Life Sciences Commons^™

Identification And Characterization Of Isoflavone Reductase Family Members In Soybean, Negin Azizkhani

Electronic Thesis and Dissertation Repository

Soybean’s yield is threatened by Phytophthora sojae, a pathogen responsible for stem and root rot disease. Glyceollins, unique antimicrobial agents specific to soybeans in partially preventing P. sojae infection, are derived from the isoflavonoid branch of the general phenylpropanoid pathway. One pivotal enzyme exclusively involved in glyceollin synthesis in soybean is the isoflavone reductase (GmIFR), which catalyzes the 2'-hydroxydaidzein conversion to 2'-hydroxy-2,3-dihydrodaidzein as a precursor for glyceollin biosynthesis. To comprehensively identify all members of the GmIFR gene family within the soybean genome, keyword and blast protein searches were conducted, identifying 98 putative GmIFRs. Among these candidates, …

Freezing Tolerance Of Herbaceous Legumes Within Southwestern Ontario: Evidence Of Disproportionate Freezing Sensitivity, Samuel L. Rycroft

Electronic Thesis and Dissertation Repository

Legumes (Fabaceae) represent a diverse and ecologically significant plant taxon; most described legumes form mutualisms with diazotrophic rhizobia, potentially fixing substantial quantities of nitrogen within habitats where they are well-established. Stressors causing lethal or sub-lethal impacts in legumes or rhizobial symbionts may therefore impact the nitrogen dynamics of such habitats. In recent decades, variability of winter temperatures, precipitation, and soil freeze-thaw cycling has increased in temperate regions. Without adequate snow cover to insulate roots and shoot bases, herbaceous plants will likely be exposed to more frequent or severe freezing. In southwestern Ontario, a pattern of disproportionate freezing sensitivity relative to …

Investigating Soil Microbiome Changes During Panax Quinquefolius Cultivation In New Gardens, Pok Man Paul Wan

Electronic Thesis and Dissertation Repository

Ginseng (Panax quinquefolius) is susceptible to ginseng replant disease (GRD), resulting in root rot and decreased yield when ginseng is grown in soils previously used for ginseng crops. Although fungal and oomycete pathogens are implicated, GRD is a complex disease and the changes in the soil when initially cultivating ginseng that lead to GRD remain unclear. This thesis reported changes in the soil microbiome from three new gardens in Norfolk County, Ontario over three years starting from seeding with ginseng. Over this period of cultivation, metabarcoding of the V4 region of the 16S ribosomal RNA gene clearly showed …

Molecular Identification And Characterization Of Heat Shock Protein 70 Family Proteins Essential For Turnip Mosaic Virus Infection In Arabidopsis Thaliana, Ziwei Tang

Electronic Thesis and Dissertation Repository

Turnip mosaic virus (TuMV) belongs to the RNA virus family of Potyviridae and genus Potyvirus. TuMV incurs agricultural losses by causing diseases in vegetable, oilseed, forage, and biofuel crops globally. Viruses are obligate intracellular parasites depending on the host cellular machinery to proliferate. Thus, molecular identification and functional characterization of host factors essential in the viral infection process may open up a new avenue towards developing genetic virus resistance. Eukaryotic translation initiation factor 4E (eIF4E) or its isoform (eIF(iso)4E) is a critical host factor for many potyviruses including TuMV. Heat shock protein 70 family proteins (HSP70) have been identified in …

Nitrogen Transfer From Cover Crops To The Subsequent Grain Crop And The Influence Of Variability In Winter Conditions, Spencer Heuchan

Electronic Thesis and Dissertation Repository

Cover crops, which are used to provide ground cover after the harvest of the grain crop, can potentially improve the sustainability of agroecosystems by reducing nutrient losses. However, few data are available to document the extent to which cover crops improve both the retention of soil nitrogen (N) and the transfer of this N to the grain crop. The efficiency of this N transfer may be further influenced by variation in winter soil temperature; for example, reduced snow cover can increase the frequency and intensity of soil freezing, which can affect the survival of cover crops and the timing of …

Cadmium Uptake In Plants As Influenced By Selenium Uptake And Sulphate Availability, Marnie J. Demand

