First Report of Tomato torrado virus Infecting Tomato in Italy

In 2009 and 2010, approximately 2% of plants had disease symptoms, including initial leaflet chlorosis that later developed into necrotic spots and general necroses along the leaflet. Fruit production on affected plants was substantially reduced and necroses were also present. Total RNA was extracted from five symptomatic plant samples using the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and analyzed by reverse transcription (RT)-PCR with specific primer pair: TR2F (5' GAAGGACGAAGAGCGACTG 3'), and TR2R (5' AAGGTAGGTATGCGTTTGC 3') (1). The primers amplified a 575-bp fragment within the coat protein Vp23 of Tomato torrado virus (ToTV). No RT-PCR products were observed when water or asymptomatic tomato plants were used as controls. The RT-PCR products were purified and directly sequenced in both directions. Pair-wise similarity analysis confirmed the presence of ToTV with 99% similarity to isolate PRI-ToTV0301 (GenBank Accession No. DQ388880) and 98% similarity to isolate Kra (Accession No. EU652402). A representative sequence was deposited with GenBank (Accession No. GU903899). To further confirm the presence of ToTV, dsRNA analysis was conducted on all five symptomatic plants and one healthy tomato plant (2). Electrophoresis of dsRNA showed two bands of approximately 5,400 and 7,800 nucleotides long, typical of ToTV in all samples, while a third band between the other two (approximately 6,400 nt) was detected. Serological testing using double-antibody sandwich-ELISA was also conducted on the five symptomatic and 25 additional plants from the same greenhouse that displayed typical Pepino mosaic virus (PepMV) symptoms only. Antibodies used for serological testing screened for the presence of PepMV, Tomato spotted wilt virus, Cucumber mosaic virus, and Tomato mosaic virus (Loewe Biochemica, Sauerlach, Germany). These tests detected PepMV in all samples with disease symptoms typical of PepMV, and in three of the five samples with the newly described symptoms. To our knowledge, this is the first report of ToTV in Italy, and in some plants, co-infection with PepMV was likely. All ToTV-infected tomato plants in the greenhouse were destroyed. References: (1) H. Pospieszny et al. Plant Dis. 91:1364, 2007. (2) J. Sambrook et al. Molecular Cloning. A Laboratory Manual. 2nd ed. Cold Spring Harbor Laboratory Press, Woodbury, NY, 1989.