Life Sciences Commons^™

Quantitative Proteome Analysis Of Alfalfa In Drought Stress Under The Influence Of Mir156, Alpa Puri

Electronic Thesis and Dissertation Repository

Medicago sativa is one of the most produced perennial forage crops in Canada. Drought stress is a major form of abiotic stress affecting the productivity and annual yield of alfalfa. A small noncoding RNA, miR156 has a role in abiotic stress tolerance, while regulating downstream SPL genes. In this study, whole leaf proteome and amino acid concentrations of miR156OE (A8) genotype of alfalfa under drought stress were quantified. In results, 3,000 proteins groups were identified using MaxQuant when searched against Medicago truncatula protein sequence database. Gene ontology analysis showed enriched proteins were involved in biological and molecular processes such as …

Suberin Biosynthesis And Deposition In The Wound-Healing Potato (Solanum Tuberosum L.) Tuber Model, Kathlyn Natalie Woolfson

Electronic Thesis and Dissertation Repository

Suberin is a heteropolymer comprising a cell wall-bound poly(phenolic) domain (SPPD) covalently linked to a poly(aliphatic) domain (SPAD) that is deposited between the cell wall and plasma membrane. Potato tuber skin contains suberin to protect against water loss and microbial infection. Wounding triggers suberin biosynthesis in usually non-suberized tuber parenchyma, providing a model system to study suberin production. Spatial and temporal coordination of SPPD and SPAD-related metabolism are required for suberization, as the former is produced soon after wounding, and the latter is synthesized later into wound-healing. Many steps involved in suberin biosynthesis remain uncharacterized, and the mechanism(s) that regulate …

Investigating The Role Of Brachypodium Distachyon Cellulose Synthase 8 In Gluconacetobacter Diazotrophicus Colonization, Xuan Yang

Electronic Thesis and Dissertation Repository

Nitrogen is an essential nutrient for plant growth. Significant amount of nitrogen fertilizer is applied to crop field to maintain high yield. Alternatives to chemical nitrogen fertilizer are needed to reduce the costs of crop production and offset environmental damage. Gluconacetobacter diazotrophicus is a nitrogen fixing bacterium that was originally isolated from sugarcane and has been proposed as a possible biofertilizer for monocot crop production. However, the colonization of G. diazotrophicus in most monocot crops is limited and deep understanding of the response of the host plants to G. diazotrophicus colonization is still lacking. In this study, research was conducted …

Characterization Of The Coat Protein Of Turnip Mosaic Virus And Its Arabidopsis Interactors In The Virus Infection Process, Zhaoji Dai

Electronic Thesis and Dissertation Repository

Viruses are infectious and obligate intracellular parasites. Turnip mosaic virus (TuMV) is a member of the genus Potyvirus which comprises many agriculturally important viral pathogens that threaten crop production. Potyviruses are fully dependent on the host cellular machinery to fulfil their infection cycle in plant hosts. It is well accepted that viral coat protein (CP) is a multifunctional protein that plays key roles in virus propagation and host-virus interactions. This dissertation project aimed to investigate the role of CP in TuMV cell-to-cell movement, to identify the host interactors of TuMV CP, and further to characterize their roles in TuMV infection. …

Phylogeny, Heat-Stress And Enzymatic Heat-Sensitivity In The Antarctic Psychrophile, Chlamydomonas Sp. Uwo 241, Marc Possmayer

Electronic Thesis and Dissertation Repository

Psychrophilic species, micro-organisms which are unable to grow at temperatures of or above 20°C, are abundant in perennially cold ecosystems across the globe. Intensifying scientific investigation of these organisms from ecological to molecular scales has underscored the ability of life on Earth to adapt to environments which seem inhospitable due to high or low temperatures, high salinity, pressure and light, and ultra-low nutrient availability. Psychrophilic organisms that are also photosynthetic represent a much more limited group than psychrophiles generally, as their habitats must be well buffered against the warming influence of the infra-red energy accompanying sunlight. Photosynthetic psychrophiles face the …

