Plant Sciences Commons^™

Key Interplay Between The Co-Opted Sorting Nexin-Bar Proteins And Pi3p Phosphoinositide In The Formation Of The Tombusvirus Replicase, Zhike Feng, Nikolay Kovalev, Peter D. Nagy

Plant Pathology Faculty Publications

Positive-strand RNA viruses replicate in host cells by forming large viral replication organelles, which harbor numerous membrane-bound viral replicase complexes (VRCs). In spite of its essential role in viral replication, the biogenesis of the VRCs is not fully understood. The authors identified critical roles of cellular membrane-shaping proteins and PI(3)P (phosphatidylinositol 3-phosphate) phosphoinositide, a minor lipid with key functions in endosomal vesicle trafficking and autophagosome biogenesis, in VRC formation for tomato bushy stunt virus (TBSV). The authors show that TBSV co-opts the endosomal SNX-BAR (sorting nexin with Bin/Amphiphysin/Rvs- BAR domain) proteins, which bind to PI(3)P and have membrane-reshaping function during …

Evaluating The Current Weed Community In Wild Blueberry Fields And Ipm Strategies For Spreading Dogbane (Apocynum Androsaemifolium), Anthony G. Ayers

Electronic Theses and Dissertations

Lowbush blueberry (Vaccinium angustifolium) is Maine’s third largest crop (USDA 2020 a). From 2017 – 2019 the three seasons yield average was 27,200 tons were harvested from 19,500 acres for a value of $22,468,000 (USDA 2020 c). Lowbush blueberries are managed on a two-year cycle. Every other year, lowbush blueberry fields are pruned to the ground either through the use of a tractor mounted flail mower or a prescribed burn (Yarborough 2009). Pruning is a necessary part of managing lowbush blueberries as the second-year growth produces the highest yield but steadily declines in subsequent years (Drummond et al. …

Strawberry Powdery Mildew Caused By Podosphaera Aphanis: Fungicide Resistance And Host Plant Resistance, Michael G. Palmer

Master's Theses

Strawberry powdery mildew, caused by Podosphaera aphanis, affects leaves, fruit, and runners of strawberry plants. Infected leaves have reduced photosynthetic capability and infected fruit become unmarketable. Both of these factors translate to economic loss for the grower and therefore merit taking measures to control the disease. One objective of this study was to evaluate the resistance developed in populations of strawberry powdery mildew to chemical control measures. A fungicide assay was developed to evaluate the efficacy of six treatments (penthiopyrad, quinoxyfen, myclobutanil, trifloxystrobin, cyflufenamid, fluopyram + trifloxystrobin) for control of the disease. Nineteen isolates of strawberry powdery mildew were …

The Virome Of Peony And The Population Structure Of Its Most Prominent Viruses, Cullen Shaffer

Graduate Theses and Dissertations

Peony (Peonia lactiflora, Pall.) is a popular ornamental that has been cultivated for millennia. Due to its popularity, plant material is frequently moved across international borders allowing for the spread of viruses. The virome of several peony plants was investigated and four viruses; namely Amazon lily mild mottle virus (ALiMMV), Cycas necrotic stunt virus (CNSV), Gentian Kobu-sho associated virus (GKaV) and Lychnis mottle virus (LycMoV) were detected for the first time in the Western Hemisphere. Incidence ranged from a few plants for ALiMMV to near universal infection for CNSV. GKaV was found in individuals that were infected with Lemoine’s disease …

Parallel Strategies To Control Bacterial Panicle Blight Of Rice, Laura Ortega

Graduate Theses and Dissertations

Bacterial Panicle Blight (BPB) of rice is a seed-borne disease caused by the bacterium Burkholderia glumae. This disease has affected rice production worldwide and its effects are likely to become more devastating with the continuous increase in global temperatures especially during the growing season. Field data has shown that the disease has been more prevalent in years when the temperatures have been unusually high especially at night possibly due to the bacterial adaptation to grow at temperatures higher than 40oC. With the continuous rise in global temperatures, it is likely that this disease will be more problematic. The bacterium can …