Electronic Thesis and Dissertation Repository

With cadmium uptake by plants posing a risk to plants and consumers alike, strategies to reduce metal uptake are desirable. One strategy may be to apply selenium (as selenate) to the growth medium. I hypothesized selenate would yield greater lignification, with a higher proportion of cadmium bound to root cell walls. Consequently, higher selenium in plants would result in greater tolerance to cadmium. Additionally, since selenate is taken up in place of sulphate, providing the plants with high sulphate would inhibit uptake and translocation of selenium, mitigating selenate’s benefits of reducing cadmium uptake and translocation. Experimental results did not support …

The Biosynthesis Of Non-Protein Sulfur Amino Acid In Developing Seeds Of Common Bean, Zixuan Lu

Electronic Thesis and Dissertation Repository

The protein quality of common bean (Phaseolus vulgaris) is associated with the level of dietary essential sulphur amino acids – methionine and cysteine. Extra sulphur that cannot be stored in the protein pool accumulates as the non-protein amino acid S-methylcysteine (S-methylCys) and its dipeptide γ-glutamyl-S-methylcysteine (γ-Glu-S-methylCys). Previous studies have indicated that S-methylhomoglutathione (S-methylhGSH) is present in the developing seed of common bean. It is hypothesized that S-methylhGSH is the key intermediate in the biosynthetic pathway of the γ-Glu-S-methylCys that leads to …

Utilizing Rnai Technology To Develop Novel Agricultural Pesticides, Ethan B. Zand

Undergraduate Student Research Internships Conference

A general description of why RNAi based pesticide technology is a breakthrough technology able to target only pests while not harming others. This presentation gives a summary of RNAi technology, the current drawbacks of conventional pesticides, and our research on how RNAi can be used against the two-spotted spidermite; a polyphagic pest that causes significant financial damage to Canadian and worldwide agriculture

My Summer Working With Two-Spotted Spider Mites, Renée A. Smith

Undergraduate Student Research Internships Conference

Two-spotted spider mites are a polyphagous pest, capable of eating a magnitude of food crops which causes a large problem for Canadian agriculture. Their ability to consume various crops stems from their ability to adapt to various chemical defence mechanisms. This ability allows them to acquire resistance to many commonly used pesticides. This has resulted in large infections in Canadian farms with few options to prevent the pests from affecting crop yields. Take a look at my project if you'd like to see how the Grbic lab is working to combat this issue using genetic engineering techniques!

Fungal Co-Pathogenicity On Panax Quinquefolius, Andrea Ong

Undergraduate Student Research Internships Conference

American ginseng (Panax quinquefolius) is a perennial crop commonly grown for its medicinal properties. Ginseng replant disease (GRD) is a condition that prevents the re-cultivation of ginseng in previous ginseng gardens and is normally associated with extensive root rot caused by the fungus Ilyonectria mors-panacis. My project aims to investigate the relationship common GRD fungal pathogens and their pathogenicity on 1 year old ginseng seedlings.

A Bacterial Microbiome Analysis Of Solarized Ginseng Garden Soils, Anka Colo

Undergraduate Student Research Internships Conference

American ginseng (Panax quinquefolius) is a highly valued perennial crop grown for its roots during a four-year cultivation cycle. American ginseng is subject to ginseng replant disease (GRD) in which severe root rot develops in newly planted ginseng grown in a former ginseng garden. A common strategy to mitigating GRD is not available and techniques such as fumigation, fungicides, and biocontrol are ineffective, banned, or are slowly being phased out. Alternatively, soil solarization is a pre-plant technique used to treat soil to reduce disease inoculum and alter soil microbiomes. In summer 2019, a six-week soil solarization experiment was …

Manipulating The Root Mycobiome To Improve Plant Performance And Reduce Pathogen Pressure In Corn (Zea Mays), Noor F. Saeed Cheema

Electronic Thesis and Dissertation Repository

Crop yield often varies within a field of a single genetically uniform crop plant, with the causes presumed to be a mix of both biotic and abiotic factors. Manipulating crop root mycobiomes could potentially increase yield by reducing pathogen impacts and improving access to soil water and nutrients. This study aimed to identify different fungal inoculation treatments that could increase the growth of corn seedlings sown in low productivity soils to that in high productivity soils and shift the root mycobiome composition. Fungal inoculation treatments did not have significantly different root mycobiome composition than seedlings grown in low yield control …

Dr. Laurie L. Consaul Herbarium (Uwo), Lauren H. Rego

Community Engaged Learning Final Projects

Along with the provided databased species, students scanned 257 specimens within the physical herbarium at Wester.

