FIRST REPORT ON THE OCCURRENCE OF TOBACCO STREAK VIRUS IN SUNFLOWER IN IRAN
S. Hosseini, M. Koohi Habibi, G. Mosahebi, M. Motamedi, S. Winter
Sunflower (Helianthus annuus), an important oilseed crop grown in Iran and many other countries, is a frequent host of Tobacco streak virus (TSV, genus Ilarvirus), which infects a wide range of crops and weeds. To study the occurrence and distribution of TSV in Iran, 1,272 samples were collected from sunflower fields in Kerman, Golestan, Isfahan, Mazandaran, Qom, Azarbayejan-Gharbi, Markazi, Hamedan and Tehran provinces during 2006 to 2008. TSV was detected by DAS-ELISA in 20.9% of the samples. The characterization of two Iranian virus isolates 43R (from Tehran) and IR (from Isfahan) showed that both have isometric particles 26 to 35 nm in diameter, and coat protein (CP) subunits with a molecular weight of 30.9 kDa. In mechanical inoculation assays, the Iranian TSV isolate induced local lesions on a number of plant species of the families Chenopodiaceae and Solanaceae. Vicia faba and sunflower reacted with systemic symptoms. A fragment of 747 nt in length from the CP gene of each isolate was amplified, cloned and sequenced. BLAST analysis of the CP sequences showed that both isolates are similar to Sudanese TSV isolates and belong to the same group. This is the first report on the detection of TSV in Iran.