New Test to Study Fungi that Causes Fusarium Head Blight in Wheat

May 16, 2005

Monday, May 16, 2005

(05/16/05 10:40)

OMAHA (DTN) -- 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 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.

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