Long-Term Vs. Short-Term Plant Responses To Warming And Nitrogen Addition In A Temperate Old Field, Breanna Craig

Electronic Thesis and Dissertation Repository

Climate warming and atmospheric nitrogen (N) deposition are expected to have strong effects on plant productivity in temperate ecosystems over the next century. However, short-term experiments may not adequately address their potential effects because of lags in changes in species composition. I added new plots to a pre-existing field experiment to compare the short-term (1-2 year; new plots) vs. long-term (14-15 year; old plots) effects of warming and N addition on plant productivity, relative species abundances, plant tissue N content, and litter decomposition. In 2020, N addition increased aboveground plant productivity most in old plots and only increased belowground biomass …

Optimization Of Dna Extraction From Difficult Sandy-Loam Soils, Anka Colo

Undergraduate Student Research Internships Conference

Ginseng is a high value perennial crop grown for its roots. A four-year cultivation cycle is required to obtain marketable ginseng roots, during which a condition called ginseng replant disease (GRD) develops. GRD is characterized by a severe root rot disease, and prevents the growth of newly planted ginseng in a former ginseng garden1. Microbiome analysis of ginseng garden soil will help our understanding of the formation of GRD and its severity. However, extracting DNA from the sandy-loam soils required for ginseng cultivation is difficult. Commercial kits are either too expensive or not applicable to the large volumes of soil …

Using Wgcna For Comprehensive Understanding Of Genes Involved In Suberin Biosynthesis From Rna-Seq Data Analysis, Stephanie Wu

Undergraduate Student Research Internships Conference

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 (Woolfson 2018). Previous studies have measured phenolic and/or fatty acid compounds in suberized tissues, and for many of these the biosynthesis is known, However, restricting analyses to only those biomolecules that are known does not yield new information about other genes that may be involved. This experiment serves to identify suberin associated gene clusters within Modules, based on an analysis of their expression patterns using Weighted Gene Correlation Network Analysis (WGCNA). Once …

The Analysis Of Ginsenosides In Ginseng Garden Soil, Karina Marie Kaberi

Electronic Thesis and Dissertation Repository

American ginseng (Panax quinquefolius L.) produces natural products called ginsenosides. The biggest challenge Ontario commercial ginseng farmers face is ginseng replant disease. To understand the function of ginseng root exudates, ginsenoside accumulation and persistence over time were investigated. Currently, no reliable ginsenoside specific extraction method, characterizing the changes in soil chemistry exists. Ginsenoside extraction protocol optimization was required to determine how ginsenoside composition changed over time. Overall, protocol optimization resulted in a 30% increase in yield of ginsenosides compared to previous extraction protocols. In the ginseng gardens, ginsenoside accumulation occurs slowly and did not reach significantly measurable amounts until the …

Reconstructing Carbon Dynamics Of Alpine And Temperate Zone Lakes Using Stable Isotopic Analysis, Rebecca M. Doyle

Electronic Thesis and Dissertation Repository

Lake sediments integrate signals from the catchment, atmosphere and water column, offering a unique window through which to view changes in the carbon cycle. Carbon dynamics in lakes are changing due to nitrogen loading and anthropogenic climate warming (ACW), threatening the water quality of lakes. This thesis identifies how the carbon dynamics of lakes have responded to anthropogenically-driven forcings by comparing pre- and post- AD 1850 records preserved in lake sediments. First, the carbon dynamics of Barry Lake (Ontario, Canada), a low-elevation temperate lake, are investigated. Effective moisture (the net of water inputs and evaporation) is reconstructed using the carbon …

Molecular Identification And Characterization Of Viral Pathogens Infecting Sweet Cherry, Aaron J. Simkovich

Electronic Thesis and Dissertation Repository

Stone fruits are a valuable crop grown worldwide, however pathogens such as viruses threaten fruit production by reducing tree health and fruit yield. In an orchard within the Niagara region of Ontario, symptoms typical of viral infection such as chlorosis and leaf deformation were seen on sweet cherry (Prunus avium L.) trees. Next generation sequencing was performed on symptomatic and asymptomatic leaves and four viruses were identified. On the tree displaying the most severe symptoms, Prune dwarf virus (PDV), was the only virus detected. A survey conducted during this work showed 42% of cherry trees on a single …

