Plant Biology Commons^™

Automated Conserved Non-Coding Sequence (Cns) Discovery Reveals Differences In Gene Content And Promoter Evolution Among Grasses, Gina Marie Turco, James C. Schnable, Brent S. Pedersen, Michael Freeling

Department of Agronomy and Horticulture: Faculty Publications

Conserved non-coding sequences (CNS) are islands of non-coding sequence that, like protein coding exons, show less divergence in sequence between related species than functionless DNA. Several CNSs have been demonstrated experimentally to function as cis-regulatory regions. However, the specific functions of most CNSs remain unknown. Previous searches for CNS in plants have either anchored on exons and only identified nearby sequences or required years of painstaking manual annotation. Here we present an open source tool that can accurately identify CNSs between any two related species with sequenced genomes, including both those immediately adjacent to exons and distal sequences separated by …

Rate Of Shattercane × Sorghum Hybridization In Situ, Jared J. Schmidt, Jeffrey F. Pedersen, Mark L. Bernards, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Cultivated sorghum [Sorghum bicolor (L.) Moench subsp. bicolor] can interbreed with a feral weedy relative shattercane [S. bicolor nothosubsp. drummondii (Steud.) de Wet ex Davidse]. Traits introduced from cultivated sorghum could contribute to the invasiveness of a shattercane population. An experiment was conducted to determine the potential for pollenmediated gene flow from grain sorghum to shattercane. Shattercane with juicy midrib (dd) was planted in soybean [Glycine max (L.) Merr.] fields during 2 yr in concentric arcs at varying distances from a 0.39 ha sorghum pollen source with dry midrib (DD). The arcs …

Uromyces Appendiculatus In Honduras: Pathogen Diversity And Host Resistance Screening, Maricelis Acevedo, James R. Steadman, Juan C. Rosas

Department of Plant Pathology: Faculty Publications

Bean rust, caused by the fungus Uromyces appendiculatus, is a major constraint for common bean production worldwide. Virulence of U. appendiculatus collected from wild and cultivated Phaseolus spp. was examined in 28 locations across Honduras. Host accessions representing wild and domesticated Phaseolus spp. collected at the same sampling locations were evaluated for resistance against U. appendiculatus. In total, 91 pathotypes were identified from 385 U. appendiculatus isolates according to their virulence on each of the 12 host differentials. No significant difference in pathogen total virulence, measured as the mean disease score, was found between locations. However, significant differences …

Citrus Tristeza Virus-Host Interactions, W. O. Dawson, S. M. Garnsey, Satyanarayana Tatineni, S. Y. Folimonova, S. J. Harper, S. Gowda

Department of Plant Pathology: Faculty Publications

Citrus tristeza virus (CTV) is a phloem-limited virus whose natural host range is restricted to citrus and related species. Although the virus has killed millions of trees, almost destroying whole industries, and continually limits production in many citrus growing areas, most isolates are mild or symptomless in most of their host range. There is little understanding of how the virus causes severe disease in some citrus and none in others. Movement and distribution of CTV differs considerably from that of well-studied viruses of herbaceous plants where movement occurs largely through adjacent cells. In contrast, CTV systemically infects plants mainly by …

Response Of Nebraska Horseweed (Conyza Canadensis) Populations To Dicamba, Roberto Crespo, Mark L. Bernards, Greg Kruger, Donald Lee, Robert Wilson Jr.

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

Dicamba-resistant soybeans are being developed to provide an additional herbicide mechanism-of-action for postemergence weed control in soybean. Numerous broadleaf species, including horseweed, have evolved resistance to glyphosate. It is anticipated that dicamba will be used by farmers as a primary tool to manage these weeds. Studying and understanding variability in horseweed response to dicamba will aid in developing appropriate risk management strategies to extend the utility of the dicamba-resistance technology. Horseweed plants from ten Nebraska populations were treated with one of nine doses of dicamba in greenhouse experiments. At 28 days after treatment (DAT) visual injury estimations were made and …

Neofusicoccum Luteum As A Pathogen On Tejocote (Crataegus Mexicana), Anthony O. Adesemoye, Joey S. Mayorquin, Akif Eskalen

