Other Plant Sciences Commons^™

Estimating Yield Gaps At The Cropping System Level, Nicolas Guilpart, Patricio Grassini, Victor O. Sadras, Jagadish Timsina, Kenneth Cassman

Department of Agronomy and Horticulture: Faculty Publications

Yield gap analyses of individual crops have been used to estimate opportunities for increasing crop production at local to global scales, thus providing information crucial to food security. However, increases in crop production can also be achieved by improving cropping system yield through modification of spatial and temporal arrangement of individual crops. In this paper we define the cropping system yield potential as the output from the combination of crops that gives the highest energy yield per unit of land and time, and the cropping system yield gap as the difference between actual energy yield of an existing cropping system …

Modeling Pollen-Mediated Gene Flow From Glyphosate-Resistant To -Susceptible Giant Ragweed (Ambrosia Trifida L.) Under Field Conditions, Zahoor A. Ganie, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

A field experiment was conducted to quantify pollen mediated gene flow (PMGF) from glyphosateresistant (GR) to glyphosate-susceptible (GS) giant ragweed under simulated field conditions using glyphosate resistance as a selective marker. Field experiments were conducted in a concentric design with the GR giant ragweed pollen source planted in the center and GS giant ragweed pollen receptors surrounding the center in eight directional blocks at specified distances (between 0.1 and 35 m in cardinal and ordinal directions; and additional 50 m for ordinal directions). Seeds of GS giant ragweed were harvested from the pollen receptor blocks and a total of 100,938 …

Gene Silencing Of Argonaute5 Negatively Affects The Establishment Of The Legume-Rhizobia Symbiosis, Maria Del Rocio Reyero-Saavedra, Zhenzhen Qiao, Maria Del Socorro Sanchez-Correa, M. Enrique Diaz-Pineda, Jose L. Reyes, Alejandra A. Covarrubias, Marc Libault, Oswaldo Valdes-Lopez

Department of Agronomy and Horticulture: Faculty Publications

The establishment of the symbiosis between legumes and nitrogen-fixing rhizobia is finely regulated at the transcriptional, posttranscriptional and posttranslational levels. Argonaute5 (AGO5), a protein involved in RNA silencing, can bind both viral RNAs and microRNAs to control plant-microbe interactions and plant physiology. For instance, AGO5 regulates the systemic resistance of Arabidopsis against Potato Virus X as well as the pigmentation of soybean (Glycine max) seeds. Here, we show that AGO5 is also playing a central role in legume nodulation based on its preferential expression in common bean (Phaseolus vulgaris) and soybean roots and nodules. We also …

Genes Linked To Production Of Secondary Metabolites In Talaromyces Atroroseus Revealed Using Crispr-Cas9, Maria Lund Nielsen, Thomas Isbrandt, Kasper Bøwig Rasmussen, Ulf Thrane, Jakob Blæsbjerg Hoof, Thomas Ostenfeld Larsen, Uffe Hasbro Mortensen

Department of Plant Pathology: Faculty Publications

The full potential of fungal secondary metabolism has until recently been impeded by the lack of universal genetic tools for most species. However, the emergence of several CRISPR-Cas9-based genome editing systems adapted for several genera of filamentous fungi have now opened the doors for future efforts in discovery of novel natural products and elucidation and engineering of their biosynthetic pathways in fungi where no genetic tools are in place. So far, most studies have focused on demonstrating the performance of CRISPR-Cas9 in various fungal model species, and recently we presented a versatile CRISPR-Cas9 system that can be successfully applied in …

Muti Site Screening Identifies And Verifies Levels Of Resistance To White Mold In Common Bean In 2016, Robert Higgins, James R. Steadman

Department of Plant Pathology: Faculty Publications

The development of common bean cultivars with partial resistance and/ or avoidance to white mold (WM) caused by Sclerotinia sclerotiorum would benefit producers by reducing yield loss and reducing input costs for fungicides. Our main objective in this study is to identify bean germplasm supplied by bean breeders from across the USA and Belgium with levels of partial resistance to WM. Breeders sent seed of 9 bean lines for field testing and 25 bean lines for greenhouse testing with putative sources of resistance to our laboratory. The seeds were divided in equal amounts for field (400g/line) and/or greenhouse (25 seeds/ …

