Abstract
All key families of plant-infecting fungi have been observed to be infected by mycoviruses, which are substantial and ubiquitous viruses. Mycoviruses, like all other plant and animal viruses, must reproduce in live cells. These viruses spread either during spore production or cell division. Few mycoviruses are known to have a positive single-stranded RNA genome, while the majority have double-stranded RNA genomes. Few mycoviruses have been identified as the causative agents of triggering atypical pigmentation and sporadic growth to alter the sexual reproduction of the host. These viruses are categorized into taxonomic groups as developed from plant viruses. mycoviruses are notable due to their amazing capacity to cause a dramatic decrease in the virulence (hypovirulence) of the host. It has been observed that mycoviruses do not necessarily cause hypovirulence, but they also impart hypervirulence to the host fungi. The current effort summarizes the data regarding mycoviral diversity, taxonomy and their role in the pathogenesis of pathogenic fungi.