Genomic characterization of a new torradovirus from common fleabane (Erigeron annuus)

Authors: ALVAREZ-QUINTO, ROBERT - Oregon State University; Grinstead, Sam; Bolus, Stephen; DAUGHTREY, MARGERY - Cornell University; Hammond, John; Wintermantel, William - Bill; Mollov, Dimitre

Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2022
Publication Date: 6/19/2022
Citation: Alvarez-Quinto, R., Grinstead, S.C., Bolus, S.J., Daughtrey, M., Hammond, J., Wintermantel, W.M., Mollov, D.S. 2022. Genomic characterization of a new torradovirus from common fleabane (Erigeron annuus). Archives of Virology. https://doi.org/10.1007/s00705-022-05497-5.
DOI: https://doi.org/10.1007/s00705-022-05497-5

Interpretive Summary: Common fleabane is an annual flowering plant taxonomically belonging to the same family as lettuce. In this study we investigated plants from the state of New York showing yellow mosaic symptoms. Our findings indicated infection with a new virus. The complete genomic sequence of this new virus was determined. Further analysis showed that the new fleabane virus is most closely related to lettuce necrotic leaf curl virus (LNLCV). LNLCV is economically important for lettuce production and not present in the U.S. This information is useful for regulatory officials and to facilitate the development of detection assays that can be used in monitoring lettuce production areas in case the new fleabane virus infects lettuce or other crops.

Technical Abstract: A new virus was detected from common fleabane (Erigeron annuus) showing virus-like symptoms including leaf yellowing, mosaic, and mottling. This virus is tentatively named fleabane yellow mosaic virus (FbYMV). The complete genome sequence consists of two RNA segments of 7,133 nt (RNA1) and 4,810 nt (RNA2) excluding the poly (A) tract. Sequence analysis showed a genome organization comparable to that of members of the genus Torradovirus. RNA-1 encodes a single polyprotein with conserved protein domains corresponding to the replication block of picorna-like viruses (Helicase-Protease-Polymerase). RNA-2 contains two open reading frames (ORFs). RNA2-ORF1 encodes a putative protein of unknown function that is prevalent amongst the genus Torradovirus. RNA2-ORF2 encodes a polyprotein with a putative movement protein and three coat protein domains. Pairwise comparisons of the Pro-Pol region of RNA1 showed the highest sequence identity to isolates of Carrot torradovirus 1 (67 % at the amino acid level). The highest level of identity for the combined CPs of FbYMV was 51% (aa) to the torradovirus, lettuce necrotic leaf curl virus, isolate JG3. The level of sequence identity between FbYMV and known members of the genus Torradovirus was below the cutoff established by the ICTV for species demarcation, with Pro-Pol and CP identities <80% and <75%, respectively. Therefore, FbYMV should be classified as a new member of the genus, Torradovirus.