Antiviral Double-Stranded RNA Sensing Immunity in Plants

Plant viruses, which can cause devastating plant diseases, are obligate intracellular pathogens that replicate their genomes inside cells and spread infection by cell-to-cell movement through cell wall nanochannels called plasmodesmata (PD). Double-stranded RNA, which occurs as a replication intermediate of RNA viruses, triggers adaptive and innate host defense responses that are controlled by virus-encoded effector proteins. These defenses include RNA silencing and RNA decay, which target viral RNA and inhibit virus accumulation, and pattern-triggered immunity (PTI), which targets PD and inhibits virus movement. This review discusses the role of RNA silencing, RNA decay, PTI, and effector-triggered immunity as antiviral defense mechanisms, how they are interrelated, and how viruses interact with these mechanisms to ensure their successful replication and spread throughout the plant organism.