DNA test tackles deadly cereal disease

Developed by Agricultural Research Service (ARS) scientists 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. 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. FHB became a serious problem in the US in 1993, when over 156 million bushels of wheat and 69 million bushels of barley were lost to FHB in the upper Midwest region alone. Since that time, annual yield losses to due FHB, while declining somewhat from the record year of 1993, have remained high and currently stand at approximately 8 per cent of the crop. From 1998 to 2000, these pathogens accounted for $2.7 billion in losses to U.S. agriculture. The DNA test could therefore save US agriculture billions in the short-term. But it also has enormous long-term potential. Molecular geneticist at the ARS's Peoria center Todd Ward believes that it could be used 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". 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.

DNA test tackles deadly cereal disease

A new DNA-based test could make the identification of fungi that cause Fusarium head blight (FHB) in cereal grains far easier to detect.

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