Life Sciences Commons^™

Characterization Of The Alternative Oxidase From The Psychrophilic Green Alga Chlamydomonas Sp. Uwo241, Michael Sj Inman

Electronic Thesis and Dissertation Repository

The alternative oxidase (AOX) was studied in the psychrophilic green alga Chlamydomonas sp. UWO241. AOX is the sole component of the alternative pathway of mitochondrial electron transport and is present in all plant and algal species. In silico analysis of the deduced protein sequence of the cloned AOX cDNA showed that the UWO241 protein has lower amounts of proline and higher amounts of lysine and tryptophan compared to the AOX sequence of the mesophilic alga C. reinhardtii. These changes have been seen in other studies of cold-adapted enzymes. Interestingly, unlike C. reinhardtii, AOX transcript abundance in UWO241 …

Effects Of Excitation Pressure On Variegation And Global Gene Expression In Arabidopsis Thaliana, Rainer Bode

Electronic Thesis and Dissertation Repository

I assessed the effects of photosystem II excitation pressure on chloroplast biogenesis and leaf sectoring in the Arabidopsis thaliana variegated mutants im, spotty, var1, var2, chs5 and atd2. The plants were grown under varying degrees of excitation pressure induced by growth at increasing irradiance at different temperatures and the extent of variegation was quantified throughout the plant’s development. I found that the degree of variegation was positively correlated with excitation pressure, regardless of whether high light or low temperature was used to induce increased excitation pressure in all the mutants tested. This was irrespective of …

Increasing Atmospheric Nitrogen Deposition: Implications For Tallgrass Prairie Restoration, Jennifer M. Mcphee

Electronic Thesis and Dissertation Repository

Continued intensification of agriculture and combustion of fossil fuels will increase rates of atmospheric nitrogen (N) deposition over the next century. N is typically a limiting resource for terrestrial plants, and many species are adapted to low-N conditions. Increased N availability can affect both plant biomass and species composition, often favouring N-demanding, adventive species. These effects can be adverse in the context of ecological restoration, where the end product often relies on establishing a particular community composition. I used a field experiment in Norfolk County, Ontario, to examine how N addition affects species composition and plant productivity of a tallgrass …

Expression Analysis Of Histone Acetyltransferases In Rice Under Drought Stress, Hui Fang

Electronic Thesis and Dissertation Repository

Histone acetylation is one of the vital reversible modifications in eukaryotes. Histone acetyltransferases (HATs) and histone deacetylases (HDACs) maintain the homeostasis of histone acetylation. HATs are associated with genome-wide transcriptional activation and various biological processes in response to various stresses. Drought stress causes a range of physiological and biochemical responses in plants. Eight HATs which belong to four different families (CBP, GNAT, MYST, and TAFII250 family) have been identified in rice. In this research, four OsHATs, one from each family, were chosen based on in silico domain and promoter analysis. The real-time qPCR analysis demonstrated that drought stress caused …

Characterization Of A Putative Activation Domain In The Hulk Gene Family, Christopher Doan

Electronic Thesis and Dissertation Repository

The HULK gene family participates in regulation of both flowering time and development in the plant Arabidopsis thaliana. The proteins encoded by these genes share conserved domain structures including a proline-rich region (PRR) in the carboxyl-terminus. Based on sequence analysis and the presence of a proline-rich domain, it has been suggested that the HULKs are putative transcription factors in which HUA2 is known to regulate several late-flowering genes: FLC, FLM and MAF2.

To investigate the putative transcriptional activation domain in the carboxyl-terminus of the HULKs, full-length HULKs and deletion constructs were 3-AT titrated in yeast-one hybrids. It …

Absence Of Phosphoenolpyruvate Carboxylase Atppc3 Increases Sensitivity Of Arabidopsis Thaliana To Cadmium, Ian R. Willick

