A new capulavirus infecting sugar beet (Beta vulgaris L.) in France

A novel capulavirus was identified by high-throughput sequencing in four sugar beet (Beta vulgaris L.) plants collected in April 2023 in Normandy (France). The complete genome of 2744 nucleotides (nt) was sequenced and found to have an organization similar to that of known capulaviruses, with which it showed close phylogenetic relationships. In addition, data mining of a publicly available Thalictrum thalictroides whole-genome shotgun sequence assembly allowed the identification of a contig (JABWDY010003008.1) representing a longer-than-unit length, likely episomal, genome with 99.4% nt sequence identity to the genome of the French beet isolate. The genome of the novel virus shares only 60.7-66.9% nt sequence identity with known capulaviruses, which is well below the species demarcation threshold of 78%, suggesting that a new species should be created to accommodate it. The common name "beet capulavirus 1" (BCV1) is proposed for this novel virus. Given that BCV1 was identified in plants that were coinfected with beet yellows virus, no conclusions can be drawn at this stage about its potential pathogenicity.