Plant Stimuli-Responsive Biodegradable Polymers For The Use In Timed Release Fertilizer Coatings, Spencer Heuchan

Electronic Thesis and Dissertation Repository

The use of nitrogen-based fertilizers continues to accelerate with human population growth and increases in global food requirements. Enhanced efficiency fertilizers (EEFs) have been developed to improve the synchronization between nutrient supply and crop nutrient demand. However, many of the current controlled release fertilizers are coated with non-degradable polymers that contribute to accumulation of microplastics within ecosystems. This thesis describes research towards the development of a new class of fertilizer coatings using a self-immolative polymer known as poly (ethyl glyoxylate) (PEtG). PEtG itself does not have suitable properties to produce a viable coating but once blended with another degradable polyester …

Defective Aba-Mediated Sugar Signalling Pathway In An Established Arabidopsis Thaliana Cell Suspension Culture Explains Its Stay-Green Phenotype At High Sugar Concentrations, Avery Mccarthy

Electronic Thesis and Dissertation Repository

An unusual sugar insensitive phenotype was identified in an established cell suspension culture of Arabidopsis thaliana. We characterized the physiology, biochemistry and genetics of the sugar insensitive cell culture, in order to identify factors contributing to the phenotype. Chlorophyll levels of the cell suspension culture were insensitive to high sucrose (6-15% w/v) and maintained a green phenotype. Immunoblotting indicated that levels of key photosynthetic proteins (PsaA, Lhcb2 and Rubisco) increased as a function of external sucrose concentration. The green cell culture was photosynthetically competent based on light-dependent, CO₂-saturated rates of O₂ evolution as well as Fv/Fm …

Evaluating Plant Root Uptake Of Dsrna For Application In Pest Management, Kaitlyn Ludba

Electronic Thesis and Dissertation Repository

The greenhouse whitefly Trialeurodes vaporariorum is an agricultural pest that damages crops by feeding on plant sap and by vectoring plant viruses. Control of whiteflies has been managed through application of insecticides, but this strategy is not entirely effective and alternative control strategies are needed. In this thesis, I evaluated the efficacy of RNA interference as a means to control whiteflies on greenhouse-grown tomatoes. I found that root uptake of dsRNA synthesized from the v-ATPase subunit A gene caused significant gene knock-down and mortality in feeding whiteflies. This effect was, however, sensitive to the concentration of dsRNA delivery, and concentration …

Effects Of Elevated Temperature, Elevated Co2 And Photoperiod On Conifer Carbon Fluxes, Joseph R. Stinziano

Electronic Thesis and Dissertation Repository

Increasing temperatures due to rising atmospheric CO₂ concentrations will have direct effects on plant physiology, specifically photosynthetic carbon uptake. Changes in photosynthetic carbon uptake will alter feedbacks between vegetation and atmospheric CO₂, and changes in forest carbon dynamics will be important in determining whether vegetation amplifies or attenuates the effects of anthropogenic CO₂ emissions on climate. Coniferous trees, which are a large component of the boreal forest, are understudied in relation to thermal acclimation of photosynthesis and temperature effects on growth. In the present work, I assess the impact of rising temperatures on carbon fluxes in …

Characterization Of Plant-Spider Mite Interactions And Establishment Of Tools For Spider Mite Functional Genetic Studies, Nicolas Bensoussan

Electronic Thesis and Dissertation Repository

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most polyphagous herbivores feeding on cell contents of over 1100 plant species including more than 150 crops. However, despite its important pest status and a growing understanding of the molecular basis of its interactions with plant hosts, knowledge of the way mites interface with the plant while feeding and the plant damage directly inflicted by mites is lacking. Likewise, while the use of the reverse genetic tools in plants facilitated our understanding of the establishment of defense mechanisms against spider mite herbivory, such tools are lacking for …

