Digital Commons Network^™

Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis: Final Report, Scott R. Abella

Fire Science

Species selection can make the difference between successful revegetation projects and costly failures. Candidate native species for revegetating burned arid lands in the southwestern United States must meet at least two criteria. These species must: (1) be competitive in postfire environments typically dominated by exotic grasses, and (2) be able to become established reliably by seeding or planting. In response to Manager’s Request Task 3 (reestablishment of native vegetation after fires on arid lands) in the 2006 JFS announcement for proposals, this research tackled the problem of selecting native species with the greatest chance of revegetation success by conducting synergistic …

Conjugated Polymer Nanoparticles For Effective Sirna Delivery To Tobacco By-2 Protoplasts, Asitha T. Silva, Alien Nguyen, Changming Ye, Jeanmarie Verchot, Joong Ho Moon

Department of Chemistry and Biochemistry

Background

Post transcriptional gene silencing (PTGS) is a mechanism harnessed by plant biologists to knock down gene expression. siRNAs contribute to PTGS that are synthesized from mRNAs or viral RNAs and function to guide cellular endoribonucleases to target mRNAs for degradation. Plant biologists have employed electroporation to deliver artificial siRNAs to plant protoplasts to study gene expression mechanisms at the single cell level. One drawback of electroporation is the extensive loss of viable protoplasts that occurs as a result of the transfection technology.

Results

We employed fluorescent conjugated polymer nanoparticles (CPNs) to deliver siRNAs and knockdown a target gene in …

The Interaction Of Fire And Grazing In Oklahoma Artemisia Filifolia Shrubland, Stephen L. Winter

School of Natural Resources: Dissertations, Theses, and Student Research

I. FIRE-RESILIENCY OF A NORTH AMERICAN ARTEMISIA (ASTERACEAE) SHRUB: IMPLICATIONS FOR RESTORATION OF A CRITICAL ECOSYSTEM PROCESS. Conclusions: Unlike most North American Artemisia shrub species, our research suggests that A. filifolia is highly resilient to the effects of fire. Therefore, use of prescribed fires for the restoration and maintenance of ecosystem processes and properties is appropriate in A. filifolia shrublands of the southern Great Plains in North America.

II. RESTORATION OF THE FIRE-GRAZING INTERACTION IN ARTEMISIA FILIFOLIA SHRUBLAND OF THE SOUTHERN GREAT PLAINS, NORTH AMERICA. Synthesis and applications. Vegetation structure in Artemisia filifolia shrublands of our study were readily altered …

Is Orthoptera Abundance And Distribution Across A Small Grassland Area Affected By Plant Biomass, Plant Species Richness, And Plant Quality?, Caitlin Falcone

Department of Environmental Studies: Undergraduate Student Theses

The choice of a specific microhabitat represents a compromise among a number of different factors organisms use to monitor habitat suitability. Grassland vegetation structure can vary widely along environmental gradients over a relatively small area. This vegetation structure can have a large influence on habitat selection by grasshoppers (Orthoptera). However, it is not clear which vegetation characteristics are most important in determining grasshopper abundance. We found that plant biomass, plant species richness, and plant quality all have an effect on grasshopper abundance and distribution. We observe that these affects vary both within and among the two years of data collection. …

Analysis Of The Response Of Medicago Truncatula Calcium Oxalate Mutants To Abiotic Stress, Wayra Gabriela Navia-Gine

Graduate Theses and Dissertations

Calcium oxalate crystals are found in most plant species. In Medicago truncatula wild-type A17, crystals accumulate in leaves along the secondary veins and the only role attributed to them so far is defense against chewing insects. Calcium oxalate deficient (cod) mutants were isolated in M. truncatula; the cod mutants include cod5, which completely lack crystals in the leaves and cod6 that accumulates fewer and smaller crystals compared to A17. We analyzed gene expression in the cod mutants and A17 using GeneChip® Medicago Genome Arrays and found important differences in transcriptome between the three genotypes. In particular, we found a gene …

Phenotypic And Genetic Characterization Of Wildland Collections Of Western And Searls Prairie Clovers For Rangeland Revegetation In The Western Usa, Kishor Bhattarai

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Western prairie clover [Dalea ornata (Douglas ex Hook.) Eaton & J. Wright] is a perennial legume that occurs in the northern Great Basin, Snake River Basin, and southern Columbia Plateau, whereas Searls prairie clover [Dalea searlsiae (A. Gray) Barneby], also a perennial legume, occurs in the southern Great Basin and surrounding areas. Understanding the genetic and ecotypic variation of these prairie clovers is a prerequisite for developing populations suitable for rangeland revegetation in the western USA. DNA sequences of internal transcribed spacer (ITS/5.8S) and trnK/matK were used to study the phylogeny of these species. The species were distinguished …

