Nanoparticle carriers enhance RNA stability and uptake efficiency and prolong the protection against Rhizoctonia solani

Abstract

Spray-induced gene silencing (SIGS) can inhibit plant diseases by topical application of double- (dsRNA) or single-stranded (sRNA) RNA molecules onto plants to silence virulence-related pathogen genes. However, the on-field application of SIGS is limited by the instability of naked RNA and low RNA uptake by pathogens. Nanoparticles have been used as RNA carriers to enhance RNA silencing. Rice sheath blight caused by Rhizoctonia solani (R. solani) is one of the most devastating fungal diseases in rice (Oryza sativa L.). In this study, we aimed to explore the protective effects of nanoparticle-delivered dsRNA against rice sheath blight. The key pathogenic genes, RsAGO1 and RsAGO2, of R. solani were screened as targets for dsRNA. Chitosan (CS), polyethyleneimine (PEI), protamine, carbon quantum dot (CQD), polyamidoamine (PAMAM), and chitosan/SPc complex (CSC) were selected as dsRNA carriers. All the evaluated nanoparticles could assemble with dsRNA to form nanoparticle-dsRNA complexes, and CQD and CSC showed improved dsRNA load capacity. Particularly, CSC could enhance the stability of dsRNA and cause a 7% reduction in fluorescence intensity after nuclease treatment. CSC and CS effectively enhanced the efficiency of dsRNA uptake by pathogens. Furthermore, CSC could reduce pathogen infection and prolong the protection time of dsRNA by up to 20 days. Overall, this study provides a novel and efficacious SIGS-based strategy for producing RNA-based fungicides.