Genetics and Genomics Commons^™

Upland Cotton And Nematodes: An Analysis Of Historical Resistance, Upcoming Threats, And Co-Inoculation Effects, Amanda Gaudin

Theses and Dissertations

Upland cotton (Gossypium hirsutum ) is an important fiber crop grown throughout the southern United States. Plant-pathogenic nematodes are worm-like animals that feed on the roots of most agronomic crops, including cotton. The southern root-knot nematode (Meloidogyne incognita, RKN) and the reniform nematode (Rotylenchulus reniformis, RN) cause significant yield losses in cotton every year. Current sources of resistance are effective but limited, therefore historical screenings of cotton accessions were revisited in search for novel resistance sources. None were identified but many of the screened accessions possessed markers of known root-knot nematode and reniform nematode resistance. …

Genome-Wide Association Study For Agronomic Traits In Bermudagrass (Cynodon Spp.), Lovepreet Singh

Theses and Dissertations

Bermudagrass (Cynodon spp.) breeding and cultivar development is hampered by limited information regarding its genetic and phenotypic diversity. A germplasm collection of 206 bermudagrass accessions from 29 countries was genotyped with high-throughput genotyping-by-sequencing technique. Genomic diversity in this diverse germplasm panel was assessed with multifaceted approaches including population structure, phylogenetic analysis, principal component analysis, and genetic diversity parameters. This study revealed substantial genetic variation in the Cynodon accessions, demonstrating the potential of this germplasm panel for further genetic studies and cultivar development in breeding programs. Another critical issue in turfgrass breeding is the lack of information regarding the genetic …

Sequence Analysis Of Herbicide Target Genes In Herbicide-Tolerant Rice, Jonathan Kearney, Nilda R. Burgos, Gulab D. Rangani

Biological Sciences Undergraduate Honors Theses

The tolerance of mutagenized rice (Oryza sativa) lines to selector herbicides was investigated and the sequence of ALS gene was analyzed in plants that survived treatment with 4x the label rate of imazethapyr herbicide. This was done to determine if insensitivity to imazethapyr is due to mutation(s) in the herbicide binding site. Seedlots previously treated with ethyl-methyl sulfonate were planted in the field and 3-leaf seedlings were treated with various herbicides to screen for herbicide-tolerant mutants. Seeds from survivors composed the rice lines tested in the current research. Seeds were planted in the greenhouse and 3-leaf seedlings were …

Morphological And Genetic Analysis Of The Root System In Two American Grapevines (Vitis Species), Parinaz Mohtasebi

MSU Graduate Theses

The North American grapes species Vitis rupestris Scheele and Vitis riparia Michx have been the pillars of rootstock breeding for many decades. Though a large body of viticultural knowledge has been accumulated on their impact on grafted scions, the genetic basis of their root system architecture (RSA) has received limited scientific attention. In this study, I generated and analyzed adventitious root systems from dormant cuttings of 22 V. riparia and 19 V. rupestris accessions, as well as 162 interspecific F1 hybrid progeny from a cross between V. rupestris (♀) and V. riparia (♂). I photographed the roots and then extracted …

Connections Between Mechanosensitive Ion Channel Msl10 And Er-Plasma Membrane Contact Sites, Jennette Marie Codjoe

Arts & Sciences Electronic Theses and Dissertations

Mechanosensitive (MS) ion channels are an evolutionarily conserved way for cells to sense mechanical forces and transduce them into ionic signals. A plasma membrane-localized MS channel from Arabidopsis thaliana, MscS-Like (MSL)10, senses cell swelling and initiates a signaling cascade that triggers programmed cell death. Whereas the channel properties of MSL10 have been well studied, how MSL10 signals remains largely unknown. I worked collaboratively to show that important lesions for cell death signaling in the cytosolic N- and C-terminal domains of MSL10 interact genetically. I also helped show that ionic flux through MSL10 is dispensable for signaling, which suggested that MSL10 …

Development Of Functional Markers For Resistance To Smut And Identification Of Genes Differentially Expressed In Response To Brown Rust In Sugarcane, Jose David Cortes

