Characterization of a novel mitovirus in Curvularia fungus isolated from pear

Abstract

A double-stranded RNA virus termed Curvularia thermal tolerance virus was identified in fungus Curvularia protuberata, conferring thermal tolerance to the host fungus and tropical panic grass, while no other mycoviruses have characterized in this fungal genus. Here, a mitovirus, tentatively named Curvularia pseudobrachyspora mitovirus 1 (CpMV1), was detected by high-throughput sequencing (HTS) approach in Curvularia pseudobrachyspora isolated from a pear leaf, and its full genome was determined by Sanger sequencing of the RT-PCR amplification products of the assembled contigs and the terminal regions determined by rapid amplification of cDNA ends. CpMV1 is 2497 nucleotides (nt) in length excluding the poly (A) tail and contains an open reading frame (ORF), which encodes an RNA-dependent RNA polymerase (RdRp) with 724 amino acids when the fungal mitochondrial genetic code is used. A BLASTp search revealed that CpMV1 RdRp shares high amino acid sequence identities (33.84–75.94%) with those of other mitoviruses. Phylogenetic analysis based on RdRps indicated that CpMV1 is a new member under Unuamitovirus of the family Mitoviridae, with the closest relationship with Plasmopara viticola lesion associated mitovirus 6 and Alternaria brassicicola mitovirus. To our knowledge, this is the first report of a mitovirus infecting Curvularia fungi.