Plant Pathology Commons^™

Relevance Of Lysine Snorkeling In The Outer Transmembrane Domain Of Small Viral Potassium Ion Channels, Manuela Gebhardt, Leonhard M. Henkes, Sascha Tayefeh, Brigitte Hertel, Timo Greiner, James L. Van Etten, Dirk Baumeister, Christian Cosentino, Anna Moroni, Stefan M. Kast, Gerhard Thiel

Department of Plant Pathology: Faculty Publications

Transmembrane domains (TMDs) are often flanked by Lys or Arg because they keep their aliphatic parts in the bilayer and their charged groups in the polar interface. Here we examine the relevance of this so-called “snorkeling” of a cationic amino acid, which is conserved in the outer TMD of small viral K+ channels. Experimentally, snorkeling activity is not mandatory for KcvPBCV-1 because K29 can be replaced by most of the natural amino acids without any corruption of function. Two similar channels, KcvATCV-1 and KcvMT325, lack a cytosolic N-terminus, and neutralization of their equivalent cationic amino acids inhibits their function. To …

Rna-Seq Analysis Of The Sclerotinia Homoeocarpa – Creeping Bentgrass Pathosystem, Angela M. Orshinsky, Jinnan Hu, Stephen O. Opiyo, Venu Reddyvari-Channarayappa, Thomas K. Mitchell, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Sclerotinia homoeocarpa causes dollar spot disease, the predominate disease on highly-maintained turfgrass. Currently, there are major gaps in our understanding of the molecular interactions between S. homoeocarpa and creeping bentgrass. In this study, 454 sequencing technology was used in the de novo assembly of S. homoeocarpa and creeping bentgrass transcriptomes. Transcript sequence data obtained using Illumina’s first generation sequencing-by-synthesis (SBS) were mapped to the transcriptome assemblies to estimate transcript representation in different SBS libraries. SBS libraries included a S. homoeocarpa culture control, a creeping bentgrass uninoculated control, and a library for creeping bentgrass inoculated with S. homoeocarpa and incubated for …

Gene Expression Profiling Of The Plant Pathogenic Basidiomycetous Fungus Rhizoctonia Solani Ag 4 Reveals Putative Virulence Factors, Dilip K. Lakshman, Nadim Alkharoud, Daniel P. Roberts, Savithiry S. Natarajan, Amitava Mitra

Department of Plant Pathology: Faculty Publications

Rhizoctonia solani is a ubiquitous basidiomycetous soilborne fungal pathogen causing damping- off of seedlings, aerial blights and postharvest diseases. To gain insight into the molecular mechanisms of pathogenesis a global approach based on analysis of expressed sequence tags (ESTs) was undertaken. To get broad gene-expression coverage, two normalized EST libraries were developed from mycelia grown under high nitrogen-induced virulent and low nitrogen/methylglucose-induced hypovirulent conditions. A pilot-scale assessment of gene diversity was made from the sequence analyses of the two libraries. A total of 2280 cDNA clones was sequenced that corresponded to 220 unique sequence sets or clusters (contigs) and 805 …

Effects Of Early Application Timing Of Foliar Fungicides In Field Corn In Central Nebraska, 2011, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

A foliar fungicide early application timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 3 May in 30 in. rows with a target population of 32,000 plants/A. The trial area was disked with a crop history of seven years of continuous corn. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 …

Glycerolipids And The Plant Cuticle Contribute To Plant Immunity, Qing-Ming Gao

Theses and Dissertations--Plant Pathology

The conserved metabolites, oleic acid (18:1), a major monounsaturated fatty acid (FA), and glycerol-3-phosphate (G3P) are obligatory precursors of glycerolipid biosynthesis in plants. In Arabidopsis, the SSI2-encoded SACPD is the major isoform that contributes to 18:1 biosynthesis. Signaling induced upon reduction in oleic acid (18:1) levels not only upregulates salicylic acid (SA)-mediated responses but also inhibits jasmonic acid (JA)- inducible defenses. I examined the transcription profile of ssi2 plants and identified two transcription factors, WRKY50 and WRKY51. Although the ssi2 wrky50 and ssi2 wrky51 plants were constitutively upregulated in SA-derived signaling, they were restored in JAdependent defense signaling. Not only …

Glycerol-3-Phosphate Is A Novel Regulator Of Basal And Induced Defense Signaling In Plants, Bidisha Chanda

Theses and Dissertations--Plant Pathology

Plants use several strategies to defend themselves against microbial pathogens. These include basal resistance, which is induced in response to pathogen encoded effector proteins, and resistance (R) protein-mediated resistance that is activated upon direct or indirect recognition of pathogen encoded avirulence protein(s). The activation of Rmediated signaling is often associated with generation of a signal, which, upon its translocation to the distal uninfected parts, confers broad-spectrum immunity against related or unrelated pathogens. This phenomenon known as systemic acquired resistance (SAR) is one of the well-established forms of induced defense response. However, the molecular mechanism underlying SAR remains largely unknown. Induction …

