Corn
leaves infected by Georgia Unknown virus. Below, electron micrograph of virus.
Credits
Corn
leaves showing first signs of maize necrotic streak virus. Leaves gradually
turn papery and translucent, with brown spots, as they die. Below, electron
micrograph of virus. Credits
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Two New Corn Viruses Discovered
By Don Comis
April 20, 2001
Agricultural Research
Service scientists and cooperators at
Ohio State University have
discovered two new corn viruses, one in Georgia and one in Arizona. The Arizona
virus is in a family of viruses previously known only to attack broadleaf
plants such as tomatoes and peppers, not grain crops like corn.
Peg Redinbaugh, an ARS plant molecular biologist at Wooster,
Ohio, and colleagues named the Arizona virus "maize necrotic streak."
The team of scientists receives and identifies viruses in
samples of infected corn leaves from around the world. The service provides
global producers of corn and corn seed a first line of defense against new
diseases.
Maize necrotic streak is in the Tombusvirus family, which
comprises viruses that tend to spread by soil rather than by insects, making
them less likely to spread widely. Another reason this virus promises not to be
spread beyond Arizona is that it doesn't seem to spread from plant to plant.
Its symptoms first show as white- or cream-colored streaks on leaves. It
eventually kills the leaves, turning them papery and translucent, with brown
spots.
Lab tests indicate that a cornfield infected by the new virus
would be unlikely to yield any corn. That's why scientists have to take it
seriously. Other Tombusviruses, like tomato bushy stunt virus, cause growers
significant losses.
The Georgia virus, temporarily called the Georgia Unknown, is
one of the plant-infecting rhabdoviruses, a family of bullet-shaped viruses
which includes maize mosaic virus, a major corn disease in the tropics. Viruses
in this family tend to be transmitted by any of a number of different common
aphids, thrips, mites and other insects.
The team is currently testing its living collection of insects
to see which of them transmit the Georgia Unknown, which may be limited to the
southern United States.
ARS is the chief scientific research agency in the
U.S. Department of Agriculture.
Scientific contact: Peg Redinbaugh, ARS Corn and Soybean
Research Unit, Wooster, Ohio, phone (330) 263-3965, fax (330) 263-3841,
redinbaugh.2@osu.edu.
Images courtesy of
Ohio Agriculture Research and
Development Center (OARDC), Ohio State University. Photos: Margaret Latta
(maize necrotic streak) and Ken Chamberlain (Georgia Unknown), OARDC
Communications and
Technology. Electron micrographs: OARDC
Molecular and Cellular Imaging
Center. |