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Evolution On The Hawaiian Hotspot: Biogeography And Divergence Time Estimation Of Kadua (Rubiaceae), Kenneth L. Parker

Biological Sciences Theses & Dissertations

Recent studies on the colonization time of Hawaiian plant and animal lineages have suggested certain lineages arrived to the archipelago before the formation of the extant islands. Kadua, a recently resurrected genus, is mostly endemic to the Hawaiian Archipelago, with many member taxa autochthonous to individual islands. This work investigates the colonization time of Kadua to the Hawaiian Islands. Sequence analyses of the quickly evolving nuclear regions ITS, ETS and 5s-NTS regions for 20 Hawaiian and 7 French Polynesian species of Kadua were used to create dated phylogeny calibrated with island ages. The phylogeny suggests a single colonization of Hawaii …

Naturalization Of Sequoiadendron Giganteum (Cupressaceae) In Montane Southern California, Rudolf Schmid, Mena Schmid

Aliso: A Journal of Systematic and Floristic Botany

After the August 1974 fire in the upper Hall Canyon area on the southwestern flank of Black Mountain in the northwestern San Jacinto Mountains, Riverside County, California, the United States Forest Service revegetated the burn in the mixed-conifer forest with the Sierra Nevada endemic Sequoiadendron giganteum (Cupressaceae). On 1 May 2009 a GPS census starting at the head of Hall Canyon revealed both in the canyon and upslope beyond it at least 157 individuals in the vicinity of the Black Mountain Trail, plus an outlier 450 m distant near the summit. This species alien to southern California is regenerating prolifically …

Euphorbia (Subgen. Chamaesyce Sect. Anisophyllum) Jaegeri, A Shrubby New Species From The Deserts Of California, United States, Victor W. Steinmann, James M. André

Aliso: A Journal of Systematic and Floristic Botany

Euphorbia jaegeri (Euphorbiaceae), an endemic to southeastern California, United States, is described as new and illustrated with photographs. It is known from two general locations, one in the Orocopia Mountains (Riverside County) and the other in the Marble Mountains and adjacent Bristol Mountains (San Bernardino County). The habitat is desert scrub on rocky hillsides and along arroyos, primarily in rock crevices or gravelly soils, at elevations from approximately 600 to 850 m. The new species belongs to Euphorbia subgen. Chamaesyce sect. Anisophyllum. It is distinguished by the combination of a shrubby habit and involucral appendages that are deeply parted …

Cover Page

Aliso: A Journal of Systematic and Floristic Botany

No abstract provided.

A Revision Of Erythranthe Montioides And Erythranthe Palmeri (Phrymaceae), With Descriptions Of Five New Species From California And Nevada, Usa, Naomi S. Fraga

Aliso: A Journal of Systematic and Floristic Botany

The genus Erythranthe (Phrymaceae) continues to be a source of floristic novelty, especially in the American West, as evidenced by recent discoveries presented here. Two species in Erythranthe section Paradantha (E. montioides and E. palmeri) have long been a source of taxonomic confusion. Recent research reveals that a total of ten species have previously been treated as part of these two species. Here I present a revised taxonomy for E. montioides and E. palmeri including clarification of species circumscriptions (E. montioides, E. palmeri), recognition of three species that have previously been treated as synonyms …

Wood Anatomy Of Gnetales In A Functional, Ecological, And Evolutionary Context, Sherwin Carlquist

Aliso: A Journal of Systematic and Floristic Botany

New scanning electron microscope (SEM) and light microscope data and illustrations are presented in order to compare hydraulic adaptations of non-gnetalean conifers and angiosperms to relevant wood features of Gnetales. Gnetales have essentially all of the adaptations of both groups, yet have not competed well, despite predating angiosperms in origin and radiation. Angiosperms may be advantaged more by life cycle abbreviation and by heterochronic possibilities than by wood features. Wood features of Gnetales that relate to conduction (torus-margo differentiation of tracheid pit membranes, distribution of tori within the wood, perforation plate simplification, growth rings, vesturing, helical thickenings, and axial parenchyma) …

Influence Of Microsite Disturbance On The Establishment Of Two Congeneric Invasive Thistles, Emily S.J. Rauschert, Katriona Shea

