Digital Commons Network^™

Identification Of Markers Linked To Genes For Sprouting Tolerance (Independent Of Grain Color) In Hard White Winter Wheat (Hwww), Juthamas Fakthongphan, Guihua Bai, Paul St. Amand, Robert A. Graybosch, P. Stephen Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Key message Hard red wheats can donate genes to hard white wheats for tolerance to preharvest sprouting, the effects are quantitative in nature, and may be tracked with previously described DNA markers.

Abstract Pre-harvest sprouting (PHS) of wheat (Triticum aestivum L.) can negatively impact end-use quality and seed viability at planting. Due to preferences for white over red wheat in international markets, white wheat with PHS tolerance has become increasingly desired for worldwide wheat production. In general, however, red wheat is more tolerant of sprouting than white wheat. The main objective of this study was the identification of PHS …

Soil Water Improvements With The Long-Term Use Of A Winter Rye Covercrop, Andrea D. Basche, Thomas C. Kaspar, Sotirios V. Archontoulis, Dan B. Jaynes, Thomas J. Sauer, Timothy B. Parkin, Fernando E. Miguez

Department of Agronomy and Horticulture: Faculty Publications

The Midwestern United States, a region that produces one-third of maize and one-quarter of soybean grain globally, is projected to experience increasing rainfall variability. One approach to mitigate climate impacts is to utilize crop and soil management practices that enhance soil water storage and reduce the risks of flooding as well as drought-induced crop water stress. While some research indicates that a winter cover crop in maize-soybean rotations increases soil water availability, producers continue to be concerned that water use by cover crops will reduce water for a following cash crop. We analyzed continuous in-field soil water measurements from 2008 …

Engaging Middle School Students Through Locally Focused Environmental Science Project-Based Learning, Andrea D. Basche, Vincent Genareo, Adah Leshem, Amy Kissell, Judith Pauley

Department of Agronomy and Horticulture: Faculty Publications

Increasing scientific literacy through education is one way to promote awareness of current environmental challenges, and can be enhanced through project-based learning (PBL), a pedagogical approach in which students explore authentic topics and demonstrate their learning publically. The National Science Foundation–funded GK–12 program at Iowa State University partnered doctoral-level graduate students (fellows) with middle and high school science teachers. This study analyzed results from one such middle school partnership in Iowa, where a PBL approach was implemented. Classroom practices focused on local environmental case studies of energy development, water pollution, soil science, climate change, plant biology, and ecology. Results from …

Impact Of Pre-Anthesis Water Deficit On Yield And Yield Components In Barley (Hordeum Vulgare L.) Plants Grown Under Controlled Conditions, Zakaria I. Al-Ajlouni, Ayed Al-Abdallat, Abdul Latief A. Al-Ghzawi, Jamal Y. Ayad, Jamal M. Abu Elenein, Nisreen A. Al-Quraan, P. Stephen Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Drought at pre-anthesis stages can influence barley growth and results in yield losses. Therefore, it is important to understand how drought at pre-anthesis can affect different traits associated with yield reduction in barley. The objective of this study was to understand the relevance of the genetic background of major flowering time genes in barley plants subjected to pre-anthesis drought and its impact on yield and yield components. A glasshouse experiment using a Randomized Complete Block Design was conducted to investigate the effect of drought and its timing on yield and yield components on eleven barley genotypes, which were selected to …

Predicting Long-Term Cover Crop Impacts On Soil Quality Using A Cropping Systems Model, Fernando E. Miguez, Sotirios Archontoulis, Andrea D. Basche

Department of Agronomy and Horticulture: Faculty Publications

Increased attention is being paid to cover crops as an option to reduce water pollution and decrease soil degradation in Iowa. More producers are experimenting with cover crops to increase soil productivity. However, when this project began there was little research to demonstrate the long-term impacts that cover crops have on crop yields. There were no estimates to quantify how much environmental benefit a cover crop could provide in terms of erosion and soil carbon changes. Such estimates are beneficial to demonstrate the long-term improvements that a cover crop affords in Iowa, particularly for corn-soybean rotations where the winter planting …

Corn Response To Nitrogen Management Under Fully-Irrigated Vs. Water-Stressed Conditions, Bijesh Maharjan, Carl J. Rosen, John A. Lamb, Rodney T. Venterea

Department of Agronomy and Horticulture: Faculty Publications

Characterizing corn (Zea mays L.) grain yield (GY) response to N is critical for maximizing profits, increasing N use efficiency and minimizing environmental impacts. Although a large database of GY response to N exists for highly productive soils, few data exist for less productive soils. While changes in precipitation are expected in the future, few studies have compared GY response to varying N management practices under conditions of varying water availability. We measured GY and basal stalk nitrate nitrogen (BSN) at harvest using split-applied urea at eight N rates under fully-irrigated (FI) and water-stressed (WS) conditions in a loamy …

