First report of watermelon mosaic virus on Malva verticillata in Korea.
Watermelon mosaic virus (WMV; genus Potyvirus) is one of the most prevalent and widespread viruses affecting cucurbit crops. Symptoms of chlorosis and mosaic were reported on ginseng (Panax ginseng) leaves from South Korea and were found to be caused by WMV; however, the isolate (WMV-Insam) was not mechanically transmissible to cucurbit plants. In June 2013, during a survey of viral diseases in fields on ginseng farms in Gyeongsangbuk-do, Korea, WMV was detected by reverse transcription polymerase chain reaction (RT-PCR) on 43 out of 44 samples including ginseng, cluster mallow (Malva verticillata) and squash (Cucurbita moschata). Plant infection, RT-PCR assay and subsequent sequencing were further carried out to confirm the presence of MWV in cluster mallow. This is thought to be the first report of natural infection of WMV in M. verticillata in Korea. This report demonstrates that cluster mallow could be a potentially important host for transmission of WMV to cucurbits.