Document Type

Dissertation - Open Access

Award Date

2018

Degree Name

Doctor of Philosophy (PhD)

Department

Plant Science

First Advisor

Karl D. Glover

Keywords

celiac disease, genotype-by-envrioment interaction, gliadin, wheat

Abstract

Misconceptions regarding plant breeding objectives have led to speculation regarding the increasing prevalence of gluten intolerance, wheat allergy, and celiac disease. It is thought that contemporary wheat cultivars accumulate more immunogenic proteins than older cultivars because of supposed genetic changes effected through plant breeding strategies. This study evaluated the stability of gliadin accumulation in 191 hard red spring wheat cultivars grown in 12 location-years. Two enzyme-linked immunosorbent assays (ELISAs) were developed. A paired t test (N = 34) failed to find a statistically significant difference between the experimental ELISAs and the commercial R5 assay measures of mean gliadin (t = 0.37, p = 0.7). A Bland-Altman analysis indicated sufficient agreement between the assays, despite a low proportion of shared variance (R2 = 0.29) and moderate correlation (r = 0.446). The experimental ELISAs overestimated gliadin by 0.412 g kg-1 flour (CI95 = -12.52, 13.34) relative to the commercial assay. Agronomic, milling quality, gluten, and baking quality traits were assessed for 154 cultivars. Correlation between gliadin and the expected predictors whole-grain protein, flour protein, and dry gluten was not significant at the α = 0.05 level. Weak correlations were observed with Falling Number score (r = 0.32), test weight (r = 0.36), shorts (r = 0.43), and flour yield (r = -0.36). Nonparametric stability analysis indicated that genotype-by-environment interaction was significant at a critical value of χ2 = 36.41 with one degree of freedom. Nonparametric stability and genotype and genotype-byenvironment (GGE) analysis identified SD4416 as one of the three the most broadly adapted cultivars. A two-sample t test of gliadin accumulated by old and new cultivars grown in the same environments did not identify statistically significant differences in gliadin accumulation. Ten D genome-specific point mutation markers were used to screen 40 cultivars chosen by rank and assigned to either the low- or high-gliadin accumulation groups. The cultivars screened showed little to no genotypic polymorphism for these markers. No conclusive evidence was found to support the hypothesis that plant breeding selection practices have increased gliadin accumulation in contemporary wheat cultivars. Environment exerted the greatest influence on gliadin accumulation in the 191 cultivars.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

327

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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