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Occurrence of Impatiens necrotic spot virus in Ornamentals in Mahallat and Tehran Provinces in Iran

Impatiens necrotic spot virus (INSV) (genus Tospovirus, family Bunyaviridae) has been detected in commercial nurseries and field-grown ornamentals in Mahallat (Markazi) and Tehran provinces of Iran. INSV on ornamentals was first reported in 1990 (2). Ornamental plants with small necrotic spots, leaf yellowing, ring spots, necrotic vein clearing, wilting, and dwarf symptoms were collected. For mechanical inoculation on selected host species, leaf samples were triturated in chilled 0.01 phosphate buffer, pH 7.2, containing 0.02% sodium sulfite. Cowpea (cv. Mashad local), Chenopodium amaranticolor, Datura mete, Nicotiana rustica, N. tabacum (cv. White Burly), and Lycopersicon sp. produced local necrotic symptoms 5 days postinoculation. N. rustica, N. tabacum cv. White Burley, and D. metel also developed systemic mosaic symptoms that were followed by total wilting and death of the plant. The severity of the disease was higher in warm weather (July and August in greenhouses). Thrips tabaci and Frankliniella intonsa were often present at the site of INSV infection. Triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) was applied using a commerical polyclonal antibody kit (As-0115) in combination with monoclonal antibody 5E4 (As-0117) prepared against nucleoprotein of INSV isolate Pv-0280 (antibody kits and positive control were a gift from DSMZ, Braunschweig, Germany). Samples were tested for the presence of TSWV and INSV. The ornamental species found infected with INSV were Rosa sp., Gazania sp., Chrysanthemum sp., Leucanthemum sp., Matricaria camomila, Pelargonium roseum, Salvia sp., and Dianthus caryophyllus, which were collected from the Mahallat area; and Gazania sp. and Bougainvillea spectabilis collected from the Tehran Province. ELISA values of field-infected samples (OD⁴⁰⁵, read after 1h) diluted at 1:10 (wt/vol) were 0.317 (minimum) and 0.914 (maximum), and 0.312 for the positive control. None of the samples reacted in TAS-ELISA with Tomato spotted wilt virus (TSWV) (antibody kits, As-0105, As-0106, and As-01106, gift from DSMZ). A few samples of Chrysanthemum sp. and Leucanthemum sp. (collected from the Mahallat area) reacted in TAS-ELISA with TSWV, indicating they were doubly infected with TSWV and INSV. Within the genus Tospovirus the TSWV peanut isolate has been reported from Iran (1). To our knowledge, this is the first report of the occurrence of INSV on ornamentals in Iran.

References: (1) A. R. Golnaraghi et al. Plant Dis. 85:1286, 2001 (2) M. D. Law and J. W. Moyer. J. Gen.Virol.71:933, 1990.