Other Plant Sciences Commons^™

Co-Culture Of Yeast Antagonists Of Fusarium Head Blight And Their Effect On Disease Development In Wheat, D. A. Schisler, P. J. Slininger, Michael J. Boehm, P. A. Paul

Department of Plant Pathology: Faculty Publications

Multistrain mixtures of biocontrol agents which can reduce plant disease to a greater extent than the individual strains of the mixture, commonly, are prepared by blending separately produced fermentation products. Co-cultivation of strains to equivalent biomass yields would provide mixture advantages without incurring the cost disadvantages of multiple fermentation and processing protocols. Fusariwn Head Blight (FHB) antagonists Cryptococcus flavescens OR 182.9 (NRRL Y-302l6), C. aureus OH 181.1 (NRRL Y-302l5) and C. aureus OR 181.1 (NRRL Y -30215), were grown in two- and three-strain co-cultures to assess the quality and efficacy of the fermentation end products produced. Final cell counts of …

The Gc-Rich Mitochondrial And Plastid Genomes Of The Green Alga Coccomyxa Give Insight Into The Evolution Of Organelle Dna Nucleotide Landscape, David Roy Smith, Fabien Burki, Takashi Burki, Jane Grimwood, Igor V, Grigoriev, James L. Van Etten, Patrick J. Keeling

Department of Plant Pathology: Faculty Publications

Most of the available mitochondrial and plastid genome sequences are biased towards adenine and thymine (AT) over guanine and cytosine (GC). Examples of GC-rich organelle DNAs are limited to a small but eclectic list of species, including certain green algae. Here, to gain insight in the evolution of organelle nucleotide landscape, we present the GC-rich mitochondrial and plastid DNAs from the trebouxiophyte green alga Coccomyxa sp. C-169. We compare these sequences with other GC-rich organelle DNAs and argue that the forces biasing them towards G and C are nonadaptive and linked to the metabolic and/or life history features of this …

What Controls Toxic Phytoplankton Blooms In Long Island Sound?, Hans G. Dam Ph.D., Michael Finiguerra, Christina Senft-Batoh, Haley Flores

Wrack Lines

TIny phytoplankton organisms known as dinoflagellates can accumulate and cause toxic blooms that can kill fish and even make people ill. It's rare in Long Island Sound but can happen. What drives this phenomenon? Professor Hans G. Dam and his lab team explain in this easy-to-understand article.

Native Trees And Shrubs For Nebraska, Justin R. Evertson, Bob Henrickson

Nebraska Statewide Arboretum: Publications

Native plants withstand Nebraska’s tough climate extremes and serve as vital habitat for wildlife like birds, butterflies, and bees. NOTE: “Nearly native” signifies a species that is native within 100 miles of Nebraska’s border and/or now naturalized within the state.

141 species, from
Acer negundo -­‐ boxelder maple
to
woodbine -­‐ Parthenocissus vitacea

Switchgrass, Kenneth P. Vogel, Gautam Sarath, Aaron J. Saathoff, Robert B. Mitchell

Department of Agronomy and Horticulture: Faculty Publications

17.1 Introduction

Switchgrass (Panicum virgatum L.) is a warm-season perennial grass that is native to North America that is being developed into a biomass energy crop. It has been used in pastures and for conservation purposes in the Great Plains and the Midwest, USA, for over 70 years.1 The research supporting its use as a pasture and conservation species was largely conducted by US Department of Agriculture (USDA) research programs, most notably the Agricultural Research Service (ARS) project located at the University of Nebraska-Lincoln and USDA Plant Materials Centers that are located throughout the United States. In this report, …

Identification Of A Second Asian Soybean Rust Resistance Gene In Hyuuga Soybean, Mandy D. Kendrick, Donna K. Harris, Bo-Keun Ha, D. L. Hyten, P. B. Cregan, Reid D. Frederick, H. Roger Boerma, Kerry F. Pedley

