Investigation of host resistance to Fusarium graminearum in common wheat (Triticum aestivum L.)

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Fusarium head blight (FHB) is a devastating disease of wheat that has cost Canadian producers in excess of one billion dollars since the early 1980s. The primary causal agent of this disease in Canada is the fungal pathogen Fusarium graminearum. Infection with F. graminearum leads to development of shrunken or shrivelled kernels which reduce crop yield and compromise end-use quality. Mycotoxins such as deoxynivalenol (DON) accumulate in the infected grain. Mycotoxins are toxic to humans and some animals, and limit the marketability and value of the grain. Low international limits for mycotoxins in food and feed pose a threat to marketability of Canadian grain. Incorporation of genetic resistance in wheat cultivars is an essential component of the multi-pronged strategy for FHB control. Five types of FHB resistance have been described in wheat. Resistance to initial infection (Type I) and resistance to spread of infection (Type II) have been well characterized by scientists and numerous sources of resistance have been identified. However, even with Type I and II resistance, some wheat genotypes accumulate significantly higher levels of mycotoxin than others. DON content poses the biggest threat to food and feed safety and is considered to be a major contributor to disease progression in Fusarium infected wheat. The long term objectives of this research are to understand the role of wheat resistance and management practices in DON accumulation in wheat. This will be achieved by: 1) Mapping genes controlling DON accumulation as well as disease incidence, severity, index and Fusarium damaged kernels in winter wheat populations and examining the relationship between the different measurements of FHB reaction, 2) Investigating the relationship between candidate resistance genes and DON accumulation, and 3) Determining the role of management, timing of infection, pre-harvest and harvest conditions in DON accumulation in grain. This research will significantly reduce losses to FHB, improve food and feed safety of wheat produced around the world.