Plant Biology Commons^™

Simulating Long-Term Impacts Of Cover Crops And Climate Change On Crop Production And Environmental Outcomes In The Midwestern United States, Andrea D. Basche, Sotririos V. Archontoulis, Thomas C. Kaspar, Dan B. Jaynes, Timothy B. Parkin, Fernando E. Miguez

Department of Agronomy and Horticulture: Faculty Publications

It is critical to evaluate conservation practices that protect soil and water resources from climate change in the Midwestern United States, a region that produces one-quarter of the world’s soybeans and one-third of the world’s maize. An over-winter cover crop in a maize–soybean rotation offers multiple potential benefits that can reduce the impacts of higher temperatures and more variable rainfall; some of the anticipated changes for the Midwest. In this experiment we used the Agricultural Production Systems sIMulator (APSIM) to understand how winter rye cover crops impact crop production and environmental outcomes, given future climate change. We first tested APSIM …

Decipher The Molecular Response Of Plant Single Cell Types To Environmental Stresses, Mehrnoush Nourbakhsh-Rey, Marc Libault

Department of Agronomy and Horticulture: Faculty Publications

The analysis of the molecular response of entire plants or organs to environmental stresses suffers from the cellular complexity of the samples used. Specifically, this cellular complexity masks cell-specific responses to environmental stresses and logically leads to the dilution of the molecular changes occurring in each cell type composing the tissue/organ/plant in response to the stress.Therefore, to generate a more accurate picture of these responses, scientists are focusing on plant single cell type approaches. Several cell types are now considered as models such as the pollen, the trichomes, the cotton fiber, various root cell types including the root hair cell, …

Draft Genome Sequence Of Erwinia Tracheiphila, An Economically Important Bacterial Pathogen Of Cucurbits, Lori R. Shapiro, Erin D. Scully, Dana Roberts, Timothy J. Straub, Scott M. Geib, Jihye Park, Andrew G. Stephenson, Erika Salaau Rojas, Quin Liu, Gwyn Beattie, Mark Gleason, Consuelo M. De Moraes, Mark C. Mescher, Shelby G. Fleischer, Roberto Kolter, Naomi Pierce, Olga Zhaxybayeva

Department of Agronomy and Horticulture: Faculty Publications

Erwinia tracheiphila is one of the most economically important pathogens of cucumbers, melons, squashes, pumpkins, and gourds in the northeastern and midwestern United States, yet its molecular pathology remains uninvestigated. Here, we report the first draft genome sequence of an E. tracheiphila strain isolated from an infected wild gourd (Cucurbita pepo subsp. texana) plant. The genome assembly consists of 7 contigs and includes a putative plasmid and at least 20 phage and prophage elements.

A Molecular Characterization Of The Fungal Endophytes Within The Needles Of Ponderosa Pine (Pinus Ponderosa), Amy E. Gray

EWU Masters Thesis Collection

"Fungal endophytes (microbial fungi that live in plant tissues without causing disease) are ubiquitous in plants studied to date. Many conifers host endophytes that produce important bioactive secondary metabolites. While the endophytes in Pinus ponderosa roots have been studied, the endophyte communities within the needles are not well characterized by molecular means: thus, the goal of this study was to do so. Needles were sampled at two sites located five kilometers apart along a slight precipitation gradient in Eastern Washington State. Fungal DNA (along with pine DNA) was isolated directly from needles of two ages. Internal transcribed spacer regions of …

Effects Of Seed Applied Fungicide On Arbuscular Mycorrhizal Colonization Of South Dakota Cultivars Of Oat, Soybean, And Corn, Jesse Cameron

Electronic Theses and Dissertations

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts that form a mutualistic relationship with approximately 80% of terrestrial plant species. These obligate symbionts have a generally beneficial effect on their host such as increased nutrient acquisition, better tolerance to biotic and abiotic stresses, and the improvement of soil qualities. Due to the recent, widespread use of seed applied fungicides on row crops in the U.S. Midwest, there are concerns that the fungicides will inhibit these beneficial mycorrhizae. This study was conducted to evaluate what effect different commonly used seed applied fungicides have on AMF in the presence of different varieties of …

A Molecular Genetic And Physiological Comparison Of The Hybrid Necrosis Response In Wheat (Triticum Aestivum L.) To Biotic And Abiotic Stress Responses, Devi R. Kandel

