Characterization of a novel mycotombus-like virus from the plant pathogenic fungus Phoma matteucciicola

Abstract Here, we report a novel mycotombus-like mycovirus, tentatively named ‘Phoma matteucciicola RNA virus 2’ (PmRV2), derived from the phytopathogenic fungus Phoma matteucciicola strain HNQH1. The complete PmRV2 genome is comprised of 3,460 nucleotides (nts), a positive-sense single-stranded RNA (+ ssRNA) with a GC content of 56.71%. Sequence analysis of PmRV2 indicated the presence of two noncontiguous open reading frames (ORFs) encoding a hypothetical protein and a RNA-dependent RNA polymerase (RdRp), respectively. PmRV2 contains a metal-binding ‘GDN’ triad in Motif C of RdRp while most + ssRNA mycoviruses contained a ‘GDD’ motif in the same region. Additionally, a BLASTp search showed that the RdRp amino acid sequence of PmRV2 was most closely related to the RdRp of Macrophomina phaseolina umbra-like virus 1 (50.72% identity) and Erysiphe necator umbra-like virus 2 (EnUlV2, 44.84% identity). Phylogenetic analysis indicated that PmRV2 grouped together with EnUlV2 within the recently proposed family of ‘Mycotombusviridae’.