Floral Traits And Carbon Dynamics Of Cucumber In Response To Climate Change, Sarah Josina Mcdonald

Electronic Thesis and Dissertation Repository

Pollination by animals is an important ecosystem service that contributes to the reproduction of many angiosperms. Climate change may alter this mutualism by affecting floral traits that are important to pollinators. Using Cucumis sativus, I tested the effects of experimentally elevated temperature and CO₂ concentration on flowering onset, flower number, flower size, and floral rewards. Additionally, to better understand plant carbon balance and investment in reproduction, I measured biomass partitioning and leaf carbon fluxes of plants under their growth conditions. Carbon dynamics were similar across treatments, and plants grown under high [CO₂] and temperature showed similar …

Characterization Of Squamosa Promoter Binding Protein Like (Spl), And Its Role In Drought Stress Tolerance In Medicago Sativa (Alfalfa)., Alexandria K. Hanly

Electronic Thesis and Dissertation Repository

Traditional breeding involving Medicago sativa (alfalfa), has resulted in minimal yield increases. Moreover, extreme environmental conditions threaten to further limit production. Strategies that make use of molecular tools – such as small non-coding RNA, miR156 – represent an innovative means by which to influence tolerance to abiotic stress. miR156 functions, at least in part, through the SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) family of transcription factors. In this study, the role of SPL9 in regulating alfalfa development and drought tolerance is evaluated. Examination of alfalfa plants with RNAi-mediated SPL9 (SPL9-RNAi) showed that plant height, stem thickness, and internode …

Investigating The Role Of Carbon Stress In The Mortality Of Tamarack Seedlings Under A Warming Environment, Bridget K. Murphy

Electronic Thesis and Dissertation Repository

Climate warming is increasing the frequency of climate-induced tree mortality events. While drought combined with heat is considered the primary cause of this tree mortality, little is known about whether high temperatures alone can induce mortality, or whether rising CO₂ will increase survival. I grew tamarack in two experiments combining warming (0-8 ˚C above ambient) and CO₂ (400-750 ppm) to investigate whether high growth temperatures led to carbon limitations and mortality. Using glasshouses, +8 ˚C warming with ambient CO₂ (8TAC) led to 40% mortality despite thermal acclimation of respiration. Dying 8TAC seedlings had lower needle carbon concentrations …

Soybean Root Exudates Increase The Physiological Diversity Of Bacteria In Cadmium-Treated Soil, Leily Kazemi Movahed

Electronic Thesis and Dissertation Repository

Three soybean cultivars with contrasting retention of cadmium (Cd) in the root were grown in Cd-spiked nutrient solution and used to determine that symplastic compartmentalization of Cd in roots is probably responsible for retention of Cd in roots. Roots of the low Cd-accumulator AC Hime treated with 30 mM Cd exuded up to 10-fold higher concentrations of citric, succinic, fumaric and malic acids into the hydroponic solution when compared to control; concentrations of the same organic acids from the high Cd-accumulator Westag 97 increased by up to 3-fold. The same cultivars were grown in Cd-spiked soil and the physiological profiles …

Microrna156: A Short Rna With A Major Role In Abiotic Stress Tolerance In Alfalfa, Biruk Ayenew Feyissa

Electronic Thesis and Dissertation Repository

The highly conserved plant microRNA156, miR156, affects various aspects of plant development and stress response by silencing SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. Our understanding of the role of miR156 and its mode of action in alfalfa’s (Medicago sativa L.) response to drought and flooding is still elusive, and thus this study was aimed at filling this gap in knowledge. Physiological parameters, metabolite and transcriptional analyses showed an interplay between miR156/SPL13 and WD40-1/DFR to mitigate drought stress. Low to moderate levels of miR156 overexpression suppressed SPL13 and increased WD40-1 to fine-tune the DIHYDROFLAVONOL-4-REDUCTASE (DFR) level for …

Biology 4920g: Companion Planting In The Community, Jacquline A. Nathaniel

Community Engaged Learning Final Projects

LIFE*SPIN is a local organization in London, Ontario that provides resources to individuals and families dependent on low income to ultimately break the poverty cycle by encouraging sustainable living and self-sufficiency. For this Seminar in Biology course, Maria Bata and I partnered with LIFE*SPIN to plan and execute a "Seeding Planting Party" to teach children about basic botany, nutrition, and leadership. The following final paper for this seminar discusses the project deliverables and efforts, biological research concerning companion planting, and personal reflection on this experience.

