Life Sciences Commons^™

Phosphate2 And Pin-Likes7 Affect Symbiotic Nodule Phenotypes In Soybean, Bhawandeep Kaur

Electronic Theses and Dissertations

Legumes and soil rhizobia share a symbiotic relationship, wherein rhizobia fix atmospheric dinitrogen in exchange for photosynthates from the host plant. This exchange of mutual benefits occurs in a specialized root structure called ‘nodule’. Soybean (Glycine max) nodules arise from root outer cortical cells. De novo cell differentiation of cortical cells during nodule development leads to the formation of two distinct nodule zones in the mature nodule: the central infection zone where nitrogen fixation occurs and the peripheral parenchyma zone that houses vascular bundles. Plant signaling mechanisms that dictate the development of these nodule zones are not known. To address …

E. Coli Persister Cell Survival And Rhizobia Attachment To Soybean Roots, Tanim Islam

Electronic Theses and Dissertations

The theme of this thesis revolves around how bacteria respond and thrive during stress. Chapters 1-3 are about how bacteria deal with life-threatening antibiotics. Chapter 4 covers new research on how bacteria can move from a stressful individual lifestyle (free-living bacteria) to initiating a symbiotic relationship with a plant (a less stressful lifestyle). In Chapter 1, I briefly summarize the current state of knowledge in the field of antibiotic resistance and persistence. In Chapter 2, I add to this knowledge by providing new insights into several antibiotics' potency and exploring the antibiotic Eagle effect. In Chapter 3, I use pyruvate …

Genome-Wide Identification Of Wrky Transcription Factor Encoding Genes In Amborella Trichopoda Baill. (Amborellaceae), Bijaya Pradhan

Electronic Theses and Dissertations

WRKY transcription factors (TFs) are DNA-binding proteins, which play important roles in managing plant stresses and regulating growth and development processes. The WRKY TF family has expanded significantly through genome/gene duplications in the plant evolutionary process. Although the WRKY TFs have been identified in hundreds of plant species, they are yet to be identified in Amborella trichopoda, a species that represents the most basal group of Angiosperms. The main objectives of this study were to conduct genome-wide identification of the WRKY gene family in A. trichopoda and to assess their homologs in Angiosperms. In this study, we identified …

Identification Of Loci Influencing Teosinte Crossing Barrier 1 (Tcb1) Efficacy In Maize By Quantitative Trait Loci (Qtl) Mapping And Genome-Wide Association Study (Gwas), Namrata Maharjan

Electronic Theses and Dissertations

Pollen cross-contamination has been a major problem for maize breeders. Various mechanical methods applied to avoid the contaminations are ineffective. The genetic factors related to maize fertilization can be used to develop an effective method to prevent pollen contamination. Pollen rejection ability controlled by Teosinte crossing barrier 1 (Tcb1) is such a genetic system. Silks possessing dominant Tcb1-s reject pollen possessing the recessive allele (tcb1). Successful fertilization occurs when Tcb1-s pollen falls upon tcb1 silks. The efficacy of dominant Tcb1-s was, however, reduced when repeatedly backcross with maize inbred lines, which suggests that there are modifiers to Tcb1-s. To find …

A Biocontrol Pesticide Derived From Mycovirus-Infected Sclerotinia Sclerotiorum Can Induce Plant Resistance, Connor Pedersen

Electronic Theses and Dissertations

Soybean leaf-associated gemycircularvirus-1 (SlaGemV-1) is a novel mycovirus discovered through the metagenomic sequencing of soybean leaves which is capable of inducing hypovirulence in the highly pathogenic fungus Sclerotinia sclerotiorum. RNASeq analysis techniques were used to determine the transcriptional changes caused by the infection of virus in S. sclerotiorum, as well as the transcriptional changes in Glycine max caused by the colonization of hypovirulent, SlaGemV-1-infected S. sclerotiorum. RNASeq results indicate that viral infection leading to hypovirulence may attenuate expression of genes relating to cell wall synthesis, microtubule formation, and metabolism of steroids and natural antibiotics. Cytochrome P450-related genes, kinesin domain genes, …

Studying Morphological, Physiological, And Molecular Regulation Of Stomatal Conductance And Its Relationship To Water Use Efficiency In Alfalfa, Surbhi Gupta

