Hong Jian Zhu

A novel single-stranded RNA virus isolated from the rice-pathogenic fungus Magnaporthe oryzae with similarity to members of the family Tombusviridae.

Here, we report a novel virus isolated from rice blast fungus, Magnaporthe oryzae, an important plant pathogen. This virus has an RNA genome of 3246 nucleotides. Its genome possesses two in-frame open reading frames (ORFs). The smaller ORF1 encodes a protein with significant similarity to a protein encoded by the ssRNA mycovirus Diaporthe ambigua RNA virus 1 (DaRV1). The larger ORF2 encodes a protein with similarity to RNA-dependent RNA polymerases (RdRp) of DaRV1 and other plant viruses of the family Tombusviridae. In silico analysis and comparisons with DaRV1 genome expression suggest that ORF2 is translated via a readthrough mechanism together with ORF1. Based upon results of this study, this virus, for which the provisional name Magnaporthe oryzae virus A (MoVA) is proposed, belongs to a new virus species. Furthermore, MoVA along with DaRV1 belong to a new taxon of mycoviruses that are evolutionarily related to plant viruses belonging to the family Tombusviridae.

Molecular identification of a novel victorivirus from the phytopathogenic fungus Nigrospora oryzae

Nigrospora oryzae is a worldwide phytopathogenic fungus that can infect many plant host species. In this study, complete sequence of a novel mycovirus from N. oryzae was reported. The viral genome is 5100 base pairs in length and possesses two overlapping open reading frames (ORFs). The two ORFs potentially encode proteins that showed significant similarity to the capsid protein and RNA-dependent RNA polymerase, in the family Totiviridae, respectively. Phylogenetic tree showed that this novel mycovirus is a new member of the genus Victorivirus in the family Totiviridae. We here designated the virus as Nigrospora oryzae victorivirus 1 (NoRV1), the first putative victorivirus identified in N. oryzae.

A novel fusarivirus isolated from the phytopathogenic fungus Nigrospora oryzae

In this study, we report the discovery and molecular characterization of a novel mycovirus, Nigrospora oryzae fusarivirus 1 (NoFV1) isolated from the rice-infecting fungus Nigrospora oryzae. Excluding a poly (A) tail, the genome of the virus is 7004 nucleotide (nt) long containing three putative nonoverlapping open reading frames (ORF1, ORF2, and ORF3). The large ORF1 encodes a polypeptide with a conserved RNA-dependent RNA polymerase (RdRp) domain and a helicase domain that functions for RNA replication. Each of the smaller ORF2 and the smallest ORF3 encodes a putative protein with an unknown function. Amino acid (aa) sequence similarities between the NoFV1-ORF1- and ORF2-encoded proteins and the homologous sequences from other mycoviruses were found. Phylogenetic analysis on the basis of the RdRp and helicase domains showed that NoFV1 is phylogenetically related to viruses in the newly proposed family Fusariviridae. Thus, we suggest that NoFV1 might be a novel member of family Fusariviridae.

Molecular characterization of a putative gammapartitivirus in the phytopathogenic fungus Nigrospora oryzae

We report the molecular attributes of a novel bisegmented double-stranded RNA (dsRNA) virus, designated “Nigrospora oryzae partitivirus 1” (NoPV1), from a phytopathogenic fungus Nigrospora oryzae. The genome of NoPV1 contains two dsRNA segments (dsRNA1 and 2), 1875 bp and 1601 bp in length, respectively. dsRNA1 and -2 both have a single open reading frame encoding the RNA-dependent RNA polymerase and coat protein, respectively. NoPV1 has a high degree of sequence identity to members of genus Gammapartitivirus in the family Partitiviridae. This is the first report of a mycovirus in the family Partitiviridae that infects N. oryzae.