Electronic Theses and Dissertations

Expression of hybrid necrosis in plants can lead to a significant reduction in productivity, or even lethality. Epistatic interactions between divergent loci that have evolved through evolution are proposed as being responsible for the genetic incompatability that is expressed as hybrid necrosis. Hybrid necrosis can also represent an obstacle to the transfer of desirable traits from wild, related species to domesticated bread wheat. In wheat, expression of dominant complementary genes Ne1 and Ne2, located to chromosomes 5B and 2B in a hybrid results the production of necrotic leaf tissue, stunted plant growth, and reduced grain yield, which are similar plant …

Evaluation And Identification Of Soybean Aphid Resistance Sources And Mapping Of Soybean Aphid Resistance Loci In Early Maturing Soybean Germplasm Accessions, Siddhi Jeewan Bhusal

Electronic Theses and Dissertations

Soybean aphid (Aphis glycines Matsumura) has been a major pest of soybean [Glycine max (L.) Merr.] in North America particularly in the northern United States and three Canadian provinces. At least four biotypes of soybean aphid have been confirmed in the United States. Identification of soybean aphid resistance sources in early-maturing soybeans and genetic characterization of new sources of resistance will facilitate to expand the gene pool of soybean aphid resistance and thus will help to develop soybean aphid resistant cultivars. To identify new sources of resistance in early maturing soybeans, 330 soybean germplasm accessions from Maturity Group (MG) I, …

Cooperation And Punishment In The Arbuscular Mycorrhizal Symbiosis: Implications For Resource Exchange & Biological Market Dynamics, Jerry A. Mensah

Electronic Theses and Dissertations

The arbuscular mycorrhizal (AM) symbiosis is arguably the world’s most abundant and important mutualism, and brings together the roots of the majority of land plants and AM fungi to great mutual advantage. The AM symbiosis can increase the uptake of nutrients, such as phosphorus (P) and nitrogen (N), and improves the abiotic and biotic stress resistance of the host plant. AM fungi have the potential to act as biofertilizers and bioprotectors in sustainable agriculture. However, despite its significance, the mechanisms that control the resource exchange between both partners in the arbuscular mycorrhizal symbiosis are largely unknown. The main aim of …

Impact Of Climate Variations On Soybean Yield In Eastern Arkansas: 1960-2014, J. W. Magugu, S. Feng, Q. Huang, K. Luthra

Journal of the Arkansas Academy of Science

Climate is the major factor affecting crop production; therefore, various agro-meteorological indicators have been frequently used to evaluate the impact of climate on crop production. In this study, we examined the temporal variations of agrometeorological indicators (growing degree days, total precipitation, dry spells and drought indices) during 1960-2014 and their impact on soybean yields in East Arkansas. Results show an increasing trend in growing degree days (GDDs) and dry spells, though the total precipitation during the soybean growing season remained nearly unchanged during the study period. Generally, GDDs and dry spells show a strong correlation with yields. We also evaluated …

2016 Virginia Wildflower Of The Year: Downy Rattlesnake Plantain, Goodyera Pubescens, W. John Hayden

Biology Faculty Publications

Regardless of season, Downy Rattlesnake Plantain is a delight to encounter in the woods of Virginia. This evergreen orchid is a perennial rhizomatous herb of the forest floor. The horizontal rhizomes, usually covered lightly by leaf litter, bear roots at intervals and terminate in a rosette of leaves. Leaves are alternate, somewhat crowded together, and only slightly elevated above ground level. Leaf blades are ovate, 3–8 cm long, and 1.5–3 cm wide, often of varying size within a rosette. Leaves are present year-round, bluish-green, with prominent white veins; on each leaf, a broad midvein is flanked by two smaller veins …

Triticum Mosaic Virus Exhibits Limited Population Variation Yet Shows Evidence Of Parallel Evolution After Replicated Serial Passage In Wheat, Melissa S. Bartels, Roy French, Robert A. Graybosch, Satyanarayana Tatineni

Department of Plant Pathology: Faculty Publications

An infectious cDNA clone of Triticum mosaic virus (TriMV) (genus Poacevirus; family Potyviridae) was used to establish three independent lineages in wheat to examine intra-host population diversity levels within protein 1 (P1) and coat protein (CP) cistrons over time. Genetic variation was assessed at passages 9, 18 and 24 by single-strand conformation polymorphism, followed by nucleotide sequencing. The founding P1 region genotype was retained at high frequencies in most lineage/passage populations, while the founding CP genotype disappeared after passage 18 in two lineages.We found that rare TriMV genotypes were present only transiently and lineages followed independent evolutionary trajectories, …

