Complete genome sequence of a novel mitovirus identified in the phytopathogenic fungus Puccinia triticina

Wheat leaf rust is caused by the obligate biotrophic fungus Puccinia triticina f. sp. tritici, which seriously affects wheat production. In this study, a novel mitovirus was identified in Puccinia triticina strain HN-1 and designated as "Puccinia triticina mitovirus 1" (PtMV1). The genome of PtMV1 consists of a single RNA molecule with a length of 2,380 nt and an A + U content of 54.7% that contains a single open reading frame (ORF). The ORF is predicted to encode a putative RNA-dependent RNA polymerase (RdRp) of 653 amino acids with a molecular mass of 74.77 kDa, containing six conserved motifs. The RdRp amino acid sequence of PtMV1 has a high degree of sequence similarity to the RdRps of unuamitoviruses. Phylogenetic analysis indicated that PtMV1 is a new member of the genus Unuamitovirus within the family Mitoviridae. To our knowledge, this is the first report of a fungal virus in Puccinia triticina.