Wheat Streak Mosaic Virus Coat Protein Is A Host-Specific Long-Distance Transport Determinant In Oat, Satyanarayana Tatineni

Department of Plant Pathology: Faculty Publications

Viral determinants involved in systemic infection of hosts by monocot-infecting plant viruses are poorly understood. Wheat streak mosaic virus (WSMV, genus Tritimovirus, family Potyviridae) exclusively infects monocotyledonous crops such as wheat, oat, barley, maize, triticale, and rye. Previously, we reported that WSMV CP amino acids 36–84 are expendable for systemic infection of wheat, maize, barley and rye. In this study, the role of coat protein (CP) in systemic infection of oat by WSMV was examined by using a series of viable deletion mutants. WSMV bearing deletions within or encompassing all of amino acids 36–57 efficiently infected oat, indicating that …

Understanding Fungicide Resistance, Tamra A. Jackson-Ziems, Loren J. Giesler, Anthony O. Adesemoye, Robert M. Harveson, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Fungicide resistance has developed in some diseases of row crops as well as specialty crops. This implies that fungicide applications to control such diseases may no longer be effective. Scientific studies have shown that fungicide resistance develops through natural selection of a mutant strain of a pathogen in a population that is resistant to fungicides. Resistance is very difficult to eliminate but can be delayed through appropriate management practices. The availability of inexpensive options with single mode of action products being available makes this an important issue so we do not repeat what was done in weed management.

Introduction

Frogeye …

Population Structure And Phenotypic Variation Of Sclerotinia Sclerotiorum From Dry Bean (Phaseolus Vulgaris) In The United States, Zhian N. Kamvar, Bimal Sajeewa Amaradasa, Rachana Jhala, Serena Mccoy, James R. Steadman, Sydney Everhart

Department of Plant Pathology: Faculty Publications

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries (wmn) with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries (a) reflect the genetic diversity of the populations in the surrounding region and (b) …

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 …

Can Cover Crop Use Allow Increased Levels Of Corn Residue Removal For Biofuel In Irrigated And Rainfed Systems?, S. J. Ruis, Humberto Blanco-Canqui, Paul J. Jasa, R. B. Ferguson, G. Slater

Department of Agronomy and Horticulture: Faculty Publications

Corn (Zea mays L.) residue removal at high rates can result in negative impacts to soil ecosystem services. The use of cover crops could be a potential strategy to ameliorate any adverse effects of residue removal while allowing greater removal levels. Hence, the objective of this study was to determine changes in water erosion potential, soil organic C (SOC) and total N concentration, and crop yields under early- and late-terminated cover crop (CC) combined with five levels of corn residue removal after 3 years on rainfed and irrigated no-till continuous corn in Nebraska. Treatments were no CC, early- and …

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

Department of Agronomy and Horticulture: Faculty Publications

The Agricultural Policy Environmental eXtender (APEX) model is capable of estimating edge-of-field water, nutrient, and sediment transport and is used to assess the environmental impacts of management practices. The current practice is to fully calibrate the model for each site simulation, a task that requires resources and data not always available. The objective of this study was to compare model performance for flow, sediment, and phosphorus transport under two parameterization schemes: a best professional judgment (BPJ) parameterization based on readily available data and a fully calibrated parameterization based on site-specific soil, weather, event flow, and water quality data. The analysis …

Influence Of Tillage On Common Ragweed (Ambrosia Artemisiifolia) Emergence Pattern In Nebraska, Ethann R. Barnes, Rodrigo Werle, Lowell Sandell, John L. Lindquist, Stevan Z. Knezevic, Peter H. Sikkema, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

