Plant Sciences Commons^™

Managing Threats To The Urban Forest: From Dutch Elm Disease To Emerald Ash Borer - Learning From Experience, Christopher J. Borman

Doctor of Plant Health Program: Dissertations and Student Research

The urban forest provides important essential services to all municipalities; however, its value is often overlooked. The urban forest contributes to energy savings, environmental benefits, psychological well-being, and social benefits. Managing the urban forest in a sustainable manner is important if we wish to benefit from these services well into the future. Reliable management techniques have been created through previous experiences with pests, and these should be utilized and improved for use on urban forests.

American elm (Ulmus americana L.) was once a major component of the urban forests of North America. In 1927, Dutch elm disease (DED) was …

Inheritance Of Virulence In The Root Rot Pathogen Phytophthora Sojae, Sirjana Devi Shrestha

Electronic Thesis and Dissertation Repository

The oomycete Phytophthora sojae causes stem and root rot of soybean plants. The interaction of pathogen avirulence (Avr) and host resistance (R)-genes determine the disease outcome. The Avr3a mRNA transcript level is variable among P. sojae strains and determines virulence towards the R-gene Rps3a. To study the inheritance of virulence, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 and P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F₅ generation. However, test-crosses of F₁ (Avr3a^ACR10/Avr3a …

Mono- And Digalactosyldiacylglycerol Lipids Function Nonredundantly To Regulate Systemic Acquired Resistance In Plants, Qing-Ming Gao, Keshun Yu, Ye Xia, M. B. Shine, Caixia Wang, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo

Plant Pathology Faculty Publications

The plant galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) have been linked to the anti-inflammatory and cancer benefits of a green leafy vegetable diet in humans due to their ability to regulate the levels of free radicals like nitric oxide (NO). Here, we show that DGDG contributes to plant NO as well as salicylic acid biosynthesis and is required for the induction of systemic acquired resistance (SAR). In contrast, MGDG regulates the biosynthesis of the SAR signals azelaic acid (AzA) and glycerol-3-phosphate (G3P) that function downstream of NO. Interestingly, DGDG is also required for AzA-induced SAR, but MGDG is not. Notably, …

Pseudomonas Syringae Type Iii Effectors: Targets And Roles In Plant Immunity, Tania Y. Toruño

Center for Plant Science Innovation: Faculty and Staff Publications

Pseudomonas syringae is a Gram-negative bacterial pathogen that infects many crops. A central virulence strategy P. syringae uses to successfully infect plants is the injection of type III effector proteins (T3Es) into plant cells through a type IIII protein secretion system (T3SS). The T3SS is a molecular syringe found in many Gram-negative bacterial pathogens of plants and animals that transport T3Es from the bacterial cytosol into eukaryotic cells. T3Es disrupt host processes in the plant immune system required to restrict pathogen ingress. The plant innate immune system is divided in two branches, pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI) and effector-triggered …

First Report Of Goss's Bacterial Leaf Blight And Wilt Of Corn Caused By Clavibacter Michiganensis Subsp. Nebraskensis In North Dakota, A. Friskop, K. Kinzer, M. Mcconnell, Z. Liu, K. A. Korus, A. Timmerman, T. Jackson

Department of Plant Pathology: Faculty Publications

In August of 2011, the North Dakota State University Plant Diagnostic Lab received a hybrid corn (Zea mays) leaf sample from Burleigh County in southcentral North Dakota (ND). The leaf had long, irregular, water-soaked lesions consistent with Goss's leaf blight of corn. Using a light microscope at 10× magnification, bacterial streaming was observed from the excised edge of leaf tissue. A bacterial suspension was created, streaked onto a semi-selective CNS medium (1), and incubated at 22°C. Dark yellow-orange colonies appeared on the medium after 5 days. Single colonies were subcultured onto additional CNS media. To verify the identity …

The Effect Of Agricultural Practices On Sugar Beet Root Aphid (Pemphigus Betae Doane) And Beneficial Epigeal Arthropods, Rudolph J. Pretorius

