Spray‐induced gene silencing for disease control is dependent on the efficiency of pathogen RNA uptake

Abstract

Summary Recent discoveries show that fungi can take up environmental RNA, which can then silence fungal genes through environmental RNA interference. This discovery prompted the development of Spray‐Induced Gene Silencing (SIGS) for plant disease management. In this study, we aimed to determine the efficacy of SIGS across a variety of eukaryotic microbes. We first examined the efficiency of RNA uptake in multiple pathogenic and non‐pathogenic fungi, and an oomycete pathogen. We observed efficient double‐stranded RNA (dsRNA) uptake in the fungal plant pathogens Botrytis cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani, Aspergillus niger and Verticillium dahliae, but no uptake in Colletotrichum gloeosporioides, and weak uptake in a beneficial fungus, Trichoderma virens. For the oomycete plant pathogen, Phytophthora infestans, RNA uptake was limited and varied across different cell types and developmental stages. Topical application of dsRNA targeting virulence‐related genes in pathogens with high RNA uptake efficiency significantly inhibited plant disease symptoms, whereas the application of dsRNA in pathogens with low RNA uptake efficiency did not suppress infection. Our results have revealed that dsRNA uptake efficiencies vary across eukaryotic microbe species and cell types. The success of SIGS for plant disease management can largely be determined by the pathogen’s RNA uptake efficiency.

External dsRNA Downregulates Anthocyanin Biosynthesis-Related Genes and Affects Anthocyanin Accumulation in Arabidopsis thaliana

“…It is well established that spraying plants with dsRNAs and siRNAs encoding key genes of plant pathogenic fungi [16][17][18][19][20][21] and viruses [22][23][24][25][26][27] effectively reduces development of the pathogens and suppresses the infection process. These externally applied dsRNAs and siRNAs have been shown to spread systemically into plant tissues and were uptaken by the fungal cells inducing a RNAi-mediated silencing of the targeted genes of the pathogens [16,17,21,27]. This strategy of plant disease control was termed as spray-induced gene silencing (SIGS) and is currently considered as an efficient and sustainable plant protection strategy and for other crop improvement strategies [29].…”

“…There is an increasing number of studies that show induction of plant fungal [16][17][18][19][20][21] and viral [22][23][24][25][26][27] resistance after external application (spraying or mechanical inoculation) of dsRNAs, siRNAs, or hpRNAs designed to target virulence-related genes of the pathogens. Recent studies have also provided evidence that both plants and infecting pathogens were capable of the RNA uptake, and this eventually triggered RNAi-mediated silencing of the pathogen virulence-related genes [16,17,21,22,27]. Exogenously induced RNAi has recently emerged as a strategy with a potential to protect plants from microbial diseases, viral infections, and invading insects [9,28,29].…”

Spray-induced gene silencing: an innovative strategy for plant trait improvement and disease control

“…Similarly, SIGS against Sclerotinia sclerotium and Botrytis cinerea on oilseed rape and Arabidopsis thaliana, and against F. asiaticum on wheat resulted in reduced fungal disease (McLoughlin et al 2018, Song et al 2018. A recent study also showed that SIGS can also be applied against the basidiomycete fungus Rhizoctonia solani to control sheath blight of rice (Qiao et al 2021). In this study, topical application of dsRNA targeting vesicle trafficking pathway genes DYNACTIN 1 (DCN1) and SUPPRESSOR OF ACTIN 1 (SAC1), or a gene coding for polygalacturonase (a known virulence factor gene of R. solani) resulted in a significant reduction of fungal biomass and disease symptoms on rice plants (Qiao et al 2021).…”

“…In addition to mediating a broad range of cellular processes related to growth and development, roles for sRNAmediated RNAi in host-pathogen interactions have been described (Chaloner et al 2016, Qiao et al 2021. While most sRNAs function endogenously, some sRNAs move bidirectionally from one species to another and modulate cellular functions of recipient cells by regulating their gene expression through targeted gene silencing (Weiberg et al 2013, Chaloner et al 2016, Cai et al 2018.…”

Plant extracellular vesicles: Trojan horses of cross‐kingdom warfare

“…Recent discovery of fungal RNA uptake makes SIGS possible to control fungal diseases in crops 41,55,62 . SIGS approaches have been successfully used to prevent fungal infections in both monocot and dicot plants, as well as in post-harvest materials 41,54,55 .…”