Plant Pathology Commons^™

The Effects Of Salinity On Pythium Disease Of Rice And Soybean, Terea Jeanette Stetina

Graduate Theses and Dissertations

Increasing salinity is an important factor limiting agricultural productivity worldwide. In addition to direct effects on growth and yield, diseases also may be affected. This study characterized the effects of soil salinity on seedling disease of soybean and rice caused by Pythium spp. Controlled environment experiments on soybean used two cultivars which differed in chloride tolerance and soil treated with a CaCl₂ solution to create a range of electrical conductivity (EC) levels. For soybean, soil was either not infested or infested with Pythium sylvaticum or P. aphanidermatum (pathogenic to soybean), or P. oligandrum (not pathogenic to soybean). Twenty-one days …

Effects Of Rain And Simulated Rain On Deoxynivalenol Levels In Grain And Chaff Of Winter Wheat With Fusarium Head Blight, Manoj Kumar Pun

Graduate Theses and Dissertations

Wheat grain affected by Fusarium head blight (FHB) contains the mycotoxin deoxynivalenol (DON) that is harmful to humans and animals. Reducing the amount of DON in grain is the goal of management practices for FHB so it is important to understand the factors affecting DON in grain. Some studies on the effects of late-season moisture found increases in DON while others found decreases due to leaching. The objectives of this study were to determine effects of late-season rain and misting on DON concentration in wheat spike tissues and to quantify the amount of DON leached from spikes. Field experiments were …

Phytophthora Foliage Blight Of Garden Phlox: Phytophthora Nicotianae On Phlox Paniculata, Daniel Drechsler

All Theses

Phytophthora foliage blight of garden phlox (Phlox paniculata ) - caused by Phytophthora nicotianae - is a devastating disease that has been seen consistently in nursery production facilities in South Carolina. However, this disease has not been characterized previously. This project was composed of three separate studies, each of which followed one of the three major components of the disease triangle (i.e., the synchronous occurrence of a susceptible host and a virulent pathogen within a conducive environment) to investigate the pathogenicity of P. nicotianae on P. paniculata . In one study, the efficacies of three inoculation methodologies to cause …

Impact Of Wheat Streak Mosaic Virus And Triticum Mosaic Virus On Transmission By Aceria Tosichella Keifer (Eriophyidae) And Virus Epidemiology In Wheat, Camila F. De Oliveira

Department of Entomology: Dissertations, Theses, and Student Research

The wheat curl mite (WCM), Aceria tosichella Keifer, transmits a complex of viruses, Wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV) and Wheat mosaic virus (WMoV), to wheat, Triticum aestivum, in the Great Plains. Co-infection of wheat by these viruses is frequently observed, increasing disease severity and yield loss.

Current genetic work classifies WCM populations into two genotypes, Type 1 and Type 2. It has been shown that different mite genotypes are able to transmit viruses at varying rates. WCM-virus relations are very specific and can impact vector biology. In this study, the primary objective was to determine …

Managing Fusarium Wilt In Watermelon Production, Zachary Snipes

All Theses

Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum , was first described in 1894 in South Carolina and Georgia and has become a limiting factor in watermelon production worldwide. In recent years, restriction on use of the soil fumigant methyl bromide and the recent development of more virulent races of Fusarium oxysporum f. sp. niveum has created a critical need for alternative management techniques. In 2011-2013 field experiments were designed to evaluate the efficacy of incorporating a cover crop of hairy vetch into the soil to manage Fusarium wilt. Colony-forming units (CFU) of Fusarium oxysporum were sampled …

Molecular And Biochemical Mechanisms Of Pathogenesis In The Maize Foliar Pathogen Cercospora Zeae-Maydis, Winfred-Peck Dorleku

Graduate Theses and Dissertations

GLS is a serious foliar disease of maize, a major staple crop grown commercially in the USA for both human and animal feed production, and increasingly, for ethanol production. The disease is caused by two Cercospora species, C. zeae-maydis and C. zeina, both of which infect maize in the USA and in other parts of the world, with yield losses potentially greater than 50%, depending on local conditions. In culture, C. zeae-maydis produces a phytotoxic, host non-specific perylenequinone, cercosporin, and abscisic acid (ABA), for which there is no known pathological or physiological function in the fungus. Experimental evidence indicates …

