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Document Type

Dissertation - University Access Only

Award Date

2014

Degree Name

Doctor of Philosophy (PhD)

Department / School

Plant Science

First Advisor

Karl D. Glover

Abstract

Preharvest sprouting (PHS) of wheat (Triticum aestivum L.) is defined as early germination of spikes during unfavorable harvest conditions, and considered a major abiotic factor that limits production of quality grain. Breeding for PHS resistance is difficult as the trait is affected both by the genetic constitution and weather conditions. Most quantitative trait loci (QTL) mapping studies used bi-parental cross populations. The QTLs detected in such populations may be of limited interest to breeders as it represents only a small fraction of the possible alleles for a trait and may not be directly applied in breeding program. Methods of simultaneous detection and manipulation of QTLs would increase the applicability of marker assisted selection. The main objective of the study was to map PHS resistance QTL within a multi-parental population. Twelve different spring wheat genotypes were crossed in either three- or four-way combinations to develop the 112 families consisting 791 individual lines in the population. The first study includes genetic analysis of phenotypic data applying a mixed linear model approach, to analyze a modified additive-dominance (AD) genetic model with GE (genotype-by-environment) effects. The simulation study showed that the modified AD model can be used to estimate variance components in an unbiased manner. Narrow-sense heritability of 0.287 for PHS resistance and genotypes possessing desirable additive effects were identified. Results should help breeders to obtain useful genetic information by using the suggested methods. The QTL analysis was done using both linkage (variance component) and association (quantitative transmission disequilibrium test; QTDT) methods, developed for complex pedigree structure. The linkage analysis identified QTLs in 3A, 4B and 4D chromosomes (heritability ranged from 17.85-23.54%, 11.35-20.54%, and 16.77-22% respectively). The QTDT analysis found several associated markers for PHS resistance from chromosome 3A, 3B, 3D, 4A, and 7B (first PHS resistance test) and 1B, 1D, 2A, 2B, 2D, 3A, 3B, 4A, 4D, 5D, and 7D (second PHS resistance test). The strongly associated markers can be used for selecting lines with desired QTLs from different chromosomes. The study showed the use of family-based mapping approach using progeny based phenotypic method for mapping QTLs in multi-parental cross population.

Library of Congress Subject Headings

Wheat -- Disease and pest resistance -- Genetic aspects
Wheat -- Preharvest sprouting
Wheat -- Genome mapping

Description

Includes bibliographical references (pages 136-140)

Format

application/pdf

Number of Pages

180

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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