Plant Biology Commons^™

Development Of Leaf Shape And Vein Homologies In Five Species Of The Genus Ipomoea (Convolvulaceae), Austin William Jones

Dissertations and Theses @ UNI

Angiosperm leaves are extremely variable in form while predominantly maintaining the function of the primary photosynthetic organ of the plant. Changes in leaf form can result from myriad physiological processes which may be influenced by ecology, physical stimuli, phylogeny, or other factors. In studying the development of divergent leaf forms among closely related species, conserved morphological elements may be identified that are not apparent in the mature form. The genus Ipomoea (Convolvulaceae) contains over 600 species and a wide range in leaf shapes. Five species, I. purpurea, I. coccinea, I. sloteri, I. quamoclit, and I. cairica show a range in …

Tracking Above- And Below- Ground Seed Persistence And Mortality In A Native Tallgrass Prairie Restoration, Carmen Pellish

Dissertations and Theses @ UNI

The large cost of seed and low seedling establishment rates make restoring native tallgrass prairies expensive and difficult. Tallgrass prairie restorations typically achieve seedling emergence rates of only 10%. This begs the question of what happens to the remaining 90% of seeds that do not emerge as seedlings. This thesis sought to assess or quantify the importance of seed predators and death by microorganisms or to senescence on seed survival and seedling establishment within a newly planted native tallgrass prairie restoration under typical restoration conditions. I hypothesized that small vertebrate seed predators would play be detrimental to overall seedling emergence …

How Do Various Maize Crop Models Vary In Their Responses To Climate Change Factors?, Simon Bassu, Nadine Brisson, Jean-Louis Durand, Kenneth J. Boote, Jon Lizaso, James Jones, Cynthia Rosenzweig, Alex Ruane, Myriam Adam, Christian Baron, Bruno Basso, Christian Biernath, Hendrick Boogaard, Sjaak Conijn, Marc Corbeels, Delphine Deryng, Giacomo De Sanctis, Sebastian Gayler, Patricio Grassini, Jerry Hatfield, Steven Hoek, Cesar Izaurralde, Raymond Jongschaap, Armen Kemanian, Christian Kersebaum, Soo-Hyung Kim, Naresh Kumar, David Makowski, Christoph Muller, Claas Nendel, Eckart Priesack, Maria Virinia Pravia, Federico Sau, Iurii Shcherbak, Fulu Tao, Edmar Teixeira, Dennis Timlin, Katharina Waha

Department of Agronomy and Horticulture: Faculty Publications

Potential consequences of climate change on crop production can be studied using mechanistic crop simulation models. While a broad variety of maize simulation models exist, it is not known whether different models diverge on grain yield responses to changes in climatic factors, or whether they agree in their general trends related to phenology, growth, and yield. With the goal of analyzing the sensitivity of simulated yields to changes in temperature and atmospheric carbon dioxide concentrations [CO2], we present the largest maize crop model intercomparison to date, including 23 different models. These models were evaluated for four locations representing a wide …

Identification Of Differentially Expressed Genes Between Sorghum Genotypes With Contrasting Nitrogen Stress Tolerance By Genome-Wide Transcriptional Profiling, Malleswari Gelli, Yongchao Duo, Anji Reddy Konda, Chi Zhang, David R. Holding, Ismail M. Dweikat

Department of Agronomy and Horticulture: Faculty Publications

Background: Sorghum is an important cereal crop, which requires large quantities of nitrogen fertilizer for achieving commercial yields. Identification of the genes responsible for low-N tolerance in sorghum will facilitate understanding of the molecular mechanisms of low-N tolerance, and also facilitate the genetic improvement of sorghum through marker-assisted selection or gene transformation. In this study we compared the transcriptomes of root tissues from seven sorghum genotypes having differential response to low-N stress.