Biological, Geological, and Environmental Faculty Publications

The successful establishment of invasive species has been shown to depend on aspects of the invaded community, such as gap characteristics. Biotic resistance may be particularly critical for stopping invaders at early life history stages, but new species can often invade following disturbances, which may create microsites with very different characteristics than are usually present. We examine the response of two invasive thistle species, Carduus nutans L. and C. acanthoides L., to three different microsite characteristics: disturbance type, size, and water availability. The two species initially responded differently to the type of disturbance: C. acanthoides had higher emergence and survival …

Growth And Physiological Responses Of Maize And Sorghum Genotypes To Salt Stress, Youping Sun, Wenwei Xu, Denise Rodriguez, Youping Sun

Plants, Soils, and Climate Faculty Publications

The growth and physiological responses of four maize inbred lines (CUBA1, B73, B5C2, and BR1) and four sorghum hybrids (SS304, NK7829, Sordan 79, and KS585) to salinity were determined. Fifteen days after sowing, seedlings were irrigated with nutrient solution (control) at electrical conductivity (EC) of 1.5 dS m−1 or saline solution at EC of 8.0 dS m−1 (salt treatment) for 40 days. Dry weight of shoots in maize was reduced by 58%, 65%, 62%, and 69% in CUBA1, B73, B5C2, and BR1, respectively, while that of sorghum was reduced by 51%, 56%, 56%, and 76% in SS304, NK7829, Sordan79, and …

Cytochrome P450s And Uses Thereof, Joe Chappell, Lyle F. Ralston

Plant and Soil Sciences Faculty Patents

The invention features isolated cytochrome P450 polypeptides and nucleic acid molecules, as well as expression vectors and transgenic plants containing these molecules. In addition, the invention features uses of such molecules in methods of increasing the level of resistance against a disease caused by a plant pathogen in a transgenic plant, in methods for producing altered compounds, for example, hydroxylated compounds, and in methods of producing isoprenoid compounds.

Arabidopsis Bhlh100 And Bhlh101 Control Iron Homeostasis Via A Fit-Independent Pathway, Alicia B. Sivitz, Victor Hermand, Catherine Curie, Grégory Vert

Dartmouth Scholarship

Iron deficiency induces a complex set of responses in plants, including developmental and physiological changes, to increase iron uptake from soil. In Arabidopsis, many transporters involved in the absorption and distribution of iron have been identified over the past decade. However, little is known about the signaling pathways and networks driving the various responses to low iron. Only the basic helix–loop–helix (bHLH) transcription factor FIT has been shown to control the expression of the root iron uptake machinery genes FRO2 and IRT1. Here, we characterize the biological role of two other iron-regulated transcription factors, bHLH100 and bHLH101, in iron homeostasis. …

Local Conditions, Not Regional Gradients, Drive Demographic Variation Of Giant Ragweed (Ambrosia Trifida) And Common Sunflower (Helianthus Annuus) Across Northern U.S. Maize Belt, Sam E. Wortman, Adam S. Davis, Brian J. Schutte, John L. Lindquist, John Cardina, Joel Felix, Christy L. Sparague, Anita Dille, Analiza H.M. Ramirez, Graig Reicks, Sharon A. Clay

Agronomy, Horticulture and Plant Science Faculty Publications

Knowledge of environmental factors influencing demography of weed species will improve understanding of current and future weed invasions. The objective of this study was to quantify regional-scale variation in vital rates of giant ragweed and common sunflower. To accomplish this objective, a common field experiment was conducted across seven sites between 2006 and 2008 throughout the north central U.S. maize belt. Demographic parameters of both weed species were measured in intra- and interspecific competitive environments, and environmental data were collected within site-years. Site was the strongest predictor of belowground vital rates (summer and winter seed survival and seedling recruitment), indicating …

Nebline, September 2012

NEBLINE Newsletter Archive from Nebraska Extension in Lancaster County

Feature: Extend Your Growing Season with a Cold Frame or Hotbed

Farm Views

Urban Agriculture

Food & Fitness

Home & Family Living

Horticulture

Environmental Focus

4-H & Youth

Community Focus

Extension Calendar

Nutrition Education Program

Family and Community Education (FCE) Clubs

and other extension news and events

Functional Analysis Of Three Arabidopsis Argonautes Using Slicer-Defective Mutants, Alberto Carbonell, Noah Fahlgren, Hernan Garcia-Ruiz, Kerrigan B. Gilbert, Taiowa A. Montgomery, Tammy Nguyen, Josh T. Cuperus, James C. Carrington

