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Horizontal Gene Acquisitions, Mobile Element Proliferation, And Genome Decay In The Host-Restricted Plant Pathogen Erwinia Tracheiphila, Lori R. Shapiro, Erin D. Scully, Timothy J. Straub, Jihye Park, Andrew G. Stephenson, Gwyn A. Beattie, Mark L. Gleason, Roberto Kolter, Miguel C. Coelho, Consuelo M. De Moraes, Mark C. Mescher, Olga Zhaxybayeva 2016 Harvard University

Horizontal Gene Acquisitions, Mobile Element Proliferation, And Genome Decay In The Host-Restricted Plant Pathogen Erwinia Tracheiphila, Lori R. Shapiro, Erin D. Scully, Timothy J. Straub, Jihye Park, Andrew G. Stephenson, Gwyn A. Beattie, Mark L. Gleason, Roberto Kolter, Miguel C. Coelho, Consuelo M. De Moraes, Mark C. Mescher, Olga Zhaxybayeva

Gwyn Beattie

Modern industrial agriculture depends on high-density cultivation of genetically similar crop plants, creating favorable conditions for the emergence of novel pathogens with increased fitness in managed compared with ecologically intact settings. Here, we present the genome sequence of six strains of the cucurbit bacterial wilt pathogen Erwinia tracheiphila (Enterobacteriaceae) isolated from infected squash plants in New York, Pennsylvania, Kentucky, and Michigan. These genomes exhibit a high proportion of recent horizontal gene acquisitions, invasion and remarkable amplification of mobile genetic elements, and pseudogenization of approximately 20% of the coding sequences. These genome attributes indicate that E. tracheiphila recently emerged as a ...


An Overview Of Plant Defenses Against Pathogens And Herbivores, Brian C. Freeman, Gwyn A. Beattie 2016 Iowa State University

An Overview Of Plant Defenses Against Pathogens And Herbivores, Brian C. Freeman, Gwyn A. Beattie

Gwyn Beattie

Plants represent a rich source of nutrients for many organisms including bacteria, fungi, protists, insects, and vertebrates. Although lacking an immune system comparable to animals, plants have developed a stunning array of structural, chemical, and protein-based defenses designed to detect invading organisms and stop them before they are able to cause extensive damage. Humans depend almost exclusively on plants for food, and plants provide many important non-food products including wood, dyes, textiles, medicines, cosmetics, soaps, rubber, plastics, inks, and industrial chemicals. Understanding how plants defend themselves from pathogens and herbivores is essential in order to protect our food supply and ...


Simplified Process For Soybean Glycinin And Â-Conglycinin Fractionation, Shaowen Wu, Patricia A. Murphy, Lawrence A. Johnson, Mark A. Reuber, Alfred R. Fratzke 2016 Iowa State University

Simplified Process For Soybean Glycinin And Â-Conglycinin Fractionation, Shaowen Wu, Patricia A. Murphy, Lawrence A. Johnson, Mark A. Reuber, Alfred R. Fratzke

Lawrence A. Johnson

A simplification of the pilot-plant scale modified Nagano method yielding two protein fractions, glycinin and â-conglycinin, by pH adjustment and ultrafiltration membrane separation was developed and compared with our pilot-plant-scale modified Nagano procedure and with a soy protein isolate pilot-plant procedure as our reference process. Two protein fractions, glycinin and â-conglycinin, were produced from our simplified process and compared to the three protein fractions, glycinin, â-conglycinin, and an intermediate protein mixture, produced with the modified Nagano method. The pilot-plant yields of glycinin, â-conglycinin, and intermediate mixture fractions from the modified Nagano method were 9.4, 10.3, and 4.8 ...


Over-Summering Ecology Of The Wheat Curl Mite (Aceria Tosichella Keifer), Anthony J. McMechan 2016 University of Nebraska - Lincoln

Over-Summering Ecology Of The Wheat Curl Mite (Aceria Tosichella Keifer), Anthony J. Mcmechan

Dissertations and Student Research in Entomology

The wheat-mite-virus complex is a consistent and significant threat to winter wheat production in the western Great Plains. This complex consists of three viruses (Wheat streak mosaic virus, Triticum mosaic virus, and Wheat mosaic virus that are transmitted by the wheat curl mite (Aceria tosichella Keifer). Yield impacts from this complex are typically associated with the presence of volunteer wheat that emerges prior to harvest as a result of hail occurring during the heading stages of wheat in early summer. Historical literature on pre-harvest germination has been primarily focused on accelerating breeding programs; however, critical gaps in knowledge exist on ...


Morphological And Molecular Identification And Characterization Of Dry Bean Fungal Root Rot Pathogens In Zambia, Chikoti Mukuma 2016 University of Nebraska-Lincoln

Morphological And Molecular Identification And Characterization Of Dry Bean Fungal Root Rot Pathogens In Zambia, Chikoti Mukuma

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Dry bean is among the most important food legume crops for direct human consumption in Latin America and Africa. Recently, root and crown rot (RCR) has emerged as an important production constraint. Root and crown rot often involve fungal complexes. Thus, the straw, detached leaf, cup and stem tests were compared on their ability to detect the most common pathogens reported to be associated with RCR: Fusarium solani, Fusarium oxysporum, Pythium ultimum, Rhizoctonia solani and Macrophomina phaseolina.Significant differences (P

Next Generation Sequencing (NGS), conventional Polymerase Chain Reaction (PCR), and classical fungal culturing methods were compared in identification of the ...


Diversity And Virulence Of Soybean Cyst Nematode (Heterodera Glycines Ichinohe) In Nebraska, Kyle C. Broderick 2016 University of Nebraska-Lincoln

Diversity And Virulence Of Soybean Cyst Nematode (Heterodera Glycines Ichinohe) In Nebraska, Kyle C. Broderick

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is one of the most economically important soybean pathogens in the United States. Best management practices are the use of resistant cultivars and crop rotation. Though there are several genetic sources of SCN resistance, most of the SCN-resistant cultivars are derived from a single resistance source (PI 88788). Other states have reported an increase in virulence to PI 88788 due to prolonged use of this resistance. In this thesis, two studies were conducted to characterize the diversity and virulent phenotypes of SCN populations in Nebraska.

The first study assessed the virulent phenotypes of ...


Timing Of Strobilurin Fungicide For Control Of Top Dieback In Corn, Eric Adee, Stu Duncan 2016 Kansas State University

Timing Of Strobilurin Fungicide For Control Of Top Dieback In Corn, Eric Adee, Stu Duncan

Kansas Agricultural Experiment Station Research Reports

Significant yield losses can result from top dieback (TDB) in dent corn (Zea mays), which is caused by infection by the fungus causing anthracnose (Colletotrichum graminicola). Research is limited on the effectiveness of fungicide application because of the unpredictable nature of the disease. Two field studies were established to assess the timing of fungicide application on TDB, one in Illinois (2010) and the other in Kansas (2015). Fungicide applications at tasseling (VT) and later were effective in reducing the incidence of TDB 20 to 30% and increasing yield 15 to 19 bu/a, or up to 10%, while earlier applications ...


Sudden Death Syndrome And Soybean Planting Date, Eric Adee, C. R. Little, I. A. Ciampitti 2016 Kansas State University

Sudden Death Syndrome And Soybean Planting Date, Eric Adee, C. R. Little, I. A. Ciampitti

Kansas Agricