Sugarcane yellow leaf virus: a novel member of the Luteoviridae that probably arose by inter-species recombination

The 5895 nucleotide long single-stranded RNA genome of Sugarcane yellow lea f virus Florida isolate (SCYLV-F) includes six major ORFs, All but the firs t of these are homologous to genes of known function encoded by viruses of the three newly defined genera in the Luteoviridae ('luteovirids'), i.e. po leroviruses, luteoviruses and the enamoviruses. SCYLV-F ORFs 1 and 2 are mo st closely related to their polerovirus counterparts, whereas SCYLV-F ORFs 3 and 4 are most closely related to counterparts in luteovirus genomes, and SCYLV-F ORF5 is most closely related to the read-through protein gene of t he only known enamovirus, These differences in affinity result from inter-s pecies recombination, Two recombination sites in the genome of SCYLV-F map to the same genomic locations as previously described recombinations involv ing other luteovirids, A fourth type of luteovirid, Soybean dwarf virus, ha s already been described. Our analyses indicate that SCYLV-F represents a d istinct fifth type.