Department of Plant Pathology: Faculty Publications

In RNA-directed silencing pathways, ternary complexes result from small RNA-guided ARGONAUTE (AGO) associating with target transcripts. Target transcripts are often silenced through direct cleavage (slicing), destabilization through slicerindependent turnover mechanisms, and translational repression. Here, wild-type and active-site defective forms of several Arabidopsis thaliana AGO proteins involved in posttranscriptional silencing were used to examine several AGO functions, including small RNA binding, interaction with target RNA, slicing or destabilization of target RNA, secondary small interfering RNA formation, and antiviral activity. Complementation analyses in ago mutant plants revealed that the catalytic residues of AGO1, AGO2, and AGO7 are required to restore the defects …

Studies Of Drought Tolerance Of Hard Red Winter Wheat (Triticum Aestivum L.) Cultivars In Nebraska, Sumardi Bin Abdul Hamid

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

In Nebraska, about 75% of the wheat production is in the western half of the state, and about 92% of the winter wheat acreage is in dryland production, where productivity is limited by low and/or uncertain rainfall. We have investigated the effects of water stress on few established winter wheat (Triticum aestivumL.) cultivars, which are known for their superior adaptation to either rainfed or irrigated wheat production systems in western Nebraska. We also began a study to investigate the variation in the root system architecture to confer drought tolerance in winter wheat. The objectives of this study were …

Rosette Iron Deficiency Transcript And Microrna Profiling Reveals Links Between Copper And Iron Homeostasis In Arabidopsis Thaliana, Brian M. Waters, Samuel A. Mcinturf, Ricardo J. Stein

Department of Agronomy and Horticulture: Faculty Publications

Iron (Fe) is an essential plant micronutrient, and its deficiency limits plant growth and development on alkaline soils. Under Fe deficiency, plant responses include up-regulation of genes involved in Fe uptake from the soil. However, little is known about shoot responses to Fe deficiency. Using microarrays to probe gene expression in Kas-1 and Tsu-1 ecotypes of Arabidopsis thaliana, and comparison with existing Col-0 data, revealed conserved rosette gene expression responses to Fe deficiency. Fe-regulated genes included known metal homeostasis-related genes, and a number of genes of unknown function. Several genes responded to Fe deficiency in both roots and rosettes. …

Plant Calcium Content: Ready To Remodel, Jian Yang, Tracy Punshon, Mary Lou Guerinot, Kendal D. Hirschi

Dartmouth Scholarship

By identifying the relationship between calcium location in the plant cell and nutrient bioavailability, the plant characteristics leading to maximal calcium absorption by humans can be identified. Knowledge of plant cellular and molecular targets controlling calcium location in plants is emerging. These insights should allow for better strategies for increasing the nutritional content of foods. In particular, the use of preparation-free elemental imaging technologies such as synchrotron X-ray fluorescence (SXRF) microscopy in plant biology may allow researchers to understand the relationship between subcellular location and nutrient bioavailability. These approaches may lead to better strategies for altering the location of calcium …

A Comparison Of Methods For Measuring Co2 And O2, Jake Nelson

Techniques and Instruments

Understanding the dynamics of respiratory gasses gives critical insight into the metabolic processes of a biological system. An efficient and effective means of measuring respiration is essential to understanding aspects of the biosphere. Many methods have been developed for measuring changes in CO₂ and O₂, both as integrated systems and as individual components. Many experiments use an alkali trap with subsequent titration as an inexpensive method for CO₂ measurement. Haney et al. (2008) compared the titration method against infrared gas analysis (IRGA) and found them to be highly correlated, with r²=0.95. The use of …

