Plant Biology Commons^™

Nutrients In The Nexus, Eric A. Davidson, Rachel L. Nifong, Richard B. Ferguson, Cheryl Palm, Deanna L. Osmond, Jill S. Baron

Department of Agronomy and Horticulture: Faculty Publications

Synthetic nitrogen (N) fertilizer has enabled modern agriculture to greatly improve human nutrition during the twentieth century, but it has also created unintended human health and environmental pollution challenges for the twentyfirst century. Averaged globally, about half of the fertilizer-N applied to farms is removed with the crops, while the other half remains in the soil or is lost from farmers’ fields, resulting in water and air pollution. As human population continues to grow and food security improves in the developing world, the dual development goals of producing more nutritious food with low pollution will require both technological and socioeconomic …

Registration Of ‘Ne05548’ (Husker Genetics Brand Panhandle) Hard Red Winter Wheat, P. Stephen Baenziger, R. A. Graybosch, T. Regassa, R. N. Klein, Greg R. Kruger, D. K. Santra, L. Xu, D. J. Rose, S. N. Wegulo, Y. Jin, J. Kolmer, G. L. Hein, M.-S. Chen, G. Bai, R. L. Bowden, J. Poland

Department of Agronomy and Horticulture: Faculty Publications

Western Nebraska wheat producers and those in adjacent areas want taller wheat (Triticum aestivum L.) cultivars that retain their height under drought for better harvestability. ‘NE05548’ (Reg. No. CV-1117, PI 670462) hard red winter wheat was developed cooperatively by the Nebraska Agricultural Experiment Station and the USDA-ARS and released in January 2014 by the developing institutions. NE05548 was released primarily for its superior performance under rainfed conditions in western Nebraska and adjacent areas of the Great Plains and its tall plant stature. NE05548 was selected from the cross NE97426/NE98574 made in 1999 where the pedigree of NE97426 is ‘Brigantina’/2*‘Arapahoe’ …

A Population Of Deletion Mutants And An Integrated Mapping And Exome-Seq Pipeline For Gene Discovery In Maize, Shangang Jia, Aixia Li, Kyla Morton, Penny Avoles-Kianian, Shahryar F. Kianian, Chi Zhang, David Holding

Department of Agronomy and Horticulture: Faculty Publications

To better understand maize endosperm filling and maturation, we used gamma irradiation of the B73 maize reference line to generate mutants with opaque endosperm and reduced kernel fill phenotypes, and created a population of 1788 lines including 47 Mo17 × F2s showing stable, segregating and viable kernel phenotypes. For molecular characterization of the mutants, we developed a novel functional genomics platform that combined Bulked Segregant RNA and Exome sequencing (BSREx-seq) to map causative mutations and identify candidate genes within mapping intervals. To exemplify the utility of the mutants and provide proof-ofconcept for the bioinformatics platform, we present detailed characterization of …

Multi-Population Selective Genotyping To Identify Soybean [Glycine Max (L.) Merr.] Seed Protein And Oil Qtls, Piyaporn Phansak, Watcharin Soonsuwon, David L. Hyten, Qijian Song, Perry B. Cregan, George L. Graef, James E. Specht

Department of Agronomy and Horticulture: Faculty Publications

Plant breeders continually generate ever-higher yielding cultivars, but also want to improve

seed constituent value, which is mainly protein and oil, in soybean [Glycine max (L.) Merr.]. Identification of genetic loci governing those two traits would facilitate that effort. Though genome-wide association offers one such approach, selective genotyping of multiple biparental populations offers a complementary alternative, and was evaluated here, using 48 F2:3 populations (n = ~224 plants) created by mating 48 high protein germplasm accessions to cultivars of similar maturity, but with normal seed protein content. All F2:3 progeny were phenotyped for seed protein and oil, but only …

Accuracy Of Genomic Prediction In Switchgrass (Panicum Virgatum L.) Improved By Accounting For Linkage Disequilibrium, Guillaume P. Ramstein, Joseph Evans, Shawn M. Kaeppler, Robert B. Mitchell, Kenneth P. Vogel, C. Robin Buell, Michael D. Casler

Department of Agronomy and Horticulture: Faculty Publications

Switchgrass is a relatively high-yielding and environmentally sustainable biomass crop, but further genetic gains in biomass yield must be achieved to make it an economically viable bioenergy feedstock. Genomic selection (GS) is an attractive technology to generate rapid genetic gains in switchgrass, and meet the goals of a substantial displacement of petroleum use with biofuels in the near future. In this study, we empirically assessed prediction procedures for genomic selection in two different populations, consisting of 137 and 110 half-sib families of switchgrass, tested in two locations in the United States for three agronomic traits: dry matter yield, plant height, …

Prospects Of Genomic Prediction In The Usda Soybean Germplasm Collection: Historical Data Creates Robust Models For Enhancing Selection Of Accessions, Diego Jarquin, James Specht, Aaron Lorenz