Results: Illumina RNA-sequencing detected several common differentially expressed genes (DEGs) between four low-N tolerant sorghum genotypes (San Chi San, China17, KS78 and high-NUE bulk) and three …

Grazing Management Effect On Micro- And Macro- Scale Fate Of C And N In Rangelands, Martha Mamo, Jeff Bradshaw, Richard Ferguson, Kent M. Eskridge, John A. Guretzky, Karla Jenkins, Walter H. Schacht, Jerry Volesky, Sean Whipple, Anita Wingeyer, Haishun Yang

Department of Agronomy and Horticulture: Faculty Publications

No abstract provided.

Quantitative Proteomic Analysis Of The Salmonella-Lettuce Interaction, Yuping Zhang, Renu Nandakumar, Shannon L. Bartelt-Hunt, Daniel D. Snow, Laurie Hodges, Xu Li

Department of Agronomy and Horticulture: Faculty Publications

Human pathogens can internalize food crops through root and surface uptake and persist inside crop plants. The goal of the study was to elucidate the global modulation of bacteria and plant protein expression after Salmonella internalizes lettuce. A quantitative proteomic approach was used to analyse the protein expression of Salmonella enterica serovar Infantis and lettuce cultivar Green Salad Bowl 24 h after infiltrating S. Infantis into lettuce leaves. Among the 50 differentially expressed proteins identified by comparing internalized S. Infantis against S. Infantis grown in Luria Broth, proteins involved in glycolysis were down-regulated, while one protein involved in ascorbate …

Switchgrass (Panicum Virgatum L) Flag Leaf Transcriptomes Reveal Molecular Signatures Of Leaf Development, Senescence, And Mineral Dynamics, Nathan A. Palmer, Teresa Donze-Reiner, David Horvath, Tiffany Heng-Moss, Brian M. Waters, Christian M. Tobias, Gautam Sarath

Department of Agronomy and Horticulture: Faculty Publications

Switchgrass flag leaves can be expected to be a source of carbon to the plant, and its senescence is likely to impact the remobilization of nutrients from the shoots to the rhizomes. However, many genes have not been assigned a function in specific stages of leaf development. Here, we characterized gene expression in flag leaves over their development. By merging changes in leaf chlorophyll and the expression of genes for chlorophyll biosynthesis and degradation, a four-phase molecular roadmap for switchgrass flag leaf ontogeny was developed. Genes associated with early leaf development were up-regulated in phase 1. Phase 2 leaves had …

Genotyping By Sequencing For Genomic Prediction In A Soybean Breeding Population, Diego Jarquin, Kyle Kocak, Luis Posadas, Katie Hyma, Joseph Jedlicka, George L. Graef, Aaron Lorenz

Department of Agronomy and Horticulture: Faculty Publications

Background: Advances in genotyping technology, such as genotyping by sequencing (GBS), are making genomic prediction more attractive to reduce breeding cycle times and costs associated with phenotyping. Genomic prediction and selection has been studied in several crop species, but no reports exist in soybean. The objectives of this study were (i) evaluate prospects for genomic selection using GBS in a typical soybean breeding program and (ii) evaluate the effect of GBS marker selection and imputation on genomic prediction accuracy. To achieve these objectives, a set of soybean lines sampled from the University of Nebraska Soybean Breeding Program were genotyped using …

Detection And Confirmation Of Quantitative Trait Loci For Soybean Seed Isoflavones, Christopher J. Smallwood, Catherine N. Nyinyi, Dean A. Kopsell, Carl E. Sams, Dennis R. West, Pengyin Chen, Stella K. Kantartzi, P. B. Cregan, D. L. Hyten, Vincent R. Pantalone

Department of Agronomy and Horticulture: Faculty Publications

Interest in soybean [Glycine max (L.) Merr.] isoflavones has increased in recent years owing to numerous reported health benefits. Consequently, quantitative trait loci (QTL) detection for marker-assisted breeding for isoflavones is being examined for genetic gains. This study sought to detect QTL for soybean isoflavones in a population of 274 recombinant inbred lines derived from a cross between ‘Essex’ and ‘Williams 82’ that were subdivided and tested by maturity (early, mid, and late). The field tests were conducted in three environments in 2009 (Knoxville, TN; Harrisburg, IL; and Stuttgart, AR). The population was genotyped with 480 polymorphic single nucleotide …

