Maize as a New Host for Oat Blue Dwarf Virus

Authors: Edwards, Michael; Weiland, John

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2009
Publication Date: 8/1/2009
Citation: Edwards, M.C., Weiland, J.J. 2009. Maize as a New Host for Oat Blue Dwarf Virus. Plant Disease. 93:972

Interpretive Summary: Oat blue dwarf virus (OBDV) is present throughout the North American Great Plains and is found at low incidence levels in barley, oats, and flax in the upper Midwestern U.S. The pattern of its spread is determined by the spread of the aster leafhopper (also known as the six-spotted leafhopper), since this virus depends upon the aster leafhopper to transmit it to its plant hosts. Cropping patterns in this region have changed considerably in recent years, with much greater acreages devoted to maize in areas historically planted to small grains. Considering that this virus is often found in small grains in the upper Midwest and that its aster leafhopper vector is commonly detected in maize, we questioned whether maize might be a host for OBDV. Although maize was reported not to be a host for OBDV, maize is the primary host for another closely-related virus, maize rayado fino virus. The latter virus primarily infects maize in Central and South America, but has also been found in the southern U.S. We re-evaluated the ability of maize to serve as a host for OBDV and determined that maize is indeed a host. Both sweet corn and field corn varieties examined were susceptible. Leafhoppers also were able to reacquire the virus from infected maize and transmit it to other hosts. The extent of natural infection of maize by OBDV or economic loss, if any, remains to be determined. This discovery extends the host range of OBDV to include maize and suggests that maize has the potential to serve as a natural reservoir for OBDV.

Technical Abstract: Oat blue dwarf virus (OBDV) is distributed throughout the North American Great Plains and is found at low incidence levels in barley, oats, and flax in the upper Midwestern U.S. Cropping patterns in this region have changed considerably in recent years, with much greater acreages devoted to maize in areas historically planted to small grains. Considering that OBDV is endemic in small grains in this region, and that its aster leafhopper vector (Macrosteles quadrilineatus) is commonly detected in maize, we questioned whether maize might be a host for OBDV. Although Westdal reported that maize was not a host for OBDV, maize is the primary host for another closely-related marafivirus, Maize rayado fino virus (MRFV). The latter virus primarily infects maize in Central and South America, but has also been found in the southern U.S. To re-evaluate the ability of maize to serve as a host for OBDV, viruliferous aster leafhoppers were allowed to feed on young maize seedlings for seven days, and plants were assayed for the presence of OBDV three weeks post inoculation. We determined that maize is indeed a host and that both sweet corn and field corn varieties examined were susceptible. Leafhoppers also were able to reacquire the virus from infected maize and transmit it to other hosts. The extent of natural infection of maize by OBDV or economic loss, if any, remains to be determined. This discovery extends the host range of OBDV to include maize and suggests that maize has the potential to serve as a natural reservoir for OBDV.