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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, May 2005 by Jan Suszkiw.

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 Todd Ward, Dave Starkey,
Kerry O'Donnell and Brent Page at the ARS National 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 another.

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
Microbial Genomics and Bioprocessing Research Unit.

ARS is the U.S. Department of Agriculture's chief scientific research
agency.

[www.ars.usda.gov]

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