Department of Entomology: Dissertations, Theses, and Student Research

This study investigated the effect of several agricultural practices on the sugar beet root aphid (Pemphigus betae Doane) and beneficial epigeal natural enemies in western Nebraska sugar beet agroecosystems. Eight glyphosate-tolerant sugar beet varieties were evaluated under field conditions for their resistance to root aphids. High levels of aphid resistance were detected for some varieties. In conjunction to this, pitfall sampling was conducted to determine the beneficial epigeal natural enemy complex in the area, which could contribute to the management of both root aphids and glyphosate-resistant weeds. Ground beetles comprised an important and abundant component of this fauna, with …

Identification Of Root-Knot Nematodes (Meloidogyne Spp.) Of Arkansas Using Molecular Diagnostics, Churamani Khanal

Graduate Theses and Dissertations

Root-knot nematodes (Meloidogyne spp.) are highly-adaptable, obligate plant parasites distributed worldwide. In addition, root-knot nematodes are an economically important genus of plant-parasitic nematodes. Meloidogyne incognita, M. arenaria, M. javanica, M. hapla and M. graminis have been reported from Arkansas during 1964 to 1994. Previous identifications were based primarily on morphological characters and host differentials. In this study, identification using molecular diagnostics methods was performed to identify Meloidogyne species present in Arkansas. A total of 106 soil and root samples from 36 of the 75 counties were collected and processed to obtain root-knot nematodes. Polymerase chain reaction (PCR) was performed …

Evaluation Of Medicago Truncatula Accessions For Triterpene Saponins And Their Potential Impacts On Plant Pests, Samantha Roberson

Graduate Theses and Dissertations

Plants have developed numerous ways to protect themselves from microbes and insects, including producing secondary metabolites that negatively impact an invading pathogen or pest. Saponins are specialized metabolites found in many plant species and may play a role in protecting the plant. Though saponins are found in many plant species, triterpene saponins are found primarily in dicotyledons, including legumes. Medicago truncatula is a model system for studying legume biology and some accessions accumulate high concentrations of saponins. Accessions of M. truncatula known to have differing levels of saponins in both foliar and root tissues were tested for their suitability as …

The Phenotypic Effects And Transcript Response Of Salt Stress, The Impact Of Viral Infection On Salt Stress Symptoms, And The Effect Of Salt Stress On Soybean Virus Vector Activity In Soybean Varieties That Vary In Chloride Uptake, Alma Glenn Laney

Graduate Theses and Dissertations

With the increase in saline soils worldwide, understanding the mechanisms for salt tolerance in plants is important to reduce yield loss due to salt stress. Soybean, Glycine max (L.) Merr., genotypes differ in chloride uptake with genotypes that take up chloride into foliar tissues tending to be salt-sensitive whereas those that partially exclude chloride from the leaves are more salt-tolerant. Transcriptional and physiological responses were measured in two soybean cultivars, Clark and Manokin, which differ in chloride uptake in response to salt stress and in combination with Soybean mosaic virus (SMV) and its aphid vector, Aphis glycines . The interaction …

Characterization Of A Novel Fungal-Specific Gene, Fug1, In Fusarium Verticillioides, John Byron Ridenour

Graduate Theses and Dissertations

Filamentous fungi are responsible for numerous plant and animal diseases. The filamentous ascomycete Fusarium verticillioides is a globally important pathogen of maize, capable of causing severe yield reductions and economic losses. Also of substantial concern is the contamination of infected kernels with fumonisins, toxic secondary metabolites linked to toxicoses in humans and livestock. The number of sequenced fungal genomes is rapidly increasing. However, functional characterization of fungal genes has not progressed at a comparable rate. In pathogenic fungi, uncharacterized genes represent a source for novel virulence factors or anti-fungal targets. Therefore, to fully understand the genetic mechanisms underlying fungal pathogenesis, …

Reniform Nematode (Rotylenchulus Reniformis) Manipulation Of Host Root Gene Expression During Syncytium Formation In Upland Cotton (Gossypium Hirsutum), Wei Li

All Theses

Background: The semi-endoparasitic reniform nematode (Rotylenchulus reniformis) is a major yield-limiting pest of multiple crops in the tropics and sub-tropics, including upland cotton (Gossypium hirsutum). Reniform-resistant cotton varieties are urgently needed, but genes that confer resistance to reniform nematode have not been identified in any species. Parasitism by reniform nematode involves significant developmental changes in plant roots, leading to the formation of multicellular feeding structures called syncytia. Here, we present de novo transcriptomes assembled from syncytial and non-syncytial cotton roots on three sampling dates across a 12-day time course. Results: Total mRNA samples extracted from reniform-infected …

