Double-Stranded RNAs in Plant Protection Against Pathogenic Organisms and Viruses in Agriculture

Abstract

Recent studies have shown that plants are able to express the artificial genes responsible for the synthesis of double-stranded RNAs (dsRNAs) and hairpin double-stranded RNAs (hpRNAs), as well as uptake and process exogenous dsRNAs and hpRNAs to suppress the gene expression of plant pathogenic viruses, fungi, or insects. Both endogenous and exogenous dsRNAs are processed into small interfering RNAs (siRNAs) that can spread locally and systemically through the plant, enter pathogenic microorganisms, and induce RNA interference-mediated pathogen resistance in plants. There are numerous examples of the development of new biotechnological approaches to plant protection using transgenic plants and exogenous dsRNAs. This review summarizes new data on the use of transgenes and exogenous dsRNAs for the suppression of fungal and insect virulence genes, as well as viruses to increase the resistance of plants to these pathogens. We also analyzed the current ideas about the mechanisms of dsRNA processing and transport in plants.

Keywords: RNA interference; double-stranded RNA; exogenous dsRNA; hairpin RNA; plant resistance; regulation of pathogen genes; transgenic plants.

Fig. 1

Schematic representation of the use of transgenic dsRNA for RNA interference in plants. Artificial dsRNA is produced from transgenic constructs. Endogenous long dsRNAs are either transported directly into the pathogen’s cytoplasm through an undefined mechanism, or dsRNA molecules (dsRNA or hpRNA) are recognized in the plant by DICER ribonuclease (DCL) that cleaves long dsRNAs into short interfering RNAs. The latter are then transferred to pathogen cells, where they are incorporated into the RNA-induced silence complex (RISC) that directs specific degradation or translational repression of pathogen mRNAs. Interfering RNAs and the RISC complex can form directly in the pathogen cells. Arrows indicate different steps of short interfering RNA induction and dsRNA/siRNA movement between plant cells and phytopathogens

Fig. 2

Schematic representation of the use of exogenous dsRNA for RNA interference induction and degradation of target plant pathogen mRNAs. Exogenous artificial dsRNA is dissolved and applied to plant leaves, flower buds, roots, or seeds. Uptake and transport of exogenous dsRNAs occur through an undefined mechanism. dsRNA or hpRNA molecules are recognized by DICER-like (DCL) ribonuclease that cleaves long dsRNAs into siRNAs. siRNAs are then incorporated into the RNA-induced silencing complex (RISC) that guides sequence-specific degradation or translational repression of homologous pathogen mRNAs. Arrows depict different steps of the RNAi induction process and dsRNA/ siRNA movement between plant cells and plant pathogens