Mycoviruses in biocontrol of plant pathogens (MYBIO)

Fusarium head blight (FHB) remains a significant issue affecting both wheat seedlings and heads, caused by a complex of highly specialized pathogens, including Fusarium culmorum and F. graminearum. While the disease and its pathways have been extensively studied, mycoviruses infecting Fusarium represent an elusive factor that may influence its phenotype. Although most known mycoviruses do not seem to harm their hosts, there are reports suggesting the possibility of hypovirulence, making them potential biocontrol agents. To investigate hypovirulent mycoviruses, we isolated F. culmorum and F. graminearum from six wheat (Triticum aestivum) cultivars and screened them for mycoviruses by extracting and sequencing double-stranded RNA. Among the 56 sequenced fungal isolates, 25 were found to be infected with mycoviruses. Interestingly, F. culmorum, which has only one previously described mycovirus, tended to host more viruses than F. graminearum, with some isolates harboring up to seven mycoviruses simultaneously.Based on RNA-dependent RNA polymerase domain analysis, 10 of the viruses were positive-sense single-stranded RNA viruses (related to families Mitoviridae, Botourmiaviridae, Narnaviridae, Tymoviridae, Gammaflexiviridae, as well as the proposed Ambiguivirus and Ormycovirus groups), one was a double-stranded RNA virus (Partitiviridae), and five were negative-sense single-stranded RNA viruses (related to orders Bunyavirales, Goujianvirales, and Mononegavirales). Efforts to further characterize these viruses are ongoing.