A Reference Genome For Common Bean And Genome-Wide Analysis Of Dual Domestications, Jeremy Schmutz, Phillip E. Mcclean, Sujan Mamidi, G. Albert Wu, Steven B. Cannon, Jane Grimwood, Jerry Jenkins, Shengqiang Shu, Qijian Song, Carolina Chavarro, Mirayda Torres-Torres, Valerie Geffroy, Samira Mafi Moghaddam, Dongying Gao, Brian Abernathy, Kerrie Barry, Matthew Blair, Mark A. Brick, Mansi Chovatia, Paul Gepts, David M. Goodstein, Michael Gonzales, Uffe Hellsten, D. L. Hyten, Gaofeng Jia, James D. Kelly, Dave Kudrna, Rian Lee, Manon M.S. Richard, Phillip N. Miklas, Juan M. Osorno, Josiane Rodrigues, Vincent Thareau, Carlos A. Urrea Florez, Mei Wang, Yeisoo Yu, Ming Zhang, Rod A. Wing, P. B. Cregan, Daniel S. Rokhsar, Scott A. Jackson

Department of Agronomy and Horticulture: Faculty Publications

Common bean (Phaseolus vulgaris L.) is the most important grain legume for human consumption and has a role in sustainable agriculture owing to its ability to fix atmospheric nitrogen. We assembled 473 Mb of the 587-Mb genome and genetically anchored 98% of this sequence in 11 chromosome-scale pseudomolecules. We compared the genome for the common bean against the soybean genome to find changes in soybean resulting from polyploidy. Using resequencing of 60 wild individuals and 100 landraces from the genetically differentiated Mesoamerican and Andean gene pools, we confirmed 2 independent domestications from genetic pools that diverged before human colonization. …

The Interaction Of Climate Change, Land Cover, And Political Representation In The Usa, Brady W. Allred, Dirac L. Twidwell, Samuel D. Fuhlendorf

Department of Agronomy and Horticulture: Faculty Publications

The difficulties in tackling climate change are inherently complex and primarily centered on political and social values. This is evident in the United States where political divisions and polarizations are fundamental barriers to advancing national policies, which in turn hinder international agreements, mitigation, and adaptation. Within the United States, the vast majority of agricultural and natural resource lands are projected to incur significant climate departures and are represented by the Republican Party. The resources and economic sectors that will be directly affected by climate change are represented by national leadership that is unlikely to accept policies to prevent or adapt …

Arabidopsis Lipins, Pdat1 Acyltransferase, And Sdp1 Triacylglycerol Lipase Synergistically Direct Fatty Acids Toward Β-Oxidation, Thereby Maintaining Membrane Lipid Homeostasis, Jilian Fan, Chengshi Yan, Rebecca Roston, John Shanklin, Changcheng Xu

Department of Agronomy and Horticulture: Faculty Publications

Triacylglycerol (TAG) metabolism is a key aspect of intracellular lipid homeostasis in yeast and mammals, but its role in vegetative tissues of plants remains poorly defined. We previously reported that PHOSPHOLIPID:DIACYLGLYCEROL ACYLTRANSFERASE1 (PDAT1) is crucial for diverting fatty acids (FAs) from membrane lipid synthesis to TAG and thereby protecting against FA-induced cell death in leaves. Here, we show that overexpression of PDAT1 enhances the turnover of FAs in leaf lipids. Using the trigalactosyldiacylglycerol1-1 (tgd1-1) mutant, which displays substantially enhanced PDAT1- mediated TAG synthesis, we demonstrate that disruption of SUGAR-DEPENDENT1 (SDP1) TAG lipase or PEROXISOMAL TRANSPORTER1 (PXA1) severely decreases …

Nonsyntenic Genes Drive Highly Dynamic Complementation Of Gene Expression In Maize Hybrids, Anja Paschold, Nick B. Larson, Caroline Marcon, James C. Schnable, Cheng-Ting Yeh, Christa Lanz, Dan Nettleton, Hans-Peter Piepho, Patrick S. Schnable, Frank Hochholdinger

