Complete genomic sequence and organization of a novel mycovirus from Phoma matteuccicola strain LG915.

The complete genome of a double-stranded RNA (dsRNA) mycovirus, Phoma matteuccicola partitivirus 1 (PmPV1) was sequenced. It consists of two dsRNA segments, 1664 bp (dsRNA-1) and 1383 bp (dsRNA-2) in length, each containing a single open reading frame (ORF) potentially encoding a 46.78-kDa protein and a 40.92-kDa protein, respectively. dsRNA-1 encodes a putative polypeptide with a conserved RNA-dependent RNA polymerase (RdRp) domain that shows sequence similarity to the corresponding proteins of partitiviruses. The protein encoded by dsRNA-2 has no significant similarity to the typical coat proteins (CPs) of partitiviruses, but structure analysis nevertheless suggested that it might function as a coat protein. Purified viral particles of PmPV1 were isometric and approximately 29 nm in diameter. Phylogenetic analysis showed that PmPV1 is closely related to members of the genus Gammapartitivirus within the family Partitiviridae but forms a separate branch with Colletotrichum acutatum RNA virus 1 and Ustilaginoidea virens partitivirus 2. This is the first report of the full-length nucleotide sequence of a novel virus of the genus Gammapartitivirus infecting P. matteuccicola strain LG915, the causal agent of leaf blight of Curcuma wenyujin.