Differential Impact of Two Wheat Streak Mosaic Virus Isolates on Wheat Growth Characteristics

Wheat streak mosaic virus (WSMV) infects most Poaceae family species. The virus is transmitted by wheat curl mites (WCM) which can acquire the virions from infected volunteer wheat (Triticum aestivum L.) and other grassy weeds, such as brome grass (Bromus tectorum) and transmit it back to wheat. This process can result in the blending of different WSMV isolates or strains infecting a host. The impact of virus strain infection on wheat symptom severity and yield components has not yet been investigated in South Dakota. The present study characterized the impact of two WSMV isolates: one from wheat (WSMV-w) and the other from brome grass (WSMV-br). Two winter wheat cultivars: Millennium and Mace, were inoculated at the 2 to 3 leaf stage with WSMV-w, WSMV-br or a buffer under growth chamber (GC) and greenhouse (GH) conditions. There were no significant differences in plant height between WSMV-br and WSMV-w inoculated plants in the GC. However, plant height was significantly different (P < 0.0001) in Millennium inoculated with WSMV-br and WSMV-w in the GH. Plant height was reduced by 10% and 15% due to WSMV-br and WSMV-w infection, respectively. For Millennium, 18% of plants inoculated with WSMV-w exhibited severe mottling compared to 12% of plants inoculated with WSMV-br. Fresh weight was reduced by 22% and 58% by WSMV-br and WSMV-w, respectively. These results suggest that although the WSMV isolate recovered from brome grass may not be as aggressive as that recovered from wheat, it still has the potential to cause significant losses.