Electronic Theses and Dissertations

Alfalfa (Medicago sativa), being a leguminous, highly fibrous, and proteinaceous plant has always been one of the top choices for the forage production but has high cost of irrigation in many dry and warm areas such as California and Arizona. Thus, a reduction of irrigation by using the higher water use efficiency (WUE) varieties can help the growers in reducing the cost and is critical for sustainable agriculture production. WUE is closely related to water loss through transpiring stomata. A study in our lab reported that Riverside (RS) an alfalfa genotype that has naturized in the national grassland in South …

Functional Analysis Of Squamosa-Promoter Binding Protein Like 13 In Controlling Flowering Time, Plant Architecture, Grain Size, And Grain Number In Wheat, Ajay Gupta

Electronic Theses and Dissertations

Higher and stable yield is always a major objective of wheat genetic improvement programs. The SQUAMOSA-promoter binding protein-like (SPL) genes constitute a small family of plant-specific transcription factors with diverse functions in plant development and growth and have great potential in improving yield and other major agronomic traits. However, the functional characterization of the SPL gene family in wheat is far behind other cereal crops such as rice. Using phylogenetic analysis, we identified 56 wheat orthologues of rice SPL genes belonging to 19 homoeologous groups. Among these 19 orthologous TaSPL genes, nine harbor the micro RNA 156 recognition element (MRE) …

Characterization Of Bacterial Endophytes Isolated From Brassica Carinata And Their Potential Use To Decrease Nutrient Requirements In Crops, Alex Soupir

Electronic Theses and Dissertations

Bacterial endophytes have the capability to enhance plant growth by producing plant growth hormones, solubilizing phosphates, suppressing pathogenic fungi, and reducing plant stress hormones. These capabilities make them desirable limiting the amount of nutrients and pesticides that are applied to crops. Through these assays and isolations, it is possible to identify novel bacterial species. In-vitro testing had shown 9 of the 20 isolates possess the ability to produce indole-3-acetic acid (IAA) with Pantoea agglomerans BC09 producing a concentration of 30.2 ng/μl over 4 days. BC09, Bacillus subilis BC10, and Pantoea sp. BC12 were able to solubilize calcium phosphate, 7 endophytes …

Developing Microbial Based Process To Produce High Value Natural Antimicrobial (Glyceollin) In Soybeans And Pullulan From Sucrose, Andrea Zavadil

Electronic Theses and Dissertations

Glyceollin is a secondary metabolite produced under stress conditions by soybean to act as a plant defender to pathogen attack. The antimicrobial nature of glyceollin makes it a promising natural alternative to antibiotics if incorporated into livestock feed. However, production of glyceollin is highly variable, dependent on soybean variety, and fungal elicitor used as inoculum. Our study compares two fungal spore elicitors, Trichoderma reesei and Aspergillus sojae on soybeans of diverse maturity level, and fungal susceptibility to determine highest glyceollin titer. Spore inoculation with T. reesei elicited highest glyceollin titers of 2.42±0.20 mg/g at 120 h, while A. sojae elicited …

Validation Of Candidate Loci For Maize Regrowability And Selection Of Near Isogenic Lines For The Loci, Tajbir Raihan

Electronic Theses and Dissertations

Developing perennial grain crops is an effective way for sustainable agriculture and it can be a tool for the betterment of the overall ecosystem. To understand how perenniality works in perennial species, we made a cross between Zea diploperennis and maize (Z. mays) inbred line B73. F1 hybrids produced from this cross were selfed to get the F2 population and later the F2 population underwent Genotyping-By- Sequencing (GBS) analysis. Based on the candidate loci identified on chromosome 2 and chromosome 7 from GBS, SNP-specific markers were developed from the candidate locus interval and used to genotype the F2 …

A Seed Dormancy Gene-Mediated Biotechnology To Mitigate Transgene Flow Into Weedy Rice, Luai Nahar Muhammad

Electronic Theses and Dissertations

Transgene flows into wild/weedy relatives may cause ecological and economic problems. Seed dormancy is an adaptive trait that distributes germination over time and promotes persistence of weeds in agroecosystems. Silencing natural genes controlling seed dormancy (SD) could promote germination and reduce weed adaptability. The goal of this project was to develop a transgenic mitigation (TM) technology by linking to a primary transgene with an SD gene-silencing structure, as a tandem construct for transformation, to reduce the risk of gene flow into weed populations. In this research, the Bar (Bialaphos) gene for resistance to the glufosinate herbicide was used as a …