Department of Agronomy and Horticulture: Faculty Publications

Asian soybean rust (ASR) is an economically significant disease caused by the fungus Phakopsora pachyrhizi. The soybean genes Rpp3 and Rpp?(Hyuuga) confer resistance to specific isolates of the pathogen. Both genes map to chromosome 6 (Gm06) (linkage group [LG] C2). We recently identified 12 additional soybean accessions that harbor ASR resistance mapping to Gm06, within 5 centimorgans of Rpp3 and Rpp?(Hyuuga). To further characterize genotypes with resistance on Gm06, we used a set of eight P. pachyrhizi isolates collected from geographically diverse areas to inoculate plants and evaluate them for differential phenotypic responses. …

Cytokinin-Mediated Source ⁄Sink Modifications Improve Drought Tolerance And Increase Grain Yield In Rice Under Water-Stress, Zvi Peleg, Maria Reguera, Ellen Tumimbang, Harkamal Walia, Eduardo Blumwald

Department of Agronomy and Horticulture: Faculty Publications

Drought is the major environmental factor limiting crop productivity worldwide. We hypothesized that it is possible to enhance drought tolerance by delaying stress-induced senescence through the stress-induced synthesis of cytokinins in crop-plants. We generated transgenic rice (Oryza sativa) plants expressing an isopentenyltransferase (IPT) gene driven by PSARK, a stress- and maturation-induced promoter. Plants were tested for drought tolerance at two yield-sensitive developmental stages: pre- and post-anthesis. Under both treatments, the transgenic rice plants exhibited delayed response to stress with significantly higher grain yield (GY) when compared to wild-type plants. Gene expression analysis revealed a significant shift in expression of hormone-associated …

Efficient And Stable Expression Of Gfp Through Wheat Streak Mosaic Virus-Based Vectors In Cereal Hosts Using A Range Of Cleavage Sites: Formation Of Dense Fluorescent Aggregates For Sensitive Virus Tracking, Satyanarayana Tatineni, Anthony J. Mcmechan, Gary L. Hein, Roy French

Department of Plant Pathology: Faculty Publications

A series of Wheat streak mosaic virus (WSMV)-based expression vectors were developed by engineering a cycle 3 GFP (GFP) cistron between P1 and HC-Pro cistrons with several catalytic/cleavage peptides at the Cterminus of GFP. WSMV-GFP vectors with the Foot-and-mouth disease virus 1D/2A or 2A catalytic peptides cleaved GFP from HC-Pro but expressed GFP inefficiently. WSMV-GFP vectors with homologous NIa-Pro heptapeptide cleavage sites did not release GFP from HC-Pro, but efficiently expressed GFP as dense fluorescent aggregates. However, insertion of one or two spacer amino acids on either side of NIb/CP heptapeptide cleavage site or deletion in HC-Pro cistron improved processing …

Another Really, Really Big Virus, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Viruses with genomes larger than 300 kb and up to 1.2 Mb, which encode hundreds of proteins, are being discovered and characterized with increasing frequency. Most, but not all, of these large viruses (often referred to as giruses) infect protists that live in aqueous environments. Bioinformatic analyses of metagenomes of aqueous samples indicate that large DNA viruses are quite common in nature and await discovery. One issue that is perhaps not appreciated by the virology community is that large viruses, even those classified in the same family, can differ significantly in morphology, lifestyle, and gene complement. This brief commentary, which …

Motus, Morphology, And Biodiversity Estimation: A Case Study Using Nematodes Of The Suborder Criconematina And A Conserved 18s Dna Barcode, Thomas O. Powers, Timothy Harris, Rebecca Higgins, Peter Mullin, Lisa Sutton, Kirsten Powers

Department of Plant Pathology: Faculty Publications

DNA barcodes are increasingly used to provide an estimate of biodiversity for small, cryptic organisms like nematodes. Nucleotide sequences generated by the barcoding process are often grouped, based on similarity, into molecular operational taxonomic units (MOTUs). In order to get a better understanding of the taxonomic resolution of a 3’ 592-bp 18S rDNA barcode, we have analyzed 100 MOTUs generated from 214 specimens in the nematode suborder Criconematina. Previous research has demonstrated that the primer set for this barcode reliably amplifies all nematodes in the Phylum Nematoda. Included among the Criconematina specimens were 25 morphologically described species representing 12 genera. …