Identification Of Evening Complex Associated Proteins In Arabidopsis By Affinity Purification And Mass Spectrometry, He Huang, Sophie Alvarez, Rebecca Bindbeutel, Zhouxin Shen, Michael J. Naldrett, Bradley S. Evans, Steven P. Briggs, Leslie M. Hicks, Steve A. Kay, Dmitri A. Nusinow

Department of Agronomy and Horticulture: Faculty Publications

Many species possess an endogenous circadian clock to synchronize internal physiology with an oscillating external environment. In plants, the circadian clock coordinates growth, metabolism and development over daily and seasonal time scales. Many proteins in the circadian network form oscillating complexes that temporally regulate myriad processes, including signal transduction, transcription, protein degradation and post-translational modification. In Arabidopsis thaliana, a tripartite complex composed of EARLY FLOWERING 4 (ELF4), EARLY FLOWERING 3 (ELF3), and LUX ARRHYTHMO (LUX), named the evening complex, modulates daily rhythms in gene expression and growth through transcriptional regulation. However, little is known about the physical interactions that …

Multidisciplinary Research And Extension Team Evolution: Processes, Outcomes, And Strategies, Daren Redfearn, Jay Parsons, Mary Drewnoski

Department of Agronomy and Horticulture: Faculty Publications

Team-based research is not an innovative concept; however, the current models of team research are based principally on self-formed teams with a defined duration. Current trends seem to point toward the development of administratively designed multidisciplinary teams. Although this seems logical, minimal guidelines exist to aid in team development or evaluate team outcomes. Critical processes in a team-based research atmosphere have not been identified, much less described, and strategies for successful implementation have not been proposed. The strength of this approach can be summarized as a unified focus during the course of problem definition and solution. Many trade-offs and obstacles …

Identification And Verification Of Qtl Associated With Frost Tolerance Using Linkage Mapping And Gwas In Winter Faba Bean, Ahmed Sallam, Mustapha Arbaoui, Mohamed El-Esawi, Nathan Abshire

Department of Agronomy and Horticulture: Faculty Publications

Frost stress is one of the abiotic stresses that causes a significant reduction in winter faba bean yield in Europe. The main objective of this work is to genetically improve frost tolerance in winter faba bean by identifying and validating QTL associated with frost tolerance to be used in marker-assisted selection (MAS). Two different genetic backgrounds were used: a biparental population (BPP) consisting of 101 inbred lines, and 189 genotypes from single seed descent (SSD) from the Gottingen Winter bean Population (GWBP). All experiments were conducted in a frost growth chamber under controlled conditions. Both populations were genotyped using the …

Temporal Dynamics Of Maize Plant Growth, Water Use, And Leaf Water Content Using Automated High Throughput Rgb And Hyperspectral Imaging, Yufeng Ge, Geng Bai, Vincent Stoerger, James C. Schnable

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Automated collection of large scale plant phenotype datasets using high throughput imaging systems has the potential to alleviate current bottlenecks in data-driven plant breeding and crop improvement. In this study, we demonstrate the characterization of temporal dynamics of plant growth and water use, and leaf water content of two maize genotypes under two different water treatments. RGB (Red Green Blue) images are processed to estimate projected plant area, which are correlated with destructively measured plant shoot fresh weight (FW), dry weight (DW) and leaf area. Estimated plant FW and DW, along with pot weights, are used to derive daily plant …

Modeling Shattercane Dynamics In Herbicide-Tolerant Grain Sorghum Cropping Systems, Rodrigo Werle, Brigitte Tenhumberg, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Traditional breeding technology is currently being used to develop grain sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] germplasm that will be tolerant to acetolactate synthase (ALS)-inhibiting herbicides. This technology (Inzen^TM, DuPont^TM) has the potential to improve sorghum production by allowing for the postemergence control of traditionally hard-to-control grasses. However, grain sorghum and shattercane [weedy Sorghum species; Sorghum bicolor (L.) Moench ssp. drummondii (Nees ex Steud.) de Wet ex Davidse] can interbreed and introduced traits such as herbicide tolerance could increase the weediness of the weedy relative. Our objective was to develop a simulation model …

Letter To The Editor Ws-2 Introgression In A Proportion Of Arabidopsis Thaliana Col-0 Stock Seed Produces Specific Phenotypes And Highlights The Importance Of Routine Genetic Verification, Mon-Ray Shao, Vikas Shedge, Hardik Kundariya, Fredric R. Lehle, Sally Ann Mackenzie

