First Report of Tomato Zonate Spot Virus Infecting Tobacco in Guizhou Province, China

Tomato zonate spot virus (TZSV), an Orthotospovirus transmitted by thrips, has caused severe losses in tomato, pepper and potato in southwest China (Xu et al., 2022; Liu et al., 2024). Tobacco (Nicotiana tabacum) is an important economic crop in Guizhou. In June 2025, symptoms including leaf shriveling, circular brown spots, and distinct blister-like protrusions along the veins were observed on tobacco plants (Yunyan 87) in a field approximately 0.133 hectares (2 mu) in size located in Qinglong County (25°83′N, 105°22′E), Qianxinan Prefecture, Guizhou Province, China. These symptoms were present in approximately 40% of the plants in the field. Total RNA was extracted from three symptomatic and two asymptomatic leaf samples using a Plant Total RNA Extraction Kit (Tiangen, China). Since the causative agent was unknown, RT-PCR was performed using specific primer sets for ten common tobacco viruses. The primers for tomato zonate spot virus were TZSV-N-F: 5'-TTAAAAAGACAGATCATTGCCTGCT-3' and TZSV-N-R: 5'-ATGTCTAACGTCCGGAGTTTAAC-3' (Yin et al., 2018). An expected 837 bp amplicon was amplified from one of the three symptomatic samples, while the other two were infected with chilli veinal mottle virus (ChiVMV), no amplicon was observed in negative controls. The amplicon was subjected using Sanger sequencing, sequence (GenBank accession PX306598) revealed 97.58% identity with the N gene of a TZSV (Accession NO. OK235648). A neighbor-joining phylogenetic tree constructed with MEGA 11 software based on the N gene sequences indicated that the isolate GZ281-TZSV (the isolate characterized in this study) clustered with other TZSV isolates from various hosts and regions, supported by high bootstrap values, confirming its identity as a TZSV isolate. Pathogenicity was confirmed in greenhouse trials, according to the method of Shen Lili et al (2025). Sap was extracted from infected tissue and mechanically inoculated onto three healthy tobacco plants (Yunyan 87), three control plants were inoculated with sterile water. Systemic symptoms resembling those observed in the field developed on three plants inoculayed with the sap extract within 14 – 21 days post-inoculation, while those inoculated with sterile water remained asymptomatic. RT-PCR was performed again to confirm the presence of TZSV. This is the first report of TZSV naturally infecting N. tabacum in Guizhou Province, China. The detection of TZSV in N. tabacum is a significant concern due to the range of viral host and its potential transmission by thrips vectors (Chen et al., 2022 ), which are also widely distributed in the region. This finding reveals a new threat to tobacco production and underscores the need to develop specific management strategies to control the spread of this virus.