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.

Didymella theifoliaspecifically infects some local varieties ofCamellia sinensisin China, representing a unique fungal species, and characterization of the mycoviruses related to this fungal species is attractive. Three double-stranded RNAs (dsRNAs; dsRNAs 1, 2 and 3 with sizes of 6338, 5910 and 727 bp, respectively) were identified in an avirulent strain CJP4-1 ofD. theifoliaexhibiting normal growth and morphologies. Characterization of the dsRNAs 1 and 2 revealed that they are genomic components of a novel botybirnavirus, tentatively named Didymella theifolia botybirnavirus 1 (DtBRV1), and encapsidated in isometric virions with a size of ∼39.8 nm in diameter. It is worth noting that dsRNA3 shares no detectable identity with those sequences deposited in NCBI database, while a high identity (36.58% and 40.93%) with the left regions of dsRNAs 1 and 2, but is not encapsidated in DtBRV1 particles, suggesting it is a unique dsRNA unit that is not a DtBRV1 component or a satellite and its taxonomic classification remains unclear. SDS-polyacrylamide gel electrophoresis in combination with peptide mass fingerprint analysis revealed that DtBRV1 capsid protein consisting of polypeptides encoded by the left regions of both genomic components. DtBRV1 is efficiently vertically transmitted through conidia while difficult in horizontal transmission from strain CJP4-1 to other strains. DtBRV1 has no effects on fungal growth and virulence as accessed with the transfectants of virulent strain JYC1-6 ofD. theifoliainfected by DtBRV1. DtBRV1 with specific molecular traits contributes useful information for a better understanding of the mycoviral community.ImportanceTea plants represent an ancient and unique plant species community cultured in China, while the mycoviruses related to the phytopathogenetic fungi infecting tea remain limited. Here, we characterized a novel botybirnavirus (tentatively named Didymella theifolia botybirnavirus1 (DtBRV1), and a specific dsRNA infectingDidymella theifoliaresponsible for a noticeable disease of tea plants. DtBRV1 contains two dsRNAs (1 and 2) encapsidated in isometric virions in size of ∼39.8 nm, while dsRNA3 is not encapsidated in the viral particles although it has a high identity with the mycoviral genomic components. Additionally, DtBRV1 coat proteins are composed of fused proteins encoded by both dsRNA-coding open reading frames most likely after cleave and fuse processing progress, which is striking unlike most mycoviruses. With some specific molecular traits, DtBRV1 and the related specific dsRNA unit expand our understanding of virus diversity, taxonomy, and evolution.