Plant Biology Commons^™

Changes In Soil Microbial Communities After 10 Years Of Winter Wheat Cultivation Versus Fallow In An Organic-Poor Soil In The Loess Plateau Of China, Hui Tian, Hui Wang, Xiaoli Hui, Zhaohui Wang, Rhae A. Drijber, Jinshan Liu

Department of Agronomy and Horticulture: Faculty Publications

Agricultural management methods, such as cultivation or fallowing, have led to significant changes in soil fertility and hence, crop yield. Such changes may have stemmed from changes in soil microbial communities and associated biogeochemical processes. This phenomenon is particularly true in organic-poor soil in the Loess Plateau of China. In this study, we examined three existing soil management regimes as part of a 10-year field experiment and evaluated their effects on fungal and bacterial community structures by performing high-throughput 454 pyrosequencing. These management regimes were (i) fertilized winter wheat (Triticum aestivum L.) (FW), (ii) continuous natural fallow with weeds …

Mapping And Characterization Of The Fefe Gene That Controls Iron Uptake In Melon (Cucumis Melo L.), Raghuprakash Kastoori Ramamurthy, Brian M. Waters

Department of Agronomy and Horticulture: Faculty Publications

Iron (Fe) deficiency in plants limits crop growth and productivity. Molecular mechanisms that plants use to sense and respond to Fe deficiency by coordinated expression of Feuptake genes are not fully understood. The C940-fe chlorotic melon (Cucumis melo) mutant known as fefe is unable to upregulate Fe-uptake genes, however, the FeFe gene had not been identified. In this study, we used two F₂ mapping populations to map and identify the FeFe gene as bHLH38, a homolog of subgroup Ib bHLH genes from Arabidopsis thaliana that are involved in transcriptional regulation of Feuptake genes in partnership with the …

Population Structure And Genetic Diversity Of Bromus Tectorum Within The Small Grain Production Region Of The Pacific Northwest, Nevin C. Lawrence, Amber L. Hauvermale, Amit Dhingra, Ian C. Burke

Department of Agronomy and Horticulture: Faculty Publications

Bromus tectorum L. is an invasive winter annual grass naturalized across the United States. Numerous studies have investigated B. tectorum population structure and genetics in the context of B. tectorum as an ecological invader of natural areas and rangeland. Despite the wealth of information regarding B. tectorum, previous studies have not focused on, or made comparisons to, B. tectorum as it persists in individual agroecosystems. The objectives of this study were to assess the genetic diversity and structure, the occurrence of generalist and specialist genotypes, and the influence of climate on distribution of B. tectorum sourced exclusively from within …

A Transcriptome‑Snp‑Derived Linkage Map Of Apios Americana (Potato Bean) Provides Insights About Genome Re‑Organization And Synteny Conservation In The Phaseoloid Legumes, Jugpreet Singh, Scott R. Kalberer, Vikas Belamkar, Teshale Assefa, Matthew N. Nelson, Andrew D. Farmer, William J. Blackmon, Steven B. Cannon

Department of Agronomy and Horticulture: Faculty Publications

Apios (Apios americana; “apios”), a tuberous perennial legume in the Phaseoleae tribe, was widely used as a food by Native Americans. Work in the last 40 years has led to several improved breeding lines. Aspects of the pollination biology (complex floral structure and tripping mechanism) have made controlled crosses difficult, and the previous reports indicated that the plant is likely primarily an outcrosser. We used a pseudo-testcross strategy to construct a genetic map specific to the maternal parent. The map was built using single-nucleotide polymorphism markers identified by comparing the expressed sequences of individuals in the mapping population …

The Trouble With Cover Crops: Farmers’ Experiences With Overcoming Barriers To Adoption, Gabrielle E. Roesch-Mcnally, Andrea D. Basche, J. G. Arbuckle, John C. Tyndall, Fernando E. Miguez, Troy Bowman, Rebecca Clay

Department of Agronomy and Horticulture: Faculty Publications

Cover crops are known to promote many aspects of soil and water quality, yet estimates find that in 2012 only 2.3% of the total agricultural lands in the Midwestern USA were using cover crops. Focus groups were conducted across the Corn Belt state of Iowa to better understand how farmers confront barriers to cover crop adoption in highly intensive agricultural production systems. Although much prior research has focused on analyzing factors that help predict cover crop use on farms, there is limited research on how farmers navigate and overcome field-level (e.g. proper planting of a cover crop) and structural barriers …