Dissection Of Gray Leaf Spot Of Maize Through Functional Genomics, Robert Louis Hirsch

Graduate Theses and Dissertations

Gray leaf spot, caused by Cercospora zeae-maydis, is a devastating disease of maize that reduces yields and increases management costs. C. zeae-maydis penetrates maize leaves through stomata, but the biological and molecular bases of this process are poorly understood. The goal of this research was to elucidate the biological parameters of stomatal infection in C. zeae-maydis, and to identify and characterize novel genetic pathways involved in stomatal sensing and pathogenesis. Histopathological observations of a GFP-expressing strain of C. zeae-maydis during infection of maize indicated that the fungus responded to host-derived stomatal cues during the infection process. C. zeae-maydis was observed …

Spatial Distribution And Genetic Variability Of Reniform And Lance Nematodes In Cotton Agroecosystems, Claudia Holguin

All Dissertations

Rotylenchulus reniformis (reniform nematode) and Hoplolaimus columbus (Columbia lance nematode) are two of the main plant-pathogenic nematode species affecting cotton production in the United States. For the selection and implementation of effective management practices it is important to understand distribution patterns and population genetic structure of these two nematodes in cotton agroecosystems. In a three-year field study, the spatial distribution of reniform nematode was characterized in two commercial fields in South Carolina to determine the effects of relations with soil texture and crop rotation on reniform nematode distribution (Chapter 1). Results of this project suggest that population densities of reniform …

Chlorovirus Atcv-1 Is Part Of The Human Oropharyngeal Virome And Is Associated With Changes In Cognitive Functions In Humans And Mice, Robert H. Yolken, Lorraine Jones-Brando, David D. Dunigan, Geetha Kannan, Faith Dickerson, Emily Severance, Sarven Sabunciyan, C. Conover Talbot Jr., Emese Prandovszky, James R. Gurnon, Irina V. Agarkova, Flora Leister, Kristin L. Gressitt, Ou Chen, Bryan Deuber, Fangrui Ma, Mikhail V. Pletnikov, James L. Van Etten

James Van Etten Publications

Chloroviruses (family Phycodnaviridae) are large DNA viruses known to infect certain eukaryotic green algae and have not been previously shown to infect humans or to be part of the human virome. We unexpectedly found sequences homologous to the chlorovirus Acanthocystis turfacea chlorella virus 1 (ATCV-1) in a metagenomic analysis of DNA extracted from human oropharyngeal samples. These samples were obtained by throat swabs of adults without a psychiatric disorder or serious physical illness who were participating in a study that included measures of cognitive functioning. The presence of ATCV-1 DNA was confirmed by quantitative PCR with ATCV-1 DNA being …

Co-Opted Oxysterol-Binding Orp And Vap Proteins Channel Sterols To Rna Virus Replication Sites Via Membrane Contact Sites, Daniel Barajas, Kai Xu, Isabel Fernández De Castro Martín, Zsuzsanna Sasvari, Federica Brandizzi, Cristina Risco, Peter D. Nagy

Plant Pathology Faculty Publications

Viruses recruit cellular membranes and subvert cellular proteins involved in lipid biosynthesis to build viral replicase complexes and replication organelles. Among the lipids, sterols are important components of membranes, affecting the shape and curvature of membranes. In this paper, the tombusvirus replication protein is shown to co-opt cellular Oxysterol-binding protein related proteins (ORPs), whose deletion in yeast model host leads to decreased tombusvirus replication. In addition, tombusviruses also subvert Scs2p VAP protein to facilitate the formation of membrane contact sites (MCSs), where membranes are juxtaposed, likely channeling lipids to the replication sites. In all, these events result in redistribution and …

Genetic And Aggressiveness Variation Among Sclerotinia Sclerotiorum Dry Bean Isolates From Brazil Fields, Willian Luis Antonio Zancan, James R. Steadman, Rebecca Higgins, Rachana Jhala, Jose Da Cruz Machado

