Plant Sciences Commons^™

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!

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.

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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: …

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. …

Inferring Plastid Metabolic Pathways Within The Nonphotosynthetic Free-Living Green Algal Genus Polytomella, Sara Asmail

Electronic Thesis and Dissertation Repository

The advent of photosynthesis facilitated the evolution of aerobic life on Earth. However, species such as Prototheca wickerhamii and Plasmodium falciparum, among many others, have lost photosynthesis and opted for a free-living/parasitic lifestyle. Despite this loss, these species have retained the plastid for its metabolic pathways, without which they would die. Polytomella is a nonphotosynthetic free-living alga, closely related to the photosynthetic model organism Chlamydomonas reinhardtii, and has been shown to lack a plastid genome. I set out to determine Polytomella plastid metabolic pathways using bioinformatics to look for mRNA and DNA homologous sequences matching pathway enzymes in model organisms. …

Planting The Chalcone Reductase Family Tree: Identification And Characterization Of Chalcone Reductase Genes In Soybean, Caroline Julia Sepiol

Electronic Thesis and Dissertation Repository

Soybean (Glycine max [L.] Merr) is an important crop grown in Canada, generating $2.4 billion in sales. Though this number may be promising, soybean farmers lose about $50 million worth of yield annually due to root and stem rot disease caused by Phytophthora sojae. Many strategies have been developed to combat the infection; however, these methods are prohibitively expensive. A ‘cost effective’ approach to this problem is to select a trait naturally found in soybean that can increase resistance. One such trait is the increased production of root glyceollins. One of the key enzymes exclusively involved in glyceollin …

Ginsenosides, Glycosidases And The Ginseng-Pythium Interaction, Dimitre A. Ivanov

Electronic Thesis and Dissertation Repository

Ginsenosides, the triterpenoid saponins produced by American ginseng (Panax quinquefolius L.), have been extensively studied for their medicinal value, however, their function in the rhizosphere remains largely unknown. Like other saponins, ginsenosides possess mild fungitoxic activity toward some common ginseng pathogens. However, numerous oomycete root pathogens of ginseng, most notably Pythium irregulare Buisman, are able to partially deglycosylate the 20 (S)-protopanaxadiol ginsenosides Rb1, Rd and gypenoside XVII via extracellular glycosidases (ginsenosidases), leading to the formation of a common product, ginsenoside F2. In this thesis the potential role(s) of these extracellular ginsenosidases and the ginsenoside products they produce (ie. ginsenoside …

Two Spotted Spider Mite (Tetranychus Urticae) Selection To Arabidopsis Thaliana, Huzefa Ratlamwala

Electronic Thesis and Dissertation Repository

Spider mite feeding on A. thaliana induces the production of indole glucosinolates (IGs), plant secondary metabolites that negatively affect mite performance. In this study I conducted selection experiments on A. thaliana with varying levels of IGs, to determine if mites could adapt to IGs and other defense compounds. After 12 months, mites reared on host with IGs performed significantly better on A. thaliana than mites maintained on beans. However, an adaptation cost was detected between selected mite lines and their ancestral host. The qRT-PCR data on different mite lines revealed that the detoxification genes previously identified may only be involved …

Growth Of The Marine Fish-Killing Phytoflagellate, Heterosigma Akashiwo Under Emerging Coastal Regimes: Temperature, Eutrophication And Ocean Acidification, Cayla M. Bronicheski

Electronic Thesis and Dissertation Repository

Coastal oceans are fundamental to human economies, nutrition and recreation. Anthropogenic stressors have led to the acceleration of the nitrogen cycle, the accumulation of inorganic carbon in the earth’s atmosphere, the loss of UV-scavenging upper atmospheric ozone and the overall accumulation of deep elements from the earth’s crust to surface exposure. These changes have caused ocean acidification and eutrophication events in coastal waters and the impacts of these events on primary production and ocean biodiversity are not yet fully understood.

This study examined the effects of predicted future ocean conditions (salinity, temperature, reduced seawater pH and modified nitrogen supplies), on …

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 …

Heterologous Production And Characterization Of Cell Wall Degrading Enzymes Using Plants As A Bioreactor, Eridan Orlando Rodrigues Pereira

Electronic Thesis and Dissertation Repository

Plants are wonderful living organisms. They are able to store solar energy into carbohydrates by fixing CO₂ through photosynthesis which can be subsequently harvested and used for fuel production. However, one of the major limitations for transforming these carbohydrates into liquid fuels is the recalcitrance of the plant cell wall. Although microorganisms have evolved a series of cell wall degrading enzymes to harvest efficiently this energy and are considered the main source of these biocatalysts, harnessing these microorganisms for the production of enzymes is a costly process and a major factor limiting the commercialization of lignocellulosic biomass-to-ethanol processes. The …

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 …

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 …

Involvement Of Hexokinase1 In Plant Growth Promotion As Mediated By Burkholderia Phytofimans, Jae Min Park

Electronic Thesis and Dissertation Repository

Burkholderia phytofirmans strain PsJN consistently enhanced the growth of potato plants in vitro. The role of hexokinase1 in glucose phosphorylation was investigated in plants with PsJN. Increased hexokinase1 activity only in roots of PsJN-treated plants cultivar Kennebec suggests that hexokinase1 is associated with plant root and stem growth.

Plant growth with PsJN was determined when plants were grown with different sugars at various concentrations. PsJN-treated plants expressed diverse forms of growth promotion. When growth promotion did occur, hexokinase1 activity also increased. Growth promotion and hexokinase1 activity appear to be correlated to the enzyme to recognize the substrate for catalytic activity. …

Cadmium Accumulation And Distribution In Lettuce And Barley, Fardausi Akhter

Electronic Thesis and Dissertation Repository

Cadmium (Cd) is a non-essential trace element and its environmental concentrations are increasing due to human activities. Edible plants can accumulate high concentrations of Cd, which could be toxic to humans. Understanding how and where Cd is stored in plants is important for ensuring lower concentration of Cd in the food. In this thesis, the accumulation and distribution of Cd in three agricultural plants, namely lettuce (Lactuca sativa L.), barley (Hordeum vulgare L.) and radish (Raphanus sativus L.), were investigated with a focus on the potential mechanisms involved in the localization of Cd in the root. The …

Hairy Roots As A Model To Investigate The Role Of Suberin In The Phytophthora Sojae-Soybean Pathosystem, Pooja Sharma

Electronic Thesis and Dissertation Repository

Part of the resistance mechanism of soybean (Glycine max [L.] Merr.) to Phytopthora sojae Kauf. & Gerd. involves pre-formed root suberin. In order to investigate the role of suberin in this host-pathogen interaction, I characterized hairy roots, formed as a result of Agrobacterium rhizogenes (Riker et al.) Conn infection, as a model to be used as a reliable soybean transformation system. I established hairy root cultures and demonstrated that they were a result of A. rhizogenes infection. The anatomy and suberin deposition in soybean hairy roots was examined, and found to be very similar to that of wild-type roots. …