Diseases associated with tomato spotted wilt orthotospovirus (TSWV) are a serious threat to vegetable production worldwide. In 2019, leaf necrosis disease was observed on cucumber plants in Fukushima Prefecture, Japan. TSWV infection was identified in the diseased plants by immunostripe tests and RT-PCR analysis. Sequencing of the complete genome of this TSWV strain showed the highest identity with previously characterized TSWV isolates, and we therefore designated the cucumber-infecting variant as TSWV-Fukushima:cucumber 2019 (TS-FC19). Phylogenetic analyses based on the intergenic regions revealed that TS-FC19 and other TSWV isolates collected from the same area clustered in a distinct clade. Cucumber plants inoculated with TS-FC19 produced leaf necrosis symptoms, whereas other TSWV strains did not induce severe symptoms in this host. Together, our findings indicate that the cucumber leaf necrosis disease in Fukushima Prefecture is caused by a new strain of TSWV that appears to have evolved locally. This is the first detailed report on the biological characteristics of a cucumber-infecting TSWV.

与番茄斑萎原病毒 (TSWV) 相关的疾病是对全球蔬菜生产的严重威胁。2019年在日本福岛县的黄瓜植株上观察到叶片坏死病害。通过免疫条带测试和RT-PCR分析在患病植物中鉴定出TSWV感染。该 TSWV 菌株的全基因组测序显示出与先前表征的 TSWV 分离株的最高同一性，因此我们将黄瓜感染变体命名为 TSWV-Fukushima:cucumber 2019 (TS-FC19)。基于基因间区域的系统发育分析表明，从同一区域收集的 TS-FC19 和其他 TSWV 分离株聚集在一个不同的进化枝中。接种 TS-FC19 的黄瓜植株产生叶片坏死症状，而其他 TSWV 菌株在该宿主中没有引起严重症状。一起，我们的研究结果表明，福岛县的黄瓜叶坏死病是由一种新的 TSWV 毒株引起的，该毒株似乎是在当地进化而来的。这是第一份关于感染黄瓜的 TSWV 的生物学特征的详细报告。