Plant Biology Commons^™

A Survey Of Soil Properties Affecting Vegetation Establishment Along Nebraska Highways, Shad D. Mills

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Vegetation along roadsides is important to prevent soil erosion, provide habitat and filter water running off the road. Along some highways in Nebraska vegetation does not readily establish and persist. It is thought that sodium and bulk density issues are the driving factor behind the lack of vegetation. After a construction project, the shoulder is seeded into the compacted soil, and salts can accumulate in the soil due to deicing agents being used during the winter. The purpose of our study was to determine if the bulk density and sodium are the driving factors of the vegetation cover. We also …

Use Of Uav Imagery And Nutrient Analyses For Estimation Of The Spatial And Temporal Contributions Of Cattle Dung To Nutrient Cycling In Grazed Ecosystems, Amanda E. Shine

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Nutrient inputs from cattle dung are crucial drivers of nutrient cycling processes in grazed ecosystems. These inputs are important both spatially and temporally and are affected by variables such as grazing strategy, water location, and the nutritional profile of forage being grazed. Past research has attempted to map dung deposition patterns in order to more accurately estimate nutrient input, but the large spatial extent of a typical pasture and the tedious nature of identifying and mapping individual dung pats has prohibited the development of a time- and cost-effective methodology. The first objective of this research was to develop and validate …

Evaluation Of A Global Spring Wheat Panel For Stripe Rust: Resistance Loci Validation And Novel Resources Identification, Ibrahim Elbasyoni, Walid M. El-Orabey, Sabah Morsy, P. S. Baenziger, Zakaria Al Ajlouni4, Ismail M. Dweikat

Department of Agronomy and Horticulture: Faculty Publications

Stripe rust (incited by Puccinia striiformis f. sp. tritici) is airborne wheat (Triticum aestivum L.) disease with dynamic virulence evolution. Thus, anticipatory and continued screening in hotspot regions is crucial to identify new pathotypes and integrate new resistance resources to prevent potential disease epidemics. A global wheat panel consisting of 882 landraces and 912 improved accessions was evaluated in two locations in Egypt during 2016 and 2017. Five prevalent and aggressive pathotypes of stripe rust were used to inoculate the accessions during the two growing seasons and two locations under field conditions. The objectives were to evaluate the panel for …

Metabolic Dynamics Of Developing Rice Seeds Under High Night-Time Temperature Stress, Balpreet K. Dhatt, Nathan Abshire, Puneet Paul, Kalani Hasanthika, Jaspreet Sandhu, Qi Zhang, Toshihiro Obata, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

High temperature stress during rice reproductive development results in yield losses. Reduced grain yield and grain quality has been associated with high temperature stress, and specifically with high night-time temperatures (HNT). Characterizing the impact of HNT on the phenotypic and metabolic status of developing rice seeds can provide insights into the mechanisms involved in yield and quality decline. Here, we examined the impact of warmer nights on the morphology and metabolome during early seed development in six diverse rice accessions. Seed size was sensitive to HNT in four of the six genotypes, while seed fertility and seed weight were unaffected. …

Understanding Nitrogen Limitation In Soybean, Nicolas Cafaro La Menza

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Meeting soybean demand on existing cropland area for a global population of 9.7 billion people by the year 2050 requires narrowing the existing gap between average producer yield and yield potential. Soybean relies on two sources on nitrogen (N): biological N₂ fixation and indigenous soil N supply. As soybean yield continues to increase, it seems critical to know if there is a yield level at which potential contribution of indigenous nitrogen sources and fixation becomes insufficient to meet crop N requirements for high yields, while still maintaining or increasing protein and oil concentration. This study evaluated N limitation across …

Legacy Effects Of Biodegradable Mulch And Soil Amendments On Vegetable Crops And The Soil, Elise V. H. Reid