LSU Doctoral Dissertations

Smut, caused by Sporisorium scitamineum and brown rust, caused by Puccinia melanocephala, are two of the most important diseases that affect sugarcane production in Louisiana and worldwide. Smut continues to cause losses in the breeding program in Louisiana. Therefore, a QTL analysis was conducted to identify molecular markers associated with resistance in F₁ progeny (162) of a biparental cross between susceptible cultivar L 99-233 and resistant HoCP 96-540. Using 1,574 single-dose SNP markers, a total of 253 linkage groups (LG) were obtained with a genome coverage of 24,580.15 cM. Six QTLs were localized on five LGs. The highest …

Unraveling The Genetic Architecture Of Somatic Embryogenesis In Upland Cotton, Adam M. Canal

All Theses

Somatic embryogenesis is the de novo development of asexual embryos because of the plasticity of the plant cell. In tissue culture, the biochemical and genetic mechanisms of dedifferentiated callus tissues can be reprogrammed to transdifferentiate into developed, polarized embryos, which can ultimately regenerate into whole plants. Although this rarely occurs in nature, scientists have exploited this process for decades to regenerate whole plants following gene transformation or for micropropagation. While some species are amenable to in vitro regeneration, upland cotton is particularly recalcitrant, with regenerative potential being confined to only several genotypes. The lack of elite, regenerable genotypes greatly restricts …

Screening For Binding Partners And Protein-Protein Interactions Of A Fungal Transcription Factor- Xdr1, Nishadi Punsara Gallala Gamage

Masters Theses

Clarireedia spp. (formerly Sclerotinia homoeocarpaF.T. Bennett) is the causal agent dollar spot, the most economically important turfgrass disease impacting golf courses in North America. The most effective strategy for dollar spot control is repeated application of multiple classes of fungicides. However, reliance on chemical application has led to resistance to four classes of fungicides as well as multidrug resistance (MDR). Fungi are known to detoxify xenobiotics, like fungicides, through transcriptional regulation of three detoxification phases: modification, conjugation and secretion. Little is known, however, of the protein-protein interactions that facilitate these pathways. Following next-generation RNA sequencing of Clarireedia spp., a …

A Functional Genomics Approach To Overwintering Mechanisms In Insects, Emily Allison Wheeler Nadeau

Theses and Dissertations--Entomology

Insects living in temperate and polar environments have developed numerous adaptations to increase survival at low temperatures. A majority of insects are freeze-intolerant and die from internal ice formation, but some are freeze-tolerant and can survive ice formation in extracellular spaces. Both categories of insects prepare for winter with a combination of seasonal and rapid acclimation responses, which differ both in time course and in underlying mechanisms. In this dissertation, I examine adaptations for winter survival in several insect species with a specific focus on molecular mechanisms. To better understand the underpinning mechanisms of these adaptations, I leverage functional genomics …

Use Of Heterothallic Mat Deletion Strains Of Fusarium Graminearum As Test Mates In Crosses To Evaluate The Genetics Of Pathogenicity And Fitness, Gabdiel Emmanuel Yulfo-Soto

Theses and Dissertations--Plant Pathology

Fusarium Head Blight (FHB), caused by Fusarium graminearum sensu stricto and other members of the F. graminearum species complex (FGSC), is a plant disease that occurs on cereal crops worldwide. FHB causes yield losses not only by reducing grain weight, but also by contaminating the kernels with dangerous trichothecene mycotoxins, especially deoxynivalenol (DON). There is a high degree of genotypic and phenotypic variation among pathogen species and strains, but current FHB risk assessment models and treatments do not account for pathogen diversity. Therefore, it is difficult to predict what will happen if a new, potentially more aggressive variant is introduced, …

Analysis Of Root System Architecture And Qtl Identification In Grapevines, Sujan Thapa

MSU Graduate Theses

The root system of the plant plays a vital role in water and nutrient uptake. Native North American grapevines adapted to a broad range of climatic and soil conditions, which led to the evolution of diverse root system architecture (RSA) within the Vitis genus. Despite the importance of RSA in viticulture, little is known about the genetic basis of the RSA in grapevine. I used novel root phenotyping tool, RhizoVision Analyzer to characterize the root system of 208 genotypes of an F₁ grapevine progeny obtained from a cross between Vitis rupestris Scheele B38 and Vitis riparia Michx. HP-1. Dormant …

Getting To The Root Cause: The Genetic Underpinnings Of Root System Architecture And Rhizodeposition In Sorghum, Farren Smith

