Performance Story: Characterization of multiple resistance components against Fusarium head blight in wheat
Wheat is a staple crop and an integral part of the Canadian economy, providing income for producers and jobs for Canadians. The Canadian wheat industry, including both bread and durum wheat, is frequently threatened by Fusarium head blight (FHB or scab), which causes hundreds of millions of dollars in losses every year in Canada. Host resistance coupled with other integrated pest management practices, is considered the best approach to mitigate FHB. To mitigate FHB for Saskatchewan wheat growers, we identified novel resistance sources to improve wheat varieties, which is a priority for the industry. Starting from 2015, we continuously screened FHB resistant lines each year from the world-wide wheat collection obtained from the Plant Gene Resource of Canada. From that preliminary evaluation, 4,000 wheat accessions were evaluated with more intensity; from these, 200 bread wheat accessions and 150 durum wheat accessions were assembled as association mapping (AM) panels and further evaluated for “field resistance” for three years (2019 to 2021) in three locations. The panels were assessed for Fusarium damaged kernels and mycotoxin content in 2020 and 2021, and then for type II resistance in a greenhouse for two cycles (2020 and 2021). Fifteen accessions in the bread wheat panel and eight in the durum panel consistently showed low disease incidence and severity across multi-year testing in the field and possessed multiple types of FHB resistance.
The researchers have communicated with wheat breeders and transferred these promising lines to them for introgression into Canadian elite cultivars. To understand the mechanism underlying FHB resistance, metabolomic profiling was performed on 150 bread wheat accessions after Fusarium infection. More than a hundred metabolites were identified to be associated with FHB resistance/susceptibility; these could be developed and applied in the evaluation of germplasm as FHB related metabolite biomarkers.
A genome wide association study was performed on each wheat panel, which identified a few molecular markers associated with the different types (Types I to III) of FHB resistance. In addition, the meta-QTL analysis generated 126 meta-QTL that captured many of the major QTL reported for bread and durum wheat and should facilitate the improvement in FHB resistance. The molecular markers developed for the new sources of resistance, the optimal gene pyramids and the best resistant lines will be available for breeders and pathologists to enhance current strategies for wheat resistance.