Detection and Identification of <i>Tomato Spotted Wilt Virus</i> in Ornamental Plants in North Khorasan Province

In recent years, the symptoms of viral diseases such as dwarfism, mosaic, discoloration, necrosis, and circular spots have been prevalent in ornamental plants in parks, gardens, and streets in North Khorasan Province. Tomato spotted wilt virus (TSWV), the type species of the genus Orthotospovirus, the family Tospoviridae, and the order Bunyavirales, is a tripartite negative/ambisense ssRNA virus. This virus is a major cause of the infection of ornamental plants in the world. In this study, to evaluate the percentage of infection to TSWV, in the early autumn of 2020, 350 samples of ornamental plants were collected based on the suspicious viral symptoms from parks, gardens, and streets of North Khorasan province (Bojnord and Shirvan cities) and were transported to the laboratory in cold conditions. In the laboratory, DAS-ELISA serological test was performed to evaluate the presence of virus in the suspected samples. Then, the infected samples identified by ELISA test were inoculated to the test plants of Chenopodium album L. (lamb's quarters), Vigna unguiculata L. (cowpea) and Datura stramonium L. (jimsonweed). After the appearance of symptoms, in order to verify the infection, they were tested again using DAS-ELISA. The molecular identification of the infected samples was done by Qiagene RNA extraction kit. Using specific primers in RT-PCR reaction, a fragment was amplified in the band of 276 bp. The results of DAS-ELISA and RT-PCR tests proved the presence of the virus on ornamental plants in North Khorasan province. In the mechanical inoculation of the virus, three above-mentioned plants showed the symptoms of the disease.