Department of Plant Pathology: Faculty Publications

Sclerotinia sclerotiorum, infection of bean fields, has increased in Brazil. Fungicides application is the control strategy used due to lack of cultivars with complete disease resistance. To guide the use of isolates in resistance screening 25 S. sclerotiorum isolates from Brazilian dry bean fields were characterized using microsatellite markers, mycelial compatibility groups (MCGs) and aggressiveness. Microsatellite primer pairs were used to identify polymorphisms among the S. sclerotiorum isolates and MCGs were determined from interaction of all isolates grown side by-side. Aggressiveness was derived from a straw test where fungal mycelium was placed over a cut bean stem and rated for …

Tal Effector-Nucleotide Targeter (Tale-Nt) 2.0: Tools For Tal Effector Design And Target Prediction, Erin L. Doyle, Nicholas J. Booher, Daniel S. Standage, Daniel F. Voytas, Volker P. Brendel, John K. Vandyk, Adam J. Bogdanove

John K. VanDyk

Transcription activator-like (TAL) effectors are repeat-containing proteins used by plant pathogenic bacteria to manipulate host gene expression. Repeats are polymorphic and individually specify single nucleotides in the DNA target, with some degeneracy. A TAL effector-nucleotide binding code that links repeat type to specified nucleotide enables prediction of genomic binding sites for TAL effectors and customization of TAL effectors for use in DNA targeting, in particular as custom transcription factors for engineered gene regulation and as site-specific nucleases for genome editing. We have developed a suite of web-based tools called TAL Effector-Nucleotide Targeter 2.0 (TALE-NT 2.0;https://boglab.plp.iastate.edu/) that enables design of custom …

An Eriophyid Mite-Transmitted Plant Virus Contains Eight Genomic Rna Segments With Unusual Heterogeneity In The Nucleocapsid Protein, Satyanarayana Tatineni, Anthony J. Mcmechan, Everlyne N. Wosula, Stephen N. Wegulo, Robert A. Graybosch, Roy French, Gary L. Hein

Department of Plant Pathology: Faculty Publications

Eriophyid mite-transmitted, multipartite, negative-sense RNA plant viruses with membrane-bound spherical virions are classified in the genus Emaravirus. We report here that the eriophyid mite-transmitted Wheat mosaic virus (WMoV), an Emaravirus, contains eight genomic RNA segments, the most in a known negative-sense RNA plant virus. Remarkably, two RNA 3 consensus sequences, encoding the nucleocapsid protein, were found with 12.5% sequence divergence, while no heterogeneity was observed in the consensus sequences of additional genomic RNA segments. The RNA-dependent RNA polymerase, glycoprotein precursor, nucleocapsid, and P4 proteins of WMoV exhibited limited sequence homology with the orthologous proteins of other emaraviruses, while …

Effect Of Post-Anthesis Fungicide Applications To Manage Fusarium Head Blight In Winter Wheat, Anna Noversoke

Open Access Theses

Fusarium head blight (FHB) of wheat, caused by the fungus Fusarium graminearum, is currently considered one of the most economically important diseases on wheat in the North Central United States. The fungus causes light-weight "tombstone" grains to form and produces the mycotoxin deoxynivalenol (DON), reducing the yield and quality of the grain. Currently, farmers rely heavily on the sterol demethylase Inhibitor (DMI) triazole fungicide Prosaro (Bayer CropScience) to protect their crop from this disease. The optimal fungicide application timing is traditionally believed to be early anthesis - Feekes Growth Stage (FGS) 10.5.1. However, environmental conditions and uneven flowering across a …

Effects Of Ocean Acidification On Chlorophyll Content, C. Del Fierro, R. Lloyd, H. El-Askary

e-Research: A Journal of Undergraduate Work

Airborne pollutants contribute to ocean acidification and hence to the associated chlorophyll content level. Previous work showed that falling aerosols causing ocean acidification would in turn result in bleaching and productivity loss in coral reef builders. Chlorophyll content has been used as a measure of the concentration of the photosynthetic pigment chlorophyll a (the most common "green" chlorophyll) in the ocean. In our work we have monitored the change in chlorophyll content obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on board Terra/Aqua satellites from 2000-2009 over selected pilot areas. Moreover, we have used the Goddard Chemistry Aerosol Radiation …

Chlorovirus Skp1-Binding Ankyrin Repeat Protein Interplay And Mimicry Of Cellular Ubiquitin Ligase Machinery, Eric A. Noel, Ming Kang, Jiri Adamec, James L. Van Etten, George A. Oyler