Assessment Of Grain Safety In Developing Nations, Jose R. Mendoza

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Grains are the most widely consumed foods worldwide, with maize (Zea mays) being frequently consumed in developing countries where it feeds approximately 900 million people under the poverty line of 2 USD per day. While grain handling practices are acceptable in most developed nations, many developing nations still face challenges such as inadequate field management, drying, and storage. Faulty grain handling along with unavoidably humid climates result in recurrent fungal growth and spoilage, which compromises both the end-quality and safety of the harvest. This becomes particularly problematic where there is little awareness about health risks associated with poor …

Polerovirus Genomic Variation And Mechanisms Of Silencing Suppression By P0 Protein, Natalie Holste

School of Biological Sciences: Dissertations, Theses, and Student Research

The family Luteoviridae consists of three genera: Luteovirus, Enamovirus, and Polerovirus. The genus Polerovirus contains 32 virus species. All are transmitted by aphids and can infect a wide variety of crops from cereals and wheat to cucurbits and peppers. However, little is known about how this wide range of hosts and vectors developed. In poleroviruses, aphid transmission and virion formation is mediated by the coat protein read-through domain (CPRT) while silencing suppression and phloem limitation is mediated by Protein 0 (P0)—a protein unique to poleroviruses. P0 gives poleroviruses a great advantage amongst plant viruses and diversifies polerovirus species, but the …

Dct4—A New Member Of The Dicarboxylate Transporter Family In C4 Grasse, Sarit Weissmann, Pu Huang, Madeline A. Wiechert, Koki Furuyama, Thomas P. Brutnell, Mitsutaka Taniguchi, James C. Schnable, Todd C. Mockler

Center for Plant Science Innovation: Faculty and Staff Publications

Malate transport shuttles atmospheric carbon into the Calvin–Benson cycle during NADP-ME C4 photosynthesis. Previous characterizations of several plant dicarboxylate transporters (DCT) showed that they efficiently exchange malate across membranes. Here, we identify and characterize a previously unknown member of the DCT family, DCT4, in Sorghum bicolor. We show that SbDCT4 exchangesmalateacrossmembranesanditsexpressionpatternisconsistentwitharoleinmalatetransportduringC4 photosynthesis. SbDCT4 is not syntenic to the characterized photosynthetic gene ZmDCT2, and an ortholog is not detectable in the maize reference genome. We found that the expression patterns of DCT family genes in the leaves of Zea mays, and S. bicolor varied by cell type. Our results suggest that …

Boxwood Dieback: Molecular Detection, In-Vitro Fungicide Efficacy, And Host Susceptibility For Managing A New Emerging Disease Caused By Colletotrichum Theobromicola, Harleen Kaur

LSU Master's Theses

Boxwood (Buxus spp. L) is one of the most common and widely planted perennial ornamentals in both home gardens and commercial landscapes. Grown for its evergreen, dark green foliage, boxwood cultivation dates back to 4000 BC in Egypt. Although considered hardy, boxwood is susceptible to several plant pathogens. Recently reported boxwood dieback, a fungal disease caused by Colletotrichum theobromicola, has been spreading at an alarming rate within the United States. Boxwood dieback consists of symptoms that resemble to those caused by Phytophthora root rot, Volutella blight, and some abiotic disorders and can be easily misdiagnosed in nurseries and …

Molecular Identification And Characterization Of Viral Pathogens Infecting Sweet Cherry, Aaron J. Simkovich

Electronic Thesis and Dissertation Repository

Stone fruits are a valuable crop grown worldwide, however pathogens such as viruses threaten fruit production by reducing tree health and fruit yield. In an orchard within the Niagara region of Ontario, symptoms typical of viral infection such as chlorosis and leaf deformation were seen on sweet cherry (Prunus avium L.) trees. Next generation sequencing was performed on symptomatic and asymptomatic leaves and four viruses were identified. On the tree displaying the most severe symptoms, Prune dwarf virus (PDV), was the only virus detected. A survey conducted during this work showed 42% of cherry trees on a single …