Larval Survival And Plant Injury Of Cry1ab-Susceptible, -Resistant, And -Heterozygous Genotypes Of The Sugarcane Borer On Transgenic Corn Containing Single Or Pyramided Bt Genes, David S. Wangila, B. Rogers Leonard, Yaoyu Bai, Graham P. Head, Fangneng Huang

Department of Entomology: Faculty Publications

Transgenic corn (Zea mays L.) products expressing multiple Bt proteins targeting a same group of insect pests have become commercially available in the U.S. The first commercialized pyramided Bt corn technologies for managing lepidopteran pests include Genuity® VT Triple Pro™ and Genuity® SmartStax™. In this study, larval survival and plant injury of Cry1Ab-susceptible (Cry1Ab-SS), -resistant (Cry1Ab-RR), and -heterozygous (Cry1Ab-RS) genotypes of the sugarcane borer, Diatraea saccharalis F., on five commercial corn hybrids were evaluated in a leaf tissue bioassay and two greenhouse trials during 2010–2011. The five hybrids included two non-Bt corn and three Bt corn hybrids representing three …

Spatial Patterns Of Brown Rot Epidemics And Development Of Microsatellite Markers For Analyzing Fine-Scale Genetic Structure Of Monilinia Fructicola Populations Within Peach Tree Canopies, Sydney E. Everhart, A. Askew, L. Seymour, T. C. Glenn, H. Scherm

Department of Plant Pathology: Faculty Publications

To better understand the fine-scale spatial dynamics of brown rot disease and corresponding fungal genotypes, we analyzed three-dimensional spatial patterns of pre-harvest fruit rot caused by Monilinia fructicola in individual peach tree canopies and developed microsatellite markers for canopy-level population genetics analyses. Using a magnetic digitizer, high-resolution maps of fruit rot development in five representative trees were generated, and M. fructicola was isolated from each affected fruit. To characterize disease aggregation, nearest-neighbor distances among symptomatic fruit were calculated and compared with appropriate random simulations. Within-canopy disease aggregation correlated negatively with the number of diseased fruit per tree (r = −0.827, …

Prothioconazole Tolerant Cryptococcus Flavescens Strains For Biological Control Of Fusarium Head Blight, David A. Schisler, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Strains of Cryptococcus flavescens which are superior antagonists of F. graminearum for suppression and control of FHB in cereals, particularly in wheat and barley, are described. The strains are prothioconazole tolerant variants of previously described C. flavescens OH 182.9 (NRRL Y-30216). Moreover, these prothioconazole tolerant variants exhibit significantly increased efficacy against F. graminearum in comparison to the parent strain OH 182.9.

Product Comparison Of Foliar Fungicide Efficacy On Diseases Of Field Corn In Nebraska, 2011, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

foliar fungicide efficacy trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. Dekalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 3 May in 30-in. rows with a target population of 32,000 plants/A. The trial area was disked with soybean as the previous year’s crop. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) was applied to the trial site. …

Efficacy Evaluation Of Foliar Fungicide Application Timing On Diseases Of Field Corn In Nebraska, 2011, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. Dekalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 3 May in 30-in. rows with a target population of 32,000 plants/A. The trial area was disked with soybean as the previous year’s crop. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) was applied to the trial …

Evaluation Of Foliar Fungicide Efficacy On Sorghum In Nebraska, 2011, 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 sorghum hybrid DKS 36-06 was planted on 23 May in 30-in. rows with a target population of approximately 120,000 plants/A. The trial area was disked with soybean as the previous year’s crop. Four treatments and a nontreated control were replicated six times in a randomized complete block design. Each plot was four rows (10 ft) wide by 40 ft in length. . . . There were significant differences in GLS AUDPC among treatments. The nontreated control exhibited the largest …

Application Timing On Foliar Fungicide Efficacy On Sorghum In Nebraska, 2009, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy trial was established at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. Grain sorghum hybrid NC+ 7R83 was planted on 18 May in 30-in. rows with a target population of 90,000 plants/A. The trial area was disked with a crop history of five years of continuous corn. Eight treatments and a non-treated control were replicated six times in a randomized complete block design. Each plot was four rows (10 ft) wide by 40 ft in length. . . . There were no significant differences in stay green. Stay green percentages ranged from …

Effects Of Crop Injury On Disease Development, Tamra A. Jackson, Loren J. Giesler, Robert M. Harveson

Department of Plant Pathology: Faculty Publications

The effect of damage caused by blowing soil and leaf contact with high speed winds and hail will all create a similar level of wounding that is often sufficient for pathogens that require wounds to enter (infect) plants. As we look at the level of disease and crop damage we can identify several examples in the corn and soybean disease systems when this can be a factor that could lead to significant disease development and possibly trigger a disease management action.

