Digital Commons Network^™

Application And Timing Effects Of Qoi And Dmi Fungicides And A Foliar Fertilizer On Overall Plant Health And Grain Yield In Corn, Jason Phillip Geis

Open Access Theses

The use of fungicides on corn has recently increased as a result of higher grain market prices, changes in cropping practices, higher disease incidence and severity, and the availability and marketing claims of new fungicides. Some of the marketed potential "plant health(TM)" benefits include improved tolerance to drought and heat, improved N utilization, and increased stalk strength. Previous studies have displayed delayed canopy senescence, changes in water use efficiency, and reduced ozone damage in controlled environments. Foliar fertilization has also increased in popularity in recent years due to an increase in grain prices, manufacturer claims, and product availability.

Large-scale field …

Investigation Of Macrophomina Phaseolina On Soybeans From A Regional Perspective, Zachary Forbes Sexton

Open Access Theses

The fungal pathogen, Macrophomina phaseolina, causes the disease charcoal rot (CR), which greatly impacts soybean production. Host resistance to CR is the primary means of managing this disease, yet resistance in commercial soybean cultivars in Maturity Groups (MG) I-III is currently unknown. Thirty (30) and sixty-seven (67) entries to the 2012 Wisconsin (MG I-II) and Indiana (MG II-III) Soybean Variety Trials, respectively, were evaluated for resistance to CR using a cut-stem assay. Disease was characterized as an area under the disease progress curve (AUDPC) based on lesion development and resistance assessed in relation to the resistant check (DT97-4290). In each …

Effects Of Wheat Grain Moisture: Quality, Germination, And Relationship To Accumulated Growing Degree Days, Kirsten Thomas

Open Access Theses

Bread wheat (Triticum aestivum L.) is a cereal crop of global importance. As global demand increases, it is essential to increase the quality and efficiency of crop production. Harvesting wheat early provides an opportunity for increased grain quality, and it may also allow the grower to double-crop soybean ( Glycine max L.) after wheat more effectively. Our objectives were to determine if harvesting grain early, at high moisture would, 1) increase milling and baking quality and 2) improve germination potential. As a result of these objectives, we will develop a model to predict dry-down of wheat. Five soft red …

Quality Changes In Hermetically Stored Corn Caused By Fungi And Sitophilus Zeamais, Nda-Agyima Addae-Mensah K

Open Access Theses

Hermetic storage has been shown to be effective in controlling insect pests and maintaining grain quality of dry grains at 13% moisture and below. However, the feasibility and use of hermetic storage for grains at intermediate mid-moisture levels under the influence of the sub-Saharan African weather conditions is relatively unknown. Hermetic storage experiments were conducted on grade 1 "6297 and 6333 VT RIB" hybrid corn under controlled temperature conditions at 10 degrees centigrade and 25 degrees centigrade at target approximate moisture content levels of 11, 15, 18 and 21% wet basis for a total storage period of 6 months. Corn …

Characterization Of Glomerella Strains Recovered From Anthracnose Lesions On Common Bean Plants In Brazil, Quélen L. Barcelos, Joyce M.A. Pinto, Lisa J. Vaillancourt, Elaine A. Souza

Plant Pathology Faculty Publications

Anthracnose caused by Colletotrichum lindemuthianum is an important disease of common bean, resulting in major economic losses worldwide. Genetic diversity of the C. lindemuthianum population contributes to its ability to adapt rapidly to new sources of host resistance. The origin of this diversity is unknown, but sexual recombination, via the Glomerella teleomorph, is one possibility. This study tested the hypothesis that Glomerella strains that are frequently recovered from bean anthracnose lesions represent the teleomorph of C. lindemuthianum. A large collection of Glomerella isolates could be separated into two groups based on phylogenetic analysis, morphology, and pathogenicity to beans. Both …