Electronic Thesis and Dissertation Repository

Phosphoenolpyruvate carboxylase (PEPC) and PEPC kinase (PPCK) catalyze a reaction feeding into the tricarboxylic acid (TCA) cycle, increasing the production of metal-chelating organic acids. Little research has been conducted on PEPC isoenzymes in Cd-stressed plants. Arabidopsis (Arabidopsis thaliana) wild-type and AtPPC1 – AtPPC3 mutants, each lacking one of three PEPC isoenzymes, grown in 0, 1, or 5 µM CdCl₂ were smaller and had increased AtPPC1 – AtPPC3 and AtPPCK1 – AtPPCK2 transcript abundance, relative phosphorylation, and PEPC activity, more so in roots than shoots. Concentrations of oxaloacetate, citrate and total organic acids increased with greater CdCl_{2 …}

Interactions Among Biotic And Abiotic Controls Of Carbon Dynamics In A Global Change Field Experiment, Eric R D Moise

Electronic Thesis and Dissertation Repository

Climate warming and increased atmospheric nitrogen deposition may substantially influence biosphere C cycling over the next century by altering ecosystem processes such as productivity and decomposition. Field studies are commonly used to explore plant responses to global change, although the underlying mechanisms can be difficult to isolate owing to the lack of control of factors such as plant-animal interactions. Ultimately, indirect effects via herbivore and detritivore responses may feedback to influence plant responses to the experimental treatments. The goal of this thesis was to explore interactions among biotic and abiotic drivers of carbon dynamics within the context of experimental warming …

Identification Of Cyclophilin Gene Family In Soybean And Characterization Of Gmcyp1, Hemanta Raj Mainali

Electronic Thesis and Dissertation Repository

I identified members of the Cyclophilin (CYP) gene family in soybean (Glycine max) and characterized the GmCYP1, one of the members of soybean CYP. CYPs belong to the immunophilin superfamily with peptidyl-prolyl cis-trans isomerase (PPIase) activity. PPIase catalyzes the interconversion of the cis- and trans-rotamers of the peptidyl-prolyl amide bond of peptides. After extensive data mining, I identified 62 different CYP genes in soybean (GmCYP1 to GmCYP62), of which 8 are multi-domain proteins and 54 are single domain proteins. At least 25% of the GmCYP genes are expressed in soybean. GmCYP1 …

Epigenetics Of Stress Adaptation In Arabidopsis: The Case Of Histone Modifications, Behnaz Najafi Majdabadi Farahani

Electronic Thesis and Dissertation Repository

Changes in the epigenetic status of plants, which contribute to changes in gene expression, in response to abiotic stress are well documented. However, their stability and transmission to subsequent generations, and their incorporation into plant stress adaptation are still a matter for debate. Using chromatin immuno-precipitation and Next Generation Sequencing (ChIP-seq), we compared genome wide enrichment of two histone marks, H3K9ac and H3K4me2, in the progeny of salt stressed and control Arabidopsis plants. Data showed less enrichment of the H3K9ac in the chromatin of the progeny of salt stressed plants, but no changes were detected in the enrichment of the …

Functional Characterization Of The Hua2 Gene Family In Arabidopsis Thaliana, Preetam Janakirama

Electronic Thesis and Dissertation Repository

HUA2 encodes a key developmental regulatory protein implicated in the coordination of induction and the maintenance of floral state in Arabidopsis. To gain further insight into the function of HUA2, I have conducted a series of studies aimed at elucidating the molecular function(s) of its individual domains. I show that the PWWP, RPR and CT-proline rich domains within HUA2 are required for the proper regulation of the flowering time phenotype. I also establish that HUA2 interacts with characterized splicing factors (FCA, AtPRP40, RBP45 and UBP1) through its CT-proline rich domain. In addition, I examine the overlap in function between HUA2 …

Sunergos1, A Lotus Japonicus Gene Required For Proper Accommodation Of Rhizobial Infection, Hwi Joong Yoon

Electronic Thesis and Dissertation Repository

Here, I characterize a symbiotic mutant of Lotus japonicus, called sunergos1 (suner1), which originated from a har1-1 suppressor screen. I have shown that suner1 supports epidermal infection by rhizobia and initiates nodule primordia organogenesis as in wild-type. However, the infection process is temporarily stalled, such that infection threads fail to ramify within the root cortex and timely release of bacteria inside the nodule primordia cells does not occur. This symbiotic defect is ephemeral and with additional time, functional nodules are formed. Using a combined approach involving map-based cloning and next-generation sequencing, I have shown that the suner1 …