Department of Plant Pathology: Faculty Publications

Tejocote (Crataegus mexicana), a small pome crab-apple-like fruit, is becoming economically important in California with increasing production, so consideration of diseases that hinder the yield is important. Diseased trees of tejocote were observed in four orchards of Riverside and San Diego Counties of California. Ten symptomatic/asymptomatic samples were studied from each of the orchards. Five most frequently isolated fungi were identified on the basis of morphological characters and sequence data of the internal transcribed spacer ITS1-5.8SITS2 and partial β-tubulin gene. Three isolates were identified as Neofusicoccum luteum and two as Phomopsis sp. Pathogenicity tests were conducted by inoculating …

Strong Genetic Differentiation Between North American And European Populations Of Phytophthora Alni Subsp. Uniformis, Jaime Aguayo, Gerard C. Adams, Fabien Halkett, Mursel Catal, Claude Husson, Zoltán Á. Nagy, Everett M. Hansen, Benoît Marçais, Pascal Frey

Department of Plant Pathology: Faculty Publications

Alder decline caused by Phytophthora alni has been one of the most important diseases of natural ecosystems in Europe during the last 20 years. The emergence of P. alni subsp. alni—the pathogen responsible for the epidemic—is linked to an interspecific hybridization event between two parental species: P. alni subsp. multiformis and P. alni subsp. uniformis. One of the parental species, P. alni subsp. uniformis, has been isolated in several European countries and, recently, in North America. The objective of this work was to assess the level of genetic diversity, the population genetic structure, and the putative reproduction …

Isolation And Characterization Of The Grain Mold Fungi Cochliobolus And Alternaria Spp. From Sorghum Using Semiselective Media And Dna Sequence Analyses, Deanna L. Funnell-Harris, Louis K. Prom, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Mold diseases, caused by fungal complexes including Alternaria, Cochliobolus, and Fusarium species, limit sorghum grain production. Media were tested by plating Fusarium thapsinum, Alternaria sp., and Curvularia lunata, individually and competitively. Dichloran chloramphenicol rose bengal (DRBC) and modified V8 juice (ModV8) agars, found to be useful, were compared with commonly used agar media, dichloran chloramphenicol peptone (DCPA) and pentachloronitrobenzene (PCNB). Radial growth, starting with mycelia or single-conidia and hyphal tips, demonstrated an effect of media. For isolation of grain fungi, DRBC and ModV8 were similar or superior to DCPA and PCNB. When seedlings were inoculated with conidia of C. lunata, …

Occurrence And Distribution Of Triticum Mosaic Virus In The Central Great Plains, E. Byamukama, D. L. Seifers, G. L. Hein, E. De Wolf, N. A. Tisserat, M. A. C. Langham, L. E. Osborne, A. Timmerman, S. N. Wegulo

Department of Plant Pathology: Faculty Publications

Wheat curl mite (WCM)-transmitted viruses—namely, Wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV), and the High Plains virus (HPV)—are three of the wheat-infecting viruses in the central Great Plains of the United States. TriMV is newly discovered and its prevalence and incidence are largely unknown. Field surveys were carried out in Colorado, Kansas, Nebraska, and South Dakota in spring and fall 2010 and 2011 to determine TriMV prevalence and incidence and the frequency of TriMV co-infection with WSMV or HPV in winter wheat. WSMV was the most prevalent and was detected in 83% of 185 season–counties (= s-counties), 73% …

Product Comparison Of Foliar Fungicide Efficacy On Diseases Of Field Corn In Nebraska, 2013, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. Corn hybrid NK ‘N68B’, rating of “fair” (7 out of 9) for gray leaf spot (GLS), not rated for common rust (CR), and “excellent” (2 out of 9) for southern rust (SR), was planted on 15 May in 30-in. rows at a target population of 31,763 plants/A. The trial area was disked with corn as the previous year’s crop. Eight treatments and a non-treated control were replicated six times in a randomized complete block design. Each plot was four rows …

Evaluating The Success Of Seed Sowing In A New England Grassland, Chad C. Jones, Glenn D. Dreyer, Nels Barrett

Botany Faculty Publications

Grassland habitat is declining in the northeastern United States, leading to a decline in associated native species. Consequently, there is considerable interest by land managers in conserving and restoring grassland habitats in the Northeast. However, unlike the Great Plains and Europe, quantitative monitoring of restoration sites is uncommon, making it difficult to improve new restoration projects. Here we evaluate a grassland restoration in Waterford, Connecticut to determine if mechanical clearing of woody vegetation combined with sowing 23 native grasses and forbs led to successful establishment of these species. We also compared cover, diversity, and colonization by exotic and woody species …