Characterization Of Acaricide Resistance, Plant-Mediated Rnai Against Two-Spotted Spider Mites (Tetranychus Urticae Koch), And Assessing Off- And Non-Target Effects, Hooman Hosseinzadeh Namin

Electronic Thesis and Dissertation Repository

The two-spotted spider mite (TSSM), Tetranychus urticae (Koch), is one of the most damaging agricultural pests in the world. It feeds on over 150 crops, causing considerable yield losses in greenhouses and agricultural fields. Currently, using synthetic acaricides is the main method to control TSSM. However, it can develop resistance to acaricides with repeated exposure, and typically resistance can occur within two to four years. To understand the underlying mechanisms of spider mite adaptation to acaricides is an essential part of resistance management strategy. The resistance ratio of the pyridaben-selected strain compared with the pre-selection strain was estimated at greater …

The Effect Of Diet On Midgut And Resulting Changes In Infectiousness Of Acmnpv Baculovirus In Trichoplusia Ni, Elizabeth Chen

Electronic Thesis and Dissertation Repository

The cabbage looper, Trichoplusia ni, a global generalist lepidopteran pest, has developed resistance to many synthetic and biological insecticides, requiring effective and environmentally acceptable alternatives. One possibility is the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). This baculovirus is highly infectious for T. ni, with potential as a biocontrol agent, however, its effectiveness is strongly influenced by dietary context. In this study, microscopy and transcriptomics were used to examine how the efficacy of this virus was affected when T. ni larvae were raised on different diets. Larvae raised on potato host plants had lower chitinase and chitin deacetylase transcript levels …

Deciphering Sulfur Amino Acid Metabolism In Developing Seeds Of Common Bean, Jaya Joshi

Electronic Thesis and Dissertation Repository

With increasing food insecurity in the populated world, the number of people affected by chronic undernourishment is also increasing. Alone, protein energy malnutrition is linked to 6 million deaths annually. Despite being a good source of protein and dietary fibre, the quality of bean protein is limited because of sub optimal levels of essential sulfur amino acids: methionine and cysteine. Levels of cysteine and methionine in developing seeds have an inverse relationship with the non-protein sulfur amino acid S-methyl-cysteine (S-methylCys) and dipeptide g-glutamyl-S-methyl-cysteine (g-Glu-S-methylCys).

One of the strategies to improve protein quality in …

A Modelling Approach: Effects Of Exuded Organic Acids And Exogenous Chelating Ligands On Bioavailability And Uptake Of Metals By Radishes (Raphanus Sativus) Grown In Hydroponics., Sergio A. Dominguez Romero

Electronic Thesis and Dissertation Repository

Metal contamination of soil can be reduced by adding chelators to improve the efficiency of metal uptake in phytoremediation, but optimal concentrations and types of chelators have not been determined. A geochemical model (Visual MINTEQ3.1) was used to estimate the effects of four chelators on the solubility of four metals in hydroponic solution. The model showed that no iron was soluble in the absence of a chelator, while the solubilities of cadmium, copper and zinc were high with or without chelators. Despite low iron uptake in all treatments, symptoms of iron-deficiency were not visible. High concentrations of exuded organic acids …

Genetic Analysis Of Nitrate Transporter 2 Family In Brachypodium Distachyon, With An Essential Role Of Bdnrt2.1 To Nitrogen Use Efficiency, Jiang Wang

Electronic Thesis and Dissertation Repository

Plant agricultural productivity relies heavily on nitrogenous fertilizers. Excess N fertilizer application can often lead to lower nitrogen use efficiency (NUE) along with energy waste and environmental problems. Therefore, understanding and improving NUE in plants are of key importance. The small monocot plant Brachypodium distachyon (Brachypodium) is rapidly emerging as a powerful model system to study questions unique to monocot crops (wheat, maize, rice, etc.).

