Viral Recognition and Evasion in Plants

Viruses, causal agents of devastating diseases in plants, are obligate intracellular pathogens composed of a nucleic acid genome and a limited number of viral proteins. The diversity of plant viruses, their diminutive molecular nature, and their symplastic localization pose challenges to understanding the interplay between these pathogens and their hosts in the currently accepted framework of plant innate immunity. It is clear, nevertheless, that plants can recognize the presence of a virus and activate antiviral immune responses, although our knowledge of the breadth of invasion signals and the underpinning sensing events is far from complete. Below, I discuss some of the demonstrated or hypothesized mechanisms enabling viral recognition in plants, the step preceding the onset of antiviral immunity, as well as the strategies viruses have evolved to evade or suppress their detection.