Silencing and innate immunity in plant defense against viruses
Molecular Plant Virology
The frontline of plant defense against non-viral pathogens such as bacteria, fungi and oomycetes is provided by PAMP-triggered immunity (PTI), induced by pathogen-associated molecular patterns (PAMPs). To counteract this innate defense, pathogens deploy effector proteins with a primary function to suppress PTI. In specific cases, plants have evolved cytoplasmic resistance proteins detecting isolate-specific pathogen effectors, leading to effector-triggered immunity. In the case of plant viruses, no PAMPs were identified so far and a primary plant defense is thought to be based on RNA silencing. Endogenous plant silencing pathways generate 21-24 nt small RNAs - microRNAs and small-interfering RNAs - that regulate gene expression post-transcriptionally and transcriptionally. Emerging evidence indicates that RNA silencing also contributes to plant defense against non-viral pathogens. Conversely, PTI-based innate responses may contribute to antiviral defense. Our working hypothesis postulates that RNA silencing and innate immunity function in concert to fight plant viruses and that viruses counteract this dual defense by effectors that must suppress both PTI and silencing to establish successful infection. We further propose that plant viruses encode two types of effectors, a viral protein-based and a viral RNA-based. We are testing our hypothesis by studying various DNA and RNA viruses in model plants including Arabidopsis thaliana and Nicotiana benthamiana as well as crop plants including cassava and rice.
Research topics
Molecular plant virology
Gene silencing
Innate immunity
Interdisciplinary
Next generation sequencing technologies to study plant-virus interactions
Development of RNA-based vaccines to cure crop plants from viral disease
