Plants send small RNAs in extracellular vesicles to fungal pathogen to silence virulence genes

TLDR

Some pathogens and pests deliver small RNAs into host cells to suppress immunity, while hosts also transfer sRNAs into pathogens to inhibit virulence, but the mechanisms of host‑to‑pathogen sRNA transfer remain unknown. We demonstrate that Arabidopsis secretes exosome‑like extracellular vesicles carrying sRNAs that accumulate at infection sites, are taken up by Botrytis cinerea, and silence fungal genes essential for pathogenicity, revealing an exosome‑mediated cross‑kingdom RNA interference defense.

Abstract

Some pathogens and pests deliver small RNAs (sRNAs) into host cells to suppress host immunity. Conversely, hosts also transfer sRNAs into pathogens and pests to inhibit their virulence. Although sRNA trafficking has been observed in a wide variety of interactions, how sRNAs are transferred, especially from hosts to pathogens and pests, is still unknown. Here, we show that host Arabidopsis cells secrete exosome-like extracellular vesicles to deliver sRNAs into fungal pathogen Botrytis cinerea These sRNA-containing vesicles accumulate at the infection sites and are taken up by the fungal cells. Transferred host sRNAs induce silencing of fungal genes critical for pathogenicity. Thus, Arabidopsis has adapted exosome-mediated cross-kingdom RNA interference as part of its immune responses during the evolutionary arms race with the pathogen.