Department of Agronomy and Horticulture: Faculty Publications

Arabidopsis thaliana is an important model organism with a robust network of resources that has been of enormous value to the plant science research community. The use of isogenic material as a reference point or control is critical for many types of experiments in plant molecular biology and genetics. Recently, we noticed that some seed from a common source of the widely-used Columbia-0 (Col-0) strain gave rise to plants showing features atypical for this strain. Whole genome DNA-sequencing and allele-specific PCR assays confirmed that the abnormal individuals contain multiple introgressions from the ecotype Wassilewskija-2 (Ws-2), as described below. This emphasizes …

Probing The Plant Cell Wall With Herbicides: A Chemical Genetics Approach, Chad B. Brabham

Theses and Dissertations--Plant and Soil Sciences

The primary cell wall is a highly organized multi-layered matrix of polysaccharides (cellulose, hemi-cellulose, and pectin). The ability of the rigid cell wall to sufficiently loosen to allow growth is a complex process that differs considerably between grasses monocots and dicots. Cellulose is the major structural component required for anisotropic cell expansion and is synthesized by CELLULOSE SYNTHASE A (CesA) proteins. Here, our objectives were two-fold: 1) dissect cell walls and cellulose biosynthesis in dicots and grasses using chemical biology and reverse genetic approaches 2) characterize and classify the inhibitory mechanisms of cellulose biosynthesis inhibitors (CBIs). A reverse genetics TILLING …

Transcriptional Regulation Of Specialized Metabolites In Arabidopsis Thaliana And Catharanthus Roseus, Craig M. Schluttenhofer

Theses and Dissertations--Plant and Soil Sciences

For millennia humans have utilized plant specialized metabolites for health benefits, fragrances, poisons, spices, and medicine. Valued metabolites are often produced in small quantities and may command high prices. Understanding when and how the plant synthesizes these compounds is important for improving their production. Phytohormone signaling cascades, such as jasmonate (JA) activate or repress transcription factors (TF) controlling expression of metabolite biosynthetic genes. TFs regulating specialized metabolite biosynthetic genes can be manipulated to engineer plants with increased metabolite production.

WRKY transcription factor are known components of both JA signaling cascades and regulation of specialized metabolism. The presence of WRKY binding …

2016 Virginia Wildflower Of The Year: Downy Rattlesnake Plantain, Goodyera Pubescens, W. John Hayden

Biology Faculty Publications

Regardless of season, Downy Rattlesnake Plantain is a delight to encounter in the woods of Virginia. This evergreen orchid is a perennial rhizomatous herb of the forest floor. The horizontal rhizomes, usually covered lightly by leaf litter, bear roots at intervals and terminate in a rosette of leaves. Leaves are alternate, somewhat crowded together, and only slightly elevated above ground level. Leaf blades are ovate, 3–8 cm long, and 1.5–3 cm wide, often of varying size within a rosette. Leaves are present year-round, bluish-green, with prominent white veins; on each leaf, a broad midvein is flanked by two smaller veins …

Evaluating The Evolutionary And Genetic Relationships Of The Andean Orchids Of Northwestern Ecuador, Kylie Bucalo

Theses and Dissertations

DNA barcoding is a molecular based technique used to separate and identify individual species. Here we establish a DNA Barcode library for the orchid flora of an Andean cloud forest in Northwestern Ecuador. The library contains 135 matK and 136 rbcL DNA Barcodes representing over 33 Orchidaceae genera. Sequence analysis shows percent species resolution was higher for matK (98.8%) than rbcL (70.24%), with a large portion of the unresolved species for the rbcL loci coming from taxonomically complex genera in the subtribe Pleurothallidinae. Neighbor Joining (NJ) trees revealed that the orchid flora of Siempre Verde is divided taxonomically into …

Comparison Of Pea Seed Germination Due To Manipulation Of Soil Conditions, Ariel M. Kershner

Faculty Curated Undergraduate Works

This experiment was done with the intent to understand optimal soil conditions for pea seed germination. We investigated this using three soil conditions – 100% potting soil, 50% potting soil/50% sand, and 100% sand. Seemingly healthy pea seeds were planted and observed over five weeks. We measured both the total number of sprouts per week and the combined weight of the plants and seeds per condition before planting and after uprooting. We expected to find that the 100% potting soil condition would germinate the best, resulting in the most sprouts and heaviest weight of the condition’s seeds and plants. This …

Successional Changes In Leaf Nutrient Concentrations Of Woody And Herbaceous Species, Daniel Walter Kuchta

Masters Theses

Leaf nutrient concentrations are an example of a functional trait, a trait that can be used to understand community dynamics by observing how plants interact with their environment. I explored how leaf nutrient concentrations were affected over successional time by environmental changes. The majority of prior research on functional traits focuses on either woody or herbaceous species, but not both life forms simultaneously. To address this, I also explored the successional changes to leaf nutrient concentrations, separating the plant community into woody and herbaceous species.