James Van Etten Publications

The ubiquitin-proteasome system is targeted by many viruses that have evolved strategies to redirect host ubiquitination machinery. Members of the genus Chlorovirus are proposed to share an ancestral lineage with a broader group of related viruses, nucleo-cytoplasmic large DNA viruses (NCLDV). Chloroviruses encode an Skp1 homolog and ankyrin repeat (ANK) proteins. Several chlorovirus-encoded ANK repeats contain C-terminal domains characteristic of cellular F-boxes or related NCLDV chordopox PRANC (pox protein repeats of ankyrin at C-terminal) domains. These observations suggested that this unique combination of Skp1 and ANK repeat proteins might form complexes analogous to the cellular Skp1-Cul1-F-box (SCF) ubiquitin ligase complex. …

A Novel Partitivirus That Confers Hypovirulence On Plant Pathogenic Fungi, Xueqiong Xiao, Jiasen Cheng, Jinghua Tang, Yanping Fu, Daohong Jiang, Timothy S. Baker, Said A. Ghabrial, Jiatao Xie

Plant Pathology Faculty Publications

Members of the family Partitiviridae have bisegmented double-stranded RNA (dsRNA) genomes and are not generally known to cause obvious symptoms in their natural hosts. An unusual partitivirus, Sclerotinia sclerotiorum partitivirus 1 (SsPV1/WF-1), conferred hypovirulence on its natural plant-pathogenic fungal host, Sclerotinia sclerotiorum strain WF-1. Cellular organelles, including mitochondria, were severely damaged. Hypovirulence and associated traits of strain WF-1 and SsPV1/WF-1 were readily cotransmitted horizontally via hyphal contact to different vegetative compatibility groups of S. sclerotiorum and interspecifically to Sclerotinia nivalis and Sclerotinia minor. S. sclerotiorum strain 1980 transfected with purified SsPV1/WF-1 virions also exhibited hypovirulence and associated traits similar …

Diversity Of Bacteria Carried By Pinewood Nematode In Usa And Phylogenetic Comparison With Isolates From Other Countries, Diogo Neves Proença, Luís Fonseca, Thomas Powers, Isabel M.O. Abrantes, Paula V. Morais

Department of Plant Pathology: Faculty Publications

Pine wilt disease (PWD) is native to North America and has spread to Asia and Europe. Lately, mutualistic relationship has been suggested between the pinewood nematode (PWN), Bursaphelenchus xylophilus the causal nematode agent of PWD, and bacteria. In countries where PWN occurs, nematodes from diseased trees were reported to carry bacteria from several genera. However no data exists for the United States. The objective of this study was to evaluate the diversity of the bacterial community carried by B. xylophilus, isolated from different Pinus spp. with PWD in Nebraska, United States. The bacteria carried by PWN belonged to Gammaproteobacteria …

Bot Canker Pathogens Could Complicate The Management Of Phytophthora Black Pod Of Cocoa, Idowu Jaiyeola, Rufus J. Akinrinlola, Gbodope S. Ige, Oluwatimilehin O. Omoleye, Abiola Oyedele, Bayode J. Odunayo, Omotayo J. Emehin, Marcus O. Bello, Anthony O. Adesemoye

Department of Plant Pathology: Faculty Publications

Black pod is a major hindrance to cocoa production in Nigeria. It is caused by three different Phytophthora species with Phytophthora megakarya as the most important species in Nigeria and West African subregion. Phytophthora spp. may enhance infections by opportunistic pathogens such as members of the Botryosphaeriacea that cause branch and trunk cankers in many woody plants across the world. Botryosphaeriacea has not been reported in cocoa nor in any woody plants in Nigeria to our knowledge. In the cocoa belt of Nigeria, research and understanding on cocoa black pod and Phytophthora is limited partly because of delayed or no …

Tombusvirus-Yeast Interactions Identify Conserved Cell-Intrinsic Viral Restriction Factors, Zsuzsanna Sasvari, Paulina Alatriste Gonzalez, Peter D. Nagy

Plant Pathology Faculty Publications

To combat viral infections, plants possess innate and adaptive immune pathways, such as RNA silencing, R gene and recessive gene-mediated resistance mechanisms. However, it is likely that additional cell-intrinsic restriction factors (CIRF) are also involved in limiting plant virus replication. This review discusses novel CIRFs with antiviral functions, many of them RNA-binding proteins or affecting the RNA binding activities of viral replication proteins. The CIRFs against tombusviruses have been identified in yeast (Saccharomyces cerevisiae), which is developed as an advanced model organism. Grouping of the identified CIRFs based on their known cellular functions and subcellular localization in yeast …