Proceedings Of The 41st Annual Meeting, Southern Soybean Disease Workers (March 5-6, 2014, Pensacola Beach, Florida), Edward Sikora, Clayton A. Hollier, Craig Rothrock, Myra Purvis, Danise Beadle, Stephen R. Koenning

Southern Soybean Disease Workers: Conference Proceedings

Contents

Schedule

Southern United Station Soybean Disease Loss Estimates for 2013. Compiled by SR Koenning

Graduate student paper competition (Ed Sikora, moderator)

Association of Phomopsis longicolla and Macrophomina phaseolina with zone lines in soybean roots at maturity. ML Zaccaron, JC Rupe, and RT Holland

Molecular Phylogenetic Redefinition of Cercospora kikuchii. S Albu, P Price, V Doyle, and R Schneider

The effects of salinity on Pythium rot of soybean. TJ Stetina, CS Rothrock, and JC Rupe

Distribution of Cercospora sojina and sensitivity to Qol fungicides in Mississippi soybean fields. J Standish, M Tomaso-Peterson, TW Allen, S Sabanadzovic, N Aboughanem-Sabanadzovic

Effect …

The Pythium Suppressive Ability Of Glomus Intraradices In Cherry Tomato Propagation, Stanley Graham

Biological Sciences

No abstract provided.

First Report Of The Root-Knot Nematode Meloidogyne Enterolobii Parasitizing Watermelon From Veracruz, Mexico, A. Ramírez-Suárez, L. Rosas-Hernández, S. Alcasio-Rangel, Guillermo Pérez Valenzuela, T. O. Powers

Department of Plant Pathology: Faculty Publications

In early April 2012, a sampling of watermelon crop Citrullus lanatus (Thunb.) Matsum & Nakai, 1916 cv. Sunsugar took place as part of the National System of Epidemiological Phytosanitary Surveillance (SINAVEF-MEX). This sampling was conducted at Riachuelos locality, Tecolutla, Veracruz, located at the geographic coordinates: 20.42008° N and 96.9627° W, within 50 meters of the Gulf of Mexico. Plants showed yellowing, stunting, and high levels of infection expressed by extensive galling on the roots. These symptoms were reproduced in the greenhouse on watermelon cv. Sunsugar. Egg masses were extracted to obtain juveniles (J2). Female necks and perineal patterns were mounted …

The C-Terminus Of Wheat Streak Mosaic Virus Coat Protein Is Involved In Differential Infection Of Wheat And Maize Through Host-Specific Long-Distance Transport, Satyanarayana Tatineni, Roy French

Department of Plant Pathology: Faculty Publications

Viral determinants and mechanisms involved in extension of host range of monocot-infecting viruses are poorly understood. Viral coat proteins (CP) serve many functions in almost every aspect of the virus life cycle. The role of the Cterminal region of Wheat streak mosaic virus (WSMV) CP in virus biology was examined by mutating six negatively charged aspartic acid residues at positions 216, 289, 290, 326, 333, and 334. All of these amino acid residues are dispensable for virion assembly, and aspartic acid residues at positions 216, 333, and 334 are expendable for normal infection of wheat and maize. However, mutants D …

Unprecedented Heterogeneity In The Synonymous Substitution Rate Within A Plant Genome, Andan Zhu, Wenhu Guo, Kanika Jain, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

The synonymous substitution rate varies widely among species, but it is generally quite stable within a genome due to the absence of strong selective pressures. In plants, plastid genes tend to evolve faster than mitochondrial genes, rate variation among species generally correlates between the mitochondrial and plastid genomes, and few examples of intragenomic rate heterogeneity exist. To study the extent of substitution rate variation between and within plant organellar genomes, we sequenced the complete mitochondrial and plastid genomes from the bugleweed, Ajuga reptans, which was previously shown to exhibit rate heterogeneity for several mitochondrial genes. Substitution rates were accelerated specifically …

Evaluation Of Constitutive Iron Reductase (Atfro2) Expression On Mineral Accumulation And Distribution In Soybean (Glycine Max. L), Marta W. Vasconcelos, Thomas E. Clemente, Michael A. Grusak