Foliar Fungicide Application Timing For Disease Management, Stay Green, And Yield In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides applied at different corn growth stages for gray leaf spot (GLS) and southern rust (SR) efficacy. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % organic matter, and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to GLS) was planted at approximately 34,000 seed/A on 26 May, which is later than normal, due to wet spring …

Foliar Fungicide Modes Of Action For Southern Rust Management, Push Lodging, And Yield In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides with different modes of action for southern rust (SR) efficacy. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % organic matter, and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to gray leaf spot (GLS)) was planted at approximately 34,000 seed/A on 26 May. Eight treatments were arranged in a randomized complete block design with six …

Deposition Aid Adjuvants Plus A Fungicide For Southern Rust Management, Stay Green, Push Lodging, And Yield Comparisons In Field Corn In Nebraska, 2015, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides for southern rust (SR) efficacy. Irrigated corn was grown based on Nebraska Extension irrigation recommendations at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % OM and the previous crop was soybean. Reduced tillage was performed to the field prior to planting. Corn (DKC 65-79 RIB, tolerant to gray leaf spot (GLS)) was planted at approximately 34,000 seed/A on 26 May. Eleven treatments were arranged in a randomized complete block design with six replications. . . . Phytotoxicity was …

Root-Lesion Nematodes, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

Root-lesion nematodes, Pratylenchus spp., are among the most commonly encountered plant-parasitic nematodes, with one or more species occurring in almost every field. Their small size (0.4-0.7 mm long) relative to most other plant-parasitic nematodes enables them to survive in almost any soil texture. Their wide host range and distribution make them one of the most damaging nematodes worldwide, ranging from cool temperate to tropical environments. At least eight species of root-lesion nematodes have been associated with sunflower.

Root-Knot Nematodes, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

Root-knot nematodes, Meloidogyne spp., are some of the most damaging plant pathogens. Several of the most common species of root-knot nematodes have been confirmed to reproduce and cause damage on sunflower, including M. arenaria, M. hapla, M. incognita, M. javanica, and M. hispanica.

Meloidogyne spp. occur worldwide but are especially common in temperate, subtropical, and tropical regions. Countries where Meloidogyne spp. have been confirmed to affect sunflower include the United States and the African nations of Egypt, Mozambique, South Africa, and Zambia. Root-knot nematodes tend to cause the most damage to plants grown in sandy …

Northern Corn Leaf Blight, Tamra A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

Northern corn leaf blight (NCLB) is a disease of corn caused by a fungus, Exserohilum turcicum (sexual stage Setosphaeria turcica). Its development is favored by cool to moderate temperatures and high relative humidity. Historically, NCLB has been more common and severe in states in the eastern Corn Belt, but its incidence has increased in Nebraska and the western Corn Belt in recent years. The disease is distributed throughout most of the corn-growing areas of the United States. The disease also occurs sporadically throughout other humid corn-producing areas of the world. In Nebraska, the disease has been most serious in …

Identification Of Erwinia Rhapontici As The Causal Agent Of Crown And Shoot Rot And Pink Seed Of Pea In Nebraska, Anthony O. Adesemoye, Hsin-Ho Wei, Robert M. Harveson

Department of Plant Pathology: Faculty Publications

Over the last five years, the production of dry yellow peas (Pisum sativum L.) has been increasing in Nebraska and other areas of the Central High Plains, according to a USDA report (Jasa 2013). Dry pea is a short-season crop with a low water requirement, making it a good rotational crop for the high plains. We have noted bacterial pathogens, potentially a disease complex, that may negatively impact the production of pea in this region, and one of the emerging pathogens is Erwinia rhapontici. This pathogen is a gram-negative bacterium that has been reported from soil, seed, and …

Transcriptome Profiling Of Buffalograss Challenged With The Leaf Spot Pathogen Curvularia Inaequalis, Bimal S. Amaradasa, Keenan Amundsen

Department of Plant Pathology: Faculty Publications

Buffalograss (Bouteloua dactyloides) is a low maintenance U. S. native turfgrass species with exceptional drought, heat, and cold tolerance. Leaf spot caused by Curvularia inaequalis negatively impacts buffalograss visual quality. Two leaf spot susceptible and two resistant buffalograss lines were challenged with C. inaequalis. Samples were collected from treated and untreated leaves when susceptible lines showed symptoms. Transcriptome sequencing was done and differentially expressed genes were identified. Approximately 27 million raw sequencing reads were produced per sample. More than 86% of the sequencing reads mapped to an existing buffalograss reference transcriptome. De novo assembly of unmapped reads …

