%0 Journal Article
%T A fungal RNA-dependent RNA polymerase is a novel player in plant infection and cross-kingdom RNA interference.
%A Cheng AP
%A Lederer B
%A Oberkofler L
%A Huang L
%A Johnson NR
%A Platten F
%A Dunker F
%A Tisserant C
%A Weiberg A
%J PLoS Pathog
%V 19
%N 12
%D 2023 Dec 20
%M 38117848
%F 7.464
%R 10.1371/journal.ppat.1011885
%X Small RNAs act as fungal pathogen effectors that silence host target genes to promote infection, a virulence mechanism termed cross-kingdom RNA interference (RNAi). The essential pathogen factors of cross-kingdom small RNA production are largely unknown. We here characterized the RNA-dependent RNA polymerase (RDR)1 in the fungal plant pathogen Botrytis cinerea that is required for pathogenicity and cross-kingdom RNAi. B. cinerea bcrdr1 knockout (ko) mutants exhibited reduced pathogenicity and loss of cross-kingdom small RNAs. We developed a "switch-on" GFP reporter to study cross-kingdom RNAi in real-time within the living plant tissue which highlighted that bcrdr1 ko mutants were compromised in cross-kingdom RNAi. Moreover, blocking seven pathogen cross-kingdom small RNAs by expressing a short-tandem target mimic RNA in transgenic Arabidopsis thaliana led to reduced infection levels of the fungal pathogen B. cinerea and the oomycete pathogen Hyaloperonospora arabidopsidis. These results demonstrate that cross-kingdom RNAi is significant to promote host infection and making pathogen small RNAs an effective target for crop protection.