Identification of nine putative novel members of plant-infecting alphaflexiviruses in public domain plant transcriptomes

Plant-infecting alphaflexiviruses cause moderate to severe diseases in economically important crops worldwide. In the present study, we identified nine putative novel alphaflexiviruses in nine plant species by exploring the publicly available plant transcriptome data in Sequence Read Archive (SRA) database. Coding-complete genomes of all the identified viruses were recovered and contained five to six open reading frames (ORFs). ORFs 1–5 encode replicase (Rep), triple gene block (TGB) proteins 1–3 and coat protein (CP), respectively. The additional ORF6, identified in two viruses, encoded the nucleic acid-binding (NB) protein or a protein with no significant similarity to known viral sequences. Genome organization of the first alphaflexivirus identified in a gymnospermic host (black pine potex-like virus 1-BlpPV1) slightly differed from that of known alphaflexiviruses and formed a distinct sub-clade in phylogenetic analysis. Thus, BlpPV1 can represent a novel taxon within the family Alphaflexiviridae. Based on phylogeny, sequence similarity to known members and sequence-based species demarcation criteria, six other identified viruses were tentatively assigned to the genera Potexvirus (4), Lolavirus (1) and Mandarivirus (1), while the two lola-like viruses may potentially represent a new genus. Further studies are needed to understand the biology and geographical spread of identified novel viruses.