Role Reversal Of Functional Identity In Host Factors: Dissecting Features Affecting Pro-Viral Versus Antiviral Functions Of Cellular Dead-Box Helicases In Tombusvirus Replication, Cheng-Yu Wu, Peter D. Nagy

Plant Pathology Faculty Publications

Positive-stranded (+)RNA viruses greatly exploit host cells to support viral replication. However, unlike many other pathogens, (+)RNA viruses code for only a limited number of genes, making them highly dependent on numerous co-opted host factors for supporting viral replication and other viral processes during their infections. This excessive dependence on subverted host factors, however, renders (+)RNA viruses vulnerable to host restriction factors that could block virus replication. Interestingly, cellular ATP-dependent DEAD-box RNA helicases could promote or inhibit the replication of Tomato bushy stunt virus (TBSV) replication. However, it is currently unknown what features make a particular DEAD-box helicase either pro-viral …

How Does Molecular Biology Help To Identify Plant Disease?, Madina Akramova

English Language Institute

This study examines a process of plant disease diagnostics in light of a particular method of molecular biology - polymerase chain reaction.

B.R. Wells Arkansas Rice Research Studies 2019, K.A. K. Moldenhauer, B. Scott, J. Hardke

Arkansas Agricultural Experiment Station Research Series

No abstract provided.

Dsrna As A Potential Tool For Cercospora Leaf Blight Management And Elucidation Of A Factors That Contribute To Late Disease Onset In The Reproductive Growth Stage Of Soybean, Marija Zivanovic

LSU Doctoral Dissertations

Cercospora leaf blight (CLB) of soybean (Glycine max L. Merr.), an important disease in Louisiana, is primarily caused by Cercospora cf. flagellaris. The pathogen produces cercosporin, a toxin necessary for fungal virulence. So far, there are few commercial cultivars of soybean with CLB resistance and few effective fungicides to manage this disease. Consequently, alternative management approaches are needed. With that in mind, the first objective was to develop a screening method to compare the effectiveness of bacterially-expressed double stranded (ds) RNAs corresponding to genes associated with cercosporin accumulation (Avr4, CTB1, CTB8, AY-1 and HN-2 …

Taxonomic And Genetic Diversity, And Pathogenicity Of Diaporthe Species Associated With Soybean, Fakhir Eraheem Hameed Al Shuwaili

Graduate Theses and Dissertations

Diaporthe species (anamorph: Phomopsis) are associated with a wide range of plant hosts as plant pathogens, asymptomatic endophytes, and saprobes. One of these hosts is soybean, which is one of the most important crops in U.S. agriculture. Several Diaporthe species cause important diseases on soybean in the U.S., and specifically in Arkansas. The taxonomy, genetic diversity, and pathogenicity of Diaporthe species associated with asymptomatic infection of soybean are rarely studied with accurate molecular tools. Therefore, this dissertation aimed to assess the diversity and boundaries of Diaporthe associated with soybean in Arkansas. Furthermore, pathogenicity and alternative lifestyles were assessed among Diaporthe …

Dissecting The Cellular Control Of Septin Organization In A Global Cereal Killer, Nawaraj Dulal

Graduate Theses and Dissertations

Rice blast disease, caused by the filamentous fungus Magnaporthe oryzae, destroys sufficient rice each year to feed 60 million people, and is a serious threat to global food security. A wheat-adapted lineage of M. oryzae now poses threat to global wheat production. Rice blast disease is currently controlled using limited fungicides, and the emergence of fungicide resistance within M. oryzae populations is a growing concern. There is a pressing need to identify new classes of fungicides to control the disease, which requires better understanding of the basic biology of the pathogen. To establish disease, M. oryzae forms a specialized dome …

Introducing An Indigenous Non-Toxigenic Aspergillus Flavus Strain Isolated From Iraqi Corn Grains As A Bio-Control Agent To Reduce Aflatoxin Contamination In Corn Grains, Ali Almatakeez

