Evolution of Mycoviruses

Mycoviruses infect a broad spectrum of fungal hosts and are thought to be of ancient origin. The strict intracellular lifestyle, transmission bottlenecks, stamping-machine mode of replication and limited transmission are probably responsible for the slow evolution of mycoviruses. Although mutation and selective sweep are the major evolutionary forces in mycoviruses, recombination, horizontal gene transfer, interactions between coinfecting mycoviruses, and host effects through codon optimization are reported in some taxa. Phylogenetic analyses of mycovirus replication and coat proteins suggest polyphyletic origins. Recent advancements in cryo-imaging provide the promise of high-resolution structural analyses of mycovirus particles to study evolution and higher-order classification.