
Gene Discovery Could Help Breeders Reduce Head Scab in WheatBy Dawn
Lyons-Johnson July 10, 1997PEORIA, Ill., July 10--U.S.
Department of Agriculture scientists have discovered a useful chink in the
genetic armor of the fungus behind head scab disease that causes billions of
dollars in crop losses annually. Anne E. Desjardins, Robert H. Proctor, Susan P. McCormick and
Thomas M. Hohn of USDA's Agricultural
Research Service pinpointed and deleted the genetic codes for an enzyme
that the fungus needs to produce the toxin trichothecene. The research team is
based at the ARS National Center for
Agricultural Utilization Research here. The head scab fungus--Fusarium graminearum--uses
trichothecene to infect and weaken cereal crops such as wheat and barley. Head
scab disease cuts crop yields and leaves the plants vulnerable to other
diseases and insect damage. The disease gets its name from the scab-like marks
it leaves on the infected plant. Hohn, a microbiologist, says studying the genetic makeup of the
fungus is a different approach in fighting cereal crop diseases. "The work we have done characterizes the disease from the fungal
perspective and demonstrates how the toxin affects the virulence of the
disease," he noted. "This new information could have a great impact on wheat
breeding strategies and development of disease-resistant crop varieties." In field tests, wheat plants were infected with a form of F.
graminearum from which the enzyme gene had been deleted. "The wheat plants
still developed some disease," says Hohn. "But we saw less damage and yield
losses." Head scab disease has baffled plant breeders and growers alike
because it severely infects crops one year, then disappears for a year or two
before reappearing. Its sporadic nature has caused head scab disease to receive
less attention from researchers than more frequently seen crop diseases. But
severe head scab outbreaks over the last four years have devastated crops in
some regions of the country and emphasized the need for effective control
strategies. Scientific contact: Thomas Hohn,
Mycotoxin Research, ARS
National Center for Agricultural Utilization Research, 1815 N. University St.,
Peoria, IL 61604, phone (309) 681-6380, fax (309) 681-6665,
[email protected]. U.S. Department of Agriculture | |