Department of Agronomy and Horticulture: Faculty Publications

Maize (Zea mays) displays an exceptional level of structural genomic diversity, which is likely unique among higher eukaryotes. In this study, we surveyed how the genetic divergence of two maize inbred lines affects the transcriptomic landscape in four different primary root tissues of their F1-hybrid progeny. An extreme instance of complementation was frequently observed: genes that were expressed in only one parent but in both reciprocal hybrids. This single-parent expression (SPE) pattern was detected for 2341 genes with up to 1287 SPE patterns per tissue. As a consequence, the number of active genes in hybrids exceeded that of …

Dt2 Is A Gain-Of-Function Mads-Domain Factor Gene That Specifies Semideterminacy In Soybean, Jieqing Ping, Yunfeng Liu, Lianjun Sun, Meixia Zhao, Yinghui Li, Zongxiang Tang, Hanh Nguyen, Zhixi Tian, Lijuan Qiu, Randall L. Nelson, Thomas E. Clemente, James Specht, Jianxin Ma

Department of Agronomy and Horticulture: Faculty Publications

Similar to Arabidopsis thaliana, the wild soybeans (Glycine soja) and many cultivars exhibit indeterminate stem growth specified by the shoot identity gene Dt1, the functional counterpart of Arabidopsis TERMINAL FLOWER1 (TFL1). Mutations in TFL1 and Dt1 both result in the shoot apical meristem (SAM) switching from vegetative to reproductive state to initiate terminal flowering and thus produce determinate stems. A second soybean gene (Dt2) regulating stem growth was identified, which, in the presence of Dt1, produces semideterminate plants with terminal racemes similar to those observed in determinate plants. Here, we report positional …

Nebraska’S Groundwater Legacy: Nitrate Contamination Beneath Irrigated Cropland, Mary E. Exner Spaulding, Aaron J. Hirsh, Roy F. Spalding

Department of Agronomy and Horticulture: Faculty Publications

A 31 year record of ~44,000 nitrate analyses in ~11,500 irrigation wells was utilized to depict the decadal expansion of groundwater nitrate contamination (N>10 mg/L) in the irrigated corn-growing areas of eastern and central Nebraska and analyze long-term nitrate concentration trends in 17 management areas (MAs) subject to N fertilizer and budgeting requirements. The 1.3 M contaminated hectares were characterized by irrigation method, soil drainage, and vadose zone thickness and lithology. The areal extent and growth of contaminated groundwater in two predominately sprinkler-irrigated areas was only ~20% smaller beneath well-drained silt loams with thick clayey-silt unsaturated layers and unsaturated …

Multilocation Corn Stover Harvest Effects On Crop Yields And Nutrient Removal, Douglas L. Karlen, Stuart J. Birrell, Jane M.F. Johnson, Shannon L. Osborne, Thomas E. Schumacher, Gary E. Varvel, Richard B. Ferguson, Jeff M. Novak, James R. Frederick, John M. Baker, John A. Lamb, Paul R. Alder, Greg W. Roth, Emerson D. Nafziger

Department of Agronomy and Horticulture: Faculty Publications

Corn (Zea mays L.) stover was identified as an important feedstock for cellulosic bioenergy production because of the extensive area upon which the crop is already grown. This report summarizes 239 site-years of field research examining effects of zero, moderate, and high stover removal rates at 36 sites in seven different states. Grain and stover yields from all sites as well as N, P, and K removal from 28 sites are summarized for nine longitude and six latitude bands, two tillage practices (conventional vs no tillage), two stoverharvest methods (machine vs calculated), and two crop rotations {continuous corn (maize) …

Do Cover Crops Increase Or Decrease Nitrous Oxide Emissions? A Meta-Analysis, Andrea D. Basche, F. E. Miguez, T. C. Kaspar, M. J. Castellano

