A new closterovirus in Alcea rosea identified by small RNA deep sequencing

• DOI: 10.1007/s42161-019-00369-5
• Publication Date: 2019-08-12T16:07:51Z
• Authors: Defu Wang; Liyan Cui; Peixia Yu; Yonghong Qi; Baoxia Wang; Yanbing Niu
• Keywords: Closterovirus

RNA silencing is a conserved and specific degradation mechanism of a target RNA by virus-derived small interfering RNAs in eukaryotic organisms. Identification of viruses of Alcea rosea by small RNA deep sequencing showed the presence of watermelon mosaic virus, malva vein clearing virus, and a putative new closterovirus, which was provisionally named Alcea rosea virus 1 (ArV1). To clarify its taxonomic position, we cloned and analyzed the entire genome of the novel virus. The complete genome of ArV1 has a size of 15318 nt, and contains nine open reading frames (ORFs), namely, a large ORF encoding a putative viral polyprotein 1a (ORF1a), an RNA-dependent RNA polymerase (ORF1b), a p7 (ORF2), a heat shock protein 70 homolog (HSP70h, ORF3), a HSP-90-like protein (ORF4), a coat protein minor (ORF5), a coat protein (ORF6), a p20 (ORF7), and a p21 (ORF8) in the 5′ to 3′ direction. ArV1 shared nucleotide sequence identities of 30.69%–62.62% with 38 other completely sequenced closteroviruses. The amino acid sequence identities between ArV1 and closteroviruses were 34.57%–58.67%. Phylogenetic analysis of HSP70h sequences placed the new virus with members of genus Closterovirus. These results indicate that ArV1 is a member of a new species of the genus Closterovirus.