Leaf Blight on Curcuma wenyujin Caused by Phoma matteucciicola in China

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

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 a positive-sense single-stranded RNA (+ssRNA) of 3,460 nucleotides (nt) 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 an RNA-dependent RNA polymerase (RdRp), respectively. PmRV2 contains a metal-binding 'GDN' triplet in motif C of RdRp, while most +ssRNA mycoviruses contained a 'GDD' motif in the same region. 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 "Mycotombusviridae".

Complete genome sequence of a novel mycovirus from Phoma matteucciicola

The complete genome sequence of a novel mycovirus, Phoma matteucciicola RNA virus 1 (PmRV1), derived from Phoma matteucciicola strain LG-01, was sequenced and analyzed. The complete cDNA sequence of PmRV1 is 3432 bp in length with a GC content of 57.17%. The genome of PmRV1 contains two putative open reading frames (ORFs): ORF1 and ORF2. ORF1 encodes a hypothetical protein with significant similarity to a protein encoded by Periconia macrospinosa ambiguivirus 1 (PmAV1). ORF2 encodes a protein of 491 amino acids with a conserved RNA-dependent RNA polymerase (RdRp) domain. Additionally, the triad within domain III has an asparagine (GDN) instead of the nearly universally conserved aspartic acid (GDD). RdRp phylogeny showed that PmRV1 grouped together with PmAV1 as a sister branch of a new member of the recently proposed family of mycotombus-like viruses. This is first report of the complete sequence of a novel mycovirus, PmRV1, infecting Phoma matteucciicola strain LG-01, the causal agent of leaf blight of Curcuma wenyujin.

Molecular Characterization of a Novel Ourmia-Like Virus Infecting Phoma matteucciicola

Here, we report a novel (+) ssRNA mycovirus, Phoma matteucciicola ourmia-like virus 1 (PmOLV1), isolated from Phoma matteucciicola strain LG915-1. The genome of PmOLV1 was 2603 nucleotides long and contained a single open reading frame (ORF), which could be translated into a product of RNA-dependent RNA polymerase (RdRp) by both standard and mitochondrial genetic codons. Cellular fractionation assay indicated that PmOLV1 RNAs are likely more enriched in mitochondria than in cytoplasm. Phylogenetic analysis indicated that PmOLV1 is a new member of the genus Penoulivirus (recently proposed) within the family Botourmiaviridae.

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.