Department of Agronomy and Horticulture: Faculty Publications

The identification and mobilization of useful genetic variation from germplasm banks for use in breeding programs is critical for future genetic gain and protection against crop pests. Plummeting costs of next-generation sequencing and genotyping is revolutionizing the way in which researchers and breeders interface with plant germplasm collections. An example of this is the high density genotyping of the entire USDA Soybean Germplasm Collection. We assessed the usefulness of 50K SNP data collected on 18,480 domesticated soybean (G. max) accessions and vast historical phenotypic data for developing genomic prediction models for protein, oil, and yield. Resulting genomic prediction models explained …

Expression Of Apoplast-Targeted Plant Defensin Mtdef4.2 Confers Resistance To Leaf Rust Pathogen Puccinia Triticina But Does Not Affect Mycorrhizal Symbiosis In Transgenic Wheat, Jagdeep Kaur, John Fellers, Alok Adholeya, Siva L.S. Velivelli, Kaoutar El-Mounadi, Natalya Nersesian, Thomas Clemente, Dilip Shah

Department of Agronomy and Horticulture: Faculty Publications

Rust fungi of the order Pucciniales are destructive pathogens of wheat worldwide. Leaf rust caused by the obligate, biotrophic basidiomycete fungus Puccinia triticina (Pt) is an economically important disease capable of causing up to 50 % yield losses. Historically, resistant wheat cultivars have been used to control leaf rust, but genetic resistance is ephemeral and breaks down with the emergence of new virulent Pt races. There is a need to develop alternative measures for control of leaf rust in wheat. Development of transgenic wheat expressing an antifungal defensin offers a promising approach to complement the endogenous resistance genes …

Corn (Zea Mays L.) Seeding Rate Optimization In Iowa, Usa, Mark A. Licht, Andrew W. Lenssen, Roger W. Elmore

Department of Agronomy and Horticulture: Faculty Publications

Collecting soil, topography, and yield information has become more feasible and reliable with advancements in precision technologies. Combined with the accessibility of precision technologies and services to farmers, there has been increased interest and ability to make site-specific crop management decisions. The objective of this research was to develop procedures to optimize corn seeding rates and maximize yield using soil and topographic parameters. Experimental treatments included five seeding rates (61 750; 74 100; 86 450; 98 800; and 111 150 seeds ha^-1) in a randomized complete block design in three central Iowa fields from 2012 to 2014 (nine …

Alkaline Stress And Iron Deficiency Regulate Iron Uptake And Riboflavin Synthesis Gene Expression Differently In Root And Leaf Tissue: Implications For Iron Deficiency Chlorosis, En-Jung Hsieh, Brian M. Waters

Department of Agronomy and Horticulture: Faculty Publications

Iron (Fe) is an essential mineral that has low solubility in alkaline soils, where its deficiency results in chlorosis. Whether low Fe supply and alkaline pH stress are equivalent is unclear, as they have not been treated as separate variables in molecular physiological studies. Additionally, molecular responses to these stresses have not been studied in leaf and root tissues simultaneously. We tested how plants with the Strategy I Fe uptake system respond to Fe deficiency at mildly acidic and alkaline pH by measuring root ferric chelate reductase (FCR) activity and expression of selected Fe uptake genes and riboflavin synthesis genes. …

Multi-Phase Us Spread And Habitat Switching Of A Post-Columbian Invasive, Sorghum Halepense, U. Uzay Sezen, Jacob N. Barney, Daniel Z. Atwater, Gary A. Pederson, Jeffrey F. Pedersen, J. Mike Chandler, T. Stan Cox, Sheila Cox, Peter Dotray, David Kopec, Steven E. Smith, Jill Schroeder, Steven D. Wright, Yuannian Jiao, Wenqian Kong, Valorie Goff, Susan Auckland, Lisa K. Rainville, Gary J. Pierce, Cornelia Lemke, Rosana Compton, Christine Phillips, Alexandra Kerr, Matthew Mettler, Andrew H. Paterson

Department of Agronomy and Horticulture: Faculty Publications

Johnsongrass (Sorghum halepense) is a striking example of a post-Columbian founder event. This natural experiment within ecological time-scales provides a unique opportunity for understanding patterns of continent-wide genetic diversity following range expansion. Microsatellite markers were used for population genetic analyses including leaf-optimized Neighbor-Joining tree, pairwise FST, mismatch analysis, principle coordinate analysis, Tajima's D, Fu's F and Bayesian clusterings of population structure. Evidence indicates two geographically distant introductions of divergent genotypes, which spread across much of the US ingeophylogeny, gene flow patterns can be inferred to have involved five phases. Centers of genetic diversity have shifted from two introduction …

Dioxygenase-Encoding Atdao1 Gene Controls Iaa Oxidation And Homeostasis In Arabidopsis, Silvana Porco, Aleš Pěnčík, Afaf Rashed, Ute Voβ, Rubén Casanova-Sáez, Anthony Bishop, Agata Golebiowska, Rahul Bhosale, Ranjan Swarup, Kamal Swarup, Pavlína Penáková, Ondrej Novák, Paul E. Staswick, Peter Hedden, Andrew L. Phillips, Kris Vissenberg, Malcolm J. Bennett, Karin Ljung