Spring tillage is a component of an integrated weed management strategy for control of early emerging glyphosate-resistant weeds such as common ragweed; however, the effect of tillage on common ragweed emergence pattern is unknown. The objectives of this study were to evaluate whether spring tillage during emergence would influence the emergence pattern or stimulate additional emergence of common ragweed and to characterize common ragweed emergence in southeast Nebraska. A field experiment was conducted for three years (2014 to 2016) in Gage County, Nebraska in a field naturally infested with glyphosate-resistant common ragweed. Treatments consisted of a no-tillage control and three …

The Effects Of Early Pruning On The Near-Ground Branch Density Of Four Live Fencing Species, Aric Devens

Dissertations, Master's Theses and Master's Reports

Crop losses in home gardens greatly impact the wellbeing of rural West African families. Herbivory by migratory or local livestock represents a significant source of crop loss. Live-fencing gardens with thorny hedges is a low-cost and sustainable strategy for reducing losses due to herbivory. However, guidance on the establishment of thorny hedges is inconsistent, poorly publicized, and often anecdotal. Therefore, this study evaluated the effects of three early pruning treatments on near-ground branch density of four thorny species: Vachellia nilotica, Senegalia laeta, Senegalia mellifera, and Prosopis juliflora. Physical measurements and photographic data indicated that after one growing season, V. …

Methane Fluxes And Porewater Dissolved Organic Carbon Dynamics From Different Peatlands Types In The Pastaza-Marañon Basin Of The Peruvian Amazon., Jhon Del Aguila-Pasquel

Dissertations, Master's Theses and Master's Reports

Relevant components of the carbon budget such as methane fluxes and porewater dissolved organic carbon (DOC) are poorly characterized in the Peruvian Pastaza Marañon basin (PMB). PMB is associated with a tropospheric hotspot for methane and therefore it may represent a significant methane source. We aimed to quantify the magnitude of CH₄ fluxes and porewater DOC; and to determine their predictors across different peatland types in the PMB (open peatland, palm swamp, and pole forest). The study was conducted in two peatland sites covering the three main vegetation types in PMB. We collected gas and water samples using chamber-based …

Pollen-Mediated Gene Flow From Glyphosate-Resistant Common Waterhemp (Amaranthus Rudis Sauer): Consequences For The Dispersal Of Resistance Genes, Debalin Sarangi, Andrew J. Tyre, Eric L. Patterson, Todd A. Gaines, Suat Irmak, Stevan Z. Knezevic, John L. Lindquist, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

Gene flow is an important component in evolutionary biology; however, the role of gene flow in dispersal of herbicide-resistant alleles among weed populations is poorly understood. Field experiments were conducted at the University of Nebraska-Lincoln to quantify pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to -susceptible (GS) common waterhemp using a concentric donorreceptor design. More than 130,000 common waterhemp plants were screened and 26,199 plants were confirmed resistant to glyphosate. Frequency of gene flow from all distances, directions, and years was estimated with a double exponential decay model using Generalized Nonlinear Model (package gnm) in R. PMGF declined by 50% …

Stress-Responsive Pathways And Small Rna Changes Distinguish Variable Developmental Phenotypes Caused By Msh1 Loss, Mon-Ray Shao, Sunil Kumar Kenchanmane Raju, John D. Laurie, Robersy Sanchez, Sally A. Mackenzie

Department of Agronomy and Horticulture: Faculty Publications

Background: Proper regulation of nuclear-encoded, organelle-targeted genes is crucial for plastid and mitochondrial function. Among these genes, MutS Homolog 1 (MSH1) is notable for generating an assortment of mutant phenotypes with varying degrees of penetrance and pleiotropy. Stronger phenotypes have been connected to stress tolerance and epigenetic changes, and in Arabidopsis T-DNA mutants, two generations of homozygosity with the msh1 insertion are required before severe phenotypes begin to emerge. These observations prompted us to examine how msh1 mutants contrast according to generation and phenotype by profiling their respective transcriptomes and small RNA populations.

