FIRST REPORT OF WATERMELON SILVER MOTTLE VIRUS INFECTING TOMATO IN YUNNAN, CHINA

Tomato is an economically important vegetable crop in Yunnan province. During a survey in November 2015, about 17% of to- mato plants showing chlorosis on leaves and the presence of thrips were observed in Mangshi county, Yunnan province. Leaves of five symptomatic plants were collected and examined by electron microscopy; tospovirus-like spherical particles 80-90 nm in diam- eter were found in the sap of diseased leaves of two samples. The positive samples were tested in ELISA with polyclonal antiserum of Tomato spotted wilt virus (TSWV), Tomato zonate spot virus (TZSV), Watermelon silver mottle virus (WSMoV), Impatiens ne- crotic spot virus (INSV), Groundnut yellow spot virus (GYSV), Hip- peastrum chlorotic ringspot virus (HCRV), and reacted positively with WSMoV polyclonal antiserum. The positive samples were mechanically inoculated onto Nicotiana benthamiana . Necrotic lesions and bud necrosis were observed 15 days after inoculation and sap of symptomatic leaves reacted positively with WSMoV antiserum. To further characterize this tospovirus isolate infect- ing tomato, total RNA was extracted from symptomatic leaves using Trizol reagent (Invitrogen, USA) and detected by RT-PCR with tospovirus universal primer J13 (5’-CCCGGATCCAGAG- CAAT-3’) (Cortez et al ., 2001). The RT-PCR products were cloned into pGEM-T Easy vector (Promega, USA) and sequenced. The M RNA 5’-end sequence of the isolate from Yunnan (YN-Tomato) was deposited in GenBank (Accession No. KU523691). The ampli- con was 1,232 nt, sharing 96% identity with WSMoV isolated from watermelon in Taiwan (DQ157768). The NSm protein gene of the YN-Tomato isolate shared 97% nucleotide sequence identity with the Taiwan isolate. WSMoV has been reported on watermelon in China (Rao et al ., 2011; Yin et al ., 2014), but never on tomato, so this is the first report worldwide of WSMoV infecting tomato. Further studies will be necessary to determine the prevalence of WSMoV in vegetable fields in the Mangshi region.