Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Genetic dissection of grain yield and yield component traits in hexaploid spring wheat(Montana State University - Bozeman, College of Agriculture, 2020) Jones, Brittney Hannah; Chairperson, Graduate Committee: Michael J. Giroux; Nancy K. Blake, Hwa-Young Heo, Jay R. Kalous, John M. Martin, Jessica A. Torrion and Luther E. Talbert were co-authors of the article, 'Improving hexaploid spring wheat by introgression of alleles for yield component traits from durum wheat' in the journal 'Crop science' which is contained within this dissertation.; Nancy K. Blake, Hwa-Young Heo, Jay R. Kalous, John M. Martin, Deanna L. Nash, Jessica A. Torrion and Luther E. Talbert were co-authors of the article, 'Impact of yield component alleles from durum wheat on end-use quality of spring wheat' in the journal 'Cereal chemistry ' which is contained within this dissertation.; Nancy K. Blake, Hwa-Young Heo, John M. Martin, Jessica A. Torrion and Luther E. Talbert were co-authors of the article, 'Allelic response of yield component traits to resource availability in spring wheat' in the journal 'Theoretical and applied genetics' which is contained within this dissertation.Hexaploid wheat accounts for 30% of global grain production, ranking in the top three major food crop species along with maize and rice. Grain yield from hexaploid wheat is an important agronomic consideration for sustainable agriculture. As the human population continues to grow and the amount of farmable land decreases it is imperative that a focus be placed on improving grain yield performance. Grain yield is a quantitative trait and as such improved performance is largely influenced by genetic variation, environment and genotype x environment interactions. Due to the quantitative nature of grain yield the mechanisms of genetic control are largely unknown. The purpose of the presented research was to genetically dissect grain yield and yield component traits in hexaploid spring wheat grown in Montana in order to leverage new understanding to improve Montana germplasm and future breeding programs. This investigation included three research aims: (i) to determine the genetic impact of introgressed durum yield component alleles on hexaploid spring wheat agronomic and end-use quality performance (Chapters 2 and 3); (ii) investigate how resource availability as simulated by plant competition and seed density impacted yield component allele response at four yield component quantitative trait loci (Chapter 4); and (iii) to better understand the mechanism of genetic control of QTn.mst-6B a quantitative trait locus associated with tiller number through high-resolution mapping (Chapter 5). This research highlights the complexity of pleotropic interaction among yield component traits and variability associated with grain yield as impacted by environment and resources availability. Results from the three aims provide a detailed investigation of single quantitative trait loci for use as novel sources of cultivar improvement and increased genetic gain as well as, a better understanding of grain yield and yield component traits.Item Application of genomic assisted breeding for improvement of barley cultivars(Montana State University - Bozeman, College of Agriculture, 2014) Pauli, William Duke; Chairperson, Graduate Committee: Thomas Blake; Gary J. Muehlbauer, Kevin P. Smith, Blake Cooper, David Hole, Don E. Obert, Steven E. Ullrich and Thomas K. Blake were co-authors of the article, 'Association mapping of agronomic QTLs in US spring barley breeding germplasm' in the journal 'The plant genome' which is contained within this thesis.; Thomas K. Blake was a co-author of the article, 'Identification of malt quality marker-trait associations in elite barley breeding germplasm' submitted to the journal 'Journal of the American Society of Brewing Chemists' which is contained within this thesis.The use of genome-wide association studies (GWAS) to detect quantitative trait loci (QTL) controlling complex traits has become a popular approach for studying key traits in crop plants. The goal of this research was to identify regions of the barley (Hordeum vulgare L.) genome that impact both agronomic and malting quality traits. By identifying these regions of the genome and their associated diagnostic markers, we gain an understanding of the genetic architecture of the traits as well as develop informative markers that can be utilized for marker-assisted selection. We used the data generated by the Barley Coordinated Agricultural Program to identify marker-trait associations impacting agronomic performance using a Q+K mixed linear model accounting for population structure and relatedness among lines. This data