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Item Effect of the WRKY76 transcription factor on starch biosynthesis and plant growth(Montana State University - Bozeman, College of Agriculture, 2016) Estabrooks, Hannah Margaret; Chairperson, Graduate Committee: Jack MartinStarch is an important contributor to plant growth as excess photosynthate is stored in leaves as starch during the day to be mobilized at night and re-synthesized in sink tissues. Starch is also the principal constituent of cereal seeds and its variation greatly influence crop yields. The starch pathway is complex and its regulation is not fully understood. Transcription Factors (TFs) are known to act as master regulators of whole biosynthetic pathways and the work presented here was aimed at gaining a better understanding of starch production in leaves by identifying a TF which specifically regulates the leaf starch biosynthetic pathway. Leaf starch levels are regulated in part by ADP-glucose pyrophosphorylase (AGPase), the rate limiting step of starch biosynthesis. Transgenic rice event (NR16+) with increased leaf AGPase activity (due to overexpression of the AGPase large and small subunit transgenes Sh2r6hs and Bt2) was subjected to RNA-sequencing. The results indicated that the leaf specific AGP transgene, which increased leaf starch, also had upregulation of the WRKY76 TF. Another regulatory protein, F-Box, was chosen as a candidate due to the F-box family's involvement in plant development. The current study examines the potential of these gene products for increasing starch biosynthesis in leaves via leaf specific overexpression. Results indicate that overexpression of WRKY76 increases leaf starch an average of 39% at both the one month and anthesis growth stages in comparison to the Varietal Control Nipponbare. WRKY76 transgenic lines have enhanced phenotype with an improved harvest index due to biomass and immature panicles trending down by 4% and 21% respectively, while seed weight trended 12% higher. Events overexpressing WRKY76 were also found to upregulate important starch biosynthetic and carbon metabolism genes including AGPL1, AGPS2, SSIIIb, GBSII, Rbcs, PRK, and GS2 as well as leading to a general upregulation of leaf tissue carbohydrates. Events 1, 2, and 12 additionally had on average 13% increased photosynthetic rate at the one month growth stage. The findings of this study support WRKY76 as a dynamic regulator of the starch biosynthetic pathway conferring more efficient carbon assimilation leading to an increased harvest index.Item An investigation into the trophic status of Canyon Ferry Reservoir, Montana(Montana State University - Bozeman, College of Agriculture, 1974) Rada, Ronald GeorgeItem Physiological ecology of aquatic macrophytes in the Madison River of Yellowstone National Park, Wyoming(Montana State University - Bozeman, College of Agriculture, 1977) Klarich, Duane A.Item Composition and structure of macrophyte vegetation of the Firehole River, Yellowstone National Park as related to physical and chemical factors(Montana State University - Bozeman, College of Agriculture, 1968) Rasmussen, Sheila MayItem Factors affecting the distribution and abundance of aquatic macrophytes in parts of the Madison, Firehole and Gibbon rivers(Montana State University - Bozeman, College of Agriculture, 1969) Horpestad, Abraham AndrewItem Primary productivity of the Madison River in Yellowstone National Park, Wyoming(Montana State University - Bozeman, College of Agriculture, 1967) Todd, Elston HerbertItem Interaction of western harvester ants with southeastern Montana soils and vegetation(Montana State University - Bozeman, College of Agriculture, 1983) Birkby, Jeffrey LawrenceItem Plant-associated fluorescent pseudomonads : their systematic analysis, microbial antagonism and iron interaction(Montana State University - Bozeman, College of Agriculture, 1982) Hemming, Bruce ClarkItem Functional studies of type II heterodimeric phytochromes and end-modified type I phyAs in arabidopsis(Montana State University - Bozeman, College of Agriculture, 2011) Liu, Peng; Chairperson, Graduate Committee: Robert Sharrock.Phytochromes (phys) are a family of dimeric chromoprotein photoreceptors that modulate plant physiological and developmental processes in response to red (R) and far-red (FR) light. In Arabidopsis thaliana, these fall into two functional groups, type I phyA and type II phyB-E. Previous findings have shown that heterodimerization occurs in type II phytochromes and suggest that diverse dimer forms may have specific functions. The first objective of this study was to characterize the activities of individual phytochrome dimer combinations by developing a novel in vivo protein engineering system. Either obligate homodimers or heterodimers of phytochrome N-terminal regions were produced in phyB mutant plants. With this system, a highly active phyB/D heterodimeric form was shown to rescue the phyB mutant phenotype. Dimers of phyB/achromo-phyB, phyB/C, and phyB/E mediated organ-specific growth in de-etiolation by functioning differentially in cotyledons but not in hypocotyls. Light labile phyA is critical in the plant transition from skotomorphogenic to photomorphogenic growth. To investigate possible in vivo phyA heterodimerization with type II phys and the relationship between phy quaternary structure and signaling mechanisms, transgenic plants were generated that express different myc- tagged N- or C-terminal end fusion phyA proteins in a Landsberg erecta (Ler) phyA mutant or a wild-type background. Co-immunoprecipitation showed that phyA only forms homodimers with itself. Compared with fully active one myc epitope (myc1)-tagged phyAs, six myc epitopes attached to the ends of the N- or C- terminus of phyA impaired phyA-mediated far-red high irradiance (FR-HIR) signaling and also attenuated degradation in the light, indicating that alteration of phyA architecture may damage protein-protein interaction both in phyA downstream signaling and in its protein turnover. Overall, these findings have expanded the structurally complex R/FR sensing systems in plants and have implications for how plant growth and development may be fine-tuned through phy heterodimer-mediated tissue-specific growth or phy-modified activity.Item Plant species diversity in the sagebrush steppe of Montana(Montana State University - Bozeman, College of Agriculture, 2006) Seipel, Timothy Fridolin; Chairperson, Graduate Committee: Matthew Lavin.Sagebrush (Artemisia tridentata) is abundant in Montana and is an obvious part of an assemblage of plant species.This community of plants; the sagebrush steppe contains a mixture of grasses, early and late season forbs and shrubs. It is found in semi-arid valleys and plains of Montana and the intermountain western United States, and has received much research attention regarding increasing livestock forage, or of wildlife's dependence on the sagebrush steppe plant communities.Yet, little information on plant species diversity exists. This thesis was undertaken to describe the plant species diversity in three intact sagebrush steppe sites in Montana. The sites were located in Gallitan and Phillips counties. An average of 130 species was found at each site documenting the high levels of diversity that exist in local communities. Diversity measures were similar yet the dissimilarity among sites was high, this could reflect the high diversity of plant species in sagebrush steppe. Of the species recorded none had a restricted range, and this may represent a high rate of migration among local communities. Contrary to a designation as mixed grass prairie at the Phillips county site we found most species representative of the sagebrush steppe and areas of the Great Basin, and the site may be better classified as sagebrush steppe. Introduced plant species were found at all sites. The Burke Park site located in the city of Bozeman has the greatest diversity and abundance of introduced species. The most abundant species were introduced forage grasses. Our results also found that introduced species were negatively associated with the distance to road or trail.This is consistent with other findings that implicate human population density and disturbance as determinants of introduced plant diversity. The implication that human related disturbance and transport of popagules are causes of introduced plant establishment highlights the need for prevention of widespread destruction of sagebrush steppe.