Efficacy Of Foliar Fungicides And Application Timing Of Stratego Yld On Field Corn In Nebraska, 2013, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. Corn hybrid NK ‘N68B’, rating of “fair” (7 out of 9) for gray leaf spot (GLS), not rated for common rust (CR), and “excellent” (2 out of 9) for southern rust (SR), was planted on 15 May in 30-in. rows at a target population of 31,763 plants/A. The trial area was disked with corn as the previous year’s crop. Nine treatments and a nontreated control were replicated six times in a randomized complete block design. Each plot was four …

Evaluation Of Foliar Fungicide And Application Timing On Field Corn Following Hail Event At Scal In Nebraska, 2013, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE to determine the potential effect of foliar fungicides and their application timing on lodging and yield after a late season hail event. Novartis corn hybrid N6800 GT with CruiserMaxx 250 seed treatment was planted on 24 May in 30 in. rows with a target population of 32,000 plants/A. Force 3G (4 oz/1,000 row ft) was applied in-furrow at planting. Lexar (3 qt/A) + Roundup UltraMax (32 fl oz/A) was applied on 5 Jun. The trial area had corn as …

Efficacy Evaluation Of Fortix And Headline Amp Application Timing In Field Corn In Nebraska, 2013, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. Corn hybrid NK ‘N68B’, rating of “fair” (7 out of 9) for gray leaf spot (GLS), not rated for common rust (CR), and “excellent” (2 out of 9) for southern rust (SR), was planted on 15 May in 30-in. rows at a target population of 31,763 plants/A. The trial area was disked with corn as the previous year’s crop. Nine treatments were replicated six times in a randomized complete block design. Each plot was four rows (10 ft) wide …

Efficacy Evaluation Of Foliar Fungicide Application Timing In Field Corn In Nebraska, 2012, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 64-83, rating of “good” (6 out of 9) for gray leaf spot (GLS), “very good” (4 out of 9) for common rust (CR), and “good” (5 out of 9) for southern rust (SR), was planted on 26 Apr in 30-in. rows at a target population of 30,600 plants/A. The trial area was disked with corn as the previous year’s crop. Six foliar fungicide treatments and a non-treated control were replicated six times in a randomized complete …

What’S New In Plant Pathology, Loren Giesler, Tamra A. Jackson-Ziems, Casey Schleicher, Kevin Korus

Department of Plant Pathology: Faculty Publications

Extension Plant Pathology Team Update

Plant and Pest Diagnostic Clinic Update

Disease Management Products

Table 1. Foliar Fungicide Label Updates

Table 2. New Products

Impacts Of Drought On Disease Development And Management, Stephen Wegulo, Loren Giesler, Robert Harveson, Tamra A. Jackson-Ziems, Bo Liu, Kevin Korus

Department of Plant Pathology: Faculty Publications

Drought conditions such as those that occurred in Nebraska in 2012 can impact the development of plant diseases. In general drought slows down or prevents the development of plant diseases caused by pathogens that thrive under moist conditions. However, some diseases are favored by drought. This is because when plants are stressed due to lack of moisture or excessive heat, they become more susceptible to these diseases. This article presents examples of diseases of agronomic crops favored by drought and how to manage them. Data are provided on the effect of dry or wet conditions on the profitability of applying …

Grain Storage Management To Minimize Mold And Mycotoxins, Thomas W. Dorn, Tamra A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

As most dryland corn producers are aware, the dry and hot growing season in 2012 resulted in reduced corn yields with moderately lower test weights. Along with the reduced test weights are concerns about potential mycotoxin contamination in the drought-stressed grain.

The only way to know for sure if there are mycotoxins in your grain and which specific mycotoxins are present is to collect representative grain samples and have them tested by a certified laboratory.

Many species of fungi can cause ear rot diseases and molding of grain. Most of these fungi become associated with the grain in the field …

Sub1a-Mediated Submergence Tolerance Response In Rice Involves Differential Regulation Of The Brassinosteroid Pathway, Aaron J. Schmitz, Jing J. Folsom, Yusuke Jikamaru, Pamela C. Ronald, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Submergence 1A (SUB1A), is an ethylene response factor (ERF) that confers submergence tolerance in rice (Oryza sativa) via limiting shoot elongation during the inundation period. SUB1A has been proposed to restrict shoot growth by modulating gibberellic acid (GA) signaling.

