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Document Type

Dissertation - University Access Only

Award Date

2013

Degree Name

Doctor of Philosophy (PhD)

Department

Plant Science

First Advisor

Karl D. Glover

Abstract

Bacterial diseases, namely bacterial leaf streak (BLS), caused by Xanthomonas campestris pv. translucens and bacterial leaf blight (BLB), caused by Pseudomonas syringae subsp. syringae have recently reemerged as potential threats to wheat (Triticum aestivum) production in the Midwest USA. Forty-five hard red spring wheat genotypes with diverse genetic backgrounds were evaluated for resistance to BLS under field conditions with artificial supplementary inoculum. Genotypes showed significantly different responses to X. campestris pv. translucens. SD4205 was found resistant to BLS with the lowest disease severity across multiple environments. Other genotypes SD4148, SD4176, ‘Alsen’, SD4023, ‘Faller’, SD4024, ‘Knudson’, and SD4199 showed moderately resistant reactions. Genotypes ‘Russ’, SD4011, and ‘Select’ were highly susceptible. Quantitative trait loci controlling resistance to BLS was mapped using a family-based mapping approach. Sixty unique families developed through crossing selected resistant and susceptible parents were used for genotyping and phenotyping. Phenotyping was done on both F1 and F2 plants. Analysis showed narrow sense heritability for BLS resistance was 0.28. Two genomic regions on chromosomes 2A and 6B were found significantly associated with the resistance of this disease in both greenhouse and field evaluations. Additionally, two QTLs on chromosomes 3B, and 6A were detected in greenhouse evaluation and one additional QTL was detected on chromosome 1B in field evaluation. Variance explained by the significant markers ranged from 0.56 to 29.56%. Xwmc522 seemed most associated with resistance. The forty-five hard red spring wheat genotypes were also evaluated for resistance to BLB after inoculation of P. syringae subsp. syringae in multiple field tests during the growing seasons of 2009 and 2010. Considerable variation in resistance to BLB among genotypes was clearly observed. A continuous distribution of disease severity was observed in each year which suggests that resistance to BLB is likely governed by several genes. Analysis of data combined over environments revealed that SD4148 was consistently least infected, followed by Faller, Knudson, and Alsen, while SD4176, SD4171, Russ, SD4011, and Select were consistently highly infected. The findings of the study will be useful for further genetic and epidemiological studies and development of resistant cultivars.

Library of Congress Subject Headings

Wheat -- Diseases and pest resistance -- Genetic aspects
Xanthomonas campestris

Description

Includes bibliographical references.

Format

application/pdf

Number of Pages

133

Publisher

South Dakota State University

Rights

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

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