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Plastic film mulches are used in horticulture to manage weeds, improve water retention, and increase soil temperature. Bioplastics and biofabrics are potentially sustainable alternatives to plastic film; however, they have different rates of in soil degradation. Polylactic acid (PLA) is a 100% biobased polymer that degrades slowly, but could fulfill organic certification to be soil incorporated. Mater-Bi is a commercially available biodegradable plastic (bioplastic), which degrades quickly, but cannot be incorporated in organic systems. Our objectives were to determine the individual and combined effects of soil amendments and residual mulch on vegetable crop yield and soil fertility. In a two-year …

Ghd8 Controls Rice Photoperiod Sensitivity By Forming A Complex That Interacts With Ghd7, Peng Wang, Rong Gong, Ying Yang, Sibin Yu

Department of Agronomy and Horticulture: Faculty Publications

Background: Flowering time is one of the most important agronomic characteristics that ultimately determine yield potential and eco-geographical adaptation in crops. Ghd8 and Ghd7, two major flowering genes, have similar functions and large pleiotropic effects in controlling the heading date, plant height and grain yield of rice. However, these gene interactions at the genetic and molecular levels have not been determined to date.

Results: In this study, we investigated the genetic interaction between Ghd8 and Ghd7 by using a set of near-isogenic lines and a panel of natural germplasm accessions in rice. We found that Ghd8 affected multiple agronomic traits …

Application Of Autofluorescence For Confocal Microscopy To Aid In Archaeoparasitological Analyses, Johnica Jo Morrow, Christian Elowsky

Department of Agronomy and Horticulture: Faculty Publications

Confocal laser scanning microscopy (CLSM) was used to examine archaeoparasitological specimens from coprolites associated with La Cueva de los Muertos Chiquitos (CMC) located near present-day Durango, Mexico. The eggs for 4 different types of parasites recovered from CMC coprolites were imaged using CLSM to assist with identification efforts. While some of the parasite eggs recovered from CMC coprolites were readily identified using standard light microscopy (LM), CLSM provided useful data for more challenging identifications by highlighting subtle morphological features and enhancing visualization of parasite egg anatomy. While other advanced microscopy techniques, such as scanning electron microscopy (SEM), may also detect …

Challenges And Opportunities For Weed Control In Nebraska Popcorn, Ethann R. Barnes

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Weed control in popcorn is challenging with limited herbicide options and popcorn’s perceived sensitivity to herbicides. Understanding the impact of weeds maximizes yield and profit. New herbicide-resistant crops increase chances of drift or misapplication into popcorn, which doesn’t have herbicide-resistant traits. Herbicides that are labeled in popcorn are often only conditionally labeled with reduce rates, warnings, or limited popcorn types. Dent-sterility in popcorn is contingent on the Ga1 gene (Ga1-s), but this system is at risk from Ga1-m field corn introduced from Mexico because it overcomes dent-sterility. This risk is under-assessed as Ga1-m carriers are undocumented and Mexican germplasm usage …

Canavalia And Dolichos Extracts For Sustainable Pest Biocontrol And Plant Nutrition Improvement In El Salvador, Carlos Martinez

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Botanical repellents and pesticides are now being rediscovered as new tools for integrated pest management in order to reduce the use of toxic chemicals in crop production. Canavalia gladiata and Dolichos lablab are two Fabaceae very well adapted to farmlands of El Salvador, effective as living barriers and mostly as cover crops, however, they are not yet very well disseminated. This document describes the potential for using the liquid extracts and the dry flour of raw seeds of those plants for economic benefit and practical convenience for pest management in Salvadorian agriculture under field conditions. Seed extracts were useful when …

Transcriptome Divergence During Leaf Development In Two Contrasting Switchgrass (Panicum Virgatum L.) Cultivars, Nathan A. Palmer, R. V. Chowda-Reddy, Anthony A. Muhle, Satyanarayana Tatineni, Gary Y. Yuen, Serge J. Edme, Robert B. Mitchell, Gautam Sarath

Department of Plant Pathology: Faculty Publications

The genetics and responses to biotic stressors of tetraploid switchgrass (Panicum virgatum L.) lowland cultivar ‘Kanlow’ and upland cultivar Summer are distinct and can be exploited for trait improvement. In general, there is a paucity of data on the basal differences in transcription across tissue developmental times for switchgrass cultivars. Here, the changes in basal and temporal expression of genes related to leaf functions were evaluated for greenhouse grown ‘Kanlow’, and ‘Summer’ plants. Three biological replicates of the 4th leaf pooled from 15 plants per replicate were harvested at regular intervals beginning from leaf emergence through senescence. Increases and decreases …

Neonicotinoid Seed Treatments Of Soybean Provide Negligible Benefits To Us Farmers, Spyridon Mourtzinis, Christian H. Krupke, Paul D. Esker, Adam J. Varenhorst, Nicholas J. Arneson, Carl A. Bradley, Adam M. Byrne, Martin I. Chilvers, Loren Giesler, Ames Herbert, Yuba R. Kandel, Maciej J. Kazula, Catherine Hunt, Laura E. Lindsey, Sean Malone, Daren S. Mueller, Seth Naeve, Emerson Nafziger, Dominic D. Reisig, William J. Ross, Devon R. Rossman, Sally Taylor, Shawn P. Conley

Department of Plant Pathology: Faculty Publications

Neonicotinoids are the most widely used insecticides worldwide and are typically deployed as seed treatments (hereafter NST) in many grain and oilseed crops, including soybeans. However, there is a surprising dearth of information regarding NST effectiveness in increasing soybean seed yield, and most published data suggest weak, or inconsistent yield benefit. The US is the key soybean-producing nation worldwide and this work includes soybean yield data from 194 randomized and replicated field studies conducted specifically to evaluate the effect of NSTs on soybean seed yield at sites within 14 states from 2006 through 2017. Here we show that across the …

Nature-Guided Synthesis Of Advanced Bio-Lubricants, Trevor Romsdahl, Asghar Shirani, Robert E. Minto, Chunyu Zhang, Edgar B. Cahoon, Kent D. Chapman, Diana Berman

Center for Plant Science Innovation: Faculty Publications

Design of environmentally friendly lubricants derived from renewable resources is highly desirable for many practical applications. Here, Orychophragmus violaceus (Ov) seed oil is found to have superior lubrication properties, and this is based on the unusual structural features of the major lipid species— triacylglycerol (TAG) estolides. Ov TAG estolides contain two non-hydroxylated, glycerol-bound fatty acids (FAs) and one dihydroxylated FA with an estolide branch. Estolide branch chains vary in composition and length, leading to their thermal stability and functional properties. Using this concept, nature-guided estolides of castor oil were synthesized. As predicted, they showed improved lubrication properties similar to Ov …

The Database Of Identified Root-Specific Genes And Their Promoters In Maize, Sorghum, And Soybean, Gleb Moisseyev, Divith Rajagopal, Alix Cui, Kiyoul Park, Edgar B. Cahoon, Chi Zhang

Center for Plant Science Innovation: Faculty Publications

Root genes are essential to plants as they dictate factors such as the strength of the plant, reproductivity success, etc. However, in the status quo, studies on root genes are simply ineffective. To be more specific, currently, there are very few online databases of root genes and promoters, which essentially deters root gene studies from being successful. To fix this problem, our lab constructed and coded an online database that contains information about the roots of maize, soybean, and sorghum. We collected 1200 root genes and assessed the strength and success of a given gene. This online database of these …

New Approaches To Use Genomics, Field Traits, And High-Throughput Phenotyping For Gene Discovery In Maize (Zea Mays), Zhikai Liang

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Maize is one of major crop species over the world. With lots of genetic resources and genomic tools, maize also serves as a model species to understand genetic diversity, facilitate the development of trait extraction algorithms and map candidate functional genes. Since the first version of widely used B73 reference genome was released, independent research groups in the maize community propagated seeds themselves for further research purposes. However, unexpected or occasional contamination may happen during this process. The first study in this thesis used public RNA-seq data of B73 from 27 research groups across three countries for calling single nucleotide …

