Deciphering the virome of Chunkung (Cnidium officinale) showing dwarfism-like symptoms via a high-throughput sequencing analysis.

BACKGROUND: Viruses have notable effects on agroecosystems, wherein they can adversely affect plant health and cause problems (e.g., increased biosecurity risks and economic losses). However, our knowledge of their diversity and interactions with specific host plants in ecosystems remains limited. To enhance our understanding of the roles that viruses play in agroecosystems, comprehensive analyses of the viromes of a wide range of plants are essential. High-throughput sequencing (HTS) techniques are useful for conducting impartial and unbiased investigations of plant viromes, ultimately forming a basis for generating further biological and ecological insights. This study was conducted to thoroughly characterize the viral community dynamics in individual plants. RESULTS: An HTS-based virome analysis in conjunction with proximity sampling and a tripartite network analysis were performed to investigate the viral diversity in chunkung (Cnidium officinale) plants. We identified 61 distinct chunkung plant-associated viruses (27 DNA and 34 RNA viruses) from 21 known genera and 6 unclassified genera in 14 known viral families. Notably, 12 persistent viruses (7 DNA and 5 RNA viruses) were exclusive to dwarfed chunkung plants. The detection of viruses from the families Partitiviridae, Picobirnaviridae, and Spinareoviridae only in the dwarfed plants suggested that they may contribute to the observed dwarfism. The co-infection of chunkung by multiple viruses is indicative of a dynamic and interactive viral ecosystem with significant sequence variability and evidence of recombination. CONCLUSIONS: We revealed the viral community involved in chunkung. Our findings suggest that chunkung serves as a significant reservoir for a variety of plant viruses. Moreover, the co-infection rate of individual plants was unexpectedly high. Future research will need to elucidate the mechanisms enabling several dozen viruses to co-exist in chunkung. Nevertheless, the important insights into the chunkung virome generated in this study may be relevant to developing effective plant viral disease management and control strategies.

Molecular characterization of a novel umbra-like virus from Thuja orientalis (arborvitae) in South Korea.

A novel umbra-like virus was identified in arborvitae in South Korea using RNA sequencing (RNA-seq). The virus identified was tentatively named "arborvitae umbra-like virus" (AULV) and contained a 4,300-nucleotide genome organized into four non-structural open reading frames (ORFs). Cloning and Sanger sequencing were used to confirm the viral contig sequence and determine the size of the genome. Genome analysis indicated that ORF2 encodes an RNA-dependent RNA polymerase that is probably expressed through ribosomal frameshifting. ORF3 encodes a putative long-distance movement protein, while the functions of ORFs 1 and 4 are unknown. The virus lacks a coat protein gene. The genome of AULV shares 27.3%-48.4% nucleotide sequence identity with closely related umbraviruses. Phylogenetic analysis based on the complete genome sequences and amino acid sequences of the RNA-dependent RNA polymerase revealed that AULV forms a monophyletic lineage with Guiyang paspalum paspaloides tombus-like virus (GPpTV1). We suggest that AULV is a novel umbra-like virus belonging to the family Tombusviridae.

Complete genome sequence of daphne virus 1, a novel cytorhabdovirus infecting Daphne odora.

A novel cytorhabdovirus was identified in Daphne odora in South Korea using high-throughput sequencing. The virus, tentatively named "daphne virus 1" (DV1), has a full-length genome sequence of 13,206 nucleotides with a genome organization comparable to that of unsegmented plant rhabdoviruses and contains seven antisense putative genes in the order 3'-leader-N-P'-P-P3-M-G-L-5'-trailer. The coding region of the genome is flanked by a 3' leader and a 5' trailer sequence, 261 and 151 nucleotides long, respectively. The DV1 genome shares 33.74%-57.44% nucleotide sequence identity with other cytorhabdoviruses. The DV1-encoded proteins share the highest amino acid sequence identity with homologues from Asclepias syriaca virus 1. Phylogenetic analysis showed that DV1 clustered with representative cytorhabdoviruses. We propose classifying DV1 in a new species within the genus Cytorhabdovirus, family Rhabdoviridae.

