Species diversity of Fusarium head blight and deoxynivalenol (DON) levels in western Canadian wheat fields and generating Leptosphaeria maculans isolates carrying single avirulent (Avr) genes

Wheat and canola are two major economically important food crops grown in western Canada, accounting for billions of dollars in revenue. Fusarium head blight (FHB) in wheat and blackleg in canola are the most destructive diseases that cause economic losses annually. Both diseases are caused by fungal pathogens, where FHB is primarily caused by Fusarium graminearum, while Leptosphaeria maculans causes the blackleg disease. This project's first objective is to evaluate the Fusarium species diversity and deoxynivalenol (DON) levels in western Canadian wheat fields in 2019 and 2020. The analysis of deoxynivalenol (DON) revealed that spring wheat grain contained higher DON levels than winter wheat grain samples. Additionally, for spring wheat, a significantly lower DON content was found in the grain than in the chaff collected from the same wheat heads for both years. The species diversity analysis showed that F. graminearum was the most frequent Fusarium species found in the infected samples except the samples from Alberta, while the highest percentage of F. graminearum was found in the spring wheat samples from Manitoba. The analysis of chemotype diversity of infected samples showed that 3ADON is the dominant chemotype in FHB disease. For the blackleg disease, a growing concern among blackleg researchers is that resistance (R) genes are identified, the same gene as two different genes by two independent laboratories, as not all research laboratories use a standard set of well-characterized isolates. To standardize the R gene identification and novel R gene discovery, the second objective of this thesis is to develop a procedure to generate L. maculans isolates that only carry a single avirulent (Avr) gene. Mating between two L. maculans isolates showed less efficiency in achieving the above objective. Thus, gene editing with the clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 was utilized. Seven transformed isolates displayed reduced virulence on