Center for Plant Science Innovation: Faculty Publications

Iron is an important micronutrient in human and plant nutrition. Adequate iron nutrition during crop production is central for assuring appropriate iron concentrations in the harvestable organs, for human food or animal feed. The whole-plant movement of iron involves several processes, including the reduction of ferric to ferrous iron at several locations throughout the plant, prior to transmembrane trafficking of ferrous iron. In this study, soybean plants that constitutively expressed the AtFRO2 iron reductase gene were analyzed for leaf iron reductase activity, as well as the effect of this transgene's expression on root, leaf, pod wall, and seed mineral concentrations. …

Identification Of Rna Silencing Components In Soybean And Sorghum, Xiang Liu, Tao Lu, Yongchao Dou, Bin Yu, Chi Zhang

Center for Plant Science Innovation: Faculty Publications

Background: RNA silencing is a process triggered by 21–24 small RNAs to repress gene expression. Many organisms including plants use RNA silencing to regulate development and physiology, and to maintain genome stability. Plants possess two classes of small RNAs: microRNAs (miRNAs) and small interfering RNAs (siRNAs). The frameworks of miRNA and siRNA pathways have been established in the model plant, Arabidopsis thaliana (Arabidopsis).

Results: Here we report the identification of putative genes that are required for the generation and function of miRNAs and siRNAs in soybean and sorghum, based on knowledge obtained from Arabidopsis. The gene families, including …

Methylation Protects Micrornas From An Ago1- Associated Activity That Uridylates 5′ Rna Fragments Generated By Ago1 Cleavage, Guodong Ren, Meng Xie, Shuxin Zhang, Carissa Vinovskis, Xuemei Chen, Bin Yu

Center for Plant Science Innovation: Faculty Publications

In plants, methylation catalyzed by HEN1 (small RNA methyl transferase) prevents microRNAs (miRNAs) from degradation triggered by uridylation. Howmethylation antagonizes uridylation of miRNAs in vivo is not well understood. In addition, 5′ RNA fragments (5′ fragments) produced by miRNA-mediated RNA cleavage can be uridylated in plants and animals. However, the biological significance of this modification is unknown, and enzymes uridylating 5′ fragments remain to be identified. Here, we report that in Arabidopsis, HEN1 suppressor 1 (HESO1, a miRNA nucleotidyl transferase) uridylates 5′ fragments to trigger their degradation.We also show that Argonaute 1 (AGO1), the effector protein of miRNAs, interacts …

Small Rnas Meet Their Targets: When Methylation Defends Mirnas From Uridylation, Guodong Ren, Xuemei Chen, Bin Yu

Center for Plant Science Innovation: Faculty Publications

Small RNAs are incorporated into Argonaute protein-containing complexes to guide the silencing of target RNAs in both animals and plants. The abundance of endogenous small RNAs is precisely controlled at multiple levels including transcription, processing and Argonaute loading. In addition to these processes, 3' end modification of small RNAs, the topic of a research area that has rapidly evolved over the last several years, adds another layer of regulation of their abundance, diversity and function. Here, we review our recent understanding of small RNA 3' end methylation and tailing.

Rna Sequence Determinants Of A Coupled Termination-Reinitiation Strategy For Translation Of Downstream Orf In Helminthosporium Victoriae Virus 190s And Other Victoriviruses (Family Totiviridae), Hua Li

Theses and Dissertations--Plant Pathology

Double-stranded RNA fungal virus Helminthosporium victoriae virus 190S (genus Victorivirus, family Totiviridae) contains two large open reading frames (ORFs) that overlap in the tetranucleotide AUGA. Translation of the downstream ORF, which encodes the RNA-dependent RNA polymerase (RdRp), was previously proposed to depend on ribosomal reinitiation following termination of the upstream ORF, which encodes the capsid protein. In this study, I provided evidence to confirm that coupled termination-reinitiation (stop-restart) is indeed used. A dual-fluorescence method was established to define the RNA sequence determinants for RdRp translation. Stop-restart depends on a 32-nt stretch of RNA sequence immediately upstream of the …