Department of Agronomy and Horticulture: Faculty Publications

There are many environmental benefits to incorporating cover crops into crop rotations, such as their potential to decrease soil erosion, reduce nitrate (NO₃) leaching, and increase soil organic matter. Some of these benefits impact other agroecosystem processes, such as greenhouse gas emissions. In particular, there is not a consensus in the literature regarding the effect of cover crops on nitrous oxide (N₂O) emissions. Compared to site-specific studies, meta-analysis can provide a more general investigation into these effects. Twenty-six peer-reviewed articles including 106 observations of cover crop effects on N₂O emissions from the soil surface …

Challenges And Opportunities In Transdisciplinary Science: The Experience Of Next Generation Scientists In An Agriculture And Climate Research Collaboration, Andrea D. Basche, Gabrielle E. Roesch-Mcnally, Lindsay A. Pease, Christopher D. Eidson, Guy Bou Lahdou, Mike W. Dunbar, Trevor J. Frank, Laura Frescoln, Lei Gu, Ryan Nagelkirk, Jose Pantoja, Adam K. Wilke

Department of Agronomy and Horticulture: Faculty Publications

Agriculture in the twenty-first century faces unprecedented challenges from increasing climate variability to growing demands on natural resources to globalizing economic markets. These emerging agricultural issues, spanning both human and natural dimensions, are uniquely formulated, exceedingly complex, and difficult to address within existing disciplinary domains (Eigenbrode et al. 2007; Reganold et al. 2011; Foley et al. 2005; Hansen et al. 2013). Therefore, the next generation of scientists working on these issues must not only be highly trained within a disciplinary context but must also have the capacity to collaborate with others to solve systems-level problems.

The Carbon-Nitrogen Balance Of The Nodule And Its Regulation Under Elevated Carbon Dioxide Concentration, Marc Libault

Department of Agronomy and Horticulture: Faculty Publications

Legumes have developed a unique way to interact with bacteria: in addition to preventing infection from pathogenic bacteria like any other plant, legumes also developed a mutualistic symbiotic relationship with one gender of soil bacteria: rhizobium. This interaction leads to the development of a new root organ, the nodule, where the differentiated bacteria fix for the plant the atmospheric dinitrogen (atmN₂). In exchange, the symbiont will benefit from a permanent source of carbon compounds, products of the photosynthesis. The substantial amounts of fixed carbon dioxide dedicated to the symbiont imposed to the plant a tight regulation of the …

Glyphosate-Resistant Giant Ragweed (Ambrosia Trifida) Control In Glufosinate-Resistant Soybean, Simranpreet Kaur, Lowell D. Sandell, John L. Lindquist, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

Glyphosate-resistant giant ragweed is one of the most competitive weeds of agronomic crops in the United States. Early emergence and rapid growth rate makes giant ragweed a competitive weed early in the season and reduces crop yields. Therefore, early spring control of giant ragweed using a preplant herbicide is critical. Glufosinate is an alternative POST herbicide for weed control in glufosinate-resistant soybean. Field experiments were conducted at David City, NE, in 2012 and 2013 to evaluate the efficacy of preplant herbicides followed by glufosinate applied alone or in tank mixes for control of glyphosate-resistant giant ragweed in glufosinate-resistant soybean. Preplant …

Common Sunflower Seedling Emergence Across The U.S. Midwest, Sharon A. Clay, Adam Davis, Anita Dille, John Lindquist, Analiza H. M. Ramirez, Christy Sprague, Graig Reicks, Frank Forcella

Department of Agronomy and Horticulture: Faculty Publications

Predictions of weed emergence can be used by practitioners to schedule POST weed management operations. Common sunflower seed from Kansas was used at six Midwestern U.S. sites to examine the variability that 16 climates had on common sunflower emergence. Nonlinear mixed effects models, using a flexible sigmoidal Weibull function that included thermal time, hydrothermal time, and a modified hydrothermal time (with accumulation starting from January 1 of each year), were developed to describe the emergence data. An iterative method was used to select an optimal base temperature (T_b) and base and ceiling soil matric potentials (ψ_b and …