Complete genome characterizations of two novel mitoviruses hosted by the hypogeous, mycorrhizal fungi Statesia pompholyx and Tuber sp.

The study of viral diversity in uncultivated fungi, including those involved in mycorrhizal relationships, alongside research on viral communities in phytopathogenic and economically important fungi, is crucial for a comprehensive understanding of mycovirus diversity and evolution. Mycorrhizal fungi host various viruses, contributing to our understanding of virus diversity and evolution. Here, we report on the identification and complete genome characterization of two novel mitoviruses that naturally infect the hypogeous, mycorrhizal fungi Statesia pompholyx and Tuber sp. The identified viruses, denominated as “Statesia pompholyx mitovirus 1” (SpMV1) and Tuber mitovirus 3 (TruMV3), have genome lengths of 2549 and 3292 nucleotides and G + C contents of 39.00% and 34.7%, respectively. Both viruses contain a single open reading frame (ORF) encoding for RNA-dependent RNA polymerase (RdRp). BLASTp analyses showed that the RdRp domains of SpMV1 and TruMV3 share sequence similarities with those of members belonging to the genera Unuamitovirus and Triamitovirus. Specifically, they exhibit the highest similarities (44.09% and 68.34% identity) to Plasmopara viticola lesion-associated mitovirus 22 and Tuber excavatum mitovirus, respectively. According to phylogenetic analysis, SpMV1 and TruMV3 are classified as members of the genera Unuamitovirus and Triamitovirus within the Mitoviridae family, respectively. SpMV1 represents the first instance of a mitovirus identified in the hypogeous mycorrhizal fungus Statesia spp. These novel mitovirus sequences enhance our understanding of the diversity and evolution within the Mitoviridae family and contribute to the rapidly expanding dataset of mycovirus sequences.