Our transcriptome analysis indicated that SUB1A differentially regulates genes associated with brassinosteroid (BR) synthesis during submergence. Consistent with the gene expression data, the SUB1A genotype had higher brassinosteroid levels after submergence compared to the intolerant genotype. Tolerance to submergence can be activated in the intolerant genotype by pretreatment with exogenous brassinolide, which results in restricted shoot elongation …

Factors Influencing The Establishment And Survival Of Native Hardwood Tree Seedlings Of The Kentucky Inner Bluegrass Blue Ash-Oak Savanna-Woodland, James D. Shaffer

Theses and Dissertations--Biology

Historically, the Kentucky Inner Bluegrass blue ash-oak savanna-woodland was the primary ecosystem of the Inner Bluegrass Region (IBR) of Kentucky. After European settlement, the majority (>99%) of Bluegrass savanna was converted to agricultural and urban land uses. Currently remnant savanna tree species are failing to recruit. Therefore, a long-term restoration ecology project researching competition and disturbance on seedling establishment, survival, and growth has been established at Griffith Woods (the largest remaining savanna in Kentucky) in Harrison Co., KY. Fourteen native hardwood tree species (a total of 6,168 seedlings) have been experimentally planted. Light, soil, surrounding vegetation, and herbivory, factors …

Variants Of Triticum Mosaic Virus Isolated From Wheat In Colorado Show Divergent Biological Behavior, Dallas L. Seifers, Satyanarayana Tatineni, Roy French

Department of Plant Pathology: Faculty Publications

Triticum mosaic virus (TriMV) is a recently discovered virus infecting wheat. We compared Colorado isolates C10-492 and C11-775 with the 06-123 isolate. Comparisons were made using enzyme-linked immunosorbent assay (ELISA), infectivity assay, host range, dry weight (DW), inoculation of ‘Mace’ wheat with temperature-sensitive resistance to Wheat streak mosaic virus, and the deduced amino acid sequence of the coat proteins (CP) and P1 proteins. Both C10-492 and C11-775 infected ‘Gallatin’ barley and, when compared with 06-123, had significantly reduced ELISA values and virus titers in wheat. Both Colorado isolates caused symptomless infections in Mace, whereas 06- 123 caused mosaic symptoms. …

Spatio-Temporal Patterns Of Pre-Harvest Brown Rot Epidemics Within Individual Peach Tree Canopies, Sydney E. Everhart, A. Askew, L. Seymour, H. Scherm

Department of Plant Pathology: Faculty Publications

Tree canopies are architecturally complex and pose several challenges for measuring and character-izing spatial patterns of disease. Recently developed methods for fine-scale canopy mapping and three-dimensional spatial pattern analysis were applied in a 3-year study to characterize spatio-temporal development of pre-harvest brown rot of peach, caused by Monilinia fructicola, in 13 trees of different maturity classes. We observed a negative correlation between an index of disease aggregation and disease incidence in the same tree (r = −0.653, P < 0.0001), showing that trees with higher brown rot incidence had lower aggregation of affected fruit in their canopies. Significant (P ≤ 0.05) within-canopy aggregation among symptomatic fruit was most pronounced for early-maturing cultivars and/or early in the epidemic. This is consistent with the notion of a greater importance of localized, within-tree sources of inoculum at the beginning of the epidemic. Four of five trees having >10 blossom blight symptoms per tree showed a significant positive spatial association of pre-harvest fruit rot to blossom blight within the …

Modifying Lignin To Improve Bioenergy Feedstocks: Strengthening The Barrier Against Pathogens?, Scott E. Sattler, Deanna L. Funnell-Harris

Department of Plant Pathology: Faculty Publications

Lignin is a ubiquitous polymer present in cell walls of all vascular plants, where it rigidifies and strengthens the cell wall structure through covalent cross-linkages to cell wall polysaccharides. The presence of lignin makes the cell wall recalcitrant to conversion into fermentable sugars for bioenergy uses.Therefore, reducing lignin content and modifying its linkages have become major targets for bioenergy feedstock development through either biotechnology or traditional plant breeding. In addition, lignin synthesis has long been implicated as an important plant defense mechanism against pathogens, because lignin synthesis is often induced at the site of pathogen attack. This article explores the …

Product Comparison Of Foliar Fungicide Efficacy On Diseases Of Field Corn In Nebraska, 2012, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide comparison trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 64-83, rating of “good” (6 out of 9) for gray leaf spot (GLS), “very good” (4 out of 9) for common rust (CR), and “good” (5 out of 9) for southern rust (SR), was planted on 26 Apr in 30-in. rows at a target population of 30,600 plants/A. The trial area was disked with corn as the previous year’s crop. Eleven treatments and a non-treated control were replicated six times in a randomized complete block design. …

