Seminarios IHSM La Mayora - Peter Brodersen (University of Copenhagen, Denmark)

Sensing of viral RNA in plants by a Dicer-like ribonuclease Peter Brodersen University of Copenhagen (Denmark) Abstract Innate antiviral immune responses in mammals involve double-stranded RNA (dsRNA) sensors. In plants, dsRNA sensing mechanisms have not been identified, but RNA interference (RNAi) that relies on production of virus-derived small interfering RNAs (siRNAs) by two DICER-LIKE (DCL) ribonucleases, DCL4 and DCL2, constitutes a potent basic antiviral defense mechanism. In this talk, I will discuss evidence that indicates that while DCL4 is dedicated to RNAi, DCL2 also mediates sensing of cytoplasmic dsRNA. In this way, dicing by DCL2 activates intracellular nucleotide-binding domain/leucine-rich repeat (NLR) immune receptors to trigger defense gene expression independent of RNAi. In Arabidopsis, basic resistance to turnip crinkle virus, a positive strand RNA virus, is abrogated upon combined inactivation of DCL4and two specific NLRs, similar to what is observed in dcl4/dcl2 mutants. These results introduce a new framework for understanding antiviral immunity in plants, and explain previous observations of DCL2-dependent growth arrest in dcl and RNA decay mutants in several plant species as manifestations of NLR-dependent autoimmunity. . Biography: 2000 MSc University of Copenhagen, 2004 PhD University of Copenhagen Subject of both: Plant Innate Immunity Supervisor/PI: Professor John Mundy 2004-2008 Post doc Institut de Biologie Moléculaire des Plantes du CNRS, Strasbourg 2008-2010 Research Associate, Institut de Biologie Moléculaire des Plantes du CNRS, Strasbourg Subject: Mechanism of miRNA action in plants PI: Olivier Voinnet 2010-2019 PI; Associate Professor, University of Copenhagen 2020- PI; Full Professor, University of Copenhagen Subjects: Gene regulation via small non-coding RNA and covalent RNA modification Links between mechanims of post-transcriptional gene control and RNA-based innate immune responses.