was also used to develop a genotyping platform specific to the Montana State University (MSU) Barley Breeding Program. This genotyping platform was used to genotype 650 advance generation lines from eleven bi-parental families to investigate the genetic basis of malting quality traits and the regions of the barley genome impacting them. We detected 41 significant marker-trait associations for the agronomic traits we studied with 31 of those being previously detected in bi-parental mapping studies. We detected 54 significant marker-trait associations for the malting quality traits with 24 of those being previously reported. The combined results from both studies indicate that major genes impacting key traits in barley are still segregating in US germplasm as well as in the MSU germplasm. This demonstrates that there is useful standing genetic variation that can be utilized for superior barley cultivar development and further genetic gain. Furthermore, by identifying the beneficial alleles, and their associated markers, we can form a "catalog" of major genes and QTL impacting agronomic and malting quality traits which can be used for marker-assisted selection. This work also demonstrates the feasibility and utility of conducting GWAS in narrow germplasm arrays like those found in regional breeding programs and serves as a paradigm for other cereal breeding programs. Together, these studies show how genomic data can be leveraged for varietal improvement in regional plant breeding programs.Item Genetic routes to modulate rate of dry-matter disappearance of barley grain in the rumen of cattle(Montana State University - Bozeman, College of Agriculture, 2007) Jewell, Jeremy Burke; Chairperson, Graduate Committee: Tom Blake.Recent research has identified important characteristics of barley grain as feed for cattle. Of these, low ruminal dry-matter digestibility (DMD) is of particular importance as it is highly correlated with animal performance and with animal health. This research attempts to identify genetic loci that contribute to the ruminal DMD of barley grain. The utility of the barley ant18 mutation for decreasing ruminal DMD was investigated. The DMD of several barley cultivars and their ant18 mutations was investigated in a randomized complete block design in two environments. Genotype by environment interaction was present: in the greenhouse the DMD of ant18 mutants was less than that of the wildtype, and in a dryland field the reverse was true. Because of this interaction, ant18 is not likely to be a reliable method of modulating DMD. With the aim of identifying markers for marker-assisted selection (MAS), a 123-member inbred population was developed from a cross of Haxby and PI 28624. PI 28624 is a low DMD accession from the USDA barley collection.Item Candidate gene association mapping in spring wheat(Montana State University - Bozeman, College of Agriculture, 2011) Kalous, Jay Robert; Chairperson, Graduate Committee: Luther E. Talbert.Association mapping (AM) is a form of quantitative trait locus (QTL) mapping that utilizes a collection of germplasm rather than a structured mapping population. Marker/trait associations are made through the application of a mixed-effects model that corrects for population stratification. The objective of this study was to evaluate the application of association mapping on a selection of elite spring wheat cultivars. We tested marker/trait associations for known "perfect" markers and markers identified as controlling traits of interest through traditional bi-parental mapping. We also wanted to evaluate the observed linkage disequilibrium (LD) surrounding genes of interest by utilizing closely linked sets of markers in specific regions of the spring wheat genome. Population structure was estimated with fifty-one unlinked microsatellite markers. Two phenotypic datasets were used for evaluation. The first was an unbalanced historical dataset, and the second was a balanced dataset taken from a two year replicated field trial. Marker/trait associations were identified for plant height, stem solidness, heading date, grain protein content, test weight, and seed color. Our analyses identified significant associations between Rht-D1 and plant height, Ppd-D1 and heading date, and Xgwm340 and stem solidness. No associations were identified between Rht-B1 and plant height, Ppd-B1 and heading date, nor Vrn-B1 and heading date. The extent of LD varied depending on breeding history and selection pressure. One LD block was identified around the stem solidness QTL and two blocks were found surrounding a productive tiller QTL. Smaller blocks of LD were observed surrounding the three genes controlling kernel color. No LD was observed surrounding the Rht-B1 locus.