Genetic Diversity Of Danthonia Spicata (L.) Beauv. Based On Genomic Simple Sequence Repeat Markers, Chandra S. Thammina, Keenan Amundsen, Shaun B. Bushman, Matthew H. Kramer, Scott E. Warnke

Department of Agronomy and Horticulture: Faculty Publications

Danthonia spicata (L.) Beauv., commonly known as poverty oatgrass, is a perennial bunch-type grass native to North America. D. spicata is often found in low input turfgrass areas on the East Coast of the United States and has potential for development as a new native low input turfgrass species. Roche 454 sequenced randomly sheared genomic DNA reads of D. spicata were mined for SSR markers using the MIcroSAtellite identification tool. A total of 66,553 singlet sequences (approximately 37.5 Mbp) were examined, and 3454 SSR markers were identified. Trinucleotide motifs with greater than six repeats and possessing unique PCR priming sites …

Molecular And Phenotypic Characterization Of Transgenic Wheat And Sorghum Events Expressing The Barley Alanine Aminotransferase, Pamela A. Peña, Truyen Quach, Shirley Sato, Zhengxiang Ge, Natalya Nersesian, Ismail M. Dweikat, Madhavan Soundararajan, Tom Clemente

Department of Agronomy and Horticulture: Faculty Publications

Main conclusion — The expression of a barley alanine aminotransferase gene impacts agronomic outcomes in a C3 crop, wheat.

The use of nitrogen-based fertilizers has become one of the major agronomic inputs in crop production systems. Strategies to enhance nitrogen assimilation and flux in planta are being pursued through the introduction of novel genetic alleles. Here an Agrobacterium-mediated approach was employed to introduce the alanine aminotransferase from barley (Hordeum vulgare), HvAlaAT, into wheat (Triticum aestivum) and sorghum (Sorghum bicolor), regulated by either constitutive or root preferred promoter elements. Plants harboring the transgenic …

Metabolism Of 2,4-Dichlorophenoxyacetic Acid Contributes To Resistance In A Common Waterhemp (Amaranthus Tuberculatus) Population, Marcelo R. A. Figueiredo, Lacy J. Leibhart, Zachary J. Reicher, Patrick J. Tranel, Scott J. Nissen, Philip Westra, Mark L. Bernards, Greg R. Kruger, Todd A. Gaines, Mithila Jugulam

Department of Agronomy and Horticulture: Faculty Publications

BACKGROUND: Synthetic auxins such as 2,4-D have been widely used for selective control of broadleaf weeds since the mid-1940s. In 2009, an Amaranthus tuberculatus (common waterhemp) population with 10-fold resistance to 2,4-D was found in Nebraska, USA. The 2,4-D resistance mechanism was examined by conducting [¹⁴C] 2,4-D absorption, translocation and metabolism experiments.

RESULTS: No differences were found in 2,4-D absorption or translocation between the resistant and susceptible A. tuberculatus. Resistant plants metabolized [¹⁴C] 2,4-D more rapidly than did susceptible plants. The half-life of [¹⁴C] 2,4-D in susceptible plants was 105 h, compared to …

Multisite Evaluation Of Apex For Water Quality: Ii. Regional Parameterization, Nathan O. Nelson, Claire Baffaut, John A. Lory, G.M.M.M. Anomaa Senaviratne, Ammar B. Bhandari, Ranjith P. Udawatta, Daniel W. Sweeney, Matt J. Helmers, Mike W. Van Liew, Antonio P. Mallarino, Charles S. Wortmann

Department of Agronomy and Horticulture: Faculty Publications

Phosphorus (P) Index assessment requires independent estimates of long-term average annual P loss from fields, representing multiple climatic scenarios, management practices, and landscape positions. Because currently available measured data are insufficient to evaluate P Index performance, calibrated and validated process-based models have been proposed as tools to generate the required data. The objectives of this research were to develop a regional parameterization for the Agricultural Policy Environmental eXtender (APEX) model to estimate edgeof- field runoff, sediment, and P losses in restricted-layer soils of Missouri and Kansas and to assess the performance of this parameterization using monitoring data from multiple sites …