Rust And Viral Mosaic Diseases In Biofuel Switchgrass, Anthony A. Muhle

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Switchgrass (Panicum virgatum L.) is a perennial warm-season monocot that is indigenous to locations in North America east of the Rocky Mountains, and is considered a model grass for biofuel feedstock production. As switchgrass production increases, diseases pose a potential threat to biomass production and ethanol extraction. The two predominant switchgrass diseases in Nebraska are rust caused by Puccinia spp. and a viral mosaic disease caused by Panicum mosaic virus (PMV) and its associated Satellite panicum mosaic virus (SPMV). In this thesis, one study determined how SPMV affects PMV infection and systemic spread in two populations of switchgrass at different …

Hormonal Signaling Induced In Soybean By Lysobacter Enzymogenes Strain C3, Jessica C. Walnut

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The biological control bacterium Lysobacter enzymogenes strain C3 has been shown to suppress fungal diseases by producing a suite of lytic enzymes and antimicrobial secondary metabolites. Previous studies have found that C3, when applied to grass and cereal plants, also is capable of inducing local and systemic resistance against fungal pathogens. It is unknown, however, whether the bacterium has the ability to induce resistance in dicots and what signaling pathways are involved. This study assessed the ability of C3 to trigger local and systemic induced resistance responses in soybean (Glycine max ‘Williams82’) by analyzing relative expression of salicylic acid …

Investigating Parental Effects On End-Use Quality In Hard Winter Wheat (Triticum Aestivum L.) Hybrids, Anthony Delaney

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

To optimize the performance and marketing of hybrid wheat, breeders need to understand the impact parents have on end-use quality. The goal of this study was to investigate the inheritance of end-use quality traits of hard winter wheat reciprocal hybrids produced by Easterly (2017). The 2016 analysis included 71 reciprocal hybrid combinations from 13 parents and the 2017 analysis included 79 reciprocal hybrid combinations from 14 parents. The reciprocals were composed of crosses between the top performing and bottom performing parents with respect to end-use quality as quantified by a Mixograph, a SDS sedimentation assay, and a SDS-SRC hybrid assay. …

An Integrated Genomics And Phenomics Approach To Study The Evolution Of C4 Photosynthesis, Daniel Santana De Carvalho

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The C4 photosynthetic pathway was first described over 50 years ago. Today, it is known that C4 evolved independently > 60 in plant lineages, which involves understanding not only the genetic, but also the metabolic features and differences involved in this process. Also, several adaptations are involved in the evolution of this type of photosynthesis, for example: changes in leaf anatomy and the evolution of kranz anatomy, physiology and metabolic pathways. In order to further investigate this pathway, different technologies and methods have been developed to unravel genes involved in C4 photosynthesis. With the advances in molecular biology and bioinformatics tools …

Microbial Response To Biodegradable Mulch: Can Degradation Rate Be Accelerated By Management?, M. Benjamin Samuelson

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Single-use, petroleum-based polyethylene mulch is ubiquitous in certified organic mulched vegetable systems, representing a broken nutrient cycle and a waste concern. Current organic-allowable biodegradable mulches cannot match the performance of polyethylene, in part because of the requirements that they contain 100% bio-based feedstock, and biodegrade within two years after soil incorporation. It is valuable to understand whether management can influence postharvest degradation rate of mulch films. Two biodegradable mulches: a potentially organic nonwoven polylactic acid and wood particle prototype (PLA), and a widely-adopted non-organic starch/copolymer blend, Bio360® (BLK), were used in field trials in two distinct ecoregions of Nebraska, at …

Assessing Anthocyanin Biosynthesis In Solanaceae As A Model Pathway For Secondary Metabolism, Zou Li, Trisha Vickrey, Moira G. Mcnally, Shirley J. Sato, Thomas E. Clemente, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

Solanaceae have played an important role in elucidating how flower color is specified by the flavonoid biosynthesis pathway (FBP), which produces anthocyanins and other secondary metabolites. With well-established reverse genetics tools and rich genomic resources, Solanaceae provide a robust framework to examine the diversification of this well-studied pathway over short evolutionary timescales and to evaluate the predictability of genetic perturbation on pathway flux. Genomes of eight Solanaceae species, nine related asterids, and four rosids were mined to evaluate variation in copy number of the suite of FBP enzymes involved in anthocyanin biosynthesis. Comparison of annotation sources indicated that the NCBI …

Network‐Based Feature Selection Reveals Substructures Of Gene Modules Responding To Salt Stress In Rice, Qian Du, Malachy Campbell, Huihui Yu, Kan Liu, Harkamal Walia, Qi Zhang, Chi Zhang

Center for Plant Science Innovation: Faculty Publications

Rice, an important food resource, is highly sensitive to salt stress, which is directly related to food security. Although many studies have identified physiological mechanisms that confer tolerance to the osmotic effects of salinity, the link between rice genotype and salt tolerance is not very clear yet. Association of gene co‐expression network and rice phenotypic data under stress has penitential to identify stress‐responsive genes, but there is no standard method to associate stress phenotype with gene co‐expression network. A novel method for integration of gene co‐expression network and stress phenotype data was developed to conduct a system analysis to link …

How Do Ecological Resilience Metrics Relate To Community Stability And Collapse?, Caleb P. Roberts, Dirac L. Twidwell Jr, David G. Angeler, Craig R. Allen

Department of Agronomy and Horticulture: Faculty Publications

The concept of ecological resilience (the amount of disturbance a system can absorb before collapsing and reorganizing) holds potential for predicting community change and collapse—increasingly common issues in the Anthropocene. Yet neither the predictions nor metrics of resilience have received rigorous testing. The crossscale resilience model, a leading operationalization of resilience, proposes resilience can be quantified by the combination of diversity and redundancy of functions performed by species operating at different scales. Here, we use 48 years of sub-continental avian community data aggregated at multiple spatial scales to calculate resilience metrics derived from the cross-scale resilience model (i.e., cross-scale diversity, …

Identification Of Loci Controlling Adaptation In Chinese Soya Bean Landraces Via A Combination Of Conventional And Bioclimatic Gwas, Ying-Hui Li, Delin Li, Yong-Qing Jiao, James C. Schnable, Yan-Fei Li, Hui-Hui Li, Huai-Zhu Chen, Hui-Long Hong, Ting Zhang, Bin Liu, Zhang-Xiong Lui, Qing-Bo You, Yu Tian, Yong Guo, Rong-Xia Guan, Li-Juan Zhang, Ru-Zhen Chang, Zhiwu Zhang, Jochen Reif, Xin-An Zhou, Patrick S. Schnable, Li-Juan Qiu

Department of Agronomy and Horticulture: Faculty Publications

Landraces often contain genetic diversity that has been lost in modern cultivars, including alleles that confer enhanced local adaptation. To comprehensively identify loci associated with adaptive traits in soya bean landraces, for example flowering time, a population of 1938 diverse landraces and 97 accessions of the wild progenitor of cultivated soya bean, Glycine soja was genotyped using tGBS. Based on 99 085 high-quality SNPs, landraces were classified into three subpopulations which exhibit geographical genetic differentiation. Clustering was inferred from STRUCTURE, principal component analyses and neighbour-joining tree analyses. Using phenotypic data collected at two locations separated by 10 degrees of latitude, …

Expression Of Multi-Domain Lytic Peptide Genes In Transgenic Plants For Disease Resistance, George Biliarski

