Healthy wheat head
(left) contrasts with one having severe symptoms of Fusarium head blight
disease. Click the image for more information about it.
pathogens in the above cultures may look alike, DNA data indicate they
represent distinctly different species within the Fusarium graminearum
complex. Click the image for more information about it.
DNA Test Developed to Study, Combat
Fusarium Head Blight in Wheat By
Jan Suszkiw May
Identifying fungi that cause Fusarium head blight in cereal
grains has become much easier, thanks to a new DNA-based test developed by
Agricultural Research Service (ARS)
scientists in Peoria, Ill.
At least 16 species of Fusarium can cause head blight, a
disease that can reduce yields and contaminate cereals with toxins that can
make grain unsafe for food or feed. From 1998 to 2000, these pathogens
accounted for $2.7 billion in losses to U.S. agriculture.
The test was developed by molecular geneticists
Page at the ARS
Center for Agricultural Utilization Research in Peoria.
The test makes it possible for the first time to simultaneously
identify all of the major head blight pathogens and predict their toxin
profiles. Ward and O'Donnell envision using the test to understand the
distribution of these pathogens worldwide, as well as to determine if
individual pathogen species prefer certain crops or environments. This
information is critical to the development of effective disease control
strategies, including the production of cereal cultivars with broad resistance
to Fusarium head blight pathogens.
Visual inspection is now used to spot these pathogens, but it cannot
be used to identify which of the species is present in a field. To improve
detection and epidemiology, the Peoria scientists devised a test that pinpoints
nucleotide variations that genetically distinguish one head blight species from
The test relies on DNA "probes" designed by Ward and colleagues. When
a probe matches the DNA in a head blight sample, the DNA is fluorescently
labeled and detected using a special camera and a high-power laser, providing
unambiguous identification of the head blight pathogen and its toxin potential.
In addition, the test has been designed to identify new head blight species,
according to Ward, who is in the Peoria center's
Genomics and Bioprocessing Research Unit.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.