Control Of Glyphosate Resistant Horseweed (Conyza Canadensis) With Saflufenacil And Tank-Mixture Partners., Brock Steven Waggoner

Masters Theses

Field and labratory studies were conducted to determine the efficacy of saflufenacil alone and with mixture partners for burndown. Field studies were conducted in 2009 and 2010 to evaluate saflufenacil in mixtures with glyphosate, glufosinate, or paraquat for control of glyphosate-resistant (GR) horseweed prior to planting cotton. Saflufenacil and saflufenacil mixtures were applied 7 days before planting (DBP). Saflufenacil at 25 and 50 g ai ha-1 in mixture with all three non-selective herbicides provided similar GR horseweed control when compared to the current standard of glyphosate plus dicamba. Control of GR horseweed was also not different at the 25 and …

Plant Ecophysiology Of Mycorrhizal Fungi, Gregory Keith Bartley Jr.

Gregory Keith Bartley Jr.

No abstract provided.

Arctic Ecosystem Responses To Changes In Water Availability And Warming: Short And Long-Term Responses, Paulo C. Olivas

FIU Electronic Theses and Dissertations

Arctic soils store close to 14% of the global soil carbon. Most of arctic carbon is stored below ground in the permafrost. With climate warming the decomposition of the soil carbon could represent a significant positive feedback to global greenhouse warming. Recent evidence has shown that the temperature of the Arctic is already increasing, and this change is associated mostly with anthropogenic activities. Warmer soils will contribute to permafrost degradation and accelerate organic matter decay and thus increase the flux of carbon dioxide and methane into the atmosphere. Temperature and water availability are also important drivers of ecosystem performance, but …

The Land Institute, Madeleine K. Charney

Madeleine K. Charney

An overview of the mission and current projects of The Land Institute in Salinas, Kansas. This organization strives to develop an agricultural system with the ecological stability of the prairie and a grain yield comparable to that from annual crops.

Effects Of Experimental Nitrogen Additions On Plant Diversity In An Old-Growth Tropical Forest, Xiankai Lu, Jiangming Mo, Frank S. Gilliam, Guoyi Zhou, Yunting Fang

Biological Sciences Faculty Research

Response of plant biodiversity to increased availability of nitrogen (N) has been investigated in temperate and boreal forests, which are typically N-limited, but little is known in tropical forests. We examined the effects of artificial N additions on plant diversity (species richness, density and cover) of the understory layer in an N saturated old-growth tropical forest in southern China to test the following hypothesis: N additions decrease plant diversity in N saturated tropical forests primarily from N-mediated changes in soil properties. Experimental additions of N were administered at the following levels from July 2003 to July 2008: no addition (Control); …

Joint Fire Science Program – Lake Mead National Recreation Area Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis: Quarterly Progress Report, Time Period: July 1 — September 30, 2010, Margaret N. Rees

Fire Science

• Article entitled “Competitive Hierarchy of Native Desert Plants with Red Brome (Bromus rubens): Towards Identifying Invasion-Reducing Species" was revised and re-submitted to the Invasive Plant Science and Management journal.
• Final data collection on soils and nursery plots is complete. Data are awaiting analysis.

Increased Plant Uptake Of Nitrogen From 15N-Depleted Fertilizer Using Plant Growth-Promoting Rhizobacteria, A. O. Adesemoye, H. A. Torbert, J. W. Kloepper

Department of Plant Pathology: Faculty Publications

Harmful environmental effects resulting from fertilizer use have spurred research into integrated nutrient management strategies which can include the use of specific microorganisms to enhance nutrient use efficiency by plants. Some strains of plant growth-promoting rhizobacteria (PGPR) have been reported to enhance nutrient uptake by plants, but no studies with PGPR have used ¹⁵N isotope techniques to prove that the increased N in plant tissues came from the N applied as fertilizer. The current study was conducted to demonstrate that a model PGPR system can enhance plant uptake of fertilizer N applied to the soil using different rates of …

Plant Immunity Directly Or Indirectly Restricts The Injection Of Type Iii Effectors By The Pseudomonas Syringae Type Iii Secretion System, Emerson Crabill, Anna Joe, Anna Block, Jennifer M. Van Rooyen, James R. Alfano

