Theses and Dissertations at Montana State University (MSU)
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/732
Browse
5 results
Search Results
Item Integration of Puccinia punctiformis into organic management of Cirsium arvense(Montana State University - Bozeman, College of Agriculture, 2023) Chichinsky, Daniel Jacob; Chairperson, Graduate Committee: Fabian D. Menalled; Tim F. Seipel (co-chair)Cirsium arvense is a perennial weed that causes significant economic losses in agriculture. An extensive rhizomatous root system makes C. arvense difficult to manage, particularly in organic cropping systems that use tillage as a primary management tool. To improve organic management of C. arvense, there is a need for the development of alternative and integrated weed management toolsets that include C. arvense biological controls. Puccinia punctiformis is a fungal pathogen that systemically infects C. arvense, with the potential to reduce host vigor. The goal of this research was to assess the impacts of P. punctiformis within organic cropping systems, using a greenhouse and a field study that examined integration of the biocontrol with cultural and mechanical management tools. In the greenhouse, P. punctiformis was integrated with a competitive annual cropping sequence, where C. arvense's biomass production and competitive ability was assessed. Cirsium arvense biomass production was significantly reduced when P. punctiformis was integrated with the cultural management tactic, more than individual use of the biocontrol or cultural management alone. Additionally, P. punctiformis reduced the competitive ability of C. arvense over time. In the field, P. punctiformis was integrated with mechanical management, where reduced and standard tillage treatments were evaluated to determine the effects on P. punctiformis and C. arvense abundance. The reduced tillage treatment caused a greater increase in P. punctiformis infected C. arvense stems compared to standard tillage, however there was no impact to asymptomatic C. arvense stem density from either tillage treatment. In both tillage treatments, there was a reduction in asymptomatic C. arvense stem density in samples where P. punctiformis infection was present. Integration of P. punctiformis with cultural and mechanical tools can be an effective way to reduce C. arvense vigor. However, successful integration of the biocontrol can be dependent on a combination of environmental factors and deliberate cropping system management. While P. punctiformis is not a singular management solution, it has potential to be integrated into reduced disturbance cropping systems for long-term and sustainable C. arvense management.Item Creating rust resistance in wheat via modification of host genes(Montana State University - Bozeman, College of Agriculture, 2020) Nyamesorto, Bernard Mensah; Chairperson, Graduate Committee: Li Huang; Hongtao Zhang and Li Huang were co-authors of the article, 'Wheat MYC4 transcriptional factor gene modification enhanced host resistance against rust pathogens' which is contained within this dissertation.; Dissertation contains an article of which Bernard Mensah Nyamesorto is not the main author.A major challenge to resistance breeding in bread wheat (Triticum aestivum L.) is limited genetic diversity. The traditional approach to combating this problem is introgression of resistant genes from other closely related species into elite but susceptible cultivars. This strategy is often associated with linkage drag. Moreover, pathogens continue to evolve into different and more virulent forms (races) that overcome these resistant genes in a process called resistance breakdown. A typical example is the outbreak of Ug99, a novel African stem rust pathotype that exhibited virulence against numerous stem rust resistance genes. Creating resistance within wheat's own genome is a panacea to the challenges surrounding the traditional method. Biotrophic plant pathogens such as wheat rusts are known to manipulate host genes as a means of overcoming host defense response and acquiring nutrients. Central to wheat-rust interactions is highly sophisticated immune repertoire consisting of diverse signal perception and intracellular signaling pathways which are regulated by transcriptional regulators and co-factors. Unfortunately, pathogen effector proteins also take advantage of host plant genes (so called pathogen susceptible host genes) including transcriptional mechanisms. Hence editing the genes targeted by these pathogens in wheat is a valuable means of creating host resistance that has been neglected. We conducted these studies to identify host genes targeted by rust pathogens through bioinformatics approaches including transcriptome analysis which showed that wheat NPR1 genes (transcriptional regulator) and MYC4 and MY21 (transcription factors) are negatively involved compatible wheat-rust interactions. Subsequently, when these genes were down regulated in susceptible Chinese Spring using Barley Mosaic Virus Induced Gene Silencing (BSMV) assay, the silenced plants became resistant to rust pathogens. Loss-of-function mutations created in these homeologs via Ethyl methanesulfonate mutagenesis conferred resistant to rust pathogens. Consequently, this study led to the development of new rust resistance germplasms.Item Relationship of ADP-glucose pyrophosphorylase to the regulation of starch accumulation in wheat leaves infected with Puccinia striiformis West(Montana State University - Bozeman, College of Agriculture, 1970) MacDonald, Paul WilliamItem Association of stripe rust (Puccinia striiformis west.) disease index with grain yield, growth rate, harvest index and other agronomic characteristics of wheat (Triticum aestivum L.)(Montana State University - Bozeman, College of Agriculture, 1982) Khan, Muhammad AqilItem Interactions of Puccinia striiformis and Mycosphaerella graminicola on wheat(Montana State University - Bozeman, College of Agriculture, 1984) Madariaga, Ricardo Burrows