Healthy, mature leaves were taken from 122 taxa of woody and herbaceous species in a …

Transcriptome Profiling Of Kentucky Bluegrass (Poa Pratensis L.) Accessions In Response To Salt Stress, Shaun B. Bushman, Keenan L. Amundsen, Scott E. Warnke, Joseph G. Robins, Paul G. Johnson

Department of Agronomy and Horticulture: Faculty Publications

Background: Kentucky bluegrass (Poa pratensis L.) is a prominent turfgrass in the cool-season regions, but it is sensitive to salt stress. Previously, a relatively salt tolerant Kentucky bluegrass accession was identified that maintained green color under consistent salt applications. In this study, a transcriptome study between the tolerant (PI 372742) accession and a salt susceptible (PI 368233) accession was conducted, under control and salt treatments, and in shoot and root tissues.

Results: Sample replicates grouped tightly by tissue and treatment, and fewer differentially expressed transcripts were detected in the tolerant PI 372742 samples compared to the susceptible …

From Seed To Sky: Impacts Of Explosive Compounds On Vegetation Across Spatial And Developmental Scales, Stephen M. Via

Theses and Dissertations

Explosive compounds are broadly distributed across the globe as a result of nearly two centuries of munitions use in warfare and military activities. Two explosive compounds have seen disproportionate use; RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and TNT (2-methyl- 1,3,5-trinitrobenzene), being the most commonly found explosives in the environment. The effects of explosives on biota have been studied in great detail; however, there is a general lack of understanding with regard to broader ecological impacts of these contaminants. My dissertation objective was to follow the impacts of explosive compounds on vegetation across scales. Impacts on vegetation at the species scale alter community composition via …

Plant Functional Trait And Hyperspectral Reflectance Responses To Comp B Exposure: Efficacy Of Plants As Landmine Detectors, Paul V. Manley Ii

Theses and Dissertations

At least 110 million landmines have been planted since the 1970s in about 70 nations, many of which remain in place today. Some risk of detection may be mitigated using currently available remote sensing techniques when vegetation is present. My study focused on using plants as phytosensors to detect buried explosives. I exposed three species representing different functional types (Cyperus esculentus (sedge), Ulmus alata (tree), Vitis labrusca (vine)) to 500 mg kg^-1 of Composition B (Comp B; 60/40 mixture of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT)), a commonly used explosive mixture, and measured functional traits and reflectance over …

Spanish River Carbonatite: Its Benefits And Potential Use As A Soil Supplement In Agriculture, James J

Theses and Dissertations (Comprehensive)

A critical problem facing agriculture today is being able to consistently and sustainably provide plants with adequate nutrients for growth. With this problem being exacerbated by the ever-increasing human population, new perspectives and techniques are required to ensure global food security. In order to fully realize potential solutions, however, plant growth and nutrition cannot be exclusively focused upon. The soil-microorganism-plant system is comprised of many interconnected and interdependent processes that together support plant growth: it is upon these processes that the focus must be placed. In this work, the agromineral Spanish River Carbonatite (SRC) is characterized using the framework of …

Plant Functionality Across An Environmental Gradient, Taylor L. Price, Julie Zinnert

Undergraduate Research Posters

Community assemblages provide insight into ecosystem processes, both spatially and temporally. They interact with biotic and abiotic factors that vary with habitat structure, influencing community composition. Ecological theory demonstrates that species have the potential for a wide fundamental niche, but habitat range may be restricted by factors exposed to species in their realized niche. In barrier island ecosystems, edaphic and environmental characteristics (e.g. elevation and distance to shoreline) are major drivers determining where and how plant communities establish. Physical stressors, such as salt stress and drought influence community grouping and can alter plant function within the environment. With projected increases …

Rna Sequencing Analysis Of The Msl2msl3, Crl, And Ggps1 Mutants Indicates That Diverse Sources Of Plastid Dysfunction Do Not Alter Leaf Morphology Through A Common Signaling Pathway, Darron R. Luesse, Margaret E. Wilson, Elizabeth S. Haswell