Hail and wind damage can result in an open canopy which can affect the microclimate and impact disease development. …

What's New In Plant Pathology: Resistance: Mystery And Misunderstandings, Amy D. Timmerman, Loren J. Giesler, Robert M. Harveson, Tamra Jackson-Ziems, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

One of the most common management recommendations for plant diseases is the use of resistant or tolerant varieties/hybrids in your production system. However, there is common confusion on the definition and differentiation of susceptible, tolerant, and resistant varieties/hybrids from a plant pathology viewpoint. A susceptible variety/hybrid allows the pathogen to reproduce and causes significant disease development and in turn compromises the productivity of the plant (i.e., yield). A tolerant variety/hybrid allows the pathogen to reproduce and cause disease at the same or at a slightly reduced rate as a susceptible variety/cultivar; however, there is no noticeable reduction in the plant’s …

Determining The Virulence Of Corn Pathogen Fusarium Verticillioides Utilizing Deletion Mutants Lacking Genes Fv_00027 Or Fv_Nps6, Abigail Zieman

Honors Program Theses

Fusarium verticillioides is an important fungal pathogen of com. Many pathogens have virulent genes which are genes that increase infectivity of the pathogen. After a bioinformatics study, it was determined that genes Fv _ 00027 and Fv _ NPS6 are potential virulent genes in F. verticillioides. To determine if either gene ·contributes to the virulence of the fungus, deletion mutants of F. verticillioides were created lacking either Fv _ 00027 or Fv _ NPS6 genes. These deletion mutants were utilized in an optimized com assay to determine the effect of infectivity on com. To test these deletion mutants, com seeds …

Synergistic Roles Of Eukaryotic Translation Elongation Factors 1bγ And 1a In Stimulation Of Tombusvirus Minus-Strand Synthesis, Zsuzsanna Sasvari, Lara Izotova, Terri Goss Kinzy, Peter D. Nagy

Plant Pathology Faculty Publications

Host factors are recruited into viral replicase complexes to aid replication of plus-strand RNA viruses. In this paper, we show that deletion of eukaryotic translation elongation factor 1Bgamma (eEF1Bγ) reduces Tomato bushy stunt virus (TBSV) replication in yeast host. Also, knock down of eEF1Bγ level in plant host decreases TBSV accumulation. eEF1Bγ binds to the viral RNA and is one of the resident host proteins in the tombusvirus replicase complex. Additional in vitro assays with whole cell extracts prepared from yeast strains lacking eEF1Bγ demonstrated its role in minus-strand synthesis by opening of the structured 3' end of the viral …

Bacterial Interactions Of Inoculated Price's Potato Bean (Apios Priceana): A Biological Study, Rhonda Walker

Masters Theses & Specialist Projects

Apios priceana is a native endangered species plant found in the Southeast United States. It is characterized as a leguminous species that bears wisteria like clusters with pea like flowers, a large tuberous root and four to six inch long seed pods. It is believed the Native Americans and early European settlers relied on this species as a source of protein and utilized the seeds for cultivation of the tuberous “potato” which formed. Apios priceana contains an average of 13% fiber, 6.9% protein, 71% carbohydrate and 9 of the 11 essential amino acids needed in human diets (Walter et al.,1986). …

Gene Expression And Physiological Analyses To Study Metabolic Shifts In Medicago Truncatula Subjected To Biotic Stresses, Michelle Ryan Martin

Graduate Theses and Dissertations

Plants are frequently under attack from pests and deploy various defense mechanisms to fight off predators. Many plant defenses are induced following herbivory or pathogen infection. An investment in defense could potentially lead to a diversion of metabolic resources away from primary metabolism, including reduction in plant commitment to photosynthesis. In this thesis, changes in expression levels of representative genes for primary and secondary metabolism were studied using real-time polymerase chain reaction (PCR) in Medicago truncatula Gaertner subjected to beet armyworm (Spodoptera exigua H¨¹bner) damage or Phoma medicaginis Malbr. & Roum. infection. Photosynthetic yield was also measured using chlorophyll fluorescence …

Ecological Disinfestation: Physical And Biological Characterization Of Filtration Substrates For Removing Zoospores Of Phytophthora Nicotianae From Water, Elizabeth Nyberg

All Theses

Although recycling irrigation water is beneficial to the nursery industry as it serves to decrease potable water usage and reduces the release of excess agrichemicals into the environment, it also poses the risk of becoming the source for and means of dispersing water-borne plant pathogens. Plant pathogens of major concern in irrigation water are species of Phytophthora. These pathogens are a significant threat because they can attack a vast number of plants, many of which are ornamental crops grown in nurseries, by releasing motile zoospores directly into irrigation water. Several treatment methods are available to remove plant pathogens from irrigation …