Detection of Switchgrass mosaic virus in Miscanthus and other grasses

A new marafivirus tentatively named Switchgrass mosaic virus (SwMV) was recently detected in Panicum virgatum L. (switchgrass). The virus is related to Maize rayado fino virus (MRFV). As Miscanthus and other grass species are grown alongside switchgrass in our experimental fields, there has been concern that the virus could be transmitted to these plants. To investigate this possibility, leaf samples from Miscanthus spp. and other grasses rotated with switchgrass in a field planting were tested for SwMV by reverse-transcriptase polymerase chain reaction (RT-PCR). Switchgrass mosaic virus was detected in leaf samples of Miscanthus × giganteus, M. sinensis, M. transmorrisonensis, Saccharum ravennae, Andropogon virginicus and Sorghastrum nutans. The nucleotide sequences of the amplicons from these samples were 99% identical to SwMV in switchgrass. This is the first report of SwMV detection in Miscanthus spp. and the other grasses, apart from switchgrass.