Graduate Theses, Dissertations, and Problem Reports

Plants are some of the most diverse organisms on earth, consisting of more than 350,000 different species. To understand the underlying processes that contributed to plant diversification, it is fundamental to identify the genetic and genomic components that facilitated various adaptations over evolutionary history. Most studies to date have focused on the underlying controls of above-ground traits such as grain and vegetation; however, little is known about the “hidden half” of plants. Root systems comprise half of the total plant structure and provide vital functions such as anchorage, resource acquisition, and storage of energy reserves. The execution of these key …

Developing A Toolbox To Engineer Quantitative Trait Variation In Legume Species Using Crispr/Cas Technologies., Petar Miletic

Electronic Thesis and Dissertation Repository

The impact of intensive agriculture on the environment is immense. This is especially dire with regard to the natural nitrogen (N) cycle, where the human driven interference, primarily associated with industrial fertilization, has reached unsustainable levels. Unlike cereals, legumes, such as soybean, alfalfa and common bean, have the ability to use atmospheric nitrogen, which limits the need for industrial fertilization. A more wide-spread use of legumes could alleviate some of the negative impacts on the biogeochemical cycle while also providing a useful alternative to meat consumption, an important factor in sustainability. To reach this goal, further improvements of legume crops …

Establishment Of A Pesticide Resistance Monitoring Tool For The Two-Spotted Spider Mite, Tetranychus Urticae, Hanna Varonina

Electronic Thesis and Dissertation Repository

Two-spotted spider mite (TSSM), or Tetranychus urticae (Koch), is a major agriculture pest known for its rapid development of resistance to pesticides. The analysis of spider mites’ pesticide resistance demonstrated that resistance patterns and frequencies vary between T. urticae strains collected from different geographic locations and host plants. This research aims at characterization of pesticide resistance patterns in mite populations present in greenhouses in the Southwestern Ontario by identifying genetic and metabolic markers of their pesticide resistance. The establishment of these markers lays the basis for development of a pesticide resistance diagnostic tool that will enable prediction of population resistance …

Marker-Assisted Selection To Determine The Introgression Of Rpv-3 Mediated Downy Mildew Resistance In 'Chambourcin' X 'Caberenet Sauvignon' Grapevine Population, Kavya Sri Tummala

MSU Graduate Theses

Downy mildew caused by the fungus, Plasmopara viticola in the grapes is one of the major diseases affecting crop yield throughout the world. Breeding grapes via conventional methods for the downy mildew resistance will take approximately 25-30 years to fully evaluate and release new cultivars. Because of the long breeding cycle in woody plant species like grape, developing DNA markers linked to genes or quantitative trait loci (QTLs) for horticultural traits can greatly accelerate the breeding process and allow a much more accurate selection of progeny. This study aims to determine the presence of resistance in the 267 F1 genotypes …

Dynamics Of The Soil Microbiome In Ginseng Gardens, Megan E. Lambert

Electronic Thesis and Dissertation Repository

Ginseng Replant Disease (GRD) is a syndrome in which ginseng cannot be cultivated in soil previously used to grow ginseng. Since GRD can persist for decades, it severely impacts the Ontario ginseng industry. To better understand the origin of GRD, the impact of ginseng cultivation on the soil microbiome was investigated in bulk soil of three newly planted ginseng gardens in Ontario, from seeding through two years of cultivation. While specific trends in species richness, diversity and composition were unclear, PERMANOVA analyses confirmed that they changed over time. Known GRD-related pathogens, including Ilyonectria mors-panacis and Fusarium oxysporum, were detected in …

The Genetic Basis Of Adaptation To Environmental Stress In Two Grass Genomic Model Systems, David Mitchell Goad

Arts & Sciences Electronic Theses and Dissertations

Plants are exposed to a wide variety of environmental stress in the wild and have developed an equally diverse set of adaptations to tolerate them. The evolutionary processes that have led to this functional diversification, and the specific genes and physiological mechanisms involved, are of immense interest to both evolutionary biologists and crop breeders. In this dissertation I investigate adaptation to different types of environmental stress in two economically important grass species, seashore paspalum (Paspalum vaginatum Sw.) and rice (Oryza sativa L.).