Here, through an intensive BLAST search, six putative orthologues of the Arabidopsis NRT2 gene family were identified in the fully sequenced Brachypodium genome (Phytozome v11.0), among which I isolated a T-DNA mutant ( …

Developing A Plant Virus-Based Expression System For The Expression Of Vaccines Against Porcine Reproductive And Respiratory Syndrome Virus, Hong Hanh Tran

Electronic Thesis and Dissertation Repository

Virus-based expression systems have been widely exploited for the production of recombinant proteins in plants during the last three decades. Advances in technology have boosted scale-up manufacturing of plant-made pharmaceuticals to high levels, via the complementation of transient expression and viral vectors. This combination allows proteins of interest to be produced in plants within a matter of days and thus, is well suited for the development of plant-made vaccines or therapeutics against emerging infectious diseases and potential bioterrorism agents. Several plant-based products are currently in varying stages of clinical development. To investigate the viability of virus-based expression systems for plant-made …

Gmmyb176 Interactome And Regulation Of Isoflavonoid Biosynthesis In Soybean, Arun Kumaran Anguraj Vadivel

Electronic Thesis and Dissertation Repository

MYB transcription factors are one of the largest transcription factor families characterized in plants. They are classified into four types: R1 MYB, R2R3 MYB, R3 MYB and R4 MYB. GmMYB176 is an R1MYB transcription factor that regulates Chalcone synthase (CHS8) gene expression and isoflavonoid biosynthesis in soybean. Silencing of GmMYB176 suppressed the expression of the GmCHS8 gene and reduced the accumulation of isoflavonoids in soybean hairy roots. However, overexpression of GmMYB176 does not alter either GmCHS8 gene expression or isoflavonoid levels suggesting that GmMYB176 alone is not sufficient for GmCHS8 gene regulation. I hypothesized that GmMYB176 acts cooperatively with another …

The Influence Of Adjacent Forest And Agriculture On Restored Grassland Diversity And Composition, Rachel A. Chambers

Electronic Thesis and Dissertation Repository

Little native grassland remains in North America due to land-use changes. Conversion to agriculture is a common means of loss. This fragmentation creates edges in the landscape and associated edge effects. Grassland plant communities are susceptible to edge effects, directly via dispersal and indirectly through environment. This study took place in Norfolk County, Ontario, Canada, in a landscape of agriculture, forest, rural development, and patches of grassland restored by Nature Conservancy Canada. I examined restored grassland edges bordering forest and crops. An intensive study at a single site identified spatial and soil environmental influences on plant diversity and composition. I …

Gatekeepers Of Nitrogen-Fixing Symbiosis: Cytokinin-Ethylene Crosstalk Regulates Symbiotic Interaction In Lotus Japonicus, Seyedehmandana Miri

Electronic Thesis and Dissertation Repository

Leguminous plants thrive under nitrogen-limited soil conditions because of their ability to symbiotically interact with nitrogen-fixing bacteria, known as rhizobia. In the presence of compatible strains of rhizobia, they develop specialized symbiotic organs, called root nodules, which host the bacteria and provide the appropriate conditions for symbiotic nitrogen fixation to occur. The plant hormone cytokinin is the key endogenous trigger for the inception of root nodule organogenesis. In the model legume Lotus japonicus, analysis of the cytokinin receptor gene Lotus histidine kinase 1 (Lhk1) showed that it is required and also sufficient for the initiation of nodule …

Cytosolic Acetyl-Coa Promotes Histone H3 Lysine 27 Acetylation In Arabidopsis, Chen Chen

Electronic Thesis and Dissertation Repository

Acetyl-coenzyme A (acetyl-CoA) serves as a central metabolite in energy metabolism and biosynthesis. High level of acetyl-CoA can fuel the tricarboxylic acid (TCA) cycle to generate energy and store excess energy in fatty acids. Meanwhile, it also provides acetyl groups for protein acetylation, which normally occurs at the lysine or arginine residues. Acetylation regulates protein functions largely due to the change of total charges. Acetylation of histones, for example, can lead to loss of the interaction between histone and DNA, thus relaxing chromatin structure and potentially promoting gene expression. However, whether and how acetyl-CoA regulates plant chromatin remains unexplored. Here, …