Presence Of Fusarium Spp. In Air And Soil Associated With Sorghum Fields, Deanna L. Funnell-Harris, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Sorghum grain, valuable for feed, food, and bioenergy, can be colonized by several Fusarium spp.; therefore, it was of interest to identify possible sources of conidia. Analysis of air and soil samples provided evidence for the presence of propagules from Fusarium genotypes that may cause grain infections. Soil population estimates of members of the Gibberella fujikuroi species complex, that includes sorghum pathogens and other Fusarium spp., suggested that adequate inoculum for systemic infections was present. Conidia in air samples within two sorghum fields were collected by passive trapping for 2 years. Subsampled Fusarium isolates indicated that numbers of G. fujikuroi …

First Report Of Goss's Bacterial Wilt And Leaf Blight (Clavibacter Michiganensis Subsp. Nebraskensis) Of Corn In Texas, K. A. Korus, A. D. Timmerman, R. D. French-Monar, T. A. Jackson

Department of Plant Pathology: Faculty Publications

In September 2009, the University of Nebraska–Lincoln Plant and Pest Diagnostic Clinic received leaf samples of hybrid corn (Zea mays L.) displaying long, necrotic lesions with wavy margins. The lesions had discontinuous water-soaked spots that are indicative of Goss's bacterial wilt and leaf blight. The symptomatic leaves were submitted from Dallam County, located in the Texas Panhandle (northwest Texas). According to the USDA Farm Service Agency and the National Agricultural Statistics Service, in 2009 Dallam County had 54,025 ha planted to corn. This is approximately 19% of the total corn planted in the 26 counties in the Texas Panhandle …

Effects Of Integrating Cultivar Resistance And Fungicide Application On Fusarium Head Blight And Deoxynivalenol In Winter Wheat, Stephen N. Wegulo, William W. Bockus, John Hernandez Nopsa, Erick D. De Wolf, Kent M. Eskridge, Kamaranga H. S. Peiris, Floyd E. Dowell

Department of Plant Pathology: Faculty Publications

Fusarium head blight (FHB) or scab, incited by Fusarium graminearum, can cause significant economic losses in small grain production. Five field experiments were conducted from 2007 to 2009 to determine the effects on FHB and the associated mycotoxin deoxynivalenol (DON) of integrating winter wheat cultivar resistance and fungicide application. Other variables measured were yield and the percentage of Fusarium-damaged kernels (FDK). The fungicides prothioconazole + tebuconazole (formulated as Prosaro 421 SC) were applied at the rate of 0.475 liters/ha, or not applied, to three cultivars (experiments 1 to 3) or six cultivars (experiments 4 and 5) differing in their …

Characterization Of Three-Dimensional Spatial Aggregation And Association Patterns Of Brown Rot Symptoms Within Intensively Mapped Sour Cherry Trees, Sydney E. Everhart, Ashley Askew, Lynne Seymour, Imre J. Holb, Harald Scherm

Department of Plant Pathology: Faculty Publications

Characterization of spatial patterns of plant disease can provide insights into important epidemiological processes such as sources of inoculum, mechanisms of dissemination, and reproductive strategies of the pathogen population. While two-dimensional patterns of disease (among plants within fields) have been studied extensively, there is limited information on three-dimensional patterns within individual plant canopies. Reported here are the detailed mapping of different symptom types of brown rot (caused by Monilinia laxa) in individual sour cherry tree (Prunus cerasus) canopies, and the application of spatial statistics to the resulting data points to de-termine patterns of symptom aggregation and association. …

Nebline, January 2011

NEBLINE Newsletter Archive from Nebraska Extension in Lancaster County

Feature: Tightening Your Belt in Tough Times

Farm Views

Horticulture

Food & Fitness

Home & Family Living

Environmental Focus

Urban Agriculture

4-H & Youth

Community Focus

Extension Calendar

Nutrition Education Program

Family and Community Education (FCE) Clubs

and other extension news and events

Annual Report Special Pullout Section

Estimation Of Surface Soil Organic Matter Using A Ground-Based Active Sensor And Aerial Imagery, D. F. Roberts, V. I. Adamchuk, J. F. Shanahan, R. B. Ferguson, J. S. Schepers