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Four non-plant multi-domain lytic peptide genes coding for antimicrobial peptides were expressed in Nicotiana benthamiana plants and tested against three fungal pathogens: Sclerotinia sclerotiorum, Rhizoctonia solani, and Pythium sp. Detached-leaf bioassay was performed for the transgenic plants carrying multi-domain lytic peptide constructs and compared with transgenic and wild type control plants. Symptom area of each leaf was measured with high precision using the Compu-Eye software and processed by SAS statistical package. The transgenic lines ORF13 and RSL1 showed substantial resistance to Sclerotinia sclerotiorum infection producing significantly smaller lesion areas compared to control plants. However, these lines were not …

Meta-Analysis Of Yield Response Of Foliar Fungicide-Treated Hybrid Corn In The United States And Ontario, Canada, Kiersten A. Wise, Damon Smith, Anna Freije, Daren S. Mueller, Yuba Kandel, Tom Allen, Carl A. Bradley, Emmanuel Byamukama, Martin Chilvers, Travis Faske, Andrew Friskop, Clayton Hollier, Tamra Jackson-Ziems, Heather Kelly, Bob Kemerait, Paul Price Iii, Alison Robertson, Albert Tenuta

Department of Plant Pathology: Faculty Publications

Foliar fungicide applications to corn (Zea mays L.) occur at one or more application timings ranging from early vegetative growth stages to mid-reproductive stages. Previous studies indicated that fungicide applications are profitable under high disease pressure when applied during the tasseling to silking growth stages. Few comprehensive studies in corn have examined the impact of fungicide applications at an early vegetative growth stage (V6) compared to late application timings (VT) for yield response and return on fungicide investment (ROI) across multiple locations.

Introduction To Sorghum Paper Production, Zachary Christman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Sorghum is a tall grass used for many commercial products such as fodder and syrup. The 10 to 15 feet stalk of the plant has lower lignin than wood and provides a fiber length of 2.31 mm in the outer covering and 1.38 mm for the leaf. Sorghum fiber makes a high quality, strong paper suitable for printing, packaging and paperboard.

Dna Barcoding Of Pratylenchus From Agroecosystems In The Northern Great Plains Of North America, Mehmet Ozbayrak

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Pratylenchus species are among the most common plant parasitic nematodes in the Great Plains Region. The objectives of this study were to barcode Pratylenchus specimens for species identification in the Great Plains region using mitochondrial CO1 DNA barcode. In order to (1) determine species boundaries, (2) assess the host associations of barcoded Pratylenchus, (3) to determine the distribution patterns across the Great Plains Region and, (4) to evaluate the species status of P. scribneri and P. hexincisus by a multivariate morphological analysis of haplotype groups identified by DNA barcoding. Soil samples, primarily associated with eight major crops, were collected …

Use Of Annual Forage Mixtures In Crop/Livestock Production Systems In Nebraska, Nathan Paul Pflueger

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Success of integrating annual forages into crop and livestock systems throughout Nebraska may be variable depending on field location, field/forage crop management, and precipitation. There are many different warm- and cool-season annual forage species available for integrating crop and livestock systems at different times of the year. Mixtures of cereal species, such as oats (Avena sativa)) and spring peas (Pisum sativum)), are often used to optimize forage quantity and forage quality. Our two-year, three location study across Nebraska’s precipitation gradient suggested that forage quantity and quality may vary by location due to different precipitation amounts received …

Effect Of Soil-Applied Protoporphyrinogen Oxidase Inhibitor Herbicides On Soybean Seedling Disease, Nicholas J. Arneson

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Seedling disease is one the most economically important diseases of soybean in the United States. It is commonly caused by Fusarium spp., Rhizoctonia solani, Pythium spp., and Phytophthora sojae, alone, or together as a disease complex. Fungicide seed treatments continue to provide the most consistent management of seedling diseases. Soil-applied protoporphyrinogen oxidase (PPO) inhibitor herbicides are used preemergence in soybean production to manage several broadleaf weeds. Applications of PPO-inhibitors can result in phytotoxic injury to soybean when environmental conditions are not favorable for soybean growth. These environmental conditions can favor seedling disease development as well. In this thesis, two …