Molecular Characterization Of Viruses Infecting Greenhouse Vegetables In Ontario, Bin Chen

Electronic Thesis and Dissertation Repository

Greenhouse vegetable production is a very important and successful agricultural sector in Ontario. However, newly emerging viral or virus-like diseases have become a major limiting factor in greenhouse vegetable production. To determine the identity of the viral pathogens in the three major greenhouse vegetables in Ontario, we conducted in-depth sequencing of small RNAs isolated from virally infected plants used next-generation sequencing technology. Subsequent bioinformatics analyses revealed six viral pathogens including Bell pepper endornavirus (BPEV), Parietaria mottle virus (PMoV), Cucumber green mottle mosaic virus (CGMMV), Tobacco streak virus (TSV), Pepper mild mottle virus (PMMoV), and Pepino mosaic virus (PepMV). The full-length …

Identification And Characterization Of The Isoflavonoid-Specific Prenyltransferase Gene Family To Prevent Stem And Root Rot In Soybean, Arjun Sukumaran

Electronic Thesis and Dissertation Repository

Soybean is one of the most predominantly grown legumes worldwide, however, one deterrent to maximizing its yield is the pathogen, Phytophthora sojae, which causes stem and root rot disease. Many strategies have been implemented to combat this pathogen such as use of pesticides and certain agricultural practices. However, these have been largely ineffective in completely preventing P. sojae infection. An alternative strategy would be to improve the innate resistance of soybean by promoting increased glyceollin production. Glyceollins are soybean-specific antimicrobial agents which are derived from the isoflavonoid branch of the general phenylpropanoid pathway. Soybeans produce 3 forms of glyceollin: …

Evapotranspiration From Extensive Green Roofs: Influence Of Climatological Conditions, Vegetation Type, And Substrate Depth, Maria Eloisa Sia

Electronic Thesis and Dissertation Repository

Green roofs are gaining popularity worldwide as a low impact development tool to mitigate increasing stormwater runoff within dense urban areas. Evapotranspiration (ET) is the key hydrologic process governing the capacity of a green roof to retain rainfall as it regenerates available water storage space in the green roof substrate (soil) between rainfall events. To date, there are limited data on how the interaction between different climatological conditions and design parameters (e.g., vegetation type, substrate depth) affect ET rates. This currently limits the ability to optimize green roof design for stormwater management. In this field study, the impact of climatological …

An Investigation Of The Plant Growth Promoting Abilities Of Pseudomonas Fluorescens Uw4 Under Toxic Metal Stress, Joshua J. Frank

Electronic Thesis and Dissertation Repository

I investigated plant-microbe-metal interactions under metal stress. In theory, plant growth promoting rhizobacteria (PGPR) promote plant growth by reducing stress ethylene and synthesizing indole-3-acetic acid (IAA). The putative PGPR Pseudomonas fluorescens UW4 and a mutant strain that lacked an enzyme critical to the reduction of plant ethylene were studied to determine if they could promote Arabidopsis thaliana growth under cadmium and copper stress conditions. Both strains of P. fluorescens UW4 adhered to roots and synthesized IAA, and the wild-type lowered metal stress-induced ethylene in Arabidopsis, but neither strain enhanced plant growth. Wildtype P. fluorescens UW4 and its mutant had …

Evaluation Of The Water Stress-Inducible Promoter Wsi18 In The Model Monocot Brachypodium Distachyon, Patrick D. Langille

Electronic Thesis and Dissertation Repository

Water deficit-inducible promoters that function in multiple species are valuable components for engineering stress-tolerant crops. Wsi18 is a water deficit-inducible promoter native to Oryza sativa. In this study, Brachypodium distachyon (B. distachyon) was used to determine if Wsi18 retained its water deficit-inducible characteristics in another monocot. Transgenic B. distachyon plants, in which the Wsi18 promoter drove the expression of the uidA reporter gene, were developed and exposed to osmotic stress generated by mannitol, salt stress conditions, and the water deficit-signaling phytohormone abscisic acid (ABA). GUS histochemical assays demonstrated increased uidA expression in the leaves and stem of …

