Mycoviruses infecting Fusarium culmorum (W.G. Smith) Sacc.

Fusarium culmorum is a plant pathogenic fungus that causes foot and root rot and ‘Fusarium head blight’ diseases in cereals and particular on wheat and barley. The fungus is also responsible for mycotoxins accumulation on grain. In the last years several studies identified mycoviruses in many fungal species that may cause hypovirulence and hence can be of value in the biocontrol of crop diseases. We analyzed the virome of 40 F. culmorum isolates from Italy, Iran and Syria and the resulting different dsRNA profiles have been associated with several species of mycoviruses. Each dsRNA fragment of the chosen strains was isolated and amplified through a random RT-PCR. PCR amplicons were cloned into plasmid vectors and sequenced. The overall rate of viral infection appears to be 60% and in particular we observed 18% of infection among Italian isolates (3 out of 16), 70% among Syrian isolates (11/16) and 87% among Iranian isolates (7/8). Sequencing results indicate the presence of single and mixed mycoviral infections by members of families Endornaviridae, Narnaviridae and Partitiviridae. Moreover a bipartitic viral species from an Italian fungal isolate has been characterized by virions isolation and full genome sequencing. Observing the low similarity of the genome with other previously described mycoviruses, we have proposed the name of Fusarium culmorum virus 1 (FcV1) for this new viral species. Further studies will focus on the effect of FcV1 on F. culmorum in order to determine its role in the biology and in particular in the fungal pathogenicity.