Seashore paspalum is a halophytic turfgrass that occupies habitats which can dramatically differ in salt concentration. Populations may …

Has Maize Overtaken Our Reality? A Personal Briefing, Biochemical Comparison, Agrigenomics, And History Of Maize, Nader Pahlevan

Honors Theses

Maize (Zea mays ssp. Mays) is a revolutionary cereal grain that has raced to the world’s most popular staple crop, transforming societies and impacting history. This paper aims to build and portray the story maize has created through its journey to world domination. The important details that encompass this literature are maize’s cultural significance in my life’s story, the comparison of various starches broken down into amylose and amylopectin ratios, a summative historical account on maize’s spread throughout numerous parts of the old world, and the genetical analysis of maize that explains the key features that have led …

Distribution And Diversity Of Heliothine And Other Lepidopteran Nudiviruses, Emrah Ozel

Theses and Dissertations--Entomology

Helicoverpa zea nudivirus 2 (HzNV-2) is the only known sterilizing and sexually-transmitted insect virus and causes pathological symptoms in H. zea reproductive tissues. HzNV-2 has features that make it a candidate as a H. zea (corn earworm) control agent, such as the ability to cause asymptomatic (latent) and symptomatic (lytic) infections and the ability to influence mating behavior of its host to favor virus spread. HzNV pathology has been studied and its genome sequenced, however, its prevalence in natural populations is largely unknown. In this study, we developed and used a low-cost PCR-based molecular survey to investigate HzNV-2 prevalence and …

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 …

Quantitative Trait Loci Analysis Of A Ril Soybean Population To Determine Chromosomal Regions Governing Seed Protein, Oil, And Linolenic Acid Content, Ronald E. Moore

Masters Theses

180 RILs (recombinant inbred lines) segregating for protein, oil, and fatty acids were produced from a cross between TN12-4098 and TN13-4303. These lines were grown across three locations spread horizontally across Tennessee: Research Education Center at Milan (RECM), Highland Rim Research and Education Center (HRREC), and East Tennessee Research and Education Center (ETREC) in 2018 and 2019. 21 quantitative trait loci (QTLs) spanning 7 chromosomes were found using WinQTLCart2.5.

Investigation Of The Individual Soybean Root Nodule Microbiome, Parris Mica Mayhood

MSU Graduate Theses

Soybean is a valuable crop that establishes a symbiotic association with nitrogen-fixing microorganisms. Previous research suggests members of the genus Bradyrhizobium are the major nitrogen-fixing inhabitants of soybean root nodules. However, results from recent studies identified the presence of other bacteria, so called non-rhizobial endophytes (NREs), inside root nodules. All previous research has pooled nodules of different plants for bacterial community analysis, but this study investigated the presence and relative abundance of rhizobia and NREs within multiple root nodules of a single plant. Three sites were selected on Kendrick Farm in Springfield, MO, where three plants and rhizosphere soil were …

Identification And Characterization Of Epigenetic Regulators In The Yellow Fever Mosquito, Aedes Aegypti, Shankar C. R. R. Chereddy

Theses and Dissertations--Entomology

Due to the increased interactions between the sylvatic and urban cycles of Aedes aegypti life cycle, there has been an increase in the incidence of vector-borne diseases. The risk involved through the transmission of viruses like Dengue, Zika, Yellow-fever and Chikungunya calls for an effective control method for the deadly vector. The possibility of pesticide resistance and the costs involved in producing new pesticides have pushed Sterile Insect Technique (SIT) into prominence. However, current methods used to sterize insects for SIT are not highly efficient. This study tackles current issues in mosquito control by identifying and characterizing epigenetic regulators that …

Rapid Evolution In Agroecosystems: Transposable Elements And Epigenetics In The Colorado Potato Beetle, Kristian Brevik

Graduate College Dissertations and Theses

Within agricultural ecosystems, humans and insects enter into complex relationships. Humans consider many of these insects to be pests, and exert significant pressures upon them, such as efforts to kill them using insecticides. One of the ways insects respond to these efforts is by rapidly evolving resistance to insecticides - but how they do this is not fully understood. DNA methylation, an epigenetic mechanism, and transposable elements, which are mobile genetic elements within genomes, may each play a role in shaping the way insects rapidly evolve in response to exposure to insecticides. Understanding the role of transposable elements and DNA …

The Potential Of Refugee Seed Systems To Promote Contemporary Adaptation In Traditional Crops: A Case Study Of African Maize In New England, Andi Kur

Graduate College Dissertations and Theses

There are many mechanisms by which landraces evolve in a contemporary agricultural setting; however, the influence of forced human migration on landrace redistribution and evolution has received little attention in comparison to the stochastic effects of drift, mutation, and gene flow in the centers of origin. Although the seed systems of forcedly-displaced people remain poorly understood, evidence suggests that refugees often continue to grow traditional crops after resettlement. From a genetics perspective, the crops that are transported to highly disparate environments provide an interesting opportunity to study adaptation.