Chlorovirus Pbcv-1 Encodes An Active Copper-Zinc Superoxide Dismutase, Ming Kang, Garry A. Duncan, Charles Kuszynski, George Oyler, Jiayin Zheng, Donald F. Becker, James L. Van Etten

James Van Etten Publications

Superoxide dismutases (SODs) are metalloproteins that protect organisms from toxic reactive oxygen species by catalyzing the conversion of superoxide anion to hydrogen peroxide and molecular oxygen. Chlorovirus PBCV-1 encodes a 187-amino-acid protein that resembles a Cu-Zn SOD with all of the conserved amino acid residues for binding copper and zinc (named cvSOD). cvSOD has an internal Met that results in a 165-amino-acid protein (named tcvSOD). Both cvSOD and tcvSOD recombinant proteins inhibited nitroblue tetrazolium reduction of superoxide anion generated in a xanthine-xanthine oxidase system in solution. tcvSOD was chosen for further characterization because it was easier to produce. Recombinant tcvSOD …

Evaluating Green Stink Bug Damage And Insect Abundance In Edamame, Benjamin Carroll Thrash

Graduate Theses and Dissertations

Edamame are an emerging crop in Arkansas, with 2013 planting estimates at 680 hectares. Although edamame are the same species as conventional soybeans grown in Arkansas, differences in use, maturity, and harvest may require creation and implementation of insect pest management approaches that differ from those used in conventional soybean production systems in order for a quality crop to be produced. Studies were conducted to determine a green stink bug damage-density relationship for edamame. Cages were used to confine green stink bugs on field-planted edamame at densities of 0, 2, 6, or 12 green stink bugs per cage (0, 0.55, …

The Hop-Like Stress-Induced Protein 1 Cochaperone Is A Novel Cell-Intrinsic Restriction Factor For Mitochondrial Tombusvirus Replication, Kai Xu, Jing-Yi Lin, Peter D. Nagy

Plant Pathology Faculty Publications

Recent genome-wide screens reveal that the host cells express an arsenal of proteins that inhibit replication of plus-stranded RNA viruses by functioning as cell-intrinsic restriction factors of viral infections. One group of cell-intrinsic restriction factors against tombusviruses contains tetratricopeptide repeat (TPR) domains that directly interact with the viral replication proteins. In this paper, we find that the TPR domain-containing Hop-like stress-inducible protein 1 (Sti1p) cochaperone selectively inhibits the mitochondrial membrane-based replication of Carnation Italian ringspot tombusvirus (CIRV). In contrast, Sti1/Hop does not inhibit the peroxisome membrane-based replication of the closely related Tomato bushy stunt virus (TBSV) or Cucumber necrosis virus …

Phenotypic Diversity In Lysobacter Enzymogenes In Relations To Biological Control, Ya Li

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

Strains of the bacterium Lysobacter enzymogenes have been isolated from various regions of the world and reported to have potential as biological control agents against plant pathogens. Previous research revealed many ecological traits and mechanisms important to biological control by L. enzymogenes. Much of the previous research, however, was conducted on individual strains with little direct comparison of different strains. In this study, L. enzymogenes strains isolated from different locations and source materials (soil, roots, leaves) were compared for biocontrol-related phenotypic traits in vitro, epiphytic and endophytic colonization of leaves, and biocontrol of Bipolaris leaf spot on tall fescue. …

Panicum Mosaic Virus Complex And Biofuels Switchgrass, Catherine Louise Stewart

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

New switchgrass (Panicum virgatum L.) cultivars are being developed for use as a biofuel pyrolysis feedstock. Viral pathogens have been reported in switchgrass, but their importance in biofuel cultivars is not well known. In 2012 surveys of five switchgrass breeding nurseries in Nebraska, plants with mottling and stunting— symptoms associated with virus infection—had an incidence of symptomatic plants within fields as high as 59%. Leaves from 120 symptomatic plants were analyzed by ELISA for Panicum mosaic virus (PMV) and four other viruses known to infect switchgrass. Most samples (87%) were positive for PMV, and fewer than 8% for the …