Other Plant Sciences Commons^™

Effects Of Sublethal Fungicides On Mutation Rates And Genomic Variation In Fungal Plant Pathogen, Sclerotinia Sclerotiorum, B. Sajeewa Amaradasa, Sydney E. Everhart

Department of Plant Pathology: Faculty Publications

Pathogen exposure to sublethal doses of fungicides may result in mutations that may represent an important and largely overlooked mechanism of introducing new genetic variation into strictly clonal populations, including acquisition of fungicide resistance. We tested this hypothesis using the clonal plant pathogen, Sclerotinia sclerotiorum. Nine susceptible isolates were exposed independently to five commercial fungicides with different modes of action: boscalid (respiration inhibitor), iprodione (unclear mode of action), thiophanate methyl (inhibition of microtubulin synthesis) and azoxystrobin and pyraclostrobin (quinone outside inhibitors). Mycelium of each isolate was inoculated onto a fungicide gradient and sub-cultured from the 50±100% inhibition zone for 12 …

Temporal Variability In Aboveground Plant Biomass Decreases As Spatial Variability Increases, Devan Allen Mcgranahan, Torre J. Hovick, R. Dwayne Elmore, David M. Engle, Samuel D. Fuhlendorf, Stephen L. Winter, James R. Miller, Diane M. Debinski

School of Natural Resources: Faculty Publications

Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass. This pattern is associated with statistical evidence for the portfolio effect and a positive relationship between temporal variability and functional …

Temporal Variability In Aboveground Plant Biomass Decreases As Spatial Variability Increases, Devan Allen Mcgranahan, Torre J. Hovick, R. Dwayne Elmore, David M. Engle, Samuel D. Fuhlendorf, Stephen L. Winter, James R. Miller, Diane M. Debinski

School of Natural Resources: Faculty Publications

Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass. This pattern is associated with statistical evidence for the portfolio effect and a positive relationship between temporal variability and functional …

Determining Factors That Influence Smooth Cordgrass (Spartina Alterniflora Loisel) Transplant Success In Community-Based Living Shoreline Projects, Steven A. Carrion

Honors Undergraduate Theses

Efforts to mitigate shoreline erosion through living shoreline methods along the USA Atlantic seaboard have often incorporated the cultivation and transplantation of smooth cordgrass, Spartina alterniflora. Assessments of these transplants at several sites in the Indian River Lagoon have shown that survival is variable after a year (survival: 10-93%). Lower survival has been attributed to environmental variables such as dislodgement by wave energy, and transplant shock due to salinity changes from cultivation to estuarine conditions. To improve living shoreline projects, we examined the effects of cultivation salinity (0 ppt, 15ppt) on transplantation success, and the success of anchoring plants …

Phytopharmaceuticals In Mongolia: Past, Present, And Future, Disan Gunbilig, Ulziinyam Rentsendorj

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

Over the last two decades, the consumption of medicinal plants has increased in Mongolia. Once banned by the post-revolutionary government, it is now valued by the practitioners of orthodox medicine, government as well as by the society. Yet the scientific community has to give this major and crucial component of traditional Mongolian medicine the attention it deserves, scientific knowledge about biologically active principles within medicinal plants remain poorly unknown. At the same time, due to over exploitation of plants many species are becoming extinct together with invaluable traditional knowledge being lost. For these reasons, there is a certain urgency to …

Mapping Qtls And Association Of Differentially Expressed Gene Transcripts For Multiple Agronomic Traits Under Different Nitrogen Levels In Sorghum, Malleswari Gelli, Sharon E. Mitchell, Kan Liu, Thomas E. Clemente, Donald P. Weeks, Chi Zhang, David R. Holding, Ismail M. Dweikat

Department of Agronomy and Horticulture: Faculty Publications

Background: Sorghum is an important C₄ crop which relies on applied Nitrogen fertilizers (N) for optimal yields, of which substantial amounts are lost into the atmosphere. Understanding the genetic variation of sorghum in response to limited nitrogen supply is important for elucidating the underlying genetic mechanisms of nitrogen utilization.

Results: A bi-parental mapping population consisting of 131 recombinant inbred lines (RILs) was used to map quantitative trait loci (QTLs) influencing different agronomic traits evaluated under normal N (100 kg.ha⁻¹ fertilizer) and low N (0 kg.ha⁻¹ fertilizer) conditions. A linkage map spanning 1614 cM was developed …

Proteomic Profiling Of Maize Opaque Endosperm Mutants Reveals Selective Accumulation Of Lysine-Enriched Proteins, Kyla J. Morton, Shangang Jia, Chi Zhang, David R. Holding

Department of Agronomy and Horticulture: Faculty Publications

Reduced prolamin (zein) accumulation and defective endoplasmic reticulum (ER) body formation occurs in maize opaque endosperm mutants opaque2 (o2), floury2 (fl2), defective endosperm*B30 (DeB30), and Mucronate (Mc), whereas other opaque mutants such as opaque1 (o1) and floury1 (fl1) are normal in these regards. This suggests that other factors contribute to kernel texture. A liquid chromatography approach coupled with tandem mass spectrometry (LC-MS/MS) proteomics was used to compare non-zein proteins of nearly isogenic opaque endosperm mutants. In total, 2762 proteins were identified that were enriched for biological processes such …

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, …

Organic Struggle: The Movement For Sustainable Agriculture In The United States [Book Review], Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Organic Struggle chronicles the challenges encountered by innovators in a growing segment of the U.S. food production and marketing system. Practiced for millennia by farmers before the introduction of chemical fertilizers and pesticides, and first developed more formally in Europe, organic farming practices began to gain prominence in the United States only in the 1950s. Far more than a system for producing food, this strategy has become a focus for those supporting healthy and pesticide-free products, for some who embrace the organic system as a food movement, and by many who disagree with the current domination of the country’s food …

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.

