Date of Award:

12-2024

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Committee Chair(s)

Paul Johnson

Committee

Paul Johnson

Committee

Jianli Chen

Committee

Margaret Krause

Committee

David Hole

Abstract

Dwarf bunt (DB), caused by the pathogen Tilletia controversa J.G. Kühn [as 'contraversa'], is a fungal disease that poses yield and grain quality risks to winter wheat (Triticum aestivum) production in the Intermountain West and abroad. The infection replaces the grain with a collection of spores that are spread by wind during the following harvest. In addition to wheat, DB also infects other cereal grains and wild grasses. Genomic selection (GS) is a plant breeding method that can determine percent infection of related varieties by using phenotypic data and genetic data within a prediction model. A panel of 384 winter wheat varieties and breeding lines from the Intermountain West were evaluated to test if GS can be used to reliably predict resistance. Genotypic data was collected from two genotyping platforms using single nucleotide polymorphisms (SNPs). Phenotypic data was collected from a disease nursery in Logan, UT during 2022 and 2023. The heritability of DB resistance was 0.84, 0.96, and 0.69 for 2022, 2023, and combined years, respectively. Multiple prediction models were tested, and prediction accuracy depended heavily upon the model type, year, and genotyping platform used. To test the impact of marker number on prediction accuracy, subsets of varying sizes were tested for each genotyping platform using the G-BLUP model. The platform with the fewest markers showed improvements with increased marker number up to the maximum available, while the platform with the most markers showed improvements up to 30 percent of the total number of markers and showed only minor improvements after that. GS appeared to perform similarly for DB compared to other wheat diseases, and moderate to high prediction accuracies suggest that GS may be useful for improving DB resistance in winter wheat breeding programs.

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