Graduate Theses and Dissertations

Mycotoxin contamination of cereal crops, such as maize and sorghum, is a global concern because of the potential health effects on humans and animals. Although substantial research has been conducting regarding mycotoxin prevention and mitigation, little information is available about the association of mycotoxin-producing fungi with corn and sorghum grain in Iraq. Identifying and refining indigenous atoxigenic strains to reduce mycotoxin contamination of maize and sorghum has the potential to enhance the nutritional value of these grains while reducing economic losses. However, to our knowledge, this tactic has not yet been adopted by agricultural authorities and farmers in Iraq. To …

Plant Defensin Antibacterial Mode Of Action Against Pseudomonas Species, Andrew E. Sathoff, Shawn Lewenza, Deborah A. Samac

Faculty Research & Publications

Background: Though many plant defensins exhibit antibacterial activity, little is known about their antibacterial mode of action (MOA). Antimicrobial peptides with a characterized MOA induce the expression of multiple bacterial outer membrane modifications, which are required for resistance to these membrane-targeting peptides. Mini-Tn5- lux mutant strains of Pseudomonas aeruginosa with Tn insertions disrupting outer membrane protective modifications were assessed for sensitivity against plant defensin peptides. These transcriptional lux reporter strains were also evaluated for lux gene expression in response to sublethal plant defensin exposure. Also, a plant pathogen, Pseudomonas syringae pv. syringae was modified through transposon mutagenesis to …

Modeling The Relationship Between Estimated Fungicide Use And Disease-Associated Yield Losses Of Soybean In The United States I: Foliar Fungicides Vs Foliar Diseases, Ananda Y. Bandara, Dilooshi K. Weerasooriya, Shawn P. Conley, Carl A. Bradley, Tom W. Allen, Paul D. Esker

Plant Pathology Faculty Publications

Fungicide use in the United States to manage soybean diseases has increased in recent years. The ability of fungicides to reduce disease-associated yield losses varies greatly depending on multiple factors. Nonetheless, historical data are useful to understand the broad sense and long-term trends related to fungicide use practices. In the current study, the relationship between estimated soybean yield losses due to selected foliar diseases and foliar fungicide use was investigated using annual data from 28 soybean growing states over the period of 2005 to 2015. For national and regional (southern and northern United States) scale data, mixed effects modeling was …

Dynamic Transcriptomic And Phosphoproteomic Analysis During Cell Wall Stress In Aspergillus Nidulans, Cynthia Chelius, Walker Huso, Samantha Reese, Alexander Doan, Stephen Lincoln, Kelsi Lawson, Boa Tran, Raj Purohit, Trevor Glaros, Ranjan Srivastava, Steven D. Harris, Mark R. Marten

Center for Plant Science Innovation: Faculty and Staff Publications

The fungal cell-wall integrity signaling (CWIS) pathway regulates cellular response to environmental stress to enable wall repair and resumption of normal growth. This complex, interconnected, pathway has been only partially characterized in filamentous fungi. To better understand the dynamic cellular response to wall perturbation, a-glucan synthase inhibitor (micafungin) was added to a growing A. nidulans shake-flask culture. From this flask, transcriptomic and phosphoproteomic data were acquired over 10 and 120 min, respectively. To differentiate statistically-significant dynamic behavior from noise, a multivariate adaptive regression splines (MARS) model was applied to both data sets. Over 1800 genes were dynamically expressed and over …

Population Structure And Reproductive Biology Of Monilinia Vaccinii-Corymbosi (Reade) Honey In Lowbush Blueberry In Maine, Katherine A. Ashley

Electronic Theses and Dissertations

Lowbush blueberry, Vaccinium angustifolium Aiton, is both an economically and culturally important crop in Maine, being one of the few endemic crops to North America. The fungus Monilinia vaccinii-corymbosi (Mvc) causes mummy berry disease and is a significant pathogen of both highbush (Vaccinium corymbosum) and lowbush blueberries. While impacts of this disease are not regularly documented, it is estimated that 30-50% of the yield in an unmanaged field can be lost because of Mvc. This disease is typically managed with fungicides or burning of the field during years when the field is pruned, however, the impacts to the …

