"April 2002" / Includes bibliographical references (leaves 193-211) / xi, 211 leaves : ill., plates ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2002

"February 2004" / Bibliography: leaves 150-185. / xiii, 185 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / "This project was designed to investgate new resistant populations of Hordeum spp; to assess the role of gene flow in spreading resistance; to determine the fitness of resistant individuals in accelerating resistance evolution; and to identify genetic relationships between resistant and susceptible populations using DNA markers." / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Faculty of Sciences, 2005

Wild barley (Hordeum vulgare subsp. spontaneum) could be a source of useful genes for improving cultivated barley. The useful genes present in Hordeum vulgare subsp. spontaneum may be new alleles at described loci, or these may be entirely new genes in the sense that there is limited allelic variation at these loci in the cultivated germplasm pool. This research was directed at gene discovery in wild barley and involved two steps: (i) characterization of diversity using genetic markers and (ii) development and characterization of novel germplasm for gene discovery. Simple Sequence Repeats (SSRs) of known map location were used to survey three representative groups of barley germplasm: a sample of crop progenitor (Hordeum vulgare subsp. spontaneum) accessions, a group of mapping population parents, and a group of varieties and elite breeding lines. The objectives were to determine the informativeness and utility of SSRs in differentiating and classifying the three sets of barley germplasm. Crop progenitors had the highest number of alleles per SSR locus, followed by mapping population parents and elite breeding lines. The cluster analysis indicated a high level of diversity within the crop progenitor accessions and within the mapping population parents. It revealed a much lower level of diversity within the elite breeding germplasm. A set of Recombinant Chromosome Substitution Lines (RCSLs) representing introgressions of Hordeum vulgare subsp. spontaneum genome in to a cultivated barley background were developed using the Advanced Backcross strategy. An accession of Hordeum vulgare subsp. spontaneum was the donor parent and the variety "Harrington" was the recurrent parent. The RCSLs were developed via two backcrosses to the recurrent parent followed by six generations of selfing. The genomic architecture of the RCSLs was determined by molecular marker fingerprinting with SSRs. The consequences of introgressions of Hordeum vulgare subsp. spontaneum genome segments into the recurrent parent were assessed in terms of inflorescence yield components, malting quality traits, and domestication-related traits. Hordeum spontaneum subsp. spontaneum, despite its overall inferior phenotype, contributed favorable alleles for some characters of agronomic performance. In other cases, the introgressions caused a disruption of the Harrington phenotype, a "reverse genetics" approach to gene discovery. / Graduation date: 2003

Characterization of the determinants of economically important phenotypes showing complex inheritance should lead to more effective use of genetic resources. This study was conducted to determine the number, genome location and effects of QTLs determining malting quality and agronomic traits in the two North American barley quality standards. Using a doubled haploid population of 140 lines from the cross of Harrington x Morex, agronomic phenotype and malting quality data sets from nine and eight environments, respectively, and a 107-marker linkage map, QTL analyses were performed using simple interval mapping and simplified composite interval mapping procedures. Thirty five QTLs were associated either across environments or in individual environments, with five grain and agronomic traits (yield, kernel plumpness, test weight, heading date and plant height). Thirteen QTLs were associated with five malting quality traits (grain protein percentage, soluble/total protein ratio, ��-amylase activity, diastatic power and malt extract percentage). QTLs for multiple traits were coincident. The loci controlling inflorescence type [vrsl on chromosome 2 (2H) and int-c on chromosome 4 (4H)] were coincident with QTLs affecting all traits except heading date and malt extract percentage. The largest effect QTLs -for yield, kernel plumpness test weight, plant height grain protein percentage, S/T ratio, and diastatic power- were coincident with the vrsl locus. QTL analyses were conducted separately for each sub-population (six-rowed and two-rowed). Ten new QTLs were detected in the sub-populations. There were significant interactions between the vrsl and int-c loci for plant height, grain protein percentage, and SIT protein ratio. Positive transgressive segregants were found for all agronomic traits. They were more prevalent in the six-rowed sub-population, indicating that more favorable alleles were fixed in the two-rowed parent. Results suggest that this mating of two parents representing different germplasm groups caused a disruption in the balance of traits involved in malting quality, which resulted in no progeny carrying all favorable alleles and therefore surpassing the quality of either parent. This study describes some of the genetic determinants of agronomic and malting quality traits in a two-rowed x six-rowed cross and it is a first step toward the further characterization and manipulation of these determinants. / Graduation date: 2001

Graduation date: 1994

Higher grain yield is a key objective in barley (Hordeum vulgare. L) breeding. Despite extensive research on the genetics of yield and its components, selection for yield per se is still the most extensively employed because of negative relationships among components, modest correlations between yield and any particular component, and the additional resources required for measuring the components. The development of quantitative trait locus (QTL) detection procedures allows for an alternative approach to this issue. The objective of this investigation was to determine the biological basis of observed grain yield QTLs, with particular reference to yield components and yield-related traits. Yield and yield component traits were assessed in a population of spring barley doubled haploids from a cross of 'Steptoe' x 'Morex'. The scope of inference of the experiment was broadened by using reference QTL data sets from the multiple environment assessment of the same population. Both positive and negative relationships among yield, component, and related trait QTLs were observed. The QTL data indicate that indirect selection for yield via yield components would be ineffective. The yield QTL effects in this germplasm were largely attributable to lodging and basal internode length. Localization and interpretation of yield QTLs may be useful for studying orthologous gene expression in other germplasm and in developing multiple character selection strategies. / Graduation date: 1994

The production of barley (Hordeum vulgare L.) haploids by crossing with H. bulbosum is a widely used tool in breeding and genetics. Certain barley genotypes have low seed set in this interspecific cross, a phenomenon known as partial incompatibility. Haploid production efficiency and gamete sampling are important issues with the bulbosum technique, particularly when partially incompatible genotypes are used. An in vitro floret culture system was developed that substantially increases haploid production efficiency by optimizing caryopsis growth, haploid embryo development, and plant regeneration. The individual and combined effects of three plant growth regulators (2,4-D, GA₃ and kinetin) on haploid production efficiency and its determinants were compared in the floret culture system. 2,4-D alone was superior to GA₃ alone in haploid production efficiency. 2,4-D alone or kinetin + 2,4-D are recommended for the purpose of haploid production in floret culture using the bulbosum method. Partial incompatibility between H. vulgare and H. bulbosum was studied by doubled haploid progeny analysis. Two different loci were hypothesized to account for the inheritance of partial incompatibility in the crosses of Vada x Klages, Harrington x Klages, and Vada x Harrington. The partial incompatibility gene in Harrington was found to be recessive. The dominant nature of the partial incompatibility gene (Inc) in Vada was confirmed. An association between the (Inc) gene and a deficiency in a stigma/stylodium-specific high pl protein was found in the cosegregation analysis of doubled haploid progeny. The Inc gene may be linked to the gene coding for the stigma/stylodium-specific protein, or the Inc gene may regulate expression of the protein-encoding locus. Segregation analysis of Mendelian markers in doubled haploid progeny showed that there is no evidence that the partial incompatibility status of the parents has an effect on gamete sampling by the bulbosum technique. / Graduation date: 1991

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1 v. (various pagings) : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy, 1973