Identification And Characterization Of Stress Responsive Genes In Soybean And Sunflower, Surendra Neupane

Electronic Theses and Dissertations

Stress responsive genes encode proteins involved in plants’ response to abiotic and biotic stresses. Among such stress responsive proteins, proteins encoded by resistance genes (R genes) or nucleotide binding site-leucine-rich repeats (NBS-LRRs) and mitogen-activated protein kinases (MAPKs) are the major groups of proteins regulating biotic and abiotic stresses, respectively. Previous studies in Nepal’s lab at SDSU identified and characterized coiled coil (CC)-NBS-LRRs (CNLs), resistance to powdery mildew8 (RPW8)-NBS-LRRs (RNLs), NBS-LRR (NLs), and MAPK proteins in soybean. This study focuses on R and MAPK genes in the recently sequenced genome of sunflower as well as the toll-interleukin-1 receptor-like nucleotide-binding site leucine-rich …

Development And Characterization Of Wheat-Thinopyrum Junceiforme Chromosome Addition Lines, Dilkaran Singh

Electronic Theses and Dissertations

Production of wheat is challenged by dynamic biotic and abiotic stresses. Genetic improvement via alien gene transfer is an effective approach to tackle such challenges. Alien gene transfer played an important role in the history of wheat crop improvement. Sea wheatgrass (SWG; Thinopyrum junceiforme, 2n = 28, genomes J1J1J2J2) is a wild relative of wheat. In our previous work, we have developed a complete amphiploid between cultivated emmer and SWG and shown that SWG is resistant to wheat streak mosaic virus, Fusarium head blight and wheat stem sawflies (due to the solid stem) and tolerant to waterlogging, salinity, heat, and …

Isolation And Identification Of Potential Bioinoculants Based On Phosphate Solubilizing And Plant Growth Promoting Benefits, Rachel Raths

Electronic Theses and Dissertations

Conservative models have shown that as populations rise, food production needs to double by 2050. Population increase and the green revolution have caused fertilizer inputs to increase since the 1960’s, increasing environmental issues and production costs. These intensive practices have led to degraded arable land and there has been an increase in urbanization meaning we need to make best use of the farming land that is available and ensure it is sustainable for future food production. Due to this, there has been a higher demand for research on more environmentally and economically friendly approaches to food production. Plant growth promoting …

Increasing Accumulation Of Glyceollins In Soybeans Via Optimization Of The Fungal Incubation Process, Stephanie Wootton

Electronic Theses and Dissertations

Continual use of antibiotics in the feed of food animals was viewed a solution to the problem of disease outbreaks in livestock produced in confinement operations. This practice also improved animal performance, likely due to the reduction in sub-clinical infections. Unfortunately, this practice led to a new problem, the development of antibiotic resistant microbes. This increase in antibiotic resistance reduced the direct benefits of antibiotics in animal production. Moreover, as antibiotic resistance spread from animal to human pathogens, this practice created a major public health concern. This led the FDA to enact the Veterinary Feed Directive in 2017 that greatly …

Interactions Of Arbuscular Mychorrhizal Fungi And Bacterial Endophytes On Disease Resistance Of Common Root Pathogens In Wheat, Janice L. Eibensteiner

Electronic Theses and Dissertations

Arbuscular mycorrhiza, a symbiosis between plants and fungi, help plants to capture nutrients such as phosphorus (P), nitrogen (N) and other micronutrients from the aggre in exchange for up to 20% of the fixed carbon (C) from the plant. In addition, arbuscular mycorrhizal (AM) fungi can improve the resistance against abiotic (drought, salinity), and also biotic (pathogen) stresses. Bacterial endophytes promote plant growth and yield by fixing N2 from the atmosphere, assimilating N and transfer it to the plant. Bacterial endophytes can also solubilize phosphate and stimulate plant defense responses, suppressing pathogens. The host plant provides sucrose and a favorable …