Department of Agronomy and Horticulture: Faculty Publications

Auxin represents a key signal in plants, regulating almost every aspect of their growth and development. Major breakthroughs have been made dissecting the molecular basis of auxin transport, perception, and response. In contrast, how plants control the metabolism and homeostasis of the major form of auxin in plants, indole-3- acetic acid (IAA), remains unclear. In this paper, we initially describe the function of the Arabidopsis thaliana gene DIOXYGENASE FOR AUXIN OXIDATION 1 (AtDAO1). Transcriptional and translational reporter lines revealed that AtDAO1 encodes a highly root-expressed, cytoplasmically localized IAA oxidase. Stable isotope-labeled IAA feeding studies of loss and …

Impact Of Derived Global Weather Data On Simulated Crop Yields, Justin Van Wart, Patricio Grassini, Kenneth Cassman

Department of Agronomy and Horticulture: Faculty Publications

Crop simulation models can be used to estimate impact of current and future climates on crop yields and food security, but require long-term historical daily weather data to obtain robust simulations. In many regions where crops are grown, daily weather data are not available. Alternatively, gridded weather databases (GWD) with complete terrestrial coverage are available, typically derived from: (i) global circulation computer models; (ii) interpolated weather station data; or (iii) remotely sensed surface data from satellites. The present study’s objective is to evaluate capacity of GWDs to simulate crop yield potential (Yp) or water-limited yield potential (Yw), which can serve …

Global Nitrogen Budgets In Cereals: A 50-Year Assessment For Maize, Rice, And Wheat Production Systems, J. K. Ladha, A. Tirol-Padre, C. K. Reddy, Kenneth Cassman, Sudhir Verma, D. S. Powlson, C. Van Kessel, Daniel De B. Richter, Debashis Chakraborty, Himanshu Pathak

Department of Agronomy and Horticulture: Faculty Publications

Industrially produced N-fertilizer is essential to the production of cereals that supports current and projected human populations. We constructed a top-down global N budget for maize, rice, and wheat for a 50-year period (1961 to 2010). Cereals harvested a total of 1551 Tg of N, of which 48% was supplied through fertilizer-N and 4% came from net soil depletion. An estimated 48% (737 Tg) of crop N, equal to 29, 38, and 25 kg ha⁻¹ yr⁻¹ for maize, rice, and wheat, respectively, is contributed by sources other than fertilizer- or soil-N. Non-symbiotic N₂ fixation appears to be …

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 …

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 …

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 …

Comprehensive Comparative Genomic And Transcriptomic Analyses Of The Legume Genes Controlling The Nodulation Process, Zhenzhen Qiao, Lise Pingault, Mehrnoush Nourbakhsh-Rey, Marc Libault

Department of Agronomy and Horticulture: Faculty Publications

Nitrogen is one of the most essential plant nutrients and one of the major factors limiting crop productivity. Having the goal to perform a more sustainable agriculture, there is a need to maximize biological nitrogen fixation, a feature of legumes. To enhance our understanding of the molecular mechanisms controlling the interaction between legumes and rhizobia, the symbiotic partner fixing and assimilating the atmospheric nitrogen for the plant, researchers took advantage of genetic and genomic resources developed across different legume models (e.g., Medicago truncatula, Lotus japonicus, Glycine max, and Phaseolus vulgaris) to identify key regulatory protein coding genes of the nodulation …

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 …

Comparison Of An Ultra-Low Volume (Ulv) Sprayer Against A Conventional Sprayer, For Foliar Fertiliser And Fungicide Applications In Turfgrass, Jason Connor Ferguson, Roch E. Gaussoin, John A. Eastin, Matthew D. Sousek, Greg R. Kruger

Department of Agronomy and Horticulture: Faculty Publications

Two field studies (I and II) at the University of Nebraska-Lincoln: John Seaton Anderson Turfgrass Research Facility near Mead, NE, USA, were conducted to determine if a new ultra-low volume (ULV) sprayer can apply foliar nutrient, growth regulator, and fungicide treatments, in a manner similar to that of a conventional sprayer. Treatments were applied over creeping bentgrass ‘L-93’ (Agrostis stolonifera L.) managed as a fairway at 561 l · ha⁻¹ and 47 l · ha⁻¹ with the conventional and ULV sprayer, respectfully. Data were collected for chlorophyll content with a chlorophyll meter, and for the normalised difference …

Organic Struggle: The Movement For Sustainable Agriculture In The United States [Book Review], Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Organic Struggle chronicles the challenges encountered by innovators in a growing segment of the U.S. food production and marketing system. Practiced for millennia by farmers before the introduction of chemical fertilizers and pesticides, and first developed more formally in Europe, organic farming practices began to gain prominence in the United States only in the 1950s. Far more than a system for producing food, this strategy has become a focus for those supporting healthy and pesticide-free products, for some who embrace the organic system as a food movement, and by many who disagree with the current domination of the country’s food …

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 …

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 …