Plant Biology Commons^™

Bottles, Butterflies, And Biomass: Recycled Glass Sand, Microbial Additions, And Herbivory Effects On Milkweed Growth, Kealey Skinner

Honors Theses

Plant-soil-microbe interactions are integral components of ecological networks and drive ecosystem function from the bottom-up. Whereas herbivores regulate ecosystem function from the top-down, having opposing and potentially complementary effects on ecosystem function. My thesis sought to understand how below-ground microbial communities contribute to herbivore preference and plant biomass across varied soil substrates. My thesis asked: how do substrate and soil microbial communities influence herbivore preference and plant biomass accumulation on swamp milkweed (Asclepias incarnata)? To address this question, seedlings of A. incarnata were sown in 2.5 cm wide × 10 cm deep pots filled with either natural beach sand or …

Degradation And Metabolic Analysis Of Synthesized Quorum-Sensing Signals By The Model Eukaryote Chlamydomonas Reinhardtii, Adam Josef Bach

Theses and Dissertations

Bacterial organisms can “talk” with one another on a colony-wide scale using a communication system known as quorum-sensing (QS) via chemical signals. These signals are produced at a basal rate throughout the life of the bacteria and are classified as autoinducers, which diffuse across the cell membrane. Once the critical concentration is reached, they begin to diffuse back into the cell and initiate a phenotypic change. As these signals exist outside the membrane of their producer, they are also accessible to other organisms. It has already been noted that some plant species uptake these compounds through their roots and break …

Impact Of Legacy Amf Communities On Vegetative Growth & Yield Of Soybean, Dylan Habeeb, Connor Morozumi, Natalie Christian

The Cardinal Edge

Soil microbial communities are increasingly recognized as an important factor in sustainable agriculture. Arbuscular mycorrhizal fungi (AMF), are key players in these communities, known to benefit their plant host in a number of ways, such as increased nutrient uptake. Plants can partner with multiple AMF species; however, little is known about how interactions between multispecies communities of AMF impact plant growth and yield. In an agricultural setting, the long-term development of these communities following practices such as rotational planting or cover cropping is also an important consideration, but there is little research on the long-term legacy of AMF communities or …

Investigating Microbe-Mediated Temperature Tolerance In Lemna Minor, Matthew Thomas Farbaniec

Honors Theses and Capstones

Temperature limits plant growth and survival more than many other environmental variables, and increases in the frequency of extreme hot or cold weather events pose significant challenges for plant growth and crop yields. Previous studies have shown that bacteria, fungi, and other microorganisms associated with plants ( i.e., the plant microbiome) can influence host response to temperature stress. These same microbes have their own temperature tolerances. We investigated whether microbial temperature tolerance correlates with plant resilience using an aquatic plant model, Lemna minor, and isolates derived from its microbiome. Microbial isolates were assessed at −10°C, 4°C, and 32°C for …

From Theory To Ecosystems: Exploring Biodiversity And Ecosystem-Function In Pitcher Plant (Darlingtonia Californica) Microbial Communities, Gavin Sutter

Cal Poly Humboldt theses and projects

The relationship between biodiversity and ecosystem-function (BEF) has been a central focus of ecological research for the last three decades, yet the role of space in shaping BEF relationships remains relatively unknown. Research has shown that community diversity and composition can strongly influence productivity, nutrient cycling, and decomposition, but much of this work treats communities as spatially isolated, leaving open how dispersal and other spatial processes shape BEF at broader scales. To begin addressing this gap, I used microbial communities inhabiting Darlingtonia californica pitcher plant leaves to evaluate how spatial organization and successional change shape biodiversity and ecosystem-functioning. I quantified …

Comparative Analysis Of Taproot And Fibrous Root System Microbiomes Under Flooding Stress, Natalie S. Kozlowski, Leighanna Jake

Humboldt Journal of Microbiology

There has been increased interest in understanding how the microbiomes of vascular plants respond to flooding stress and, many studies have focused on monocotyledonous plants with fibrous root systems. This leaves a gap in knowledge of dicotyledonous plants with taproot systems, as previous studies have been in the context of flooding to cropland affecting major food crops which are often monocotyledonous plants with fibrous root systems. Since the structural and functional differences between these root systems may influence microbial community stability and response to flooding conditions, a study looking at both is long overdue As such, this study aims to …

