Author ORCID Identifier

https://orcid.org/0009-0002-7585-5022

Date Available

7-20-2025

Year of Publication

2025

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Agriculture, Food and Environment

Department/School/Program

Plant and Soil Sciences

Faculty

David Van Sanford

Abstract

Fusarium Head Blight (FHB) is an economically devastating disease of wheat (Triticum aestivum L.) causing low yields and poor quality. FHB, caused by Fusarium graminearum, disrupts the grain filling phase and results in bleached spikes and shriveled seeds. Deoxynivalenol (DON) is a mycotoxin produced by the fungal pathogen when it infects the plant; DON is harmful when consumed by humans and causes feed rejection in livestock. Using FHB resistant varieties and timely applications of fungicides is the optimum strategy for management of this disease. However, there has been little research focusing on the impact of FHB resistance genes on wheat yield, flavor, and baking quality.

This study involved two populations, both created from a three-way cross between parents containing either FHB resistance genes, desirable characteristics (strong gluten, high yield, etc.), or both. From each of these populations, 120 lines were derived and have been evaluated for presence of FHB resistance genes. Using two years of agronomic data, genotyping calls, quality measurements, and flavor assessment, we found that various combinations of resistance genes have a strong effect on important agronomic and quality traits. Significantly (P < 0.05) reduced DON levels were observed in lines with three resistance genes. An intermediate heritability estimate (h2 = 0.43) indicates breeding for flavor intensity is possible, highly influenced by combinations of resistance genes, and moderately correlated (r = 0.48; P < 0.05) with positive flavor preferences. These findings will improve breeding efforts for FHB resistance breeding of wheat while maintaining acceptable yield and flavor.

There is a high demand for new FHB-resistant small grain crop varieties that accumulate less DON. It is difficult to breed for FHB resistance because it is a quantitative trait, and phenotyping is tedious and subjective. Implementation of high-throughput, objective phenotyping methods would advance breeding success in developing FHB resistant varieties. Optical sorting uses a camera to rapidly and efficiently separate healthy grains from Fusarium-infected grains. The sorter does not rely on potentially biased human observations but rather utilizes a calibrated camera to autonomously and reproducibly classify and separate the grains based on their appearance.

We evaluated the ability of the optical sorter to reduce DON in closely related wheat breeding lines with various combinations of scab resistance genes. The sorter did an excellent job of reducing DON content (10 – 22%). However, this did not translate into reduced DON after several cycles of selection. Combinations of resistance genes in a small subset of genotyped lines did not affect the ability of the sorter to reduce DON. Previous research has shown that Fhb1 frequency increases with cycles of selection, which was confirmed in this study. Furthermore, the frequencies of resistance QTL 1A and 4A Neuse also increased with just one cycle of selection. However, the frequency of 3B Massey decreased. Results suggest the optical sorter can be an effective tool for selecting grain with reduced DON content and more FHB resistance QTL for breeding purposes.

Wheat milling and baking traits are important quality requirements to account for in breeding programs. However, the phenotyping of these traits is difficult, time-consuming, expensive, and resource limited. Because of this, most wheat lines in a breeding program are not screened for milling and baking traits until advanced stages when there are fewer lines to be phenotyped. This potentially reduces the genetic variability within the program for milling and baking traits, thus it would be useful to have a way to assess milling and baking quality at an earlier stage.

In this study, 221 genotyped early generation wheat lines were used to test the accuracy of genomic predictions for a set of important milling and baking quality traits. A Genome Wide Association Study (GWAS) was performed to identify Single Nucleotide Polymorphisms (SNPs) that were significantly associated with the traits of interest and to provide a framework for altering prediction methods to incorporate SNPs that had not previously been associated with these traits. Genomic predictions for kernel protein, kernel hardness, softness equivalent, and flour protein were highly accurate in early generation lines. GWAS results identified 31 SNPs that were significantly associated with these four traits at a threshold of P < 0.00001. These SNPs could be incorporated as important predictors to improve genomic predictions further. Results from this study provide breeders with confidence in using genomic predictions to select milling and baking traits in early generations of wheat lines rather than waiting until late stages when genetic variation might be limited.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2025.269

Funding Information

This study was supported by the United States Wheat and Barley Scab Initiative Grant (no: 59-0206-9-054) from 2021 - 2025.

Download

Included in

Agriculture Commons

Share

COinS