Biology Faculty Research

Determining whether individual genes function in the same or in different pathways is an important aspect of genetic analysis. As an alternative to the construction of higher-order mutants, we used contemporary expression profiling methods to perform pathway analysis on several Arabidopsis thaliana mutants, including the mscS-like (msl)2msl3 double mutant. MSL2 and MSL3 are implicated in plastid ion homeostasis, and msl2msl3 double mutants exhibit leaves with a lobed periphery, a rumpled surface, and disturbed mesophyll cell organization. Similar developmental phenotypes are also observed in other mutants with defects in a range of other chloroplast or mitochondrial functions, including …

A Novel Transcription Factor In Arabidopsis Thaliana Abiotic Stress Response, Achira S. Weerathunga Arachchilage

LSU New Orleans Theses and Dissertations

Plants respond to environmental stress by altering their gene expression. Under stress conditions some genes are activated and some genes are repressed. Even though a lot of work has been done to understand mechanisms of gene activation under abiotic stress very little information is available on how stress responsive genes are kept repressed under normal growth conditions. Recent work has revealed that plants use transcriptional repression as common mechanism of gene repression. Transcriptional repression is achieved by recruitment co-repressor complexes to the target genes. Recent studies have revealed that the co-repressor LUH complexes with SLK1 and SLK2 to silence Arabidopsis …

A Desert In Disguise: The Resilience Of The Nebraska Sandhills, Jeff Hartman

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

The Nebraska Sandhills are the largest sand dune system in the Western Hemisphere, and are unique because they remain relatively undisturbed from row crop agriculture. Research in the past two decades demonstrated that the Sandhills are dynamic on millennial timescales, switching between stabilized, vegetated states to non-vegetated, mobilized states. The Sandhills are currently stabilized, but understanding how ecological processes are altered as sand dunes transition from stabilized to mobilized states, provides insight into the thresholds, stability, and resilience of this grassland ecosystem. My research investigated the impacts of vegetation disturbances on ecological processes and the sand dune surface stability. For …

Extension Agriculture And Natural Resources In The U.S. Midwest: A Review And Analysis Of Challenges And Future Opportunities, Mahdi M. Al-Kaisi, Roger Wesley Elmore, Gerald A. Miller, David Kwaw-Mensah

Department of Agronomy and Horticulture: Faculty Publications

This review addresses key changes in U.S. agricultural extension and future opportunities. Agricultural extension has been a part of the land-grant university (LGU) system for more than 100 years. The Morrill Act of 1862 established the LGU system by authorizing states access to federally controlled land and funding for public institutions offering educational opportunities focusing on agriculture and mechanical arts for farmers and the working class. Current surveys in Iowa reveal changing trends in extension: more than 90% of farmers identified private-sector crop advisers as their primary source for recommendations, whereas more than 80% of those advisors identified Iowa State …

Ubiquitin Goes Green, Zhihua Hua, Richard D. Vierstra

Biology Faculty Research

Chloroplasts depend on the nucleus for much of their proteome. Consequently, strong transcriptional coordination exists between the genomes, which is attuned to the developmental and physiological needs of the organelle. Recent studies highlight that the post-translational modifier ubiquitin adds another layer to plastid homeostasis and even helps eliminate damaged chloroplasts.

Soybean Yield And Nodulation Response To Crop History And Inoculation, Stephen Mason, Tomie Galusha, Zaher Kmail

Department of Agronomy and Horticulture: Faculty Publications

Soybean [Glycine max (L.) Merr.] inoculation was imposed on a long-term continuous grain sorghum [Sorghum bicolor (L.) Moench] and soybean cropping systems study with and without manure application at Mead, NE. The objective was to determine the influence of 28-yr history of continuous grain sorghum and soybean production, inoculation, and manure on soybean yield and nodulation. Average 2-yr soybean grain yield was 0.5 Mg ha^–1 greater on plots with continuous grain sorghum crop history rather than soybean history, even after this history was broken by 2-yr crop rotation with grain sorghum in the 2 yr previous to …

Soil Moisture Affects Growing-Season Wildfire Size In The Southern Great Plains, Erik S. Krueger, Tyson E. Ochsner, David M. Engle, J. D. Carlson, Dirac L. Twidwell, Samuel D. Fuhlendorf

Department of Agronomy and Horticulture: Faculty Publications

The increasing availability of soil moisture data presents an opportunity for its use in wildfire danger assessments, but research regarding the influence of soil moisture on wildfires is scarce. Our objective was to identify relationships between soil moisture and wildfire size for Oklahoma wildfires during the growing (May-October) and dormant seasons (November-April). We hypothesized that soil moisture influences wildfire size when vegetation is growing but is less important when most vegetation is dead or dormant. Soil moisture, as fraction of available water capacity (FAW), and commonly measured weather variables were determined for 38,419 wildfires from 2000–2012. Wildfires were grouped by …