Morphological And Molecular Characterization Of Gracilacus Wuae N. Sp. (Nematoda: Criconematoidea) Associated With Cow Parsnip (Heracleum Maximum) In Ontario, Canada, Qing Yu, Weimin Ye, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

Gracilacus wuae n. sp. from soil associated with cow parsnip in Ontario, Canada is described and illustrated. Morphologically, females have a long stylet ranging from 80 to 93 mmlong, the lip region not offset from the body contour, without lateral lips but with large and flat submedian lobes, the mouth opening slit-like elongated laterally and surrounded by lateral flaps, the excretory pore is anterior to the knobs of the stylet; males without stylet and the pharynx degenerated. The fourth-stage juveniles lack a stylet, the pharynx degenerated, and can be differentiated into preadult females and males based on the position of …

Comparison Of Pea Seed Germination Due To Manipulation Of Soil Conditions, Ariel M. Kershner

Faculty Curated Undergraduate Works

This experiment was done with the intent to understand optimal soil conditions for pea seed germination. We investigated this using three soil conditions – 100% potting soil, 50% potting soil/50% sand, and 100% sand. Seemingly healthy pea seeds were planted and observed over five weeks. We measured both the total number of sprouts per week and the combined weight of the plants and seeds per condition before planting and after uprooting. We expected to find that the 100% potting soil condition would germinate the best, resulting in the most sprouts and heaviest weight of the condition’s seeds and plants. This …

Role Of Silencing Rna Fgsir34 In Fusarium Graminearum's Pathogenicity To Wheat, Subha Dahal

Electronic Theses and Dissertations

Fusarium graminearum is an ascomycetous fungal pathogen that causes Fusarium head blight (FHB) disease in wheat and other cereal grains. Mycotoxin produced by the fungus, predominantly deoxynivalenol (DON), is considered as an important virulence factor for the spread of disease. Our previous study of a Dicer-like 2 knockdown mutant has led to our hypothesis that a silencing RNA, fgsiR34, might play a key role in regulating DON biosynthesis and some other virulent factors. To test this hypothesis, we generated an fgsiR34 over-expressing mutant (ΔfgsiR34+) using Inverse Repeat Transgene method and studied the pathogenicity of the mutant in …

Genome-Wide Discriminatory Information Patterns Of Cytosine Dna Methylation, Robersy Sanchez, Sally A. Mackenzie

Department of Agronomy and Horticulture: Faculty Publications

Cytosine DNA methylation (CDM) is a highly abundant, heritable but reversible chemical modification to the genome. Herein, a machine learning approach was applied to analyze the accumulation of epigenetic marks in methylomes of 152 ecotypes and 85 silencing mutants of Arabidopsis thaliana. In an information-thermodynamics framework, two measurements were used: (1) the amount of information gained/lost with the CDM changes I_R and (2) the uncertainty of not observing a SNP LC_R. We hypothesize that epigenetic marks are chromosomal footprints accounting for different ontogenetic and phylogenetic histories of individual populations. A machine learning approach is proposed to …

Snrna 3' End Processing By A Cpsf73- Containing Complex Essential For Development In Arabidopsis, Yunfeng Liu, Shengjun Li, Yuan Chen, Athen N. Kimberlin, Edgar B. Cahoon, Bin Yu

Center for Plant Science Innovation: Faculty Publications

Uridine-rich small nuclear RNAs (snRNAs) are the basal components of the spliceosome and play essential roles in splicing. The biogenesis of the majority of snRNAs involves 3’ end endonucleolytic cleavage of the nascent transcript from the elongating DNA-dependent RNA ploymerase II. However, the protein factors responsible for this process remain elusive in plants. Here, we show that DEFECTIVE in snRNA PROCESSING 1 (DSP1) is an essential protein for snRNA 3’ end maturation in Arabidopsis. A hypomorphic dsp1-1 mutation causes pleiotropic developmental defects, impairs the 3’ end processing of snRNAs, increases the levels of snRNA primary transcripts (pre-snRNAs), and alters …

Evolutionary Dynamics Of The Plastid Inverted Repeat: The Effects Of Expansion, Contraction, And Loss On Substitution Rates, Andan Zhu, Wenhu Guo, Weishu Fan, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

• Rates of nucleotide substitution were previously shown to be several times slower in the plastid inverted repeat (IR) compared with single-copy (SC) regions, suggesting that the IR provides enhanced copy-correction activity.

