Widespread occurrence and molecular characterization of Wheat dwarf virus in Iran.
Wheat dwarf virus (WDV), genus Mastrevirus, was associated with yellowing and dwarfing of wheat and barley in many parts of Iran. The complete nucleotide sequence of a barley isolate of the virus consisted of 2733 nucleotides and was most similar to barley isolates of WDV from Turkey, Czech Republic and Germany, but different enough to be regarded as a new strain of the virus. Phylogenetic analysis indicated that mastreviruses causing yellows and dwarfing in wheat and barley form two distinct groups. The Iranian and European barely isolates fall in one group while all wheat isolates are placed in another group. These results confirmed the division of WDV isolates into two distinct strains. WDV was also found in mixed infection with barley yellow dwarf viruses (BYDVs) in barley and wheat plants. Using dot blot hybridization with the full ssDNA genome of the Iranian barley isolate of WDV as a probe and PCR with primers which amplified the full length DNA of the virus, WDV was detected in 46 of 211 BYDV positive barley and wheat samples from northern, northwestern, northeastern, central and southern Iran. It is concluded that in addition to BYDVs, WDV is a major component of the yellows complex in cereal fields in Iran.