Arabidopsis 56–Amino Acid Serine Palmitoyltransferase- Interacting Proteins Stimulate Sphingolipid Synthesis, Are Essential, And Affect Mycotoxin Sensitivity, Athen N. Kimberlin, Saurav Majumder, Gongshe Han, Ming Chen, Rebecca E. Cahoon, Julie M. Stone, Teresa M. Dunn, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Maintenance of sphingolipid homeostasis is critical for cell growth and programmed cell death (PCD). Serine palmitoyltransferase (SPT), composed of LCB1 and LCB2 subunits, catalyzes the primary regulatory point for sphingolipid synthesis. Small subunits of SPT (ssSPT) that strongly stimulate SPT activity have been identified in mammals, but the role of ssSPT in eukaryotic cells is unclear. Candidate Arabidopsis thaliana ssSPTs, ssSPTa and ssSPTb, were identified and characterized. Expression of these 56–amino acid polypeptides in a Saccharomyces cerevisiae SPT null mutant stimulated SPT activity from the Arabidopsis LCB1/LCB2 heterodimer by >100-fold through physical interaction with LCB1/LCB2. ssSPTa transcripts were …

Response Of Near-Isogenic Sorghum Lines, Differing At The P Locus For Plant Colour, To Grain Mould And Head Smut Fungi, Deanna L. Funnell-Harris, L. K. Prom, Scott E. Sattler, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Leaves and stalks of many sorghum genotypes accumulate dark red or purple pigments upon wounding while some plants, called ‘tan,’ do not. Grains with unpigmented ‘white’ pericarps grown on tan plants are more desirable for food. The hypothesis tested was that pigments in plants protected grain against the panicle diseases grain mould and head smut. Near-isogenic tan or purple plant color genotypes with white grain were planted at Lincoln and Ithaca, NE and Corpus Christi, TX. The field grown grain was plated onto semi-selective media to detect the presence of grain colonisation by mould genera Alternaria, Fusarium and Curvularia. …

Wheat Streak Mosaic Virus Infects Systemically Despite Extensive Coat Protein Deletions: Identification Of Virion Assembly And Cell-To-Cell Movement Determinants, Satyanarayana Tatineni, Frank A. Kovacs, Roy C. French

Department of Plant Pathology: Faculty Publications

Viral coat proteins function in virion assembly and virus biology in a tightly coordinated manner with a role for virtually every amino acid. In this study, we demonstrated that the coat protein (CP) of Wheat streak mosaic virus (WSMV) (genus Tritimovirus; family Potyviridae) is unusually tolerant of extensive deletions with continued virion assembly and/or systemic infection. A series of deletion and point mutations were created in the CP cistron of wild-type and/or GFP-tagged WSMV and examined the effects of these mutations on cell-to-cell and systemic transport and virion assembly of WSMV. Mutants with overlapping deletions comprising N-terminal amino …

Calmodulin-Mediated Signal Transduction Pathways In Arabidopsis Are Fine-Tuned By Methylation, Joydeep Banerjee, Roberta Magnani, Meera Nair, Lynnette M. Dirk, Seth Debolt, Indu B. Maiti, Robert L. Houtz

Department of Plant Pathology: Faculty Publications

Calmodulin N-methyltransferase (CaM KMT) is an evolutionarily conserved enzyme in eukaryotes that transfers three methyl groups to a highly conserved lysyl residue at position 115 in calmodulin (CaM). We sought to elucidate whether the methylation status of CaM plays a role in CaM-mediated signaling pathways by gene expression analyses of CaM KMT and phenotypic characterization of Arabidopsis thaliana lines wherein CaM KMT was overexpressed (OX), partially silenced, or knocked out. CaM KMT was expressed in discreet spatial and tissue-specific patterns, most notably in root tips, floral buds, stamens, apical meristems, and germinating seeds. Analysis of transgenic plants with genetic dysfunction …