The Effects Of Plastic Mulch And Irrigation On Hemp Chemistry And Leaf Endophytes, Allison Rietman, Connor Morozumi, Robert C. Pearce, Natalie Christian

Journal of Agricultural Hemp Research

As an emerging crop, cultivation techniques for industrial hemp (Cannabis sativa L.) are still being developed and optimized. For example, irrigation and plastic mulching are some management practices that have been touted for their benefits in improving crop quality. Both techniques ensure ample water availability, which has often been attributed to improving hemp cannabinoid and terpene composition. In this study, we examined how supplemental irrigation implemented in a plastic mulch system influenced the cannabinoid and terpene profiles of one cultivar of CBD hemp, Lifter. We grew industrial hemp in field with plastic mulch and applied regular irrigation to one group …

Bridging Prairie Restoration And Regenerative Agriculture With Compost Tea, April Hersey

2025 Symposium

Inland Pacific Northwest prairie is an endangered ecosystem that has been reduced by conversion to agriculture. There is growing interest in the role of soil microorganisms in prairie ecosystems, which may be crucial for restoration of the plant community through interspecies interactions within the soil near plant roots. One method for improving soil microorganism community composition is compost tea: enriched liquid compost extract. Compost tea is used in regenerative agriculture to improve crop yields and protect against pathogens, ostensibly through the activity of the added compost microbes. While research has supported compost tea application in regenerative agriculture, it has not …

Culturable Microbial Communities In Root Nodules Of Red Alder (Alnus Rubra Bong.) And Scotch Broom (Cytisus Scoparius L.): Patterns Of Diversity And Composition, Felisha (Fay) Rene Pooler

Dissertations and Theses

Endophytes are a hyper diverse group of bacterial or fungal organisms residing within plant tissues without causing visible symptoms of disease. While their overall diversity and ecological functions are not well-understood, some endophytes can provide a range of important benefits to their host such as enhanced growth and increased tolerance to environmental stress. Nitrogen-fixing bacteria residing within nodules--specialized structures on the roots of legumes and actinorhizal plants--play an integral role in the plant microbiome by facilitating nitrogen availability in nutrient-poor environments. Remarkably, the patterns of diversity including both bacterial and fungal endophytes in root nodules are virtually known, except in …

Isolation, Characterization & Identification Of Cultivable Field Pea Seed Bacteria In South Dakota, Diana Wairimu Njuguna

Electronic Theses and Dissertations

Pea (Pisum sativum L.) is a legume, cultivated on over 25 million acres, particularly in Canada, France, China, Russia, and the United States. Its seeds harbor microbiota including bacteria and fungi, either on the surface (epiphytes) or within seed tissues (endophytes). These microbes can be pathogenic or beneficial, enhancing seedling metabolism and protection from environmental stresses. Characterizing beneficial seed microbiota enables development of microbial inoculants for seed treatment. Seeds from 12 varieties (green or yellow seed coats) were harvested from Sturgis and Dakota Lakes in 2021. Epiphytes were extracted using sonication followed by grinding the seeds to obtain endophytes. Isolates …

Quantification Of Auxin-Cytokinin Response During Lateral Root And Nodule Development In Medicago, Aniket Singh

Electronic Theses and Dissertations

Lateral roots (LRs) and nodules are post-embryonic root organs in legumes formed through the activity of de novo meristem. LRs, which are present in all vascular plants, are developed primarily via intrinsic developmental cues, whereas root nodules, found only in a small group of plants known as legumes, are formed in response to legume–rhizobium symbiosis. LRs arise from the pericycle layer of the root, whereas nodule initiation can begin either in the pericycle (indeterminate nodules with persistent meristem, as in Medicago) or in the cortex (determinate nodules with transient meristem, as in soybean), pointing toward a conserved developmental origin, especially …

Evaluating The Effectiveness Of Benguet Pine (Pinus Kesiya) Xylem For Deep Well Water Filtration, Allen Conner C. Hizon, Robert Zachary M. Santos, Juan Jose B. Lacson, Jefferson Danilo G. Villarin, Juan Carlo T. Gumangan

Sinaya: A Philippine Journal for Senior High School Teachers and Students

Even today, many rural and remote communities still do not have access to safe drinking water, which is a basic right of every human. To address this problem, the effectiveness of the Benguet pine tree (Pinus kesiya) xylem as a sustainable water filtration method for well water was investigated. The physical and chemical properties of the filtered and unfiltered deep well water were tested: the total dissolved solids (TDS) and the electrical conductivity using a 5-in-1 electronic water quality tester and the pH level using pH strips. On the other hand, the microbiological metrics, such as heterotrophic plate …