Investigation Of Candidate Loci Associated With Maize Perennialism, Anjun Ma

Electronic Theses and Dissertations

Developing perennial grain crops is an effective and crucial way to prevent soil erosion caused by conventional agriculture of using annual crops while meeting the increasing need of global food demand. We hypothesized that the regrowth in Zea might be controlled by two dominant complementary genes. F1 hybrids were created by crossing Zea diploperennis Iltis, Doebley & R. Guzman with annual Zea mays L. ssp. mays inbred line B73. A Total of 134 F2 plants derived from nine F1 were planted and phenotyped. A subpopulation of 94 F2 plants were genotyped with Genotype-by- Sequencing (GBS) and called 10,431 SNPs after …

Araucaria In The Urban Landscape: A Novel Leaning Pattern And Evidence Of Cultivated Hybridization, Jason W. Johns

Master's Theses

Our understanding of the natural world is constantly evolving and strengthening as more observations are made and experiments are performed. For example, we understand that tree stems grow toward the light (positive phototropism; Darwin 1880, Loehle 1986, Christie et al. 2013) and against gravity (negative gravitropism; Knight 1806, Hashiguchi et al. 2013). We also know that plants respond to mechanical stimulus and perturbation (thigmotropism; Braam 2005). Genes and their resulting proteins have been described to uncover some of the mechanisms for these environmental responses, but relatively speaking, we have just scratched the surface (Wyatt et al. 2013). While the discovery …

Wheat Streak Mosaic Virus Coat Protein Deletion Mutants Elicit More Severe Symptoms Than Wild-Type Virus In Multiple Cereal Hosts, Satyanarayana Tatineni, Christian G. Elowsky, Robert A. Graybosch

Department of Plant Pathology: Faculty Publications

Previously, we reported that coat protein (CP) of Wheat streak mosaic virus (WSMV) (genus Tritimovirus, family Potyviridae) tolerates deletion of amino acids 36 to 84 for efficient systemic infection of wheat. In this study, we demonstrated that WSMV mutants with deletion of CP amino acids 58 to 84 but not of 36 to 57 induced severe chlorotic streaks and spots, followed by acute chlorosis in wheat, maize, barley, and rye compared with mild to moderate chlorotic streaks and mosaic symptoms by wild-type virus. Deletion of CP amino acids 58 to 84 from the WSMV genome accelerated cell-to-cell movement, …

Effect Of Temperature On Wheat Streak Mosaic Disease Development In Winter Wheat, Everlyne N. Wosula, Satyanarayana Tatineni, Stephen N. Wegulo, Gary L. Hein

Department of Plant Pathology: Faculty Publications

Temperature is one of the key factors that influence viral disease development in plants. In this study, temperature effect on Wheat streak mosaic virus (WSMV) replication and in planta movement was determined using a green fluorescent protein (GFP)-tagged virus in two winter wheat cultivars. Virus-inoculated plants were first incubated at 10, 15, 20, and 25°C for 21 days, followed by 27°C for 14 days; and, in a second experiment, virus-inoculated plants were initially incubated at 27°C for 3 days, followed by 10, 15, 20, and 25°C for 21 days. In the first experiment, WSMV-GFP in susceptible ‘Tomahawk’ wheat at 10°C …

Detection And Characterization Of Xanthomonas Vasicola Pv. Vasculorum (Cobb 1894) Comb. Nov. Causing Bacterial Leaf Streak Of Corn In The United States, J. M. Lang, E. Ducharme, J. Ibarra Caballero, E. Luna, T. Hartman, M. Ortiz-Castro, K. A. Korus, J. Rascoe, T. A. Jackson-Ziems, K. Broders, J. E. Leach

Department of Plant Pathology: Faculty Publications

Bacterial leaf streak of corn (Zea mays) recently reached epidemic levels in three corn-growing states and has been detected in another six states in the central United States. Xanthomonas vasicola was identified as the causal agent of this disease. A multilocus sequence alignment of six housekeeping genes and comparison of average nucleotide identity from draft genome sequence were used to confirm phylogenetic relationships and classification of this bacteria relative to other X. vasicola strains. X. vasicola isolates from Nebraska and South Africa were highly virulent on corn and sugarcane and less virulent on sorghum but caused water-soaking symptoms …

Plant Disease Management, Tamra A. Jackson-Ziems, Anthony O. Adesemoye, Loren J. Giesler, Robert M. Harveson, Stephen N. Wegulo, Joshua J. Miller, James D. Harbour

Department of Plant Pathology: Faculty Publications

Fungicides are an important component of the pesticide program for some Nebraska fields. While not all fields of corn, dry bean, sorghum, soybean, sugarbeet, sunflower, and wheat will require a fungicide application, it’s critical that you know the correct product for the disease in your field when you do need it.

