First report of Southern tomato virus in tomato crops in Italy

Twenty-five tomato plants (Solanum lycopersicum) showing symptoms of viral disease were sampled from different greenhouses in the Ragusa province (Southern Italy) in summer 2015. Plants showed chlorosis on leaves and fruits and deformation and depressed spots of dark colour which later evolved into necrosis (Fig. 1). These symptoms were observed on the entire cluster of fruit making the product unsaleable. Based on these symptoms, samples were analysed for Cucumber mosaic virus, Pepino mosaic virus (PepMV), Potato virus Y (PVY), Tomato mosaic virus and Tomato spotted wilt virus by DAS-ELISA with polyclonal antibodies (Loewe Phytodiagnostica, Germany), and for the emerging Southern tomato virus (STV) by RT-PCR (Candresse et al., 2013). Three of the 25 samples analysed were positive only for PepMV whereas the rest of the samples had mixed infections: fifteen plants were co-infected with PepMV and PVY, and seven with STV, PepMV and PVY. The amplification product (894 bp) obtained from one STV-infected plant was purified using the UltraClean® PCR Clean-Up kit (Mo-Bio, USA) and the consensus nucleotide sequences were determined in both senses using an ABI 3130XL Genetic Analyzer (Life Technologies, USA) and deposited in GenBank under accession number KT948068. The nucleotide identity of the Italian STV isolate was greater than 99% with STV isolates Mexico1 (EF442780), BD-13 (KT634055), CN-12 (KT438549), MS7 (EU413670) and FR (KC333078) from Mexico, Bangladesh, China, USA and France, respectively.