Plant Biology Commons^™

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, …

Control Of White Mold Of Dry Bean And Residual Activity Of Fungicides Applied By Chemigation, Thomas J.J. Miorini, Carlos G. Raetano, Sydney E. Everhart

Department of Plant Pathology: Faculty Publications

Sclerotinia sclerotiorum is a necrotrophic fungal pathogen that causes white mold of dry bean (Phaseolus vulgaris L.). Chemigation with fungicides is used for disease control, but effectiveness of this application method and impact of irrigation level on residual fungicide activity in the plant over time under field conditions has not been well characterized. To assess the best method of application and fungicide for disease control, we conducted field studies in three field sites in São Paulo State in Brazil. Contact fungicide, fluazinam, was applied via center pivot at three irrigation levels (2.5, 5.1, 10.1 mm) at the Itaí field …

Glucose-Abl1-Tor Signaling Modulates Cell Cycle Tuning To Control Terminal Appressorial Cell Differentiation, Margarita Marroquin-Guzman, Guangchao Sun, Richard Wilson

Department of Plant Pathology: Faculty Publications

The conserved target of rapamycin (TOR) pathway integrates growth and development with available nutrients, but how cellular glucose controls TOR function and signaling is poorly understood. Here, we provide functional evidence from the devastating rice blast fungus Magnaporthe oryzae that glucose can mediate TOR activity via the product of a novel carbon- responsive gene, ABL1, in order to tune cell cycle progression during infection-related development. Under nutrient-free conditions, wild type (WT) M. oryzae strains form terminal plant-infecting cells (appressoria) at the tips of germ tubes emerging from three-celled spores (conidia). WT appressorial development is accompanied by one round …

1980 Lilley Cornett Woods Soil Data, Ryan W. Mcewan, Julia I. Chapman, Robert N. Muller

Data Files: Big Everidge Hollow Permanent Plots

Data collected in 1980 on the soil in the Big Everidge Hollow portion of the Lilley Cornett Woods Appalachian Ecological Research Station in southeastern Kentucky. Data key is provided in a supplemental file.

DOI: https://doi.org/10.26890/lcw.4b97vlypkk

Column Key, Big Everidge Hollow Permanent Plots, Ryan W. Mcewan, Julia I. Chapman, Robert N. Muller

Data Files: Big Everidge Hollow Permanent Plots

Column key for .csv data files.

Accompanying photo by Julia I. Chapman.

DOI: https://doi.org/10.26890/lcw.rx26w6rcvs

2010 Lilley Cornett Woods Overstory Data, Ryan W. Mcewan, Julia I. Chapman, Robert N. Muller

Data Files: Big Everidge Hollow Permanent Plots

Data collected in 2010 on the overstory in the Big Everidge Hollow portion of the Lilley Cornett Woods Appalachian Ecological Research Station in southeastern Kentucky. Data key is provided in a supplemental file.

Accompanying photo by Julia I. Chapman.

DOI: https://doi.org/10.26890/lcw.s3l6btsgv3

1999 Lilley Cornett Woods Overstory Data, Ryan W. Mcewan, Julia I. Chapman, Robert N. Muller

Data Files: Big Everidge Hollow Permanent Plots

Data collected in 1999 on the overstory in the Big Everidge Hollow portion of the Lilley Cornett Woods Appalachian Ecological Research Station in southeastern Kentucky. Data key is provided in a supplemental file.

Accompanying photo by Ryan W. McEwan.

DOI: https://doi.org/10.26890/lcw.5pn95oc6d7

1989 Lilley Cornett Woods Overstory Data, Ryan W. Mcewan, Julia I. Chapman, Robert N. Muller

Data Files: Big Everidge Hollow Permanent Plots

Data collected in 1989 on the overstory in Big Everidge Hollow portion of the Lilley Cornett Woods Appalachian Ecological Research Station in southeastern Kentucky. Data key is provided in a supplemental file.

Accompanying photo by Ryan W. McEwan.

DOI: https://doi.org/10.26890/lcw.jt5ds3db92

The Effect Of Artificial Selection On Phenotypic Plasticity In Maize, Joseph L. Gage, Diego Jarquin, Cinta Romay, Aaron Lorenz, Edward S. Buckler, Shawn Kaeppler, Naser Alkhalifah, Martin Bohn, Darwin A. Campbell, Jode Edwards, David Ertl, Sherry Flint-Garcia, Jack Gardiner, Byron Good, Candice N. Hirsch, Jim Holland, David C. Hooker, Joseph Knoll, Judith Kolkman, Greg Kruger, Nick Lauter, Carolyn J. Lawrence-Dill, Elizabeth Lee, Jonathan Lynch, Seth C. Murray, Rebecca Nelson, Jane Petzoldt, Torbert Rocheford, James C. Schnable, Patrick S. Schnable, Brian Scully, Margaret Smith, Nathan M. Springer, Srikant Srinivasan, Renee Walton, Teclemariam Weldekidan, Randall J. Wisser, Wenwei Xu, Jianming Yu, Natalia De Leon

Department of Agronomy and Horticulture: Faculty Publications

Remarkable productivity has been achieved in crop species through artificial selection and adaptation to modern agronomic practices. Whether intensive selection has changed the ability of improved cultivars to maintain high productivity across variable environments is unknown. Understanding the genetic control of phenotypic plasticity and genotype by environment (G × E) interaction will enhance crop performance predictions across diverse environments. Here we use data generated from the Genomes to Fields (G2F) Maize G × E project to assess the effect of selection on G × E variation and characterize polymorphisms associated with plasticity. Genomic regions putatively selected during modern temperate maize …

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 …

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% …