Center for Plant Science Innovation: Faculty and Staff Publications

Plants perceive microorganisms by recognizing microbial molecules known as pathogen-associated molecular patterns (PAMPs) inducing PAMP-triggered immunity (PTI) or by recognizing pathogen effectors inducing effector-triggered immunity (ETI). The hypersensitive response (HR), a programmed cell death response associated with ETI, is known to be inhibited by PTI. Here, we show that PTI-induced HR inhibition is due to direct or indirect restriction of the type III protein secretion system’s (T3SS) ability to inject type III effectors (T3Es). We found that the Pseudomonas syringae T3SS was restricted in its ability to inject a T3E-adenylate cyclase (CyaA) injection reporter into PTI-induced tobacco (Nicotiana tabacum) cells. …

Role Of Sabp2 In Systemic Acquired Resistance Induced By Acibenzolar-S-Methyl In Plants., Diwaker Tripathi

Electronic Theses and Dissertations

Plants have evolved an efficient mechanism to defend themselves against pathogens. Many biotic and abiotic agents have been shown to induce defense mechanism in plants. Acibenzolar-S-Methyl (ASM) is a commercially available chemical inducer of local and systemic resistance (SAR) response in plants. ASM functioning at molecular level is mostly unclear. This research was designed to investigate the mechanism of ASM action in plants. It was hypothesized that SABP2, a plant protein, plays an important role in ASM-mediated defense signaling. Biochemical studies were performed to test the interaction between SABP2 and ASM. Transgenic SABP2-silenced tobacco plants were used to determine the …

The Endosymbiotic Relationship Of Leguminosae (Fabaceae) And Rhizobium, Sabrina Mcgee, Dolores Maceda, Maria Bustos, Maryknoll Palisoc, Rachel Dahl

Undergraduate Research Opportunities Program (UROP)

This project will look at The Endosymbiotic Relationship of Leguminosae (Fabaceae) and Rizobioum. Endoysmbiosis Theory is the concept that mitochondria and chloroplasts are the result of years of evolution initiated by the endocytosis, (the process by which cells absorb material through their cell membrane) of bacteria and algae which, instead of becoming digested, became symbiotic.The mitochondria of eukaryotes evolved from aerobic bacteria, probably rickettsias, living within their host cell and the chloroplasts from cyanobacteria, also known as blue-green algae. Endoysmbiosis is a type of symbiosis in which one organism lives inside the body of another and both function as a …

Unique Functionality Of 22 Nt Mirnas In Triggering Rdr6-Dependent Sirna Biogenesis From Target Transcripts In Arabidopsis, Josh T. Cuperus, Alberto Carbonell, Noah Fahlgren, Hernan Garcia-Ruiz, Russell T. Burke, Atsushi Takeda, Christopher M. Sullivan, Sunny D. Gilbert, Taiowa A. Montgomery, James C. Carrington

Department of Plant Pathology: Faculty Publications

RNA interference pathways may involve amplification of secondary siRNAs by RNA-dependent RNA polymerases. In plants, RDR6-dependent secondary siRNAs arise from transcripts targeted by some microRNA (miRNA). Here, Arabidopsis thaliana secondary siRNA from mRNA, and trans-acting siRNA, are shown to be triggered through initial targeting by 22 nt miRNA that associate with AGO1. In contrast to canonical 21 nt miRNA, 22 nt miRNA primarily arise from foldback precursors containing asymmetric bulges. Using artificial miRNA constructs, conversion of asymmetric foldbacks to symmetric foldbacks resulted in production of 21 nt forms of miR173, miR472 and miR828. Both 21 and 22 nt forms associated …

Spatiotemporal Dynamics In A Lower Montane Tropical Rainforest, Robert Michael Lawton

Doctoral Dissertations

Disturbance in a forest’s canopy, whether caused by treefall, limbfall, landslide, or fire determines not only the distribution of well-lit patches at any given time, but also the ways in which the forest changes over time. In this dissertation, I use a 25 year record of treefall gap formation find a novel and highly patterned process of forest disturbance and regeneration, providing a local mechanism by examining the factors that influence the likelihood of treefall. I then develop a stochastic cellular automaton for disturbance and regeneration based on the analysis of this long term data set and illustrate the potential …

Insect-Damaged Corn Stalks Decompose At Rates Similar To Bt-Protected, Non-Damaged Corn Stalks, R. Michael Lehman, Shannon L. Osborne, Deirdre A. Prischmann-Voldseth, Kurt A. Rosentrater

