First report of tobacco vein banding mosaic virus infecting Solanum lyratum Thunb in China
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KeywordsSolanum lyratum Thunb Vein banding and mosaic symptoms Tobacco vein banding mosaic virus
Solanum lyratum Thunb, a species of the genus Solanum in the family Solanaceae, is a common Chinese herbal medicine. Tobacco vein banding mosaic virus (TVBMV) is a member of the genus Potyvirus and was first discovered in Taiwan in 1964 (Habera et al. 1994). In July 2018, several S. lyratum plants growing naturally along a roadside exhibited virus-like symptoms including dark green vein banding and mosaic in Zhenjiang, Jiangsu province, China. The crude sap from the symptomatic leaves of S. lyratum was rubbed onto leaves of Nicotiana benthamiana plants, resulting in mild downward leaf curling and mild mosaic symptoms at 9 days post inoculation (dpi) and severe downward leaf curling, yellowing and plant stunting at 20 dpi, indicating mechanical transmission of a virus. Mock-inoculated N. benthamiana plants did not exhibit any symptoms at 9 or 20 dpi. Double-stranded (ds) RNA was extracted from the symptomatic leaves of S. lyratum (Morris and Dodds 1979), and used as a template for sequence-independent amplification (SIA) (Agindotan et al. 2010). Polymerase chain reaction (PCR) products were ligated into pUCm-T Vector (Sangon, Shanghai, China) and sequenced (SunYa, Shanghai, China). BLAST analysis showed that the nucleotide sequence (nt) of seven fragments were 92–94% identical to a TVBMV isolate from Shandong, China (JN630469). The presence of TVBMV was further confirmed in the symptomatic S. lyratum and N. benthamiana plants inoculated with crude sap by reverse transcription (RT) PCR using virus-specific primers (forward, 5’-GGATATTGGTGAGCAGATGC-3′; and reverse, 5’-CGTTTTCGATGCACCACACCATC-3′) designed on the sequences obtained by SIA. The expected 1109 nt product was not amplified from the asymptomatic or the mock-inoculated N. benthamiana plants. Subsequently, the complete genome of this isolate (tentatively named TVBMV-lyr) was determined by sequencing RT-PCR products obtained using degenerate TVBMV primers designed from the results of multiple sequence alignments of TVBMV isolates along with TMV-lyr-specific primers designed from sequences obtained by SIA. The complete genomic sequence of TVBMV-lyr was deposited in GenBank as accession number MH898883. It is 9570 nt in length and shares the highest nucleotide identity (94.32%) with TVBMV-SDZC1 (HQ396793). To our knowledge, this is the first report of TVBMV infection in S. lyratum.
This work was partially granted by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (No. 18KJA210001).