Effects Of Elevated Temperature And Elevated Co2 On Leaf Carbon Fluxes In Boreal Conifers: Lab And Field Studies, Mirindi Eric Dusenge

Electronic Thesis and Dissertation Repository

Rising CO₂ may warm northern latitudes up to 10 °C by the end of the century. However, responses of plant physiological processes (such as photosynthesis and respiration) and growth to climate change remain uncertain. Seedlings and mature trees of tamarack (a deciduous species) and black spruce (an evergreen species), North America dominant conifers, were exposed to combined warming (up to +9 ˚C) and elevated CO₂ (up to +300 ppm). In seedlings, stomatal conductance (g_s) tended to increase with warming in tamarack seedlings, while g_sdeclined with warming in spruce. In both species, CO₂ had …

Genome-Wide Occupancy Of Polycomb Group Proteins And Chromatin Remodeler Splayed And Their Interplay In Arabidopsis, Jie Shu

Electronic Thesis and Dissertation Repository

The Polycomb group (PcG) proteins form two protein complexes, Polycomb repressive complex 1 (PRC1) and PRC2, which are key epigenetic regulators in eukaryotes. PRC2 represses gene expression by catalyzing trimethylation of histone H3 lysine 27 (H3K27me3). In Arabidopsis thaliana, CURLY LEAF (CLF) and SWINGER (SWN) are two major H3K27 methyltransferases, playing essential roles in plant growth and development. Despite their importance, genome-wide occupancy profiles of CLF and SWN have not yet been determined and compared. In this thesis, I generated transgenic lines expressing GFP-tagged CLF/SWN and determined the genome-wide distributions of CLF and SWN in Arabidopsis seedlings. I also …

Carbon And Nitrogen Dynamics In Plants Grown At Low Co2 Conditions Of The Past, Andre Galvao Duarte

Electronic Thesis and Dissertation Repository

For most of the recent evolutionary history of plants, atmospheric CO₂ concentrations have been far below modern values. However, little is known about how plants grown in a low CO₂ environment balance their carbon demand for growth while meeting their requirement for nitrogen acquisition, the establishment of mycorrhizal fungal associations, and the production of defense compounds. Here, I investigated how low CO₂ affects Elymus canadensis and Picea mariana by comparing their growth at low and current CO₂ concentrations. I found that reduced N availability exacerbated low CO₂ effects on growth, and reduced stomatal index and …

Identifying Brachypodium Distachyon Proteins Interacting With Histone Deacetylase Bdhd1, Alberto Giovanni Torrez

Electronic Thesis and Dissertation Repository

Current evidence has revealed the involvement of epigenetic mechanisms, including histone deacetylases (HDACs), in plant stress responses. In Arabidopsis thaliana, HDA19, belonging to the RPD3/HDA1 class, interacts with transcription factors to form repressor complexes. HDAC research mainly exists for dicotyledons, whereas research on monocotyledons is limited. Brachypodium distachyon is used as a model plant to investigate questions unique to monocot crops. BdHD1 is the closest homologous gene to HDA19 in B. distachyon. This study investigated potential protein-protein interactions between BdHD1 and each of BdMYB22, BdWRKY24, and BdHOS15. Protein interactions were investigated using yeast two-hybrid (Y2H) and bimolecular fluorescence …

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Partial Characterization Of Putative Cyp86a Genes From Soybean, Trish Tully

Electronic Thesis and Dissertation Repository

Soybean (Glycine max [L.] Merr.) is a globally cultivated crop that is important to the sustainability of many industries. However, like all plants, optimal cultivation of soybean is threatened by detrimental environmental factors. For example, high yield of soybean is threatened by soil-borne pathogens like Phytophthora sojae. Resistance against P. sojae was previously positively correlated with aliphatic suberin deposition in soybean. As such, a deeper understanding of the biosynthesis of suberin may assist in engineering a resistant form of soybean, based on enhanced suberin content. In soybean, the ω-OH fatty acid monomers are predominant and most strongly correlated …