Evaluation Of Application Timing On Stratego Yld Efficacy Of Field Corn In Nebraska, 2012, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 64-83, rating of “good” (6 out of 9) for gray leaf spot (GLS), “very good” (4 out of 9) for common rust (CR), and “good” (5 out of 9) for southern rust (SR), was planted on 26 Apr in 30-in. rows at a target population of 30,600 plants/A. The trial area was disked with corn as the previous year’s crop. Five foliar fungicide treatments and a non-treated control were replicated six times in a randomized complete …

Efficacy Evaluation Of Foliar Fungicide Products On Diseases Of Field Corn In Nebraska, 2012, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 64-83, rating of “good” (6 out of 9) for gray leaf spot (GLS), “very good” (4 out of 9) for common rust (CR), and “good” (5 out of 9) for southern rust (SR), was planted on 26 Apr in 30-in. rows at a target population of 30,600 plants/A. The trial area was disked with soybean as the previous year’s crop. Five foliar fungicide treatments and a nontreated control were replicated six times in a randomized complete …

Foliar Treatment Timing Trials For Management Of Goss’S Bacterial Wilt And Blight Of Field Corn In Nebraska, 2012, H. H. Oser, T. A. Jackson-Ziems, J. L. Brungardt

Department of Plant Pathology: Faculty Publications

One experimental hybrid, DKC 37-38, with a Goss’s wilt rating of 7 out of 9 (“poor”), was planted at the University of Nebraska Agricultural Research and Development Center (ARDC) near Mead, NE on 2 Jun. Corn was planted at 32,000 seeds per acre in a field that received minimum tillage. The previous year’s crop was corn. Each plot was 30 ft long and contained two rows spaced 30-in. apart. Alleys were cut between plots reducing plot length to 28 ft. All plots were irrigated with an overhead sprinkler center pivot irrigation system. . . . There were no significant differences …

Major Fusarium Diseases On Corn, Wheat, And Soybeans In Nebraska, Bo Liu, Loren J. Giesler, Tamra A. Jackson-Ziems, Stephen N. Wegulo, Robert M. Harveson

Department of Plant Pathology: Faculty Publications

Fusarium species have been associated with many important diseases of corn, wheat, and soybean, causing significant yield loss in Nebraska; some produce mycotoxins that are harmful to both human and animal consumers. These pathogens are very common in agricultural field soil across the Midwest and cause numerous types of diseases.

Corn Disease Update, Tamra A. Jackson-Ziems, Craig B. Langemeier, Greg R. Kruger

Department of Plant Pathology: Faculty Publications

Goss's Bacterial Wilt and Blight ... Symptoms ... 2011 Survey results ... New alternate hosts identified ... Goss's Wilt Management Strategies ... More Resources ... Literature Cited

Aspergillus Ear Rot and Aflatoxin Contaminated Grain ... Table 1. FDA Action Levels for Aflatoxin in Feed and Food ... Testing for Aflatoxin ... High risk factors for aflatoxin contamination in corn ... Scouting for Aspergillus Ear Rot ... Harvest and Storage ... More Resources

Stalk Rot Diseases ... Scouting for Stalk Rot Diseases ... Management ... More Resources

Immunodetection Of Triticum Mosaic Virus By Das- And Dac-Elisa Using Antibodies Produced Against Coat Protein Expressed In Escherichia Coli: Potential For High-Throughput Diagnostic Methods, Satyanarayana Tatineni, Gautam Sarath, Dallas Seifers, Roy C. French

Department of Agronomy and Horticulture: Faculty Publications

Triticum mosaic virus (TriMV), an economically important virus infecting wheat in the Great Plains region of the USA, is the type species of the Poacevirus genus in the family Potyviridae. Sensitive and high-throughput serology-based detection methods are crucial for the management of TriMV and germplasm screening in wheat breeding programs. In this study, TriMV coat protein (CP) was expressed in Escherichia coli, and polyclonal antibodies were generated against purified soluble native form recombinant CP (rCP) in rabbits. Specificity and sensitivity of resulting antibodies were tested in Western immuno-blot and enzyme-linked immunosorbent assays (ELISA). In direct antigen coating (DAC)-ELISA, …