Nebline, August 2012

NEBLINE Newsletter Archive from Nebraska Extension in Lancaster County

Feature: 9 Reasons to Shop at Farmers Markets

Farm Views

Urban Agriculture

Food & Fitness

Home & Family Living

Horticulture

Environmental Focus

4-H & Youth

Community Focus

Extension Calendar

Nutrition Education Program

Family and Community Education (FCE) Clubs

and other extension news and events

High School Horticulture Curriculum, Margaret Maratsos

Horticulture and Crop Science

Horticulture is just one of the many topics covered in a high school agriculture curriculum, and yet, there are very few lesson plans or resources available to teachers for these classes specifically. The objectives of this project were to compile a set of lesson plans, lab plans, and tests that would emphasize interactive and investigative learning. The lesson plans were written in such a way that they reflected a certain set of standards, set down by the state of California, and were meant to serve as a bare outline of topics that would be discussed within a week’s worth of …

Effects Of Meloidogyne Incognita, Soil Physical Parameters, And Thielaviopsis Basicola On Cotton Root Architecture And Plant Growth, Jianbing Ma

Graduate Theses and Dissertations

The root-knot nematode, Meloidogyne incognita, and the seedling pathogen, Thielaviopsis basicola, commonly co-exist in Arkansas cotton fields and may interact resulting in increased losses. The primary objective of this research was to evaluate the effects of soil physical parameters on these soilborne pathogens and cotton growth in controlled environmental, field, and microplot studies. Controlled environmental experiments used two soil bulk densities and four pathogen treatments: non-infested soil, soil infested with M. incognita or T. basicola and soil infested with both pathogens. The results indicated bulk density generally did not affect seedling growth or disease since soils had low penetration resistance …

Genetic Diversity, Pathogenicity/Virulence Variation And Population Structure Of Rhizoctonia Spp. Associated With Rice Sheath Blight In Arkansas And Qtl Mapping For Disease Resistance, Vanina Lilian Castroagudin

Graduate Theses and Dissertations

Rice sheath blight (ShB) is one of the most prevalent diseases in rice. The significance of this disease is increasing due to more intensive production practices globally. Rhizoctonia solani Kühn AG 1 - IA [teleomorph: Thanatephorus cucumeris (A.B. Frank) Donk] is considered the primary ShB pathogen of rice. However, Rhizoctonia oryzae-sativae, Rhizoctonia oryzae, and R. solani AG 2 and AG 11, have also been isolated from sheath blight-like lesions on rice.Up to now, there is little information on genetic diversity and patterns of molecular evolution of the fungus, and there is no study on the structure of the R. solani …

Effects Of Environment And Genotype On Charcoal Rot Development On Soybeans, Micah Diane Doubledee

Graduate Theses and Dissertations

Charcoal rot of soybean, caused by the soilborne fungus Macrophomina phaseolina (Tassi) Goid, is a disease associated with high soil temperature and low soil moisture. Above-ground symptoms, which can be difficult to distinguish from drought symptoms, include low vigor, dead leaves that remain attached to the plant, early senescence and yield loss. Irrigation limits damage, but does not prevent colonization of the tissue by the pathogen. No soybean line is immune to M. phaseolina, but a few lines may have moderate resistance. The objectives of this research were to 1) determine the effects of genotype and drought on the development …

Enhancement Or Attenuation Of Disease By Deletion Of Genes From Citrus Tristeza Virus, Satyanarayana Tatineni, William O. Dawson

Department of Plant Pathology: Faculty Publications

Stem pitting is a common virus-induced disease of perennial woody plants induced by a range of different viruses. The phenotype results from sporadic areas of the stem in which normal xylem and phloem development is prevented during growth of stems. These alterations interfere with carbohydrate transport, resulting in reduced plant growth and yield. Citrus tristeza virus (CTV), a phloem-limited closterovirus, induces economically important stem-pitting diseases of citrus. CTV has three nonconserved genes (p33, p18, and p13) that are not related to genes of other viruses and that are not required for systemic infection of some species of citrus, which allowed …

The Identification Of Quantitative Trait Loci For Sucrose And Stachyose Content In Soybean Seed, Ailan Zeng

