THE NUCLEOTIDE SEQUENCE OF COMPLETE GENOME AND TAXONOMIC POSITION OF WHEAT AND BARLEY ISOLATES OF WHEAT STRAIN OF WHEAT DWARF VIRUS IN IRAN*

Wheat dwarf virus (WDV) is one of the main factors causing stunting and yellowing diseases of cereals. Two strains of WDV have been reported from different parts of Iran. The barley strain (WDV-B) is only detected from naturally infected barley plants, while the wheat strain (WDV-W) infects both wheat and barley plants. Previous results regarding distribution of WDV strains have revealed the dominance of WDV-W compared to WDV-B in cereal fields of Iran. To investigate the taxonomic position of the Iranian WDV strains, the complete DNA genome of a wheat isolate of WDV-W from Shahrekord (WDV-Whe[Iran:Sh:Whe]) and of a barley isolate of WDV-W from Bavanat (WDV-Whe[Iran:Ba:Bar], with 2750 and 2749 nucleotides, respectively, were sequenced. Phylogenetic analysis of nucleotide sequences of the genome, revealed two main clusters designated WDV- W and WDV-B. Cluster WDV-W is composed of two Iranian isolates including WDV-Whe[Iran:Sh:Whe], WDV-Whe[Iran:Ba:Bar] and nine non-Iranian wheat isolates of WDW (WDV-W). An Iranian barley isolate of WDV (WDV-Bar[IR:Bar]) and seven exotic barley isolates of WDV formed the second cluster (WDV-B). Sequence comparison of different genomic regions of the two Iranian WDV-W isolates showed that the replication-associated protein was the most conserved while the movement protein and the large intergenic region were the most divergent regions.