A virus between families: nucleotide sequence and evolution of Strawberry latent ringspot virus

Several clones of golden ginger mint (Mentha × gracilis, ‘Variegata’) were found infected with Strawberry latent ringspot virus (SLRSV). The virus was purified and cloned and the complete nucleotide sequence of a mint isolate was obtained. RNA 1 consists of 7496 nucleotides excluding the poly-A tail and encodes a polyprotein with signature enzymatic motifs found in other picorna-like plant viruses. RNA 2 consists of 3842 nucleotides excluding the poly-A tail, encoding a polyprotein that is processed to a putative movement protein and the two coat proteins of the virus. A satellite RNA of 1117 nucleotides was associated with this isolate encoding for a putative protein of 31 kDa. Phylogenetic analysis revealed that SLRSV shares characteristics with members of the Cheravirus, Fabavirus, Comovirus and Sadwavirus genera indicative of the uniqueness of SLRSV. The close relationship of SLRSV with these genera led to the examination of aphid and beetle transmission of the virus with, however, negative results.