Mitoviruses in the conifer root rot pathogens Heterobasidion annosum and H. parviporum.

Mitoviral infections are highly common among fungi, but so far only one mitovirus has been described in Heterobasidion spp. conifer pathogens. Here, the occurrence of further mitoviruses was investigated using a previously published RNA-Seq dataset for de novo contig assembly. This allowed the identification of two additional mitovirus strains designated as Heterobasidion mitovirus 2 (HetMV2) and HetMV3 with genome lengths of ca. 2.9 and 5.0 kb. Furthermore, the occurrence of similar viruses was screened among a collection of Heterobasidion isolates using RT-PCR. Mitoviruses were detected in six more fungal isolates and two different host species, H. annosum and H. parviporum.