Abstract
Several mycoviruses that have a significant impact on fungal pathogenicity have been extensively studied over the years. However, researchers have also noticed that a number of mycoviruses that do not exhibit any noticeable effect on host phenotypes exist. This empirical fact suggests that the previously analyzed effects of mycoviruses represent exceptional cases and only provide a partial view of their function. Therefore, it is necessary to study the comprehensive effects of mycoviruses regardless of visible changes in the host phenotype. Firstly, to facilitate the study of a wide range of mycoviruses, we developed an efficient virus elimination system. In this regard, we conducted comparative analyses of virus elimination rates using various nucleoside analogs and observed that the efficacy of elimination depends on the specific combination of the analog and the viral genome type. Secondly, we also obtained virus-free strains from multiple virus-harboring fungal strains/species. Based on the comparative analyses, it was revealed that most mycoviruses induced host-phenotype change but it was limited to the specific conditions. Our data suggested that mycoviruses are not destructive but mild parasites of filamentous fungi, possibly to expand fungal phenotypic diversity without genetic change.
