First report of Tomato mosaic virus in eggplant in Iran.

Abstract

Eggplant (Solanum melongena L.) is a very popular vegetable in Iran. Between June 2009 and August 2010, symptoms of foliar mosaic, interveinal necrosis, and fruit discoloration were observed in eggplant fields in the Gorgan district of Golestan province (northern Iran). These symptoms resembled those observed by Sadeghi et al. (2008) in eggplants from southern, northern and central Iranian regions. Twenty leaf samples collected from symptomatic eggplants were tested for the presence of Tobacco mosaic virus (TMV), Tomato mosaic virus (ToMV), Arabis mosaic virus (ArMV) and Cucumber mosaic virus (CMV) by DASELISA, using commercial kits (Agdia, USA). ToMV was detected in 55% of the samples but no positive reactions were obtained for ArMV, CMV and TMV. Total RNA extracted from all samples was analysed by RT-PCR using a pair of primers flanking the ToMV coat protein gene (Letscher et al., 2002). The expected 750 bp fragment was amplified from all symptomatic samples collected from three fields in Karaj district, but not from negative controls (healthy plants and water). RT-PCR products were purified and sequenced. BLAST analysis of ToMV sequence (GenBank accession No. HQ593624) showed 98% nucleotide identity with reference sequences (AJ429083, AJ429086, AF012917, AF378152, AF067233, AF067231) from the NCBI database. Mechanical inoculations from symptomatic S. melongena plants to N. tabacum cv. Samsun NN elicited chlorotic local lesions on the leaves and a systemic mosaic in eggplants that resembled the symptom shown by field-infected plants. The presence of ToMV in the herbaceous plants was confirmed by ELISA and RT-PCR. ToMV has previously been reported from Iran by Ahoonmanesh et al. (1992), but this is its first identification in eggplant in the country.