• To examine the generality of this synonymous rate dependence on the IR, we compared plastomes from 69 pairs of closely related species representing 52 families of angiosperms, gymnosperms, and ferns.

• We explored the breadth of IR boundary shifts in land plants and demonstrate that synonymous substitution rates are, on average, 3.7 times slower in IR genes than in SC genes. In addition, genes moved from the SC into the …

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Age-Old Palms On Florida’S Ancient Ridges, Warren G. Abrahamson Ii

Faculty Journal Articles

Genetic fingerprinting, ramet growth rate determinations, and mathematical modeling (Minimum branching trees) were used to estimate clone ages of saw palmettos at Archbold Biological Station in Florida. Growth rates indicate that 500 year old saw palmetto ramets are common. Genetically identified clones (genets) are estimated to be thousands of years old, likely exceeding 5,000 years of age.

A Floristic Study Of The Oak Leaf Lake Unit Of The Swan Lake Wildlife Management Area In Nicollet County, Minnesota, Heidi Rauenhorst

All Graduate Theses, Dissertations, and Other Capstone Projects

Prairies play an integral ecological role, protecting biodiversity and providing habitat for fauna. The number of prairie acres has significantly declined in Minnesota, making the existing prairies that much more valuable. The Oak Leaf Lake Unit of the Swan Lake Wildlife Management Area in Nicollet County, Minnesota (latitude 44.311050, longitude -94.015577) was purchased by the Minnesota Department of Natural Resources in 1994 and is being managed as tallgrass prairie. Floristic surveys were performed during the 2011 and 2012 growing seasons to gather baseline data. These data were used to assess the quality of the site through calculation of various indices …

Molecular Characterization Of Resistance To Soybean Rust (Phakopsora Pachyrhizi Syd. & Syd.) In Soybean Cultivar Dt 2000 (Pi 635999), Tri D. Vuong, David R. Walker, Binh T. Nguyen, Tuyet T. Nguyen, Hoan X. Dinh, David L. Hyten, Perry B. Cregan, David A. Sleper, Jeong D. Lee, James G. Shannon, Henry T. Nguyen

Department of Agronomy and Horticulture: Faculty Publications

Resistance to soybean rust (SBR), caused by Phakopsora pachyrhizi Syd. & Syd., has been identified in many soybean germplasm accessions and is conferred by either dominant or recessive genes that have been mapped to six independent loci (Rpp1 -Rpp6), but No U. S. cultivars are resistant to SBR. The cultivar DT 2000 (PI 635999) has resistance to P. pachyrhizi isolates and field populations from the United States as well as Vietnam. A F_6:7 recombinant inbred line (RIL) population derived from Williams 82 × DT 2000 was used to identify genomic regions associated with resistance to SBR in …

Insights Into Triterpene Metabolism In Model Monocotyledonous And Oilseed Plants Genetically Engineered With Genes From Botryococcus Braunii, Chase F. Kempinski

Theses and Dissertations--Plant and Soil Sciences

Isoprenoids are one of the most diverse classes of natural products and are all derived from universal five carbon, prenyl precursors. Squalene and botryococcene are linear, hydrocarbon triterpenes (thirty carbon compounds with six prenyl units) that have industrial and medicinal values. Squalene is produced by all eukaryotes as it is the first committed precursor to sterols, while botryococcene is uniquely produced by the green algae, Botryococcus braunii (race B). Natural sources for these compounds exist, but there is a desire for more renewable production platforms. The model plant Arabidopsis thaliana was engineered to accumulate botryococcene and squalene in its oil …

Investigation Into The Cell Wall And Cellulose Biosynthesis In Model Species And In The C4 Model Plant Setaria Viridis, Mizuki Tateno

Theses and Dissertations--Plant and Soil Sciences

A uniform feature of all plant cells is the presence of a cell wall. The cell wall functions in facilitating directional expansion and is therefore important for cell shape and morphogenesis. All plant cell walls contain cellulose microfibrils embedded in a network of polysaccharides, lignin and protein. Cellulose is evolutionarily conserved and is made by all plants as well as other members of various taxonomic kingdoms. From a human perspective, the field of renewable energy has had an ever increasing interest in using the cell wall for production of renewable platform chemicals and fuels. However, the biosynthesis of these components …