Kurt A. Rosentrater

The relative decomposability of corn (Zea mays L.) residues from insect (Bt)-protected hybrids and conventional hybrids cultivated under insect pressure was investigated in two studies. Above-ground biomass, residue macromolecular composition, and stalk physical strength were also measured. In the first decomposition study, chopped residues (stalks and leaves) were used from a corn rootworm-protected (Cry3Bb1) hybrid and its non-Bt near isoline that were grown in replicated plots infested with corn rootworms (Diabrotica spp.). In the second study, residue (intact stalk sections) was used from three European corn borer (ECB, Ostrinia nubilalis Hübner)-resistant (Cry1Ab) hybrids representing different seed manufacturer/maturity date series, their …

Reestablishing Diversity In Our Hardwood Forests: A Transplant Study Of Five Spring-Flowering Herbs, Danielle Racke

Masters Theses & Specialist Projects

Herbaceous communities are critical to the functioning of forest ecosystems. They recycle nutrients, help prevent erosion, provide critical microhabitats and maintain biodiversity. In the eastern United States, most hardwood forests are growing on land once entirely cleared or used for some form of agriculture. Although some of these forests are nearly 150 years old, they still have depauperate native herbaceous communities when compared to remaining old-growth forests. This long-term depletion may result from dispersal limitation or environmental limitation.

I tested the hypothesis that dispersal was the primary factor contributing to the absence of five spring-flowering herbaceous species in four secondary …

Temporal And Spatial Assessment Of Evaporation, Transpiration, And Soil Moisture Redistribution, Brian M. Bird

UNLV Theses, Dissertations, Professional Papers, and Capstones

At a native stand of creosote bush (Larrea tridentata) in North Las Vegas, a rainfall simulation study was conducted over a 12 month period from October 2005 to October 2006. Simulated rainfall occurred during the winter, spring, summer, and fall periods. Rainfall simulation systems were positioned on each of 12 plots, each containing a single creosote bush. Simulated rainfall events occurred at night with multiple short pulses designed to maximize infiltration while minimizing ponding. Yearly simulated rainfall amounts were set at 0, 15, 30 and 60 cm (replicated three times) and were approximately 0, 1.5, 3.0 and 6.0 times the …

Alteration In Lignin Biosynthesis Restricts Growth Of Fusarium Spp. In Brown Midrib Sorghum, Deanna L. Funnell-Harris, Jeffrey F. Pedersen, Scott E. Sattler

Department of Plant Pathology: Faculty Publications

To improve sorghum for bioenergy and forage uses, brown midrib (bmr)6 and -12 near-isogenic genotypes were developed in different sorghum backgrounds. The bmr6 and bmr12 grain had significantly reduced colonization by members of the Gibberella fujikuroi species complex compared with the wild type, as detected on two semiselective media. Fusarium spp. were identified using sequence analysis of a portion of the translation elongation factor (TEF) 1-α gene. The pathogens Fusarium thapsinum, F. proliferatum, and F. verticillioides, G. fujikuroi members, were commonly recovered. Other frequently isolated Fusarium spp. likely colonize sorghum asymptomatically. The χ2 analyses showed that the …

Joint Fire Science Program – Lake Mead National Recreation Area Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis: Quarterly Progress Report, Time Period: May 1 — June 30, 2010, Margaret N. Rees

Fire Science

• Article entitled “Competitive Hierarchy of Native Desert Plants with Red Brome (Bromus rubens): Towards Identifying Invasion-Reducing Species" was submitted to the Invasive Plant Science and Management journal.
• Maintained nursery plots and added installment of nitrogen treatment.
• Took measurements in nursery (competition) plots and harvested biomass.

Following Tetraploidy In Maize, A Short Deletion Mechanism Removed Genes Preferentially From One Of The Two Homeologs, Margaret R. Woodhouse, James C. Schnable, Brent S. Pedersen, Eric Lyons, Damon Lisch, Shabarinath Subramaniam, Michael Freeling

Department of Agronomy and Horticulture: Faculty Publications

Previous work in Arabidopsis showed that after an ancient tetraploidy event, genes were preferentially removed from one of the two homeologs, a process known as fractionation. The mechanism of fractionation is unknown. We sought to determine whether such preferential, or biased, fractionation exists in maize and, if so, whether a specific mechanism could be implicated in this process. We studied the process of fractionation using two recently sequenced grass species: sorghum and maize. The maize lineage has experienced a tetraploidy since its divergence from sorghum approximately 12 million years ago, and fragments of many knocked-out genes retain enough sequence similarity …

