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Item Mapping quantitative trait loci to understand seed size variation in Camelina sativa(Montana State University - Bozeman, College of Agriculture, 2019) King, Kevin Allen; Chairperson, Graduate Committee: Chaofu LuCamelina sativa (L.) Crantz is an emerging Brassica oilseed crop. Camelina oil is high in polyunsaturated C18-fatty acids and its uses range from bio-fuels and bio-lubricants to an animal feed additive and cooking oils. A major breeding objective for camelina is to develop varieties with increased seed size. Understanding the genetics behind seed size variation would help breeders develop varieties that are more robust, easier to plant and harvest, better for oil processing, and could increase oil yield. For this study, a genetic linkage map was created and quantitative traits loci (QTL) were identified for eight agronomic traits using a bi-parental recombinant inbred population created between the two Camelina varieties: 'Suneson,' which has an average seed area of 1.35 mm2, and 'Pryzeth' with an average seed area of 2.24 mm2. Field trials were conducted in 2017 and 2018 in both dryland and irrigated treatments in Bozeman, Montana. Significant QTL were discovered for seed size and other agronomic traits measured, including flowering time, pod size, seed weight, and oil content. The results of this study could lead to marker-assisted breeding for varieties better adapted to modern agriculture.Item Genetic exploration of spike and seed morphology in a two-rowed barley nested association mapping panel(Montana State University - Bozeman, College of Agriculture, 2018) Getz, Megan Marie; Chairperson, Graduate Committee: Jamie ShermanBarley (Hordeum vulgare) is unique as it has six-rowed cultivars and two-rowed cultivars. The six-rowed has three fertile florets on each spikelet, while two-rowed has only a single fertile center floret per spikelet. This by itself affects seed uniformity as seed produced in the lateral florets tend to be less symmetrical and smaller in size than the center floret. Yield and plumpness are also affected by spike morphology. While the genes and alleles affecting six-rowed vs. two-rowed spikes are known, there are a number of other genes that affect additional spike morphological traits such as number of seeds per head, length of head, and compaction of spikelets. Here, a two-rowed Nested Association Mapping (NAM) population was used to genetically dissect barley spike and seed morphology. To create the population, 13 diverse founder lines of barley were crossed with Conlon, a high yielding, plump, spring variety. Approximately 80 progenies were selected from each of the Conlon by founder crosses, and then backcrossed to Conlon in hopes of exposing the advantageous traits while adapting lines to the Great Plains of the Northwest. The population varying for spike and seed morphology was grown out in a field trial in Bozeman, MT and Logan, UT where phenotypic data was collected throughout the stages of growth and harvest. At maturity (Zadok's 50) stage five heads from each of the lines were collected. Digital Image Analysis was used to measure spike length, kernel count, density, and seed size. Genetic maps were created for each family as well as a consensus map for the whole population. Associations between the phenotypic data and the genotypic data observed in the individual families and consensus map allowed us to identify QTLs conserved across multiple families as well as unique to individual families. Evidence of pleiotropic effects between traits was observed. Some of the QTLs previously were identified, and some are novel. One of the families was of particular interest due to unique QTLs impacting seeds per spike and seed weight. Additionally, several novel QTLs were identified on chromosome 7H that highly impact seed traits.Item Genetic surveys in combination with laboratory studies on growth and response to herbicide can help design, evaluate, and optimize Eurasian watermilfoil management plans(Montana State University - Bozeman, College of Agriculture, 2018) Guastello, Paula Ropp; Chairperson, Graduate Committee: Ryan Thum; Ryan A. Thum was a co-author of the article, 'Mesocosm evaluation of Eurasian and hybrid watermilfoil response to endothall in Jefferson Slough, Montana' in the journal 'Journal of aquatic plant management' which is contained within this thesis.Eurasian watermilfoil (Myriophyllum spicatum) is a top priority for aquatic plant managers in the United States. Dense mats of Eurasian watermilfoil obstruct irrigation and recreational activities, while drastically reducing property values and potentially providing a habitat for disease-carrying mosquitos. Nuisance populations are generally managed through herbicide use. Eurasian watermilfoil is capable of both sexual and clonal reproduction, creating a unique opportunity for adaptation: sexual reproduction generates genetic variation within a population, then fit genotypes can propagate via clonal reproduction. Pure Eurasian watermilfoil is genetically diverse, and additional genotypes result from