Impact of RNA virus infection on plant cell function and evolution.

Viruses are obligate symbionts that tightly interact with their hosts to complete their life cycle. Each infected cell is confronted with the accumulation of viral products and activities that have evolved to support the replication and spread of the virus in the context of host cell functions and defense responses. Tobacco mosaic virus encodes replicase proteins and coat protein, to replicate and protect the RNA genome, and a movement protein (MP) that binds viral RNA and manipulates the size exclusion limit of plasmodesmata to facilitate the spread of the viral genomic RNA (vRNA). The MP and replicase also interfere with the cellular RNA silencing machinery that influences plant gene expression and development. Moreover, virus-infected cells stimulate the production of a systemic signal ahead of the virus front that triggers genomic recombination leading to heritable genetic changes. Thus viruses can interact with their hosts through diverse molecular interactions. Given the high mutation rate of viruses, these interactions have implications for evolutionary processes and adaptations at the virus-host interface that may contribute to eukaryotic evolution.