Characterization Of Putative Defense Genes In Nonvascular Plants, Blaine Harlan

Undergraduate Honors Thesis Collection

Vascular plants have many known defenses against herbivory and pathogen infection. One inducible defense system that has been extensively studied in vascular plants is systemic acquired resistance (SAR), which is a plant-wide response that results in resistance to a wide range of pathogens Many genes that play a role in SAR have been characterized. Although several studies of plant-pathogen interactions in non-vascular plants have occurred, it was not until recently that the existence of SAR was shown in these plants. The goal of the present study was to confirm the presence of homologous defense genes in moss, and to study …

Chemical Control Of Turfgrass Diseases 2014, Paul Vincelli, Gregg Munshaw

Agriculture and Natural Resources Publications

Turfgrasses under intensive management are often subject to outbreaks of infectious diseases. Diseases usually are most damaging when weather or cultural conditions favor the disease-causing agent but not plant growth and vigor. Cultural conditions that predispose turfgrass to diseases include close mowing, inadequate or excessive nitrogen fertility, light or frequent irrigation, excessive thatch, poor drainage, and shade.

Good turf management practices often greatly reduce the impact of disease by promoting healthy plants that are better able to resist infections. Even under good management, however, diseases sometimes cause excessive damage to highly managed turfgrasses. The proper use of fungicides in these …

Four Common Setaria Species Are Alternative Hosts For Clavibacter Michiganensis Subsp. Nebraskensis, Causal Agent Of Goss's Bacterial Wilt And Blight Of Corn, Craig B. Langemeier, Tamra A. Jackson-Ziems, Greg R. Kruger

Department of Plant Pathology: Faculty Publications

Goss’s bacterial wilt and blight, caused by Clavibacter michiganensis subsp. nebraskensis (Cmn), has reemerged as an important disease of Zea mays (corn) in the U.S. Midwest. Results from a 2011 multistate survey indicated that Setaria spp. (foxtail) were often present in corn fields with a history of Cmn. The objective of this research was to determine if Setaria spp. that are common in the Midwest are susceptible to infection by Cmn. In the greenhouse, seedlings of four Setaria spp., including S. viridis (green foxtail), S. faberi (giant foxtail), S. verticillata (bristly foxtail), and S. pumila (yellow foxtail), and Zea mays …

What’S New In Plant Pathology, Tamra A. Jackson-Ziems, Loren Giesler, Robert M. Harveson, Stephen N. Wegulo, Kevin Korus

Department of Plant Pathology: Faculty Publications

Disease Management Products

During the past year several new products have become available for disease management. The new products are summarized in Tables 1 and 2, as well as included in the 2014 Guide for Weed Management in Nebraska with Insecticide and Fungicide Information. In addition, fungicides labeled for use on sorghum and sunflower have also been added to the publication.

Table 1. New Foliar Fungicides

Table 2. New Seed Nematicide

Disease Identification and Management Resources

Ficotylus Laselvae N. Sp. (Tylenchomorpha: Anguinidae) Associated With Ficus Colubrinae In Costa Rica, Robin M. Giblin-Davis, Natsumi Kanzaki, Kerrie A. Davies, Weimin Ye, Yongsan Zeng, Barbara J. Center, Alejandro Esquivel, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

Ficotylus laselvae n. sp. was recovered from under the bracts of figs (syconia) of Ficus colubrinae from La Selva, Costa Rica, during a survey of nematode rainforest biodiversity and is described herein. This is only the second report of an association between the nematode suborder Tylenchina and the sycones of figs. Previous reports of most nematode associates of the sycones of figs have been from the lumen and involved transmission by female fig wasp pollinators (Agaonidae) during pollination/oviposition (e.g., Schistonchus and Parasitodiplogaster spp.). The association between F. laselvae n. sp. and Ficus colubrinae may involve an invertebrate host, …