Complete genome sequence of pueraria virus A, a new member of the genus Caulimovirus.

The complete genome sequence of a new caulimovirus in Pueraria montana was determined using high-throughput sequencing. The 7,572 nucleotide genome of pueraria virus A (PVA) contains genes that encode a movement protein, an aphid transmission factor, a virion-associated protein, a coat protein, a protease + reverse transcriptase + ribonuclease H, and a transactivator/viroplasmin protein, as well as two intergenic regions, which are all common features of members of the genus Caulimovirus. A sequence alignment revealed that the complete genome of PVA shares 66.82% nucleotide sequence identity with strawberry vein banding virus (GenBank accession no. KX249738.1). The results of phylogenetic analysis and the observation that the nucleotide sequence of the polymerase coding region differed by more than 20% indicated that PVA is a member of a new species the genus Caulimovirus, family Caulimoviridae.

Complete genome sequence of cnidium closterovirus 1, a novel member of the genus Closterovirus infecting Cnidium officinale.

The genome of a novel virus identified in Cnidium officinale is composed of a monopartite ssRNA of 16,755 nucleotides that shares 68.73% (query coverage, 20%) sequence identity with carrot yellow leaf virus (CYLV, accession no. FJ869862.1). It contains 11 putative open reading frames and has an organization typical of closteroviruses. It shares 30-50% nucleotide sequence identity with other closteroviruses. The heat shock protein 70-like protein (HSP70), putative RNA-dependent RNA polymerase (RdRp), and coat protein (CP) show 39-66%, 16-60%, and 24-41% amino acid sequence identity, respectively, to the homologous proteins of previously identified closteroviruses. Molecular and HSP70-based phylogenetic analysis of the genome and encoded protein sequences suggested that this virus is a novel member of the genus Closterovirus in the family Closteroviridae, which we have tentatively named "cnidium closterovirus 1" (CnClV1).

Complete genome sequence of cnidium virus 1, a novel betanucleorhabdovirus infecting Cnidium officinale.

The complete genomic sequence of a plant rhabdovirus that was identified in Cnidium officinale in Yeongyang-dun, South Korea, is reported here. The virus, tentatively named "cnidium virus 1" (CnV1), has a negative-sense RNA genome of ~ 14 kb, and its organization most closely resembles that of unsegmented plant rhabdoviruses, containing six antisense open reading frames (ORFs) in the order 3'-N-P-P3-M-G-L-5'. Intergenic regions containing conserved sequences separate the genes. The genome of CnV1 is 37.8-56% identical in its complete nucleotide sequence to betanucleorhabdoviruses and other related rhabdoviruses. Therefore, based on the sequence similarity criteria for species demarcation, its genome organization, and its phylogenetic position, CnV1 should be classified as a new member of the genus Betanucleorhabdovirus in the family Rhabdoviridae. CnV1 is the first rhabdovirus found in C. officinale.

Complete genome sequence of Codonopsis torradovirus A, a novel torradovirus infecting Codonopsis lanceolata in South Korea.

We herein present the complete genome sequence of codonopsis torradovirus A (CoTVA), which was isolated from Codonopsis lanceolata (deodeok) in Gangwon-do, South Korea. The CoTVA genome contains two positive-sense RNA segments, namely RNA1 (6922 nucleotides), which encodes a predicted polyprotein, and RNA2 (4613 nucleotides), which encodes a movement protein and coat proteins (CPs). The proteinase-polymerase (Pro-Pol) and CP amino acid sequences were 75% and 54% identical, respectively, to those of motherwort yellow mosaic virus. Pairwise comparisons of the Pro-Pol and CP sequences revealed that the virus described in this study should be considered a member of a new torradovirus species. Phylogenetic analysis of the Pro-Pol sequence encoded by RNA1 and the CP region encoded by RNA2 indicated that CoTVA is a new member of the genus Torradovirus in the family Secoviridae. CoTVA is the first torradovirus detected in Codonopsis lanceolata.