Results: Using RNA-seq, we analyze …

Patterns Of Gene Expression In Western Corn Rootworm (Diabrotica Virgifera Virgifera) Neonates, Challenged With Cry34ab1, Cry35ab1 And Cry34/35ab1, Based On Next-Generation Sequencing, Haichuan Wang, Seong-Il Eyun, Kanika Arora, Sek Yee Tan, Premchand Gandra, Etsuko N. Moriyama, Chitvan Khajuria, Jessica D. Jurzenski, Huarong Li, Maia Donahue, Kenneth E. Narva, Blair Siegfried

Department of Agronomy and Horticulture: Faculty Publications

With Next Generation Sequencing technologies, high-throughput RNA sequencing (RNAseq) was conducted to examine gene expression in neonates of Diabrotica virgifera virgifera (LeConte) (Western Corn Rootworm, WCR) challenged with individual proteins of the binary Bacillus thuringiensis insecticidal proteins, Cry34Ab1 and Cry35Ab1, and the combination of Cry34/Cry35Ab1, which together are active against rootworm larvae. Integrated results of three different statistical comparisons identified 114 and 1300 differentially expressed transcripts (DETs) in the Cry34Ab1 and Cry34/35Ab1 treatment, respectively, as compared to the control. No DETs were identified in the Cry35Ab1 treatment. Putative Bt binding receptors previously identified in other insect species were not identified …

Allelic Variants Of Oshkt1;1 Underlie The Divergence Between Indica And Japonica Subspecies Of Rice (Oryza Sativa) For Root Sodium Content, Malachy T. Campbell, Nonoy Bandillo, Fouad Razzaq A. Al Shiblawi, Sandeep Sharma, Kan Liu, Qian Du, Aaron J. Schmitz, Chi Zhang, Anne-Alienor Very, Aaron J. Lorenz, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Salinity is a major factor limiting crop productivity. Rice (Oryza sativa), a staple crop for the majority of the world, is highly sensitive to salinity stress. To discover novel sources of genetic variation for salt tolerance-related traits in rice, we screened 390 diverse accessions under 14 days of moderate (9 dS m^-1) salinity. In this study, shoot growth responses to moderate levels of salinity were independent of tissue Na⁺ content. A significant difference in root Na+ content was observed between the major subpopulations of rice, with indica accessions displaying higher root Na⁺ and japonica …

Regeneration And Invasion Of Cottonwood Riparian Forest Following Wildfire, Carissa L. Wonkka, Dirac L. Twidwell Jr., Christine H. Bielski, Craig R. Allen, Michael C. Stambaugh

Department of Agronomy and Horticulture: Faculty Publications

Populus deltoides is considered to be a weak resprouter and highly susceptible to wildfire, but few post-wildfire studies have tracked P. deltoides response and resprouting within the Great Plains of North America. Following a wildfire in southwestern Kansas, U.S.A., we surveyed burned and unburned areas of a cottonwood riparian forest along the Cimarron River that included a major understory invader, tamarisk (Tamarix ramosissima Ledeb.). We tested the following hypotheses, which are consistent with the current understanding of P. deltoides response to wildfire in the Great Plains: (1) regeneration of P. deltoides will be low in areas burned by the …

Robust Spatial Frameworks For Leveraging Research On Sustainable Crop Intensification, Patricio Grassini, Cameron M. Pittelkow, Kenneth Cassman, Haishun S. Yang, Sotirios Archontoulis, Mark Licht, Kendall R. Lamkey, Ignacio A. Ciampitti, Jeffrey A. Coulter, Sylvie M. Brouder, Jeffrey J. Volenec, Noemi Guindin-Garcia

Department of Agronomy and Horticulture: Faculty Publications

Meeting demand for food, fiber, feed, and fuel in a world with 9.7 billion people by 2050 without negative environmental impact is the greatest scientific challenge facing humanity. We hypothesize that this challenge can only be met with current and emerging technologies if guided by proactive use of a broad array of relevant data and geospatial scaling approaches to ensure local to global relevance for setting research priorities and implementing agricultural systems responsive to real-time status of weather, soils, crops, and markets. Despite increasing availability of field-scale agricultural data, robust spatial frameworks are lacking to convert these data into actionable …