Smrt Sequencing Of Paramecium Bursaria Chlorella Virus-1 Reveals Diverse Methylation Stability In Adenines Targeted By Restriction Modification Systems, Samantha R. Coy, Eric R. Gann, Spiridon E. Papoulis, Michael E. Holder, Nadim J. Ajami, Joseph F. Petrosino, Erik R. Zinser, James L. Van Etten, Steven W. Wilhelm

James Van Etten Publications

Chloroviruses (family Phycodnaviridae) infect eukaryotic, freshwater, unicellular green algae. A unique feature of these viruses is an abundance of DNA methyltransferases, with isolates dedicating up to 4.5% of their protein coding potential to these genes. This diversity highlights just one of the long-standing values of the chlorovirus model system; where group-wide epigenomic characterization might begin to elucidate the function(s) of DNA methylation in large dsDNA viruses. We characterized DNA modifications in the prototype chlorovirus, PBCV-1, using single-molecule real time (SMRT) sequencing (aka PacBio). Results were compared to total available sites predicted in silico based on DNA sequence alone. SMRT-software detected …

Effects Of Increased Atmospheric Carbon Dioxide Levels On Tobacco Mosaic Virus And Root-Knot Nematodes In Genetically Resistant And Susceptible Tomato Plants, Angie Nicholas

Electronic Theses and Dissertations

Rising atmospheric carbon dioxide (CO₂) may affect plant/pathogen interactions. This study focused on the effects of elevated CO₂ on Root-Knot Nematode (Meloidogyne arenaria) and Tobacco Mosaic Virus (TMV) infection in genetically resistant versus susceptible tomatoes (Solanum lycopersicum). Both resistant and susceptible tomatoes were grown in chambers with either ambient CO₂ or CO₂ elevated to 750 ppm and infected with M. arenaria or TMV. Measurements were taken at regular intervals to determine the effects of the pathogens on the plants. Resistant plants infected with M. arenaria maintained resistance while susceptible plants remained …

An Evaluation Of Unmanned Aircraft Systems' Ability To Assess Stripe Rust In Large Wheat Breeding Nursies, Jamison T. Murry

Graduate Theses and Dissertations

Stripe Rust (Puccinia striiformis f. sp. tritici) is a foliar disease that significantly impacts global wheat production, and resistant cultivars provide the most efficient method of control. High-throughput phenotyping using unmanned aircraft systems (UAS) offers a potentially more efficient method for field-based phenotyping compared to visual assessment. Here we tested the ability of remote sensing to predict stripe rust severity in a diverse population of 594 soft red winter wheat lines, planted in single-rows, and evaluated them by visually rating stripe rust intensity and remotely using the dark green color index (DGCI), normalized difference vegetation index (NDVI) and blue NDVI. …

Mapping Quantitative Trait Loci For Peach (Prunus Persica) Resistance To Xanthomonas Arboricola Pv. Pruni (Xap) And Determining The Diversity And Virulence Of A United States Xap Collection, Maxwell Vonkreuzhof

Graduate Theses and Dissertations

Bacterial spot, caused by the bacterium Xanthomonas arboricola pv. pruni (Xap), is a threat to the peach [Prunus persica (L.) Batsch], Japanese and European plum (P. salicina L. and P. domestica L.), and tart and sweet cherry (P. cerasus L. and P. avium L.) industries. Markers for fruit resistance to bacterial spot have been developed however, markers associated with foliar resistance have yet to be developed. A total of 130 progeny and 13 parents (n=143) were evaluated for foliar and fruit Xap resistance in 2013, 2014, and 2015, and 162 progeny and eight parents (n=170) in 2017 and 2018 as …

An Evaluation Of Biopesticide Combinations On Yield Performance And Disease/Arthropod Control Of Strawberries Grown In High Tunnel Plasticulture Production Systems In Arkansas., Karlee B. Pruitt

