The hallmarks of “green” viruses: Do plant viruses evolve differently from the others?

All viruses are obligatory parasites that must develop tight interactions with their hosts to complete their infectious cycle. Viruses infecting plants share many structural and functional similarities with those infecting other organisms, particularly animals and fungi. Quantitative data regarding their evolutionary mechanisms – generation of variability by mutation and recombination, changes in populations by selection and genetic drift have been obtained only recently, and appear rather similar to those measured for animal viruses.This review presents an update of our knowledge of the phylogenetic and evolutionary characteristics of plant viruses and their relation to their plant hosts, in comparison with viruses infecting other organisms.

► Plant virus taxonomy is still evolving with increasing knowledge on viral genomes.
► Quantification of mechanisms driving plant virus evolution is recent.
► In the few known cases, they appear in the same range as in animal viruses.
► Specific adaptations to their hosts have shaped the evolution of plant viruses.