Viruses As Nanoparticles: Structure Versus Collective Dynamics, S. Sirotkin, A. Mermet, M. Bergoin, V. Ward, James L. Van Etten

James Van Etten Publications

In order to test the application of the “nanoparticle” concept to viruses in terms of low-frequency dynamics, large viruses (140–190 nm) were compared to similar-sized polymer colloids using ultra-small-angle x-ray scattering and very-low-frequency Raman or Brillouin scattering. While both viruses and polymer colloids show comparable highly defined morphologies, with comparable abilities of forming self-assembled structures, their respective abilities to confine detectable acoustic vibrations, as expected for such monodisperse systems, differed. Possible reasons for these different behaviors are discussed.

Viruses Infecting Marine Picoplancton Encode Functional Potassium Ion Channels, Fenja Siotto, Corinna Martin, Oliver Rauh, James L. Van Etten, Indra Schroeder, Anna Moroni, Gerhard Thiel

James Van Etten Publications

Phycodnaviruses are dsDNA viruses, which infect algae. Their large genomes encode many gene products, like small K+ channels, with homologs in prokaryotes and eukaryotes. Screening for K+ channels revealed their abundance in viruses from fresh-water habitats. Recent sequencing of viruses from marine algae or from salt water in Antarctica revealed sequences with the predicted characteristics of K+ channels but with some unexpected features. Two genes encode either 78 or 79 amino acid proteins, which are the smallest known K+ channels. Also of interest is an unusual sequence in the canonical α-helixes in K+ channels. Structural prediction algorithms indicate that the …

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 found after extensive deletions are made. A series of deletion and point mutations was created in the CP cistron of wild-type and/or green fluorescent protein-tagged WSMV, and the effects of these mutations on cell-to-cell and systemic transport and virion assembly of WSMV …

Phytophthora Ramorum, Sydney E. Everhart, Javier F. Tabima, Niklaus J. Grünwald

Department of Plant Pathology: Faculty Publications

Phytophthora ramorum is a recently emerged plant pathogen and causal agent of one of the most destructive and devastating diseases currently affecting US horticulture and forests (Rizzo et al. 2002, 2005). This oomycete pathogen was discovered in Marin County, California, in the mid-1990s, causing sudden oak death on coast live oak (Quercus agrifolia) and tanoak (Notholithocarpus densiflorus) and simultaneously discovered in Europe causing foliar blight on Rhododendron and Viburnum (Rizzo et al. 2002; Werres et al. 2001). It is now known to affect more than 100 plant species, including economically important nursery and forest host species …

Characterization Of The Role Of Salicylic Acid In Plant-Pathogen Interactions In Moss, Erica Grabinski

Undergraduate Honors Thesis Collection

The central objective of this project is to explore defense systems that are induced in two moss species, Amblystegium serpens and Physcomitrella patens, upon inoculation with the fungus, Pythium irregulare. In vascular plants, systemic defense is associated with the plant hormone salicylic acid (SA). I hypothesize that when the moss are treated exogenously with SA, the organisms will undergo a systemic defense response, which will involve the induction of defense-related genes and increased resistance to future P. irregulare infection, that is directly correlated with the amount of hormone applied. If the role of SA in plant defense in A. serpens …

Response Of Fusarium Thapsinum To Sorghum Brown Midrib Lines And To Phenolic Metabolites, Deanna L. Funnell-Harris, Scott E. Sattler, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Sorghum lines were bred for reduced lignin for cellulosic bioenergy uses, through the incorporation of brown midrib (bmr)6 or -12 into two backgrounds (RTx430 and Wheatland) as either single or doublemutant lines. When these lines were assessed for resistance to Fusarium thapsinum stalk rot, a cause of lodging, they were as resistant to F. thapsinum as the near-isogenic wild type. Peduncles of newly identified bmr lines from an ethyl-methanesulfonate-mutagenized population, inoculated with F. thapsinum, were as resistant as the wild-type line, BTx623. One bmr line (1107) had significantly smaller mean lesion lengths than BTx623, suggesting that a mutation …