Vittatidera Zeaphila (Nematoda: Heteroderidae), A New Genus And Species Of Cyst Nematode Parasitic On Corn (Zea Mays), Ernest C. Bernard, Zafar A. Handoo, Thomas O. Powers, Patricia A. Donald, Robert D. Heinz

Department of Plant Pathology: Faculty Publications

A new genus and species of cyst nematode, Vittatidera zeaphila, is described from Tennessee. The new genus is superficially similar to Cactodera but is distinguished from other cyst-forming taxa in having a persistent lateral field in females and cysts, persistent vulval lips covering a circumfenestrate vulva, and subventral gland nuclei of the female contained in a separate small lobe. Infective juveniles (J2) are distinguished from all previously described Cactodera spp. by the short stylet in the second-stage juvenile (14-17 mm); J2 of Cactodera spp. have stylets at least 18 mm long. The new species also is unusual in that …

Botanical Report Of Tierra Redonda Mountain Blm Area Of Critical Environmental Concern, San Luis Obispo County, California (W120˚59’41”; N35˚45’59”)., Anthony Baniaga, Andrew Theo Fitanides

Biological Sciences

The purpose of this document is to report the results of a botanical survey of a portion of the Tierra Redonda Mountain Area of Critical Environmental Concern. The survey was conducted for the Bureau of Land Management, and executed between October 2009 and June 2010. Tierra Redonda Mountain is the type locality for the Tierra Redonda formation, and has weathered to form steep slopes of exposed chaparral and protected woodlands. Four general community types were found; foothill woodland, chaparral, southern coastal scrub and dune scrub. Alliances determined by The Manual of California Vegetation (2nd ed.) were: Quercus douglasii Woodland, Quercus …

Good Agricultural Practices For Food Safety Of Fresh Produce, Laurie Hodges

Department of Agronomy and Horticulture: Faculty Publications

What are the guiding principles of food safety for fresh produce?

• Once contaminated, removing or killing pathogens on produce is very difficult.

• Preventing microbial contamination at all steps, from production to distribution, is strongly favored over treatments to eliminate contamination that may have occurred.

• Document the implementation of prevention programs, and educate workers at all levels of the agricultural and packing environments on food safety.

Key Signatures of a Credible Food Safety Program

The following is a condensed checklist of practices and conditions that reduce the potential for fresh produce to be exposed to pathogenic microbes. Review …

Origin Of The Polycomb Repressive Complex 2 And Gene Silencing By An E(Z) Homolog In The Unicellular Alga Chlamydomonas, Scott Shaver, J. Armando Casas-Mollano, Ronald L. Cerny, Heriberto D. Cerutti

Center for Plant Science Innovation: Faculty and Staff Publications

Polycomb group proteins play an essential role in the maintenance of cell identity and the regulation of development in both animals and plants. The Polycomb Repressive Complex 2 (PRC2) is involved in the establishment of transcriptionally silent chromatin states, in part through its ability to methylate lysine 27 of histone H3 by the Enhancer of zeste [E(z)] subunit. The absence of PRC2 in unicellular model fungi and its function in the repression of genes vital for the development of higher eukaryotes led to the proposal that this complex may have evolved together with the emergence of multicellularity. However, we report …

Characteristics Of Nectar Production And Standing Crop In Campsis Radicans (Bignoniaceae)., Andrea Alexis Edge

Electronic Theses and Dissertations

We examined several aspects of nectar production in Campsis radicans to better understand how standing crop is affected and how production affects pollinator visitation. In all experiments, nectar and concentration of flowers were measured and total sugar was calculated. Flowers do not produce additional nectar unless nectar is removed, and it is not resorbed. Volume of standing crop and total sugar fluctuates throughout the day, whereas concentration remains constant. Age and time of day significantly affect regeneration of nectar and sugar. The number of removals did not significantly affect the amount of nectar or sugar regenerated; however, concentration declined significantly …

Optimizing The Physical And Nutritional Environment Of Unleached Root-Zones, Curtis B. Adams

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Unleached root-zones represent an environmental ideal by eliminating wasteful leaching of nutrients and water. NASA grows plants in space in unleached root-zones, incorporating polymer-coated fertilizer (PCF) into a ceramic media (Turface or Profile). However, lack of growth productivity in space has led to the need for research to improve the nutritional and physical environment of the root-zone, which is the objective of this research. PCF types are diverse in release characteristics and the effects of temperature and substrate water content have not been well characterized. In spite of widespread use, studies on chemical properties and applied studies to verify soil …