Muts Homolog1 Silencing Mediates Orf220 Substoichiometric Shifting And Causes Male Sterility In Brassica Juncea, Na Zhao, Xinyue Xu, Yashitola Wamboldt, Sally Ann Mackenzie, Xiaodong Yang, Zhongyuan Hu, Jinghua Yang, Mingfang Zhang

Department of Agronomy and Horticulture: Faculty Publications

Cytoplasmic male sterility (CMS) has consistently been associated with the expression of mitochondrial open reading frames (ORFs) that arise from genomic rearrangements. Spontaneous fertility reversion in CMS has been observed in several cases, but a clear understanding of fertility reversion controlled by nuclear genetic influences has been lacking. Here, we identified spontaneous fertile revertant lines for Brassica juncea CMS cytoplasm in which the mitochondrial genome has undergone substoichiometric shifting (SSS) to suppress ORF220 copy number. We placed ORF220, with or without a mitochondrial targeting presequence, under the control of the CaMV35S and AP3 promoters in Arabidopsis to confirm that ORF220 …

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 …

Prospects Of Genomic Prediction In The Usda Soybean Germplasm Collection: Historical Data Creates Robust Models For Enhancing Selection Of Accessions, Diego Jarquin, James Specht, Aaron Lorenz

Department of Agronomy and Horticulture: Faculty Publications

The identification and mobilization of useful genetic variation from germplasm banks for use in breeding programs is critical for future genetic gain and protection against crop pests. Plummeting costs of next-generation sequencing and genotyping is revolutionizing the way in which researchers and breeders interface with plant germplasm collections. An example of this is the high density genotyping of the entire USDA Soybean Germplasm Collection. We assessed the usefulness of 50K SNP data collected on 18,480 domesticated soybean (G. max) accessions and vast historical phenotypic data for developing genomic prediction models for protein, oil, and yield. Resulting genomic prediction models explained …

Corn (Zea Mays L.) Seeding Rate Optimization In Iowa, Usa, Mark A. Licht, Andrew W. Lenssen, Roger W. Elmore

Department of Agronomy and Horticulture: Faculty Publications

Collecting soil, topography, and yield information has become more feasible and reliable with advancements in precision technologies. Combined with the accessibility of precision technologies and services to farmers, there has been increased interest and ability to make site-specific crop management decisions. The objective of this research was to develop procedures to optimize corn seeding rates and maximize yield using soil and topographic parameters. Experimental treatments included five seeding rates (61 750; 74 100; 86 450; 98 800; and 111 150 seeds ha^-1) in a randomized complete block design in three central Iowa fields from 2012 to 2014 (nine …

Construction Of High Resolution Genetic Linkage Maps To Improve The Soybean Genome Sequence Assembly Glyma1.01, Qijian Song, Jerry Jenkins, Gaofeng Jia, David L. Hyten, Vince Pantalone, Scott A. Jackson, Jeremy Schmutz, Perry B. Cregan

Department of Agronomy and Horticulture: Faculty Publications

Background: A landmark in soybean research, Glyma1.01, the first whole genome sequence of variety Williams 82 (Glycine max L. Merr.) was completed in 2010 and is widely used. However, because the assembly was primarily built based on the linkage maps constructed with a limited number of markers and recombinant inbred lines (RILs), the assembled sequence, especially in some genomic regions with sparse numbers of anchoring markers, needs to be improved. Molecular markers are being used by researchers in the soybean community, however, with the updating of the Glyma1.01 build based on the high-resolution linkage maps resulting from this research, …

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 …

Expression Of Apoplast-Targeted Plant Defensin Mtdef4.2 Confers Resistance To Leaf Rust Pathogen Puccinia Triticina But Does Not Affect Mycorrhizal Symbiosis In Transgenic Wheat, Jagdeep Kaur, John Fellers, Alok Adholeya, Siva L.S. Velivelli, Kaoutar El-Mounadi, Natalya Nersesian, Thomas Clemente, Dilip Shah

Department of Agronomy and Horticulture: Faculty Publications

Rust fungi of the order Pucciniales are destructive pathogens of wheat worldwide. Leaf rust caused by the obligate, biotrophic basidiomycete fungus Puccinia triticina (Pt) is an economically important disease capable of causing up to 50 % yield losses. Historically, resistant wheat cultivars have been used to control leaf rust, but genetic resistance is ephemeral and breaks down with the emergence of new virulent Pt races. There is a need to develop alternative measures for control of leaf rust in wheat. Development of transgenic wheat expressing an antifungal defensin offers a promising approach to complement the endogenous resistance genes …

Nebline, January 2016

NEBLINE Newsletter Archive from Nebraska Extension in Lancaster County

Feature: Extension 2015 Highlights

Food & Health

Farm & Acreage

Horticulture

Family Living

Pests & Wildlife

4-H & Youth

Extension Calendar

and other extension news and events

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 …

Grain Sorghum Leaf Reflectance And Nitrogen Status, Akwasi A. Abunyewa, Richard B. Ferguson, Charles S. Wortmann, Stephen C. Mason

Department of Agronomy and Horticulture: Faculty Publications

Nitrogen deficiency is a common but readily managed constraint to grain yield. A quick and nondestructive detection of crop N status using remote sensing could be a means to increased N use efficiency. Research was conducted in a greenhouse in 2006 at the University of Nebraska-Lincoln to establish the relationship of spectral reflectance with N status in leaves of grain sorghum, to develop indices for interpretation of the results and to predict chlorophyll content. Nitrogen stress decreased chlorophyll meter reading and leaf N content, but increased leaf and canopy reflectance. The SPAD values were significantly increased by both water and …