frequent hybridization with native northern watermilfoil (Myriophyllum sibiricum). Recent studies have shown that genetic variation in Eurasian watermilfoil populations may affect herbicide efficacy in managed populations. Given the variability in herbicide response, I propose conducting site-specific studies to evaluate the response of genotypes in a waterbody to evaluate and optimize management strategies. In my thesis, I evaluated the potential to control nuisance pure and hybrid Eurasian watermilfoil with endothall in a riverine environment (Jefferson Slough, Montana). Molecular genetic surveys indicated that only one genotype of each taxon was present throughout the slough. I first compared vegetative growth and endothall response of the hybrid and Eurasian genotypes in the greenhouse, where I did not identify a difference in endothall sensitivity. Next, I evaluated the efficacy of an operational endothall treatment in Jefferson Slough. Similar to the greenhouse study results, hybrid and Eurasian watermilfoil were reduced to the same average biomass seven weeks after operational endothall treatment. Taken together, the greenhouse and operational field treatment indicate that the genotypes in Jefferson Slough were similarly susceptible to endothall. However, vegetative growth differences may have important management implications over time. In the greenhouse, Jefferson Slough hybrids grew significantly more than Eurasian watermilfoil in the absence of endothall. Additionally, there was a qualitative shift towards higher frequency of hybrids where the taxa intermixed. These results suggest a relatively higher potential for re-growth of hybrids compared to Eurasian watermilfoil following treatment. Jefferson Slough hybrids may require additional treatment to achieve sufficient long-term control. In conclusion, I discuss integration of genetic surveys into management and research priorities.Item Generating novel milling and baking properties in bread wheat via the development of novel puroindoline and glutenin alleles(Montana State University - Bozeman, College of Agriculture, 2016) Kammeraad, Jakob Darby; Chairperson, Graduate Committee: Jack Martin; Michael Giroux (co-chair); Michael J. Giroux, Andrew C. Hogg and John M. Martin were co-authors of the article, 'Mutagenesis-derived puroindoline alleles in Triticum aestivum and their impacts on milling and bread quality' in the journal 'Journal of cereal chemistry' which is contained within this thesis.The lack of natural allelic variation in genes impacting wheat quality limits the ability to make improvements based on selection among natural variation. Improvements to wheat quality can be made by generating new alleles in quality related genes via ethyl methane sulfonate mutagenesis. A series of novel puroindoline alleles were selected because each imparted a unique level of grain hardness. The impact of each allele upon wheat milling properties was tested by creating isolines in two wheat varieties. The results demonstrated that specific levels of grain hardness associated with individual puroindoline alleles result in modified break and total flour yield and modified flour particle size. A similar project was undertaken to create modified forms of several glutenin genes, which impact wheat flour mixing properties. The creation of novel glutenin alleles resulted in major loss of gluten function in nonsense mutations, while missense mutations generally did not significantly impact protein quality traits. Generating novel alleles in genes that have limited natural allelic variation is worthwhile, which is reinforced with the unique milling properties created in the puroindoline study. However, the application of EMS mutagenesis may not be equally useful for all genes impacting quality traits, since the generation of novel glutenin alleles did not result in significant improvements to wheat protein quality.Item Quantitative trait loci associated with lodging, stem strength, yield, and other important agronomic traits in dry field peas(Montana State University - Bozeman, College of Agriculture, 2017) Smitchger, Jamin A.; Chairperson, Graduate Committee: Kevin McPhee; Norman F. Weeden (co-chair)In pea, lodging changes canopy structure, increases disease pressure, reduces yield, and reduces harvest efficiency. In order to discover the quantitative trait loci (QTLs) influencing lodging resistance and other important agronomic traits in pea, a recombinant inbred line (RIL) population was created from a relatively wide cross between the commercial variety Delta and an unnamed pea variety. The RIL population was grown for 6 site-years in Bozeman and Moccasin, MT, USA, and phenotypic data was collected for 22 quantitative morphological traits and seven categorical traits which were thought to be associated with lodging resistance. Genotypic data was derived from genotype by sequencing, microsattelite markers, and cleaved amplified sequence tagged sites. QTL analysis identified a total of 135 putative QTLs for the 22 traits examined in the study. There were 12 specific regions where 115 QTLs co-located, indicating that