Evidence For A Transketolase-Mediated Metabolic Checkpoint Governing Biotrophic Growth In Rice Cells By The Blast Fungus Magnaporthe Oryzae, Jessie Fernandez, Margarita Marroquin-Guzman, Richard A. Wilson

Department of Plant Pathology: Faculty Publications

The blast fungus Magnaporthe oryzae threatens global food security through the widespread destruction of cultivated rice. Foliar infection requires a specialized cell called an appressorium that generates turgor to force a thin penetration hypha through the rice cuticle and into the underlying epidermal cells, where the fungus grows for the first days of infection as a symptomless biotroph. Understanding what controls biotrophic growth could open new avenues for developing sustainable blast intervention programs. Here, using molecular genetics and live-cell imaging, we dismantled M. oryzae glucose-metabolizing pathways to reveal that the transketolase enzyme, encoded by TKL1, plays an essential role …

Evaluation Of Pcr-Based Methods For Rapid, Accurate Detection And Monitoring Of Verticillium Dahliae In Woody Hosts By Real-Time Polymerase Chain Reaction, Baker Diwan Getheeth Aljawasim

Theses and Dissertations--Plant Pathology

Verticillium wilt, caused by Verticillium dahliae Kleb, is one of the most economically important diseases of woody hosts such as ash (Fraxinus spp.), sugar maple (Acer saccharum), and redbud (Cercis canadensis). The causal agent has a broad host range, including not only woody hosts but also important vegetable and field crops, and it is distributed worldwide. Diagnosis of V. dahliae in infected woody hosts is often based on the occurrence of vascular discoloration and time-consuming isolation. However, not all woody hosts exhibit vascular discoloration symptoms, and not all vascular discoloration symptoms are due to infection …

Development Of Fad7-1 Single Mutant Arabidopsis Thaliana Plants That Are Resistant To Aphids, Kaleb L. Vaughn, Carlos A. Avila, Carmen S. Padilla-Marcia, Fiona L. Goggin

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Aphids are a group of sap-feeding insects that attack most of the world’s crops. The loss of function of fatty acid desaturase7 (FAD7) in Solanum lycopersicum (tomato plant) induces aphid resistance that is dependent upon the accumulation of plant defense hormones such as salicylic acid (SA). Tomato lacks most of the genetic resources found in the model plant Arabidopsis (Arabidopsis thaliana). There is an analogous fad7-1 line of Arabidopsis; however, the line has a background mutation, the glabra-1 (gl1), that causes the absence of trichomes (small hairs), which are essential to plant defense. In order to study aphid resistance, a …

Dynamics Of Small Rna Profiles Of Virus And Host Origin In Wheat Cultivars Synergistically Infected By Wheat Streak Mosaic Virus And Triticum Mosaic Virus: Virus Infection Caused A Drastic Shift In The Endogenous Small Rna Profile, Satyanarayana Tatineni, Jean-Jack M. Riethoven, Robert A. Graybosch, Roy French, Amitava Mitra

Department of Plant Pathology: Faculty Publications

Co-infection of wheat (Triticum aestivum L.) by Wheat streak mosaic virus (WSMV, a Tritimovirus) and Triticum mosaic virus (TriMV, a Poacevirus) of the family Potyviridae causes synergistic interaction. In this study, the effects of the synergistic interaction between WSMV and TriMV on endogenous and virus-derived small interfering RNAs (vsiRNAs) were examined in susceptible (‘Arapahoe’) and temperature-sensitive resistant (‘Mace’) wheat cultivars at 18 degrees C and 27 degrees C. Single and double infections in wheat caused a shift in the profile of endogenous small RNAs from 24 nt being the most predominant in healthy plants to 21 nt …