A novel virus of the family Secoviridae detected in lettuce in the United Kingdom and in dandelion in Slovakia

During the screening of lettuce (Lactuca sativa L.) samples from the United Kingdom in 2015 using high throughput sequencing (HTS) technology, the genome of a novel virus was identified in a plant showing symptoms of stunting and yellowing. The virus genome consisted of two RNA molecules; an RNA1 of 6001 nt encoding a polyprotein with protein cofactor, helicase, protease and RNA-dependent RNA polymerase motifs and an RNA2 of 6553 nt encoding a polyprotein with viral movement and coat protein motifs. Independently, in 2018, an analysis of ribodepleted total RNA from a dandelion (Taraxacum officinale L.) displaying leaf malformation and puckering revealed a complex infection involving a secovirus related to the UK lettuce virus. Moreover, a small survey confirmed the presence of the secovirus in environmental dandelion samples in Slovakia. Detailed analysis of these sequences suggests they all belonged to the same putative species, a member of the subgenus Stramovirus, genus Sadwavirus, family Secoviridae named lettuce secovirus 1 with the tentative Latin binomial Sadwavirus lactucae.