Graduate Studies
Embargoed Master's Theses
First Advisor
Katherine Frels
Committee Members
Blaine Johnson, Marshall Clinesmith
Date of this Version
5-2025
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the Degree of Master of Science
Major: Agronomy
Under the supervision of Professor Katherine Frels
Lincoln, Nebraska, May 2025
Abstract
Anther extrusion (AE) is an important flowering trait to produce hybrid wheat which requires high levels of cross-pollination. In hybrid wheat production, females are created by chemical application or genetic mechanisms like cytoplasmic male sterility (CMS) that sterilize them making cross-pollination necessary for seed to form (Singh et. al., 2015). Lines with good AE make better male candidates because pollen is available outside of the floret allowing it to blow in the wind and contact the stigma of a female plant (Longin et. al., 2013). Genome-wide association studies (GWAS) was completed on the Hard Winter Wheat Association Mapping Panel (HWWAMP) to identify potential marker-trait associations (MTAs) for AE. In this analysis, three traits were assessed, AE, plant height (PH), and heading date (HD), however, only findings for AE will be discussed in this research. In total, there were six locations, four of which were in Lincoln, NE and two from Junction City, KS. Five of the six datasets were collected in the field with one being observed in the greenhouse. Heritability was calculated for AE ranged from 0.54 to 0.86. Significant correlations were observed in most field locations for AE indicating that this trait can be collected across environments. Best linear unbiased estimates (BLUEs) were used to calculate adjusted means for each trait and GWAS was run using the BLINK model on each location x year separately and on all locations combined. Three QTLs were identified, two on chromosome 4B and one on 6B in the greenhouse location only. These QTLs explain small portions of phenotypic variance with BobWhite_c162_145 and Excalibur_c29568_163 on chromosome 4B contributing to 4.9% and 6.8% respectively, while IWA1494 on chromosome 6B contributes 5%. In conclusion, AE is a complex quantitative trait that is difficult to capture in field environments. By identifying QTLs such as these, breeders may be able to employ marker-assisted selection to bring higher levels of AE into their breeding populations.
Comments
Copyright 2025, Chelsea N. Puncochar. Used by permission