Abstract
Over the last decade, several studies have revealed the enormous potential of RNA-silencing strategies as a potential alternative to conventional pesticides for plant protection. We have previously shown that targeted gene silencing mediated by an in planta expression of non-coding inhibitory double-stranded RNAs (dsRNAs) can protect host plants against various diseases with unprecedented efficiency. In addition to the generation of RNA-silencing (RNAi) signals in planta, plants can be protected from pathogens, and pests by spray-applied RNA-based biopesticides. Despite the striking efficiency of RNA-silencing-based technologies holds for agriculture, the molecular mechanisms underlying spray-induced gene silencing (SIGS) strategies are virtually unresolved, a requirement for successful future application in the field. Based on our previous work, we predict that the molecular mechanism of SIGS is controlled by the fungal-silencing machinery. In this study, we used SIGS to compare the silencing efficiencies of computationally-designed vs. manually-designed dsRNA constructs targeting ARGONAUTE and DICER genes of Fusarium graminearum (Fg). We found that targeting key components of the fungal RNAi machinery via SIGS could protect barley leaves from Fg infection and that the manual design of dsRNAs resulted in higher gene-silencing efficiencies than the tool-based design. Moreover, our results indicate the possibility of cross-kingdom RNA silencing in the Fg-barley interaction, a phenomenon in which sRNAs operate as effector molecules to induce gene silencing between species from different kingdoms, such as a plant host and their interacting pathogens.
Highlights
Diseases of cereal crops, such as Fusarium head blight caused by phytopathogenic fungi of the genus Fusarium and primarily by the ascomycete Fusarium graminearum (Fg), exert great economic and agronomic impacts on global grain production and the grain industry (Goswami and Kistler, 2004; Kazan et al, 2012; McMullen et al, 2012)
In addition to the generation of RNA-silencing signals in planta, plants can be protected from pathogens and pests by spray-applied RNA biopesticides designated as spray-induced gene silencing (SIGS) (Koch et al, 2016; Wang et al, 2016; Konakalla et al, 2016; Mitter et al, 2017a; Kaldis et al, 2018; Koch et al, 2019)
The highest infection reduction of 60% was reached with double-stranded RNAs (dsRNAs) targeting ago1/ago2_365nt and ago1/dcl1_1570nt (Figure 1)
Summary
Diseases of cereal crops, such as Fusarium head blight caused by phytopathogenic fungi of the genus Fusarium and primarily by the ascomycete Fusarium graminearum (Fg), exert great economic and agronomic impacts on global grain production and the grain industry (Goswami and Kistler, 2004; Kazan et al, 2012; McMullen et al, 2012). RNA-Spray-Mediated Control of Fusarium to human and animal health (Ismaiel and Papenbrock, 2015). Plant-protection and toxin-reduction strategies are presently mediated by chemical treatments. The application of systemic fungicides, such as sterol demethylation inhibitors (DMIs), is essential for controlling Fusarium diseases and to assist in reaching the maximum attainable production level of high-yield cultivars. It is hardly surprising that reduced sensitivity, or even resistance to DMI fungicides, has begun to develop in many plant pathogenic fungi (Yin et al, 2009; Spolti et al, 2014). These alarming developments demonstrate that novel strategies in pathogen and pest control are urgently needed
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