Bodine: An Agent-Based Modeling Approach To Studying Localized Coexistence Across Environmental Heterogeneity, Alexandra Campbell

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Microbiological Quality Of Irrigation Water And Leafy Vegetables In Dar Es Salaam, Tanzania, Bubelwa L. Kamara, Godwill D. Mrema, Thomas J. Lyimo

Tanzania Journal of Science

The quality of water used for the irrigation of leafy vegetables in urban settings is in doubt due to contamination associated with poor hygiene and water pollution. This study examined the microbiological quality of irrigation water and leafy vegetables at Chang’ombe in Dar es Salaam, Tanzania as well as the perceptions and level of awareness of nearby consumers. Water and leafy vegetable samples were analysed for faecal coliform (FC) using standard techniques. Perception and awareness of consumers were collected using a questionnaire survey. The results showed an average FC count of 406.1 ± 16.40 MPN/100 ml for the irrigation water. …

Ammonium Chemotaxis In Chlamydomonas Reinhardtii, Gabela Nelson

LSU Doctoral Dissertations

Analysis of ammonium chemotaxis in Chlamydomonas reinhardtii is largely hindered, compared to that of phototaxis, despite equal importance on flagellated microalgal physiology. A major contribution of this shortfall is the lack of proper assay method. We developed a simple Petri dish assay method in which light is homogenously exposed while patterns of the cellular migration are tracked with a function of time. Using the method, new findings were revealed. First, this research presented that a strain lacking the eyespot organelle required for light gradient-sensing exhibits similar chemotactic behavior compared to a wild-type strain, suggesting Chlamydomonas sense an ammonium gradient not …

The Plant Disease Triangle Facing Climate Change: A Molecular Perspective, Charles Roussin-Léveillée, Christina A. M. Rossi, Christian Castroverde, Peter Moffett

Biology Faculty Publications

No abstract provided.

Effect Of Dietary Flavonoids On Growth In Saccharomyces Cerevisiae, Vivian Rivera

Mahurin Honors College Capstone Experience/Thesis Projects

Plant foods contain a diversity of biologically active compounds called phytochemicals, produced by plant species as secondary metabolites. A phytochemical group known as flavonoids has received much scientific attention in recent times with respect to their antioxidative and anti-inflammatory roles. This investigation examined how quercetin and naringenin, the most common dietary flavonoids, affect growth potential of yeast under optimal and stress conditions (temperature, glucose, and oxidative stress). Using Saccharomyces cerevisiae as a model, a dose dependency effect of quercetin and naringenin was observed under optimal conditions when liquid cultures were treated with three different concentrations (75 μM, 150 μM, and …

Role Of Ph And Plant Age On The Selection Of Rhizobial Endophytes In Soybean Root Nodules, Cole Alexander Roman

Graduate Theses/Dissertations

Soybeans form symbiotic relationships with nitrogen-fixing bacteria in their root nodules to acquire most of their nitrogen requirement; nitrogen is often one of the limiting nutrients in the soil. Members of the Bradyrhizobium, Sinorhizobium, Mesorhizobium, and Rhizobium genera can nodulate soybeans. Bradyrhizobium is preferentially selected over other types of rhizobia in varying environmental conditions and is often found in acidic soils. Sinorhizobium is often identified in the root nodules of soybeans in neutral and alkaline soil. So far, the potential role of soil pH on the selection of rhizobial endophytes with soybean root nodules is unknown. Likewise, …

Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia

Journal of Nonprofit Innovation

Urban farming can enhance the lives of communities and help reduce food scarcity. This paper presents a conceptual prototype of an efficient urban farming community that can be scaled for a single apartment building or an entire community across all global geoeconomics regions, including densely populated cities and rural, developing towns and communities. When deployed in coordination with smart crop choices, local farm support, and efficient transportation then the result isn’t just sustainability, but also increasing fresh produce accessibility, optimizing nutritional value, eliminating the use of ‘forever chemicals’, reducing transportation costs, and fostering global environmental benefits.