Graduate Theses and Dissertations

This two-year study investigated combinations of biopesticides to determine impacts on strawberry fruit marketable fruit yields, and effectiveness in controlling strawberry pests in a high tunnel production system at the University of Arkansas, Division of Agriculture Research and Extension Center in Fayetteville, Arkansas. Two strawberry cultivars Fragaria × ananassa (Duch.), Camino Real and Sweet Sensation were grown in a high tunnel from early-October to mid-May for two consecutive growing seasons, (2017-18 and 2018-19) with six treatment combinations of biopesticides including an untreated (water) control, nutrient spray and selected biological based fungicides and insecticides, arranged into a split-plot randomized block design. …

Subcellular Localization Of Tobacco Sabp2 Under Normal And Stress Conditions, Sanjeev Das

Undergraduate Honors Theses

Subcellular Localization of Tobacco SABP2 under Normal and Stress Conditions

Salicylic acid (SA), a phytohormone, plays an important role in plant physiology. SA mediated innate immune pathway is an important pathway for plant immunity against pathogens. Plants resisting pathogen infection synthesize higher levels of Methyl Salicylate (MeSA), which is then converted to SA by the esterase activity of Salicylic Acid Binding Protein 2 (SABP2). The high level of the converted SA leads to enhanced pathogen resistance. The study of subcellular localization of a protein is critical in explaining its potential biochemical functions. SABP2 tagged with eGFP was expressed transiently in …

Prevalence, Genetic Relationships, And Quantity Of Grapevine Vein Clearing Virus In Aphis Illinoisenesis, Adam Louis Uhls

MSU Graduate Theses

Grapevine vein clearing virus (GVCV) is an emerging pathogen causing severe damage to cultivated grapevines in the Midwest area of the United States. The prevalence of GVCV has been reported in native Vitis spp. and Ampelopsis cordata, a close relative of vitis in the Vitaceae family, which act as a reservoir for the virus. GVCV can be transmitted from wild A. cordata to Vitis spp. by Aphis illinoisensis (grape aphids) under greenhouse conditions, but the prevalence and transmission in native populations remains unknown. Knowing the prevalence and diversity of GVCV variants in natural grape aphid populations would help monitor …

Fungicide Sensitivity Of Sclerotinia Sclerotiorum Isolates From Five States With Different Fungicide Treatments, Cristian Wulkop Gil, Edgar Nieto-Lopez, Sydney Everhart

UCARE Research Products

Sclerotinia sclerotiorum is a plant pathogenic fungus that causes a disease called white mold that can infect more than 450 plant species including soybeans, dry beans, green beans, canola, and sunflower. This pathogen is capable of up to $252M in losses every year (U.S. Canola Association, 2014). Fungicides are widely used in developed agricultural systems to control disease. However, resistance to the most effective fungicides has emerged and spread in pathogen populations and there have been multiple reports of S. sclerotiorum isolates becoming resistant to certain fungicides. Since different fields in different states use different fungicide treatments on plants and …

A Transcriptional Regulatory Network Of Rsv3-Mediated Extreme Resistance Against Soybean Mosaic Virus, Lindsay C. Demers, Neelam R. Redekar, Aardra Kachroo, Sue A. Tolin, Song Li, M. A. Saghai Maroof

Plant Pathology Faculty Publications

Resistance genes are an effective means for disease control in plants. They predominantly function by inducing a hypersensitive reaction, which results in localized cell death restricting pathogen spread. Some resistance genes elicit an atypical response, termed extreme resistance, where resistance is not associated with a hypersensitive reaction and its standard defense responses. Unlike hypersensitive reaction, the molecular regulatory mechanism(s) underlying extreme resistance is largely unexplored. One of the few known, naturally occurring, instances of extreme resistance is resistance derived from the soybean Rsv3 gene, which confers resistance against the most virulent Soybean mosaic virus strains. To discern the regulatory mechanism …