Disease Resistance In Wheat And Its Relatives, Ethan James Andersen

Electronic Theses and Dissertations

Plants have evolved a complex defense system against pests and pathogens utilizing many types of receptors, signaling factors, and defense compounds to detect pathogen presence and respond effectively. Since many pathogens have evolved immunesuppressing effectors used to reduce plant resistance, plants have evolved a family of receptors that detect pathogenic effectors as a result of an evolutionary arms race. These receptors contain Nucleotide-Binding Site and Leucine-Rich Repeat domains and are called NBS-LRR or NLR proteins. Many grasses possess huge genomes with hundreds of NLR-encoding genes, often found in clusters at the extra-pericentromeric regions of chromosomes, where unequal crossing over causes …

Tripartite Interactions Of Legumes With Arbuscular Mycorrhizal Fungi And Rhizobial Bacteria: Insight Into Plant Growth, Seed Yield, And Resource Exchange, Arjun Kafle

Electronic Theses and Dissertations

Under natural conditions, legumes, such as alfalfa (Medicago) and soybean (Glycine max) are colonized with arbuscular mycorrhizal (AM) fungi and rhizobial bacteria forming tripartite interactions. Legumes are important crop species due to their high nutritional and economic values. Most of the previous literatures focused on experiments with an individual symbiont: either AM fungi or rhizobial bacteria, but not with both symbionts at the same time, thus our current understanding of resource exchange in tripartite interactions is limited. It has been reported that AM fungi primarily provide phosphate (P), nitrogen (N), and other nutritional and non-nutritional benefits while rhizobial bacteria solely …

Identification Of Qtl Modifying The Activity Of The Tcb1-S Locus And Characterization And Sequencing Of Two Plutonium-Beryllium Induced Reduced Gametophyte Transmission Mutants In Maize, Merritt Bryer Burch

Electronic Theses and Dissertations

This thesis is split into two independent projects both involving the male gametophyte generation of maize. The first project looks at how pollen interacts with the female gametophyte to reduce its transmission in cross-incompatible reactions controlled by the unilateral cross-incompatibility system, teosinte crossing barrier 1. The second project explores two plutonium-beryllium induced male gametophyte mutants and attempts to uncover their genetic basis.

Identification of QTL Modifying the Activity of the Tcb1-s Locus
Teosinte crossing barrier 1 (Tcb1) is a unilateral cross-incompatibility system present in maize that provides a pre-zygotic pistil barrier to plants carrying Tcb1-s (strong allele) from pollen …

Regulation Of Local Auxin Metabolism During Soybean Nodule Development, Suresh Damodaran

Electronic Theses and Dissertations

Legume-rhizobia symbiosis leads to the development of secondary root organs called nodules. Rhizobia bacteria housed inside nodules assimilate atmospheric nitrogen and convert them into plant usable forms thereby reducing the need for fertilizer application in crop legumes like soybean. Nodule development is a coordinated process orchestrated by multiple plant hormones. In soybean, the auxin responsive gene expression was detected in nodule primordia and in the periphery of mature nodules, primarily in nodule vasculature. Auxin hypersensitivity reduces nodule formation in soybean and also polar auxin transport inhibition at the site of nodule development is not crucial for determinate nodule formation. Therefore, …

Expression Analyses And Identification Of Key Molecular Participants In Plant Responses To Environmental Cues, Praveena Kanchupati

Electronic Theses and Dissertations

Plants constantly engage and interact with the environment and respond to the changes in conditions like temperature, water, and photoperiod, by regulating expression of genes of multiple regulatory and signaling pathways. Insight into these pathways and their participants has provided and will provide candidates to improve various agronomically important traits in crops through marker-assisted breeding and genetic manipulation. With this aim in mind, in the present study, I attempted to identify key candidate genes that are involved in the regulation of; i) plant response to low temperature stress, ii) plant roots’ response to soil moisture content and iii) flowering time. …

Investigation Of Candidate Loci Associated With Maize Perennialism, Anjun Ma

Electronic Theses and Dissertations

Developing perennial grain crops is an effective and crucial way to prevent soil erosion caused by conventional agriculture of using annual crops while meeting the increasing need of global food demand. We hypothesized that the regrowth in Zea might be controlled by two dominant complementary genes. F1 hybrids were created by crossing Zea diploperennis Iltis, Doebley & R. Guzman with annual Zea mays L. ssp. mays inbred line B73. A Total of 134 F2 plants derived from nine F1 were planted and phenotyped. A subpopulation of 94 F2 plants were genotyped with Genotype-by- Sequencing (GBS) and called 10,431 SNPs after …

