Mycoviruses and their ecological impacts on fungi.

Mycoviruses, as components of the endohyphal microbiome, have been extensively identified in major fungal and oomycetous groups. While most mycoviral infections are asymptomatic, quite a few mycoviruses significantly affect biological characteristics of their hosts. This review emphasizes the roles of mycoviruses in the ecological adaptation of host fungi and oomycetes. Traditional views suggest that mycoviruses are primarily transmitted vertically through spores or horizontally among different individuals via hyphal fusion or anastomosis. However, recent studies have documented instances of mycoviral transmission between species, even across different kingdoms, as well as through specific vectors, suggesting the presence of additional transmission pathways. Although the majority of mycoviruses exert little to no influence on host phenotypes, certain mycoviral infections can significantly impact host fitness. Notably, recent research indicates that mycoviruses can alter interactions between fungi and plants. These findings may offer innovative strategies for the application of mycoviruses in management of plant diseases caused by fungi and oomycetes.