Role Of Fatty Acid Omega-Hydroxylase 1 And Abscisic Acid In Potato Tuber Suberin Formation, Meg Haggitt

Electronic Thesis and Dissertation Repository

Suberin is a complex biopolymer composed of two distinct but covalently-linked domains. The first domain is composed of polymerized phenolic monomers, whereas the second domain is predominately fatty acid derivatives esterified with glycerol. Deposited in specialized cells during development or in response to abiotic stress, suberin functions as a barrier to water loss and pathogen attack. In potato, more than 65% of suberin monomers undergo ω-hydroxylation, representing a major class of fatty acids in the final biopolymer. The ω-hydroxylation reaction is catalyzed by Cytochrome P450 (CYP) proteins, of which few have been characterized to date. In 2009, CYP86A33 from potato …

Photosynthetic Acclimation To Warming And Elevated Co2 In Two Antarctic Vascular Plant Species, Vi Nt Bui

Electronic Thesis and Dissertation Repository

Climate change can affect the performance of the only two vascular plant species found in Antarctica, Deschampsia antarctica and Colobanthus quitensis. I investigated the response of these two species to warming and elevated CO₂ in terms of photosynthesis and leaf anatomy. While photosynthesis increased directly with rising temperature and CO₂, it showed no acclimation to changes in growth temperature, and a small degree of acclimation to growth under elevated CO₂. Likewise, leaf anatomy displayed little plasticity in response to changes in the growth environment, although D. antarctica’s stomatal groove structure was modified under …

Glucan Synthase-Like 8: A Key Player In Early Seedling Development In Arabidopsis, Behnaz Saatian

Electronic Thesis and Dissertation Repository

Plants’ cell walls have unique chemical composition and features which enable them to play essential roles during plant development as shaping the cells and providing intercellular communication between adjacent cells. Polysaccharides, including callose, and glycoproteins are known as the main constituents of the cell wall. Callose, a linear β-1,3-glucan polymer, is accumulated at the cell plate during cytokinesis, in plasmodesmata, where it regulates cell-to-cell communication, in dormant phloem, where it seals sieve plates after mechanical injury and pathogen attack, and in male and female gametophytes. GLUCAN SYNTHASE-LIKE (GSL) genes in Arabidopsis comprise a family of 12 members. A …

Inheritance, Differential Expression, And Candidate Gene Analyses For Avr2 In Phytophthora Sojae, Chelsea S. Ishmael

Electronic Thesis and Dissertation Repository

Phytophthora sojae is an oomycete responsible for seed, root and stem rot of soybean plants. Managing this disease relies on growing soybean cultivars with race-specific resistance (Rps) genes that deliver complete host immunity in the presence of corresponding pathogen avirulence (Avr) effector proteins. The aims of this study were to characterize virulence towards Rps2 among different P. sojae strains, track the inheritance of this trait, and attempt to identify an Avr2 gene. Fifteen P. sojae strains were tested for virulence towards Rps2 and crosses were performed between selected virulent and avirulent strains to follow the inheritance of virulence. …

Functional Analysis Of The Mir156 Regulatory Network In Arabidopsis Siliques, Zhishuo Wang

Electronic Thesis and Dissertation Repository

Siliques are photosynthetically active seed capsules and their development is strongly influenced by embryo development. MicroRNA156 (miR156)-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) network is involved in regulating plant growth and development, but the downstream genes of this network are still not fully elucidated. Here, I show that the miR156/SPL2 pathway controls the development of floral organs, regulates pollen production, and thus affects male fertility in Arabidopsis thaliana. I present evidence that SPL2 binds to the 5’UTR of the ASYMMETRIC LEAVES 2 (AS2) gene in vivo, indicating that AS2 acts downstream of SPL2. When compared to wild-type plants, AS2 loss-of-function mutants …