Graduate Theses and Dissertations

Sucrose is a desirable sugar in soybean seed that affects the quality and taste of soyfoods, while stachyose is a non-digestible sugar that induces flatulence in non-ruminant animals. Therefore, soybean cultivars with high sucrose and/or low stachyose would be valuable for soyfood and meal markets. The objectives of this study were to identify quantitative trait loci (QTL) or genes associated with seed sucrose and stachyose content using simple sequence repeat (SSR) or single nucleotide polymorphism (SNP) markers. A low sucrose line, MFS-553, was crossed with a high sucrose plant introduction, PI 243545, to develop the sucrose QTL mapping population. A …

The Evolution Of Natural Plant Communities Through Crop Migration And Crop-To-Weed Gene Flow, Meredith G. Schafer

Graduate Theses and Dissertations

With the rising demand for food and biofuels, the efficiency of crop production has become vital to assuring food security. Genetically engineered (GE) crop varieties are broadly thought to be a solution for improving the efficiency of crop production, but concerns regarding their release have heightened as more discoveries have focused on the influence of genetically engineered crops on native and weedy plant species. Risk assessment of GE crop varieties focuses on two main areas: feralization of crop systems and crop-weed hybridization. Risks include naturalization, transgene introgression, and the formation of novel genotypes in natural systems. In this study, roadside …

Soybean Maturity Group Tradeoffs: Irrigation, Weed Control, And Nitrogen Fixation, Ryan Wegerer

Graduate Theses and Dissertations

This thesis is divided into four chapters. Chapter I introduces the rationale behind the study and gives a brief overview of the overall study covering weed control, irrigation needs and nitrogen fixation amounts across soybean maturity group. Chapter II will go into further detail outlining the first applied experiment dealing with weed control and irrigation issues. Alternative weed control methods are analyzed in conjunction with irrigation risk analysis across soybean maturity group in response to agricultural issues of glyphosate resistance and declining ground water supply in the Arkansas delta region. Chapter III will jointly examine irrigation application amounts and nitrogen …

Identification Of Stem Rust Resistance In Three Synthetic Wheat Populations, Russell A. Ward

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

Wheat stem rust incited by Puccinia graminis Pers.:Pers. = P. graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn is a major disease of wheat, with the potential to cause severe losses every year, hence making breeding for resistance important. For this project, two resistant synthetic wheat lines were studied using populations consisting of susceptible and resistant lines to determine the genetic basis of their stem rust resistance. Goodstreak has one dominant and one recessive resistance gene. Synthetics 303 and 370 each had two dominant genes present. For the Goodstreak/synthetic populations, testing F₂ and F_2:3 generations indicated the …

High-Throughput Transcriptome Sequencing For Snp And Gene Discovery In A Moth, Nicholas J. Miller, Jing Sun, Thomas W. Sappington

Department of Entomology: Faculty Publications

The western bean cutworm, Striacosta albicosta (Smith) (Leptidoptera: Noctuidae) is a pest of corn (Zea mays L.) and dry beans that underwent a dramatic range expansion in North America during the first decade of the 21st century. Research into the population genetics of this species has been hindered by a lack of genetic markers. The transcriptome of adult male S. albicosta was partially sequenced using Illumina sequencing-by-synthesis. Assembly of the sequence reads yielded 16,847 transcript sequences, of which 6,631 could be assigned a putative function. A search for single nucleotide polymorphisms (SNPs) identified 2,487 candidate SNPs distributed among 1,265 …

B.R. Wells Rice Research Studies 2011, R. J. Norman, K.A. K. Moldenhauer

Arkansas Agricultural Experiment Station Research Series

No abstract provided.

Functional Characterization Of A Jacalin-Like Lectin Domain-Containing Protein In Arabidopsis Thaliana, Shane Reighard

All Theses

Jacalin-related lectins (JRLs) are proteins that bind carbohydrates. Functionally, JRLs are thought to be involved in a diverse array of functions including biotic stress defense, intracellular storage, abiotic stress response, and plant development. Recent Arabidopsis thaliana microarray data indicate that a Jacalin-like domain-containing protein (JLL1) exhibits highly root specific expression. Previous transcriptomic and proteomic studies indicate that JLL1 may have a dual role in planta as a biotic stress defense protein and in plant development. In order to better understand the physiological function of JLL1 in Arabidopsis, several different analyses were conducted examining its regulatory sequences, spatial expression, responsiveness to …