Imagine Doris, who is …

Mimicking Biofilms: Photosynthetic Assessments Of C. Reinhardtii In 3 Physical Forms, John Michael Roesgen

Biology ETDs

Oxygenic photosynthesis supports the majority of life on Earth through the capture of energy from sunlight and the assimilation of CO₂ into basic building blocks of cells. Microalgae are fast growing and account for about half of global photosynthesis. In addition, they can be cultivated and their metabolism can be redirected to generate additional useful products ranging from biofuels to pharmaceuticals. However, the efficiency of metabolite production is severely impacted by the slow diffusion of CO₂ through water and the high energetic costs of harvesting microalgae from liquid cultures. Microalgae grow in open water, but they also form …

Investigating The Impact Of Edaphobacter Aggregans (Wbg-1) On Arabidopsis Thaliana Development, Julia Talbert

Undergraduate Research Symposium

Acidobacteria is a phylum of bacteria that make up 50% of soil microbes. While making up a large proportion of bacteria found in soil, this phylum is largely unexplored with limited information about the bacteria and their impact on plant growth. The selected target of this study is Edaphobacter aggregans, WBG-1, which is a part of a subdivision of acidobacteria. Examining the bacteria’s effects on the development of the model plant Arabidopsis thaliana will provide insight into understanding this unknown phylum of soil-dwelling bacteria. Acidobacteria are an important realm to investigate as they affect agriculture practices. With Missouri being such …

Variation In Synthetic Floral Microbiome Composition Is Largely Ignored By Foraging Bumblebees, Nevin P. Cullen

2023 Midwest Ecology & Evolution Conference

Most flowers are occupied by diverse communities of microbes, which can alter floral attractiveness to key pollinators and floral fitness by interacting with floral traits. Different species of flower often acquire unique communities of microbes. Consequently, pollinators are frequently forced to choose between two flowers with distinct floral microbiomes while foraging. However, it is currently unknown whether pollinators have an inherent preference for flowers containing one floral microbiome over another, and whether microbial preference is modified by variation in floral traits. We investigated this knowledge gap using distinct bacteria and yeasts cultured from a nickel-hyperaccumulating plant and its non-accumulating relative. …

Ethanol Extracts From Selected Tanzanian Medicinal Plants Selectively Inhibit Plasmodium Falciparum Growth In Vitro, Robert Christopher, Amina Msonga, Heinrich C. Hoppe, Fabrice F. Boyom

Tanzania Journal of Science

This study aimed to assess the in vitro antiplasmodial and cytotoxic activities of ethanol extracts from the root barks, leaves and stem barks of seven medicinal plant species growing in Tanzania. The antiplasmodial activities of extracts against chloroquine-sensitive (3D7) and multidrug-resistant (Dd2) strains of Plasmodium falciparum were determined using a SYBR green I-based fluorescence assay, while the cytotoxicity of active extracts was determined against the human HepG2 cell line using a resazurin-based assay. Out of twenty-one extracts screened, two of them, namely, DFRE from Dracaena fragrans root bark (IC50Pf3D7 = 2.4 mg/mL) and EHSE from Erythrina haerdii stem bark (IC50Pf3D7 …

Molecular Regulation Of The Salicylic Acid Hormone Pathway In Plants Under Changing Environmental Conditions, Christina A. M. Rossi, Eric J. R. Marchetta, Jong Hum Kim, Christian Castroverde

Biology Faculty Publications

Salicylic acid (SA) is a central plant hormone mediating immunity, growth, and development. Recently, studies have highlighted the sensitivity of the SA pathway to changing climatic factors and the plant microbiome. Here we summarize organizing principles and themes in the regulation of SA biosynthesis, signaling, and metabolism by changing abiotic/biotic environments, focusing on molecular nodes governing SA pathway vulnerability or resilience. We especially highlight advances in the thermosensitive mechanisms underpinning SA-mediated immunity, including differential regulation of key transcription factors (e.g., CAMTAs, CBP60g, SARD1, bHLH059), selective protein–protein interactions of the SA receptor NPR1, and dynamic phase separation of the recently identified …

Changes And Relationships Of Soil Aluminum, Organic Matter, And Hydrogen Ion Concentration With Rye Cover Crop, Arron Wilder

Cal Poly Humboldt theses and projects

Soil acidity is a common agricultural problem worldwide, as approximately 50% of all potentially arable soils are affected by pH limitations. At soil pH 3+) is considered to be the chemical form of aluminum in acid soil that hinders plant growth the most. Potentially, soil organic matter (SOM) can ameliorate the toxic effects of Al³⁺ on plants and microbes by binding with Al³⁺, thus preventing Al³⁺ (and other species of aluminum) from interacting in the rhizosphere. Increasing SOM also increases soil health indicators (i.e., microbial activity, soil water holding capacity, aggregate stability, porosity, etc.) while the …

