Characterization of a new Tymovirus from Erysimum

Erysimum is a genus of flowering plants in the family Brassicaceae, which includes many cultivated and wild forms commonly used as bedding plants. In 2019, an Erysimum plant showing severe yellow mottle symptoms was screened by ELISA for presence of viruses, however, with inconclusive results. As a universal approach for virus detection, dsRNA was extracted from symptomatic plants and a prominent fragment of about 6 kbp was isolated that served as template for random RT-PCR and cloning. Partial virus sequences obtained showed nt sequence identities of 75-80% to the Tymovirus turnip yellow mosaic virus (TYMV), indicating for a putative new species. To reconstruct the complete genome, total RNA was isolated and subjected to a high-throughput sequencing approach, which then resulted in the assembly of the entire genome of a new Tymovirus. Its sequence showed the highest overall nt sequence identity (76.0%) to watercress white vein virus (WWVV, JQ001816), followed by TYMV (73.4%, NC_004063) while it was only 55% identical to another Tymovirus species identified in Erysimum (Erysimum latent virus, NC_001977). The virus was transmitted mechanically to other Brassicaceae, oilseed rape and turnip, resulting in systemic infections. A strong serological cross-reaction in ELISA with a TYMV antiserum (DSMZ AS-0125) was observed and this was confirmed by immuno electron microscopy. The name Erysimum leaf mottle virus (ELMV) is proposed for the putative new species, and reference material is available at the DSMZ Plant Virus Collection under accession no. PV-1249.