First Complete Genome Sequence of Tulip Mild Mottle Mosaic Virus (Ophiovirus Tulipae)

Tulip mild mottle mosaic disease, caused by tulip mild mottle mosaic virus (TMMMV, species Ophiovirus tulipae), was first reported in Japan in 1979. TMMMV has a negative-sense ssRNA genome and is closely related to ophioviruses such as Mirafiori lettuce big vein virus (MLBVV, Ophiovirus mirafioriense). However, its complete nucleotide sequence has not yet been reported. Therefore, in this study, we determined the complete nucleotide sequences of all four TMMMV segments. The 5'-terminal tetranucleotide sequences were highly conserved, and the five bases at the 5' end were identical in all segments. Nucleotide sequence comparisons of the four segments showed the highest sequence identity to those of MLBVV (70-76% for the genomic RNA sequences and 81-87% for the amino acid sequences of each ORF, except for ORF2). The amino acid sequences of the coat proteins of TMMMV and MLBVV were found to be 83.1% identical, which is below the 85% threshold for assignment to the same species, indicating that these viruses belong to different species in the same genus.