Effect Of Soil Ph And Indigenous Bacterial Populations In Selecting Rhizobial Endophytes Within Soybean Root Nodules, Brianne Danielle Edwards

Graduate Theses/Dissertations

Soybean plants fulfill most of their nitrogen requirement by developing symbiotic associations with four different rhizobial genera, including Bradyrhizobium, Sinorhizobium, Mesorhizobium, and genus Rhizobium. In general, members of Bradyrhizobium and Sinorhizobium have been reported as dominant root nodule endophytes under acidic soils and alkaline soil conditions, respectively. So far, it is unknown whether the selection of rhizobial endophytes is regulated by their ability to survive under different soil pH or driven by host plants regardless of their relative abundance in soil. This study was focused on the assessment of the potential role of soil pH in …

Increasing The Resilience Of Plant Immunity To A Warming Climate, Jong Hum Kim, Christian Castroverde, Shuai Huang, Chao Li, Richard Hilleary, Adam Seroka, Reza Sohrabi, Diana Medina-Yerena, Bethany Huot, Jie Wang, Sharon Marr, Mary Wildermuth, Tao Chen, John Macmicking, Sheng Yang He

Biology Faculty Publications

Extreme weather conditions associated with climate change affect many aspects of plant and animal life, including the response to infectious diseases. Production of salicylic acid (SA), a central plant defence hormone, is particularly vulnerable to suppression by short periods of hot weather above the normal plant growth temperature range via an unknown mechanism. Here we show that suppression of SA production in Arabidopsis thaliana at 28 °C is independent of PHYTOCHROME B (phyB) and EARLY FLOWERING 3 (ELF3), which regulate thermo-responsive plant growth and development. Instead, we found that formation of GUANYLATE BINDING PROTEIN-LIKE 3 (GBPL3) defence-activated biomolecular condensates (GDACs) …

Nitrogen Availability In Dune Systems And Its Effect On Root Fungal Endophyte Communities., Haley E. Sage

College of Arts & Sciences Senior Theses

As global change persists, changes in resource availability can influence plant-microbe interactions. To understand how resource availability can influence these interactions and species diversity, I focused this research on how varying nitrogen (N) levels affect root endophyte communities in the plant species Ammophila breviligulata, an ecosystem engineer in the dune system. I analyzed the relationship between nitrogen addition and microbial community composition across 60 plots treated with three nitrogen addition levels (control, low, and high) in a long-term experimental field site in the Lake Michigan dunes. I identified Ammophila breviligulata's root endophyte community after creating a culture collection and …

Effects Of Neem Aqueous Extract (Azadirachta Indica) Against Aphids And Aphid-Borne Virus In Cowpea (Vigna Unguiculata L. Walp), Kehinde T. Kareem, Rachael B. Olayinka, Juliana A. Ugwu, Olubusola F. Oduwaye

Tanzania Journal of Science

Pests and diseases are among the major factors limiting plant growth and yields. Pests are known vectors of pathogens including viruses. Proper management of plant pests is an indirect means of controlling viral diseases in plants. This study aimed at comparing the potential of neem extract and a synthetic insecticide (lambda cyhalothrin) for the management of aphids and Cowpea aphid-borne mosaic virus (CABMV) in five different cowpea (Vigna unguiculata) genotypes and to determine the residual effects of the insecticide in the cowpea grains. The experimental field was laid out in randomized complete block design with three replicates. Treatments included; spraying …

Degradation And Nitrogen Cycling In The Context Of Biodiversity-Ecosystem Function Relationships In The Inquiline Bacterial Community Of Darlingtonia Californica, Megan Teigen

Cal Poly Humboldt theses and projects

Biodiversity-ecosystem function (BEF) research aims to explain how species and their environments interact with each other. Microbial communities engage in vital biogeochemical pathways in a variety of natural ecosystems, and yet there are large knowledge gaps about the specific metabolic pathways in which they are involved. Degradation specifically contributes to nitrogen cycling globally through the breakdown of large organic nitrogen compounds into small inorganic nitrogen that is necessary for the survival of many other organisms. In this study, I focused on the degradative function of the inquiline microbial communities found within the carnivorous pitcher plant, Darlingtonia californica. Darlingtonia grows in …