Quantitative Relationship Of Soil Texture With The Observed Population Density Reduction Of Heterodera Glycines After Annual Corn Rotation In Nebraska, Oscar Perez-Hernandez, Loren J. Giesler

Department of Plant Pathology: Faculty Publications

Soil texture has been commonly associated with the population density of Heterodera glycines (soybean cyst nematode: SCN), but such an association has been mainly described in terms of textural classes. In this study, multivariate analysis and a generalized linear modeling approach were used to elucidate the quantitative relationship of soil texture with the observed SCN population density reduction after annual corn rotation in Nebraska. Forty-five commercial production fields were sampled in 2009, 2010, and 2011 and SCN population density (eggs/100 cm3 of soil) for each field was determined before (Pi) and after (Pf) annual corn rotation from ten 3 3 …

The Role Of Soil Microorganisms In The Resistance Of Giant Ragweed, Horseweed, And Common Lambsquarters To Glyphosate, Jessica Renee Schafer-Bugg

Open Access Dissertations

Continuous glyphosate use has contributed to an increasing number of problematic glyphosate-resistant (GR) weeds. The mechanism of resistance in many GR weeds is poorly understood, in part, due to a poor understanding of how exactly glyphosate kills a plant. In previous research, the efficacy of glyphosate was demonstrated to be strongly influenced by root invading soil-borne microorganisms. However, this interaction among plants, glyphosate, and soil microorganisms has only been studied in a number of crop plants, but not in weed species. This is surprising since the soil biotic environment has a strong impact on the activity of this important herbicide. …

Construction Of A Sonchus Yellow Net Virus Minireplicon: A Step Toward Reverse Genetic Analysis Of Plant Negative-Strand Rna Viruses, Uma Ganesan, Jennifer N. Bragg, Min Deng, Sharon Marr, Mi Yeon Lee, Shasha Qian, Manling Shi, Justin Kappel, Cole Peters, Yeon Lee, Michael M. Goodin, Ralf G. Dietzgen, Zhenghe Li, Andrew O. Jackson

Plant Pathology Faculty Publications

Reverse genetic analyses of negative-strand RNA (NSR) viruses have provided enormous advances in our understanding of animal viruses over the past 20 years, but technical difficulties have hampered application to plant NSR viruses. To develop a reverse genetic approach for analysis of plant NSR viruses, we have engineered Sonchus yellow net nucleorhabdovirus (SYNV) minireplicon (MR) reporter cassettes for Agrobacterium tumefaciens expression in Nicotiana benthamiana leaves. Fluorescent reporter genes substituted for the SYNV N and P protein open reading frames (ORFs) exhibited intense single-cell foci throughout regions of infiltrated leaves expressing the SYNV MR derivatives and the SYNV nucleocapsid (N), phosphoprotein …

Ozonation Systems As A Non-Chemical Alternative For Stored Grain Protection, Carlos A. Campabadal

Open Access Dissertations

The use of ozone as a non-chemical alternative in stored grain protection was studied by conducting scale-up demonstrations using a fixed bed ozonation system and developing a semi-continuous counterflow and a continuous flow ozonation treatment system. The objectives of this research were to determine the efficacy of ozonation to control insect pests without affecting end-use quality; to prove the concept of the semi-continuous counterflow ozonation system to ozonate grain at a faster rate and quantify its effect on mold growth reduction; to evaluate the efficacy of a modified screw conveyor for pest control by treating grain in a continuous-flow ozonation …

Tall Fescue Endophyte Effects On Tolerance To Water-Deficit Stress, Padmaja Nagabhyru, Randy D. Dinkins, Constance L. Wood, Charles W. Bacon, Christopher L. Schardl

Plant Pathology Faculty Publications

BACKGROUND: The endophytic fungus, Neotyphodium coenophialum, can enhance drought tolerance of its host grass, tall fescue. To investigate endophyte effects on plant responses to acute water deficit stress, we did comprehensive profiling of plant metabolite levels in both shoot and root tissues of genetically identical clone pairs of tall fescue with endophyte (E+) and without endophyte (E-) in response to direct water deficit stress. The E- clones were generated by treating E+ plants with fungicide and selectively propagating single tillers. In time course studies on the E+ and E- clones, water was withheld from 0 to 5 days, during which …

Comparison Of Arsenic Uptake And Oxidative Stress By Christmas Fern And Spider Brake Fern, Paul Lkanich, Pratheek Koneru, Robert Wei

Undergraduate Research Posters 2013

Plants are widely considered the most cost effective and environmentally friendly way to clean soils and waters contaminated with toxic metals, e.g. arsenic and mercury. We have focused our research on the uptake of arsenic and its biochemical effect on two species of fern, Spider brake fern and Christmas fern. Spider brake fern is known to be capable of accumulating significant amounts of arsenic. We wish to determine whether the levels of arsenic uptake in Christmas fern are comparable to Spider Brake fern (>1g kg-1 plant biomass) when both are grown under the same conditions. Another aim of the …

Metagenomic Profiling Reveals Lignocellulose Degrading System In A Microbial Community Associated With A Wood-Feeding Beetle, Erin D. Scully, Scott M. Geib, Kelli Hoover, Ming Tien, Susannah G. Tringe, Kerrie W. Barry, Tijana Glavina Del Rio, Mansi Chovatia, Joshua R. Herr, John E. Carlson

Department of Plant Pathology: Faculty Publications

The Asian longhorned beetle (Anoplophora glabripennis) is an invasive, wood-boring pest that thrives in the heartwood of deciduous tree species. A large impediment faced by A. glabripennis as it feeds on woody tissue is lignin, a highly recalcitrant biopolymer that reduces access to sugars and other nutrients locked in cellulose and hemicellulose. We previously demonstrated that lignin, cellulose, and hemicellulose are actively deconstructed in the beetle gut and that the gut harbors an assemblage of microbes hypothesized to make significant contributions to these processes. While lignin degrading mechanisms have been well characterized in pure cultures of white rot basidiomycetes, little …

The History Of Trial Gardens, Hallie Schmidt

Horticulture and Crop Science

Essay explores the history of home gardening and seed industry in America and the conditions that led to the development of the All-America Selections.

Dynamic Expression Of Imprinted Genes Associates With Maternally Controlled Nutrient Allocation During Maize Endosperm Development, Mingming Xin, Ruolin Yang, Guosheng Li, Hao Chen, John Laurie, Chuang Ma, Dongfang Wang, Yingyin Yao, Brian A. Larkins, Qixin Sun, Ramin Yadegari, Xiangfeng Wang, Zhongfu Ni

Center for Plant Science Innovation: Faculty Publications

In angiosperms, the endosperm provides nutrients for embryogenesis and seed germination and is the primary tissue where gene imprinting occurs. To identify the imprintome of early developing maize (Zea mays) endosperm, we performed highthroughput transcriptome sequencing of whole kernels at 0, 3, and 5 d after pollination (DAP) and endosperms at 7, 10, and 15 DAP, using B73 byMo17reciprocal crosses.Weobserved gradually increased expression of paternal transcripts in 3- and 5-DAP kernels. In 7-DAP endosperm, the majority of the genes tested reached a 2:1 maternal versus paternal ratio, suggesting that paternal genes are nearly fully activated by 7 DAP. …

Real-Time Quantitative Pcr Assays For Evaluation Of Soybean Varieties For Resistance To The Stem And Root Rot Pathogen Phytophthora Sojae, Mursel Catal, Fedai Erler, Dennis W. Fullbright, Gerard C. Adams

Department of Plant Pathology: Faculty Publications

Phytophthora root and stem rot caused by Phytophthora sojae is one of the most destructive disease of soybeans in the world. Effective management of the disease depends on selection and use of soybean varieties resistant to the disease. Fast and reliable procedures are vital to screen soybean varieties against the pathogen. Novel real-time quantitative (qPCR) assays were developed for both absolute and relative quantification of P. sojae in infected root tissues. QPCR assays were based on the detection of the internal transcribed spacer (ITS) gene of the pathogen and 18S ribosomal gene of the host plant. Absolute qPCR allowed the …