as few as 12 genes may be responsible for multiple pleiotropic effects. Ten QTLs were found for lodging resistance. Due to the large amount of phenotypic data collected, the putative mechanism of lodging resistance was determined for each QTL. In nearly every case, lodging resistance was associated with reduced plant height, a change in tendril number, or increased stem strength. This conclusion was supported by mathematical modeling. Branch number, which determines the number of tendrils per plant, was also positively associated with lodging resistance during all site-years, indicating that increasing tendril number also increases lodging resistance. Yield was controlled by eight QTLs. All QTLs for yield had pleiotropic effects on lodging resistance and yield per plant. Seed size was not correlated with yield, and a model was created which explained why no association between yield and seed size was found. The pleiotropic effects and utility of the QTLs discovered in this study are discussed. The results of this study further refine the ideotype for pea, and can be used for marker assisted selection in this crop.Item Genetic dissection of stay-green and other traits related to dry land spring wheat performance(Montana State University - Bozeman, College of Agriculture, 2016) Acharya, Roshan Kumar; Chairperson, Graduate Committee: Jamie ShermanSpring wheat production in the upper Great Plains is at risk due to increased occurrence of low moisture and high temperatures during grain-fill. Wheat yield is impacted by several often counteracting traits, including seed number per head, seed weight and number of productive tillers. A variety of morphological and phenological plant characteristics impact performance in conditions of low moisture and high temperatures during grain-fill. In this study, we dissect traits associated with grain yield using a recombinant inbred line (RIL) mapping population derived from parents with contrasting phenotypes for several yield and drought related traits. Importantly, differences in quantitative trait loci (QTL) for yield and yield components were observed in the RIL between rain-fed and irrigated environments. We report important QTLs associated with yield and drought stress in spring wheat, with the long term goal of identifying traits useful to molecular breeding programs for the creation of lines better adapted to our changing environments. We also confirmed six grain-fill QTLs in association mapping (AM) panel which were identified by using this RIL population.Item Characterization of two different genetic mechanisms involved in the rust resistance defense response in wheat(Montana State University - Bozeman, College of Agriculture, 2013) Talajoor, Mina Rachelle; Chairperson, Graduate Committee: Li Huang; Li Huang, Jesse Poland and Peng Zhang were co-authors of the article, 'MNR220 mediates pre-haustorial defense response to rusts at the seedling stage' which is contained within this thesis.; Li Huang, Xianming Chen and Yue Jin were co-authors of the article 'A stem rust suppressor on 7DL in the spring wheat cultivar canthatch' which is contained within this thesis.Wheat leaf rust, stem rust, and stripe rust are major fungal diseases of wheat caused by Puccinia triticina, P. graminis f. sp. tritici, and P. striiformis f. sp. tritici, respectively. Development of wheat varieties with genetic resistance to pathogens is a common strategy to protect against significant yield loss. However, incorporating resistance is not always straightforward, and understanding the mechanisms responsible for triggering host resistance is key. Here, were characterized two different genetic mechanisms involved in the rust resistance defense response in wheat. Two spring wheat cultivars and their respective EMS mutants, which displayed enhanced resistance to leaf, stem, and/or stripe rust, were studied. The cultivar Canthatch possesses a stem rust resistance suppressor on chromosome 7DL. We characterized the spectrum of resistance of Canthatch and the mutant CTH-NS, confirming the specificity of this suppressor is stem rust-specific. The cultivar Alpowa mutant MNR220 displays broad-spectrum resistance to a number of wheat rust races at the seedling stage. We characterized the functional resistance of MNR220 to a race of leaf rust by sampling inoculated tissues at various time points and tracking the disease progress microscopically. The mutant MNR220 confers resistance at the pre-haustorial stage; formation of haustoria is delayed or inhibited in MNR220 relative to the wild type Alpowa.Item Molecular mapping and characterization of two chloroplast-encoded chlorophyll deficient mutants of alfalfa (Medicago sativa L.)(Montana State University - Bozeman, College of Agriculture, 1988) Lee, Donald JohnItem Genetic analysis of the MAT-1 pheromone gene of Ustilago hordei and the study of morphogenesis during the mating response(Montana State University - Bozeman, College of Agriculture, 1999) Anderson, Cynthia MarieItem Genetic studies of cold tolerance in barley(Montana State University - Bozeman, College of Agriculture, 1992) Tragoonrung, Somvong