotide dsRNA (CYP3RNA) targeting all three copies of the CYP51 gene (FgCYP51A, FgCYP51B, FgCYP51C) in Fusarium graminearum (Fg), inhibited fungal infection via a process designated as host-induced gene silencing (HIGS) [21, 33]
We demonstrated that HIGSmediated targeting of the structural sheath protein (Shp) mandatory for aphid feeding, produced significantly lower levels of Shp mRNA compared to aphids feeding on wild-type plants [1]

Summary

Introduction

Small (s) RNA molecules are crucial factors in the communication between hosts and their interacting pathogens/pests that can modulate both host defense and microbial virulence/pathogenicity known as crosskingdom RNA interference (ckRNAi). Consistent with this, sRNAs and their double-stranded (ds) RNA precursors have been adopted to control plant diseases through exogenously applied RNA biopesticides, known as spray-induced gene silencing (SIGS). (2020) 2:12 gene expression at the whole-plant level by sequencespecific degradation of targeted mRNA [14, 34, 35]. These scientists were the first who linked systemic RNA signaling with a process known as RNA silencing. RNA silencing has emerged as a powerful genetic tool for scientific research over the past several years It has been utilized in fundamental research for the assessment of gene function, and in various fields of applied research, such as agriculture. We demonstrated that HIGSmediated targeting of the structural sheath protein (Shp) mandatory for aphid feeding, produced significantly lower levels of Shp mRNA compared to aphids feeding on wild-type (wt) plants [1]

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