Multifactorial Analysis Of Mortality Of Soybean Cyst Nematode (Heterodera Glycines Ichinohe) Populations In Soybean And In Soybean Fields Annually Rotated To Corn In Nebraska, Oscar Perez-Hernandez

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

The soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is the most economically important pathogen of soybean in the U.S. The effect of annual corn rotation, soil properties, weather, and agronomic factors on SCN population densities was quantified in 45 fields in Nebraska over three years. SCN population densities (eggs/100 cm³ of soil) in each field were determined before (Pi) and after (Pf) annual corn rotation. Average SCN population density reduction was 50.62%. Multivariate analysis was used to describe the relationship of soil texture (% of sand, silt, and clay), Pi, and Pf. Two principal components explained 92% of the …

Spatial Distributions Of Rhizoctonia Species In Soybean Fields Undergoing Annual Rotations With Rice, Terry Neil Spurlock

Graduate Theses and Dissertations

Aerial blight is caused by Rhizoctonia solani AG1-IA. This pathogen also causes sheath blight of rice. In Arkansas, many soybean and rice fields undergo an annual rotation of these two crops which facilitates a continuous source of inoculum from one year to the next. Aerial blight is a two stage disease in that R. solani AG1-IA colonizes the plant during the early vegetative growth stages and then aerial blight develops after the soybean canopy closes in the later reproductive stages of development. As a result of the upper portion of the canopy often being asymptomatic, significant yield loss can occur …

Functional Analysis Of A Glutathione S-Transferase Gene From Reniform Nematode On Soybean, Jing Hou

All Theses

Nematode glutathione S-transferases (GSTs) have been implicated in plant-nematode interactions as effector proteins with an important role in the establishment of feeding sites. Studies with root-knot nematode in Arabidopsis thaliana suggest that GSTs may protect the nematode against oxidative plant defenses and modulate plant responses to parasitism. Our objective was to study the function of a GST from reniform nematode (Rotylenchulus reniformis) in soybean. We used a virus-induced gene silencing (VIGS) system, utilizing a Bean pod mottle virus (BPMV)-based vector and a partial sequence of gsts-1 from Meloidogyne incognita to silence the putative reniform nematode homolog. The effect of silencing …

Diversity Among Isolates Of Phytophthora Cinnamomi From Ornamental Plants In South Carolina, Simon Schreier

All Theses

Phytophthora cinnamomi is a devastating pathogen that can attack over 900 hosts. It is the most common species of Phytophthora isolated from woody ornamental crops in South Carolina but little is known about variability among isolates of P. cinnamomi that attack these plants. Therefore, 142 isolates of P. cinnamomi recovered from diseased plant samples submitted to the Clemson University Plant Problem Clinic between 1995 and 2011 were characterized for mycelium growth habit, growth rate, mefenoxam sensitivity, mating type, and sporangium morphology. Mycelium growth habit on PARPH-V8 selective medium was classified as aerial, appressed, or dwarf; 87% of isolates had the …

Cause And Impacts Of The Early Season Collapse Of Lilium Grayi (Gray’S Lily), On Roan Mountain, Tn/Nc, Russell J. Ingram

Electronic Theses and Dissertations

A population of the rare Southern Appalachian endemic species Lilium grayi, (Gray’s lily) Roan Mountain, TN/NC was monitored for 2 years to determine the cause and impact of an early season collapse. High concentrations of the Lilium spp. host-specific fungal phytopathogen, Pseudocercosporella inconspicua (G. Winter) U. Braun were associated with 19/20 symptomatic and 0/30 asymptomatic plants. Strength of the association between pathogen and disease and the replication of disease symptoms in 4/4 healthy hosts showed that P. inconspicua was the causal agent of the disease referred to as lily leaf spot. Disease had a severe impact on the population …

Soybean (Glycine Max) Response To Imazosulfuron Drift And Carryover From Rice (Oryza Sativa), Sandeep Singh Rana

