Characterization of youcai mosaic virus isolated from <i>Chelidonium majus</i> var. <i>asiaticum</i> in Korea

Abstract

Youcai mosaic virus (YoMV) is a member of the genus Tobamovirus, and mainly infects Brassicaceae plants. In 2017, we collected Chelidonium majus var. asiaticum showing chlorosis and vein banding symptoms in Chuncheon, Korea. RT-PCR results using total RNA of C. majus var. asiaticum showed the presence of a tobamovirus. The RT-PCR product was shown to be YoMV by sequencing (named YoMV-Chm). To fulfill Koch's postulates, YoMV-Chm was obtained by single local lesion isolation and mechanically inoculated to two C. majus var. asiaticum. At 14 days post-inoculation, YoMV-Chm did not induce any symptoms, but systemic infection was confirmed by RT-PCR in C. majus var. asiaticum. In molecular characterization, the complete genome of YoMV-Chm was sequenced and analyzed (GenBank Accession No. LC390003). The genome structure of YoMV-Chm was like typical YoMV isolates. In sequence analysis with other YoMV isolates, YoMV-Chm is most closely related to YoMV isolates from Brassicaceae plants. In biological testing, YoMV-Chm was inoculated to ten indicator species, including Brassicaceae crops, and systemically infected all Brassicaceae crops tested. To investigate the transmission of the virus, seed transmission rates of YoMV-Chm were tested using C. majus var. asiaticum. YoMV-Chm was detected on the seeds; however, YoMV was not transmitted by seeds like other Tobamovirus species. Overall, this is first report of YoMV isolated from C. majus var. asiaticum and its characteristics.