This research addresses how forced human migration has impacted contemporary landrace evolution …

Application Of Short Tandem Target Mimic (Sttm) Technique For Functional Analysis Of Micro-Rna396 In Transgenic Poplar Trees, Surattana Boonsai

Dissertations, Master's Theses and Master's Reports

Short Tandem Target Mimic (STTM) is a commonly technique used for functional studies of a number of genes in several plant model systems. However, very little is known about application of STTM technique in tree species. In this study, STTM was applied to knock down microRNA396 (miR396) in transgenic poplar trees for the first time. STTM396 expression resulted in dramatic decrease in miR396 expression levels leading to taller plants with larger leaves and larger leaf cell size. Additionally, an expression analysis of growth regulating factor genes (GRFs) that are members of miR396 target gene family showed up-regulation of GRF07 gene …

Arabidopsis Tt8 Orthologue Of Pinto Bean (Phaseolus Vulgaris L.) Regulates Proanthocyanidin Genes And Seed Coat Darkening, Nishat Shayala Islam

Electronic Thesis and Dissertation Repository

Postharvest darkening of seed coat in pinto bean (Phaseolus vulgaris L.) is an undesirable trait that hinders its market potential. Darkening is more rapid in the cultivars like CDC Pintium than the newly developed slow darkening cultivar 1533-15. A single gene, SLOW DARKENING (Sd), is responsible for the slow darkening in pinto beans and the trait co-segregates with two simple sequence repeat (SSR) markers. The objective of this research is to identify and characterize the Sd gene to understand the slow darkening mechanism in pinto bean seed coat. A search for Sd within the linkage distance from …

The Identification Of Interspecific Hybrids Between Jaeger 70 X Vignoles Grapes Using Ssr Markers, Carl William Knuckles Iv

MSU Graduate Theses

Jaeger 70 cultivar is an interspecific hybrid of Vitis linececumii x Vitis rupestris, with an interesting past. It was created by Hermann Jaeger of Neosho, MO, who is most notable for saving the French wine industry by developing phylloxera resistant rootstocks in the mid-1800s. Traditionally the Jaeger 70 variety has been grafted to French wine grape cultivars to impart disease resistance and cold hardiness while retaining desirable wine characteristics. One interesting characteristic of Jaeger 70 is that it is a female-only plant, allowing for many interesting areas of study. Vitis interspecific hybrid Vignoles, is a cold hardy cultivar of largely …

Grapevine Vein Clearing Virus: Epidemiological Patterns And Construction Of A Clone, Cory Von Keith

MSU Graduate Theses

Grapevine vein clearing virus (GVCV) is a recently discovered virus belonging to the Badnavirus genus. Characteristic to its name, the virus is associated with a disease where symptoms manifest as pronounced vein-clearing, resulting in severe berry deformation and vine decline in susceptible grape varieties. Sustainable production of wine is dependent on healthy plants. The associated disease is mainly found in Midwest vineyards. Attempts were made in this thesis to provide evidence of causality of the virus to the associated disease and to infer the historical path and migration pattern of GVCV. Conclusions and discussions will provide grape producers with the …

Production Of A Candidate Recombinant Protein Vaccine For Mannheimia Haemolytica In Lettuce And Tobacco Chloroplasts, Coby K. Martin

Electronic Thesis and Dissertation Repository

The cattle industry worldwide is ravaged by bovine respiratory disease (BRD), a bacterial disease caused by Mannheimia haemolytica. Recent efforts to design vaccines against M. haemolytica focus on a virulence factor, leukotoxin, in addition to surface lipoproteins. Plant-based protein production is a safe and inexpensive alternative to traditional methods. Edible vaccines deliver antigens to pharyngeal tissues, which can provide local immunization against M. haemolytica prior to its progression into the lungs. In this project, a chimeric protein containing M. haemolytica antigens was produced in tobacco chloroplasts as a candidate edible vaccine for BRD. Attempts were made to transform lettuce …