Graduate Theses and Dissertations

In the Midsouth, soybean is often grown in close proximity to rice or in rotation with rice. Herbicides used in rice can injure soybean via drift or carryover. Consequently, field trials were conducted to determine the response of soybean (cv. AG 4703) to imazosulfuron drift and carryover (at Fayetteville, Marianna, Keiser and Pine Tree, AR) from rice. To assess the potential for carryover, soybean was planted into rice fields treated the previous year with imazosulfuron (rotation study). To evaluate in-season sensitivity of soybean to imazosulfuron (tolerance study) relative to halosulfuron, a common sulfonylurea herbicide applied to rice, both imazosulfuron and …

Distribution And Control Of Glyphosate-Resistant Johnsongrass (Sorghum Halepense) In Arkansas Soybean, Dennis Brent Johnson

Graduate Theses and Dissertations

Johnsongrass, once the most persistent and troublesome grass weed of row crops throughout the southern U.S., has previously been confirmed resistant to the acetolactate synthase (ALS) and acetyl-coenzyme A carboxylase-inhibiting herbicides in the Midsouth and has recently evolved resistance to glyphosate in Arkansas. The goal of this research was to establish the geographical distribution of herbicide-resistant johnsongrass in Arkansas and to develop herbicide programs for controlling glyphosate-resistant johnsongrass in Arkansas soybean. Johnsongrass accessions were collected from 14 counties in the Mississippi River Delta region of Arkansas and screened for resistance to four of the most commonly used postemergence herbicides for …

Abiotic And Biotic Factors Affecting The Japanese Beetle In Arkansas, Bryan Mathew Petty

Graduate Theses and Dissertations

Japanese beetles are a relatively new pest to Arkansas. During my Ph.D. research I investigated the pathogens and environmental factors influencing Japanese beetle populations in the state. The prevalence of various pathogens and parasitoids attacking Popillia japonica were recorded annually from wild populations. Of specific interest was the microsporidian pathogen Ovavesicula popilliae, which I introduced as a biological control agent in the state. Details of the relationship between this pathogen and the Japanese beetle were investigated, including dose response, host range, and spore production. Additionally, annual abundance of the beetle in the region was recorded and tracked over the course …

Identification Of Species Of Botryosphaeriaceae Causing Bot Gummosis In Citrus In California, A.O. Adesemoye, J.S. Mayorquin, D.H. Wang, M. Twizeyimana, S.C. Lynch, Akif Eskalen

Department of Plant Pathology: Faculty Publications

Members of the Botryosphaeriaceae family are known to cause Bot gummosis on many woody plants worldwide. To identify pathogens associated with Bot gummosis on citrus in California, scion and rootstock samples were collected in 2010 and 2011 from five citrusgrowing counties in California. Symptoms observed on citrus included branch cankers, dieback, and gumming. Various fungal species were recovered from necrotic tissues of branch canker and rootstock samples. Species were identified morphologically and by phylogenetic comparison as ‘Eureka’ lemon, ‘Valencia’, ‘Washington Navel’, ‘Fukumoto’, grapefruit, ‘Satsuma’, and ‘Meyer’ lemon. Species were identified morphologically and by phylogenetic comparison of the complete sequence of …

Plant Micrornas Display Differential 3' Truncation And Tailing Modifications That Are Argonaute1 Dependent And Conserved Across Species, Jixian Zhai, Yuanyuan Zhao, Stacey A. Simon, Sheng Huang, Katherine Petsch, Siwaret Arikit, Manoj Pillay, Lijuan Ji, Meng Xie, Xiaofeng Cao, Bin Yu, Marja Timmermans, Bing Yang, Xuemei Chen, Blake C. Meyers

Center for Plant Science Innovation: Faculty Publications

Plant small RNAs are 3' methylated by the methyltransferase HUA1 ENHANCER1 (HEN1). In plant hen1 mutants, 3' modifications of small RNAs, including oligo-uridylation (tailing), are associated with accelerated degradation of microRNAs (miRNAs). By sequencing small RNAs of the wild type and hen1 mutants from Arabidopsis thaliana, rice (Oryza sativa), and maize (Zea mays), we found 39 truncation prior to tailing is widespread in these mutants. Moreover, the patterns of miRNA truncation and tailing differ substantially among miRNA families but are conserved across species. The same patterns are also observable in wild-type libraries from a broad …