Genetic diversity of Wheat dwarf virus.

The complete sequence of a new wheat-infecting isolate of Wheat dwarf virus from Sweden (WDV-[Enk1]) was determined, as well as a 726-nt region covering part of rep and the long intergenic region (LIR) of six other wheat-infecting Swedish isolates and a barley-infecting isolate from Hungary (WDV-Bar[HU]). Analyses including these and previously published sequences showed that the wheat-infecting isolates of WDV displayed less than 3% of divergence. Most of the nucleotide changes were silent and the largest variation was detected in LIR. In contrast, the barley-infecting isolate was clearly different with 16% of sequence divergence compared to the wheat isolates. The WDV isolates infecting barley or wheat seem to represent two differentiated strains.