Complete genome sequence of platycodon closterovirus 1, a novel putative member of the genus Closterovirus

A new member of the genus Closterovirus was detected in Platycodon grandiflorus using high-throughput RNA sequencing analysis. The complete genome sequence of this new virus isolate, tentatively named "platycodon closterovirus 1" (PlaCV1), comprises 16,771 nucleotides with nine predicted open reading frames (ORFs) having the typical closterovirus genome organization. PlaCV1 shares 37%-50% nucleotide sequence identity with other known closterovirus genome sequences. The putative RNA-dependent RNA polymerase (RdRp), heat shock protein 70-like protein (HSP70h), viral heat shock protein 90-like protein (HSP90h), minor coat protein (CPm), and coat protein (CP) show 47-68%, 39-66%, 24-52%, 21-57%, and 16-35% amino acid sequence identity, respectively, to homologous proteins in previously identified closteroviruses, suggesting that it represents a distinct, new species in the genus. Phylogenetic analysis of HSP70h sequences places PlaCV1 alongside other members of the genus Closterovirus in the family Closteroviridae. To our knowledge, this study is the first report of the complete genome sequence of PlaCV1 infecting P. grandiflorus in the Republic of Korea.