Natural occurrence of Tomato ringspot virus on grapevines in Iran

During the last few years several virus-like disease symptoms, including fan leaf, mosaic, leaf and vein yellowing, leaf distortion and decline were observed in grapevine (Vitis vinifera) gardens in Ourmia province of north west of Iran; an area which produces 178,000 tonnes of grapes annually. A survey was conducted between May and September 2001, with a total of 348 leaf samples collected from symptomatic plants of 24 grapevine gardens in the Ourmia province. The samples were tested for the presence of three important grapevine nepoviruses: Grapevine fanleaf virus (GFLV), Tobacco ringspot virus (TRSV) and Tomato ringspot virus (ToRSV) by double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA), using specific antisera against GFLV (No. 51318), TRSV (No. 51617) and ToRSV (No. 51306), (all from Sanofi, France). GFLV, TRSV and ToRSV were found in 2.6, 0 and 1.4% of the samples respectively. Mechanical inoculation with sap extracts from the ToRSV-positive leaf samples induced chlorotic local lesions with systemic top necrosis on Chenopodium amaranticolor, necrotic local lesions followed by systemic ring pattern on Nicotiana tabacum and chlorotic lesions followed by chlorosis on Cucumis sativus. Inoculations using extracts from the GFLV-positive leaf samples induced mild systemic mottling and leaf malformation on C. quinoa and N. tabacum and systemic chlorosis on C. sativus. These symptoms are characteristic of TRSV and GFLV respectively (Brunt et al., 1996) and the presence of the viruses was confirmed in the indicator plants by ELISA. GFLV has previously been reported from Iran (Ghorbani, 1988; Pourrahim et al., 2000), but this is the first report of ToRSV in grapevines in Iran. ToRSV can significantly affect the growth of grapevine and causes grapevine decline (Pearson & Goheen, 1990).