Tomato mottle mosaic virus (ToMMV), a tentative member in genus Tobamovirus, was first reported from a greenhouse tomato sample collected in Mexico in 2013 (2). In August 2013, foliar mottle, shrinking, and necrosis were observed on pepper plants in several vegetable greenhouses of Lhasa, Tibet Autonomous Region, China. Seven symptomatic samples were collected and tested by dot-blot ELISA with antisera against Cucumber mosaic virus, Tobacco mosaic virus (TMV), Cucumber green mottle mosaic virus, Tomato spotted wilt virus, Turnip mosaic virus, and Broad bean wilt virus 2 (kindly provided by Dr. Xueping Zhou of Zhejiang University, China) (3). One of the bell pepper (Capsicum annuum var. grossum) samples reacted with the TMV antibody. Rod-shaped virus particles 300 nm in length were observed in this sample under electron microscopy. The results suggested that a tobamovirus closely related to TMV might be a causal agent. Total nucleic acids were then extracted from all seven samples using a CTAB method (1) and tested by RT-PCR using a pair of tobamovirus degenerate primers, TobamoF (GCWAAGGTKGTWYTBGTRGAYGG) and TobamoR (GTAATTGCTATTGDGTWCCWGC). These two primers were designed according to a conserved region of the TMV, Tomato mosaic virus, and ToMMV genomes (nt 2551-3433 of ToMMV genome [KF477193]). An amplicon of approximately 880 bp was obtained only from the TMV-positive sample. The amplicon was cloned and sequenced (GenBank Accession No. KJ605653). NCBI BLAST search showed that it shared the highest identity (99%) with ToMMV (KF477193), and shared the sequence homology of 82% to Tomato mosaic virus (AF332868) and 77% to TMV (V01408). The results indicated that the symptomatic pepper was infected with ToMMV. To investigate the distribution and incidence of ToMMV, 313 samples of symptomatic pepper, tomato, pumpkin, cucumber, radish, Chinese cabbage, broad bean, pea, and kidney bean samples were collected from 65 fields in Yunnan Province and Tibet Autonomous Region, and tested in RT-PCR with ToMMV-specific primers ToMMVF (AGAGAGATGGCGATAGGTTAAC, identical to nt 830-851 of ToMMV genome, GenBank Accession No. KF477193) and ToMMVR (CTGCAGTCATAGGATCTACTTC, complementary to nt1849-1828). The virus was detected in three tabasco peppers (C. frutescens) from Yunnan and one bell pepper plant from Tibet, suggesting that ToMMV has a restricted host range and is not common in these two regions. To our knowledge, this is the first report of natural infection of ToMMV in peppers as well as in China.
References: (1) R. Li et al. J. Virol. Methods 154:48, 2008. (2) R. Li et al. Genome Announc. 1(5):e00794-13, 2013. (3) Y. Xie et al. Virol. J. 10:142, 2013.
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