Evaluation And Identification Of Soybean Aphid Resistance Sources And Mapping Of Soybean Aphid Resistance Loci In Early Maturing Soybean Germplasm Accessions, Siddhi Jeewan Bhusal

Electronic Theses and Dissertations

Soybean aphid (Aphis glycines Matsumura) has been a major pest of soybean [Glycine max (L.) Merr.] in North America particularly in the northern United States and three Canadian provinces. At least four biotypes of soybean aphid have been confirmed in the United States. Identification of soybean aphid resistance sources in early-maturing soybeans and genetic characterization of new sources of resistance will facilitate to expand the gene pool of soybean aphid resistance and thus will help to develop soybean aphid resistant cultivars. To identify new sources of resistance in early maturing soybeans, 330 soybean germplasm accessions from Maturity Group (MG) I, …

Cooperation And Punishment In The Arbuscular Mycorrhizal Symbiosis: Implications For Resource Exchange & Biological Market Dynamics, Jerry A. Mensah

Electronic Theses and Dissertations

The arbuscular mycorrhizal (AM) symbiosis is arguably the world’s most abundant and important mutualism, and brings together the roots of the majority of land plants and AM fungi to great mutual advantage. The AM symbiosis can increase the uptake of nutrients, such as phosphorus (P) and nitrogen (N), and improves the abiotic and biotic stress resistance of the host plant. AM fungi have the potential to act as biofertilizers and bioprotectors in sustainable agriculture. However, despite its significance, the mechanisms that control the resource exchange between both partners in the arbuscular mycorrhizal symbiosis are largely unknown. The main aim of …

Effects Of Seed Applied Fungicide On Arbuscular Mycorrhizal Colonization Of South Dakota Cultivars Of Oat, Soybean, And Corn, Jesse Cameron

Electronic Theses and Dissertations

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts that form a mutualistic relationship with approximately 80% of terrestrial plant species. These obligate symbionts have a generally beneficial effect on their host such as increased nutrient acquisition, better tolerance to biotic and abiotic stresses, and the improvement of soil qualities. Due to the recent, widespread use of seed applied fungicides on row crops in the U.S. Midwest, there are concerns that the fungicides will inhibit these beneficial mycorrhizae. This study was conducted to evaluate what effect different commonly used seed applied fungicides have on AMF in the presence of different varieties of …

A Molecular Genetic And Physiological Comparison Of The Hybrid Necrosis Response In Wheat (Triticum Aestivum L.) To Biotic And Abiotic Stress Responses, Devi R. Kandel

Electronic Theses and Dissertations

Expression of hybrid necrosis in plants can lead to a significant reduction in productivity, or even lethality. Epistatic interactions between divergent loci that have evolved through evolution are proposed as being responsible for the genetic incompatability that is expressed as hybrid necrosis. Hybrid necrosis can also represent an obstacle to the transfer of desirable traits from wild, related species to domesticated bread wheat. In wheat, expression of dominant complementary genes Ne1 and Ne2, located to chromosomes 5B and 2B in a hybrid results the production of necrotic leaf tissue, stunted plant growth, and reduced grain yield, which are similar plant …

Role Of Silencing Rna Fgsir34 In Fusarium Graminearum's Pathogenicity To Wheat, Subha Dahal

Electronic Theses and Dissertations

Fusarium graminearum is an ascomycetous fungal pathogen that causes Fusarium head blight (FHB) disease in wheat and other cereal grains. Mycotoxin produced by the fungus, predominantly deoxynivalenol (DON), is considered as an important virulence factor for the spread of disease. Our previous study of a Dicer-like 2 knockdown mutant has led to our hypothesis that a silencing RNA, fgsiR34, might play a key role in regulating DON biosynthesis and some other virulent factors. To test this hypothesis, we generated an fgsiR34 over-expressing mutant (ΔfgsiR34+) using Inverse Repeat Transgene method and studied the pathogenicity of the mutant in …