Department of Agronomy and Horticulture: Faculty Publications

Active canopy sensors are currently being studied as a tool to assess crop N status and direct in-season N applications. The objective of this study was to use a variety of strategies to evaluate the capability of an active sensor and a wide-band aerial image to estimate surface soil organic matter (OM). Grid soil samples, active sensor reflectance and bare soil aerial images were obtained from six fields in central Nebraska before the 2007 and 2008 growing seasons. Six different strategies to predict OM were developed and tested by dividing samples randomly into calibration and validation datasets. Strategies included uniform, …

Stacking Resistance Alleles From Wild And Domestic Soybean Sources Improves Soybean Cyst Nematode Resistance, Myungsik Kim, D. L. Hyten, Terry L. Niblack, Brian W. Diers

Department of Agronomy and Horticulture: Faculty Publications

The soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is the most economically important soybean [Glycine max (L.) Merr.] pathogen in the United States. Field SCN populations are adapting to the narrowly based SCN resistance currently deployed in soybean cultivars. The objective of our research was to measure the effects of combinations of SCN resistance genes or quantitative trait loci (QTL) from the wild soybean (Glycine soja Siebold & Zucc.) PI 468916 and the domesticated soybean accessions PI 88788 and PI 437654. Two populations were developed to test the combinations of QTL and genes. Both populations segregated for the …

Control Of Glucosylceramide Production And Morphogenesis By The Bar1 Ceramide Synthase In Fusarium Graminearum, William B. Rittenour, Ming Chen, Edgar B. Cahoon, Steven D. Harris

Department of Plant Pathology: Faculty Publications

The contribution of plasma membrane proteins to the virulence of plant pathogenic fungi is poorly understood. Accordingly, the objective of this study was to characterize the acyl-CoA dependent ceramide synthase Bar1 (previously implicated in plasma membrane organization) in the wheat pathogen Fusarium graminearum. The role of Bar1 in mediating cell membrane organization was confirmed as DBAR1 mutants failed to display a distinct sterol-rich domain at the hyphal tip. The DBAR1 mutants were non-pathogenic when inoculated onto wheat heads, and their in vitro growth also was severely perturbed. DBAR1 mutants were incapable of producing perithecia (sexual fruiting structures) and only produced …

The Sugar Sensor, Trehalose-6-Phosphate Synthase (Tps1), Regulates Primary And Secondary Metabolism During Infection By The Rice Blast Fungus: Will Magnaporthe Oryzae’S “Sweet Tooth” Become Its “Achilles’ Heel”?, Jesse Fernandez, Richard Wilson

Department of Plant Pathology: Faculty Publications

Rice blast disease is considered one of the most serious diseases of cultivated rice and is mediated by the causal agent, Magnaporthe oryzae. During infection, dome-shaped fungal cells, called appressoria, form on the surface of the leaf and generate turgor through the accumulation of glycerol. This enormous pressure is directed down onto a thin penetration hypha emerging from the base of the cell, forcing it through the surface of the rice leaf and allowing fungal colonization of the plant interior. The non-reducing disaccharide, trehalose, is present in conidia of M. oryzae and is mobilized during appressorium formation. The first …

Mechanisms Of Contact-Mediated Killing Of Yeast Cells On Dry Metallic Copper Surfaces, Davide Quaranta, Travis Krans, Christophe Espirito Santo, Christian Elowsky, Dylan W. Domaille, Christopher J. Chang, Gregor Grass

Department of Plant Pathology: Faculty Publications

Surfaces made of copper or its alloys have strong antimicrobial properties against a wide variety of microorganisms. However, the molecular mode of action responsible for the antimicrobial efficacy of metallic copper is not known. Here, we show that dry copper surfaces inactivate Candida albicans and Saccharomyces cerevisiae within minutes in a process called contact-mediated killing. Cellular copper ion homeostasis systems influenced the kinetics of contact-mediated killing in both organisms. Deregulated copper ion uptake through a hyperactive S. cerevisiae Ctr1p (ScCtr1p) copper uptake transporter in Saccharomyces resulted in faster inactivation of mutant cells than of wild-type cells. Similarly, lack of the …