Exogenous dsRNA triggers sequence-specific RNAi and fungal stress responses to control Magnaporthe oryzae in Brachypodium distachyon

Commun Biol. 2025 Jan 25;8(1):121. doi: 10.1038/s42003-025-07554-6.

Abstract

In vertebrates and plants, dsRNA plays crucial roles as PAMP and as a mediator of RNAi. How higher fungi respond to dsRNA is not known. We demonstrate that Magnaporthe oryzae (Mo), a globally significant crop pathogen, internalizes dsRNA across a broad size range of 21 to about 3000 bp. Incubation of fungal conidia with 10 ng/µL dsRNA, regardless of size or sequence, induced aberrant germ tube elongation, revealing a strong sequence-unspecific effect of dsRNA in this fungus. Accordingly, the synthetic dsRNA analogue poly(I:C) and dsRNA of various sizes and sequences elicited canonical fungal stress pathways, including nuclear accumulation of the stress marker mitogen-activated protein kinase Hog1p and production of ROS. Leaf application of dsRNA to the cereal model species Brachypodium distachyon suppressed the progression of leaf blast disease. Notably, the sequence-unspecific effect of dsRNA depends on higher doses, while pure sequence-specific effects were observed at low concentrations of dsRNA ( < 0.03 ng/µL). The protective effects of dsRNA were further enhanced by maintaining a gap of at least seven days between dsRNA application and inoculation, and by stabilising the dsRNA in alginate-chitosan nanoparticles. Overall, our study opens up additional possibilities for the development and use of dsRNA pesticides in agriculture.

MeSH terms

  • Ascomycota / genetics
  • Ascomycota / pathogenicity
  • Ascomycota / physiology
  • Brachypodium* / genetics
  • Brachypodium* / microbiology
  • Plant Diseases* / microbiology
  • Plant Diseases* / prevention & control
  • RNA Interference*
  • RNA, Double-Stranded* / genetics
  • RNA, Double-Stranded* / metabolism
  • Stress, Physiological

Substances

  • RNA, Double-Stranded

Supplementary concepts

  • Pyricularia oryzae