Identification. The first step with any disease management program is to make sure you have correctly identified the problem. Identification is critical as there are many bacterial diseases with symptoms similar to fungal diseases, and fungicides will have no activity on them. For help identifying crop diseases, visit the …

What's New In Plant Pathology, Joshua J. Miller, Anthony O. Adesemoye, Loren Giesler, Robert M. Harveson, Tamra A. Jackson-Ziems, Stephen N. Wegulo, James D. Harbour, Terra Hartman

Department of Plant Pathology: Faculty Publications

Changes to the Disease Management Section of the 2017 Guide for Weed, Disease, and Insect Management in Nebraska

Bacterial Leaf Streak of Corn—An Emerging Disease in Nebraska and First Report in the United States

Pest and Plant Diagnostic Clinic Position Change

New Products … Ethos XB … Majestene

Table 1. Foliar products for disease control that were updated in the 2017 Guide for Weed, Disease, and Insect Management in Nebraska

Table 2. Seed treatment products for disease control that were updated in the 2017 Guide for Weed, Disease, and Insect Management in Nebraska

Table 3. Biological products that were updated …

Response Of Sorghum Stalk Pathogens To Brown Midrib Plants And Soluble Phenolic Extracts From Near Isogenic Lines, Deanna L. Funnell-Harris, Patrick M. O'Neill, Scott E. Sattler, Tammy Gries, Mark A. Berhow, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Sorghum [Sorghum bicolor (L.) Moench] has drawn attention as potential feedstock for lignocellulosic biofuels production, and reducing lignin is one way to increase conversion efficiency. Little research has been previously conducted to assess the response of reduced lignin sorghum lines to the Fusarium stalk rot pathogens Fusarium verticillioides and Fusarium proliferatum and the charcoal rot pathogen, Macrophomina phaseolina. Loss of function mutations in either the Brown midrib (Bmr) 6 or 12 gene that both encode a monolignol biosynthetic enzyme in the pathway that produces subunits of the lignin polymer, results in reduced lignin content. Near-isogenic bmr6, …

Best Practices For Population Genetic Analyses, Niklaus J. Grünwald, Sydney E. Everhart, B. J. Knaus, Z. N. Kamvar

Department of Plant Pathology: Faculty Publications

Population genetic analysis is a powerful tool to understand how pathogens emerge and adapt. However, determining the genetic structure of populations requires complex knowledge on a range of subtle skills that are often not explicitly stated in book chapters or review articles on population genetics. What is a good sampling strategy? How many isolates should I sample? How do I include positive and negative controls in my molecular assays? What marker system should I use? This review will attempt to address many of these practical questions that are often not readily answered from reading books or reviews on the topic, …

Phenotypic And Genotypic Characterization Of Relevant Sclerotinia Sclerotiorum Isolates, Thomas J. Justo Miorini, Anthony G. Pannullo, T. Hornby, Robert Higgins, Sydney E. Everhart, James R. Steadman

Department of Plant Pathology: Faculty Publications

Knowledge of pathogen population structure is useful to identify isolates for screening cultivars and lines for resistance. For S. sclerotiorum, causal agent of white mold in more than 400 plant species, including common bean and soybean, breeding for resistance is particularly challenging. The objective of this study was to characterize phenotypic and genotypic variation of S. sclerotiorum isolates from soybean production areas of the U.S.A. (15), Brazil (75), and Argentina (5) to compare them with 366 isolates from dry bean characterized previously (Everhart et al., 2016).

Best Practices For Population Genetic Analyses, Niklaus J. Grünwald, Sydney E. Everhart, B. J. Knaus, Zhian N. Kamvar

Department of Plant Pathology: Faculty Publications

Population genetic analysis is a powerful tool to understand how pathogens emerge and adapt. However, determining the genetic structure of populations requires complex knowledge on a range of subtle skills that are often not explicitly stated in book chapters or review articles on population genetics. What is a good sampling strategy? How many isolates should I sample? How do I include positive and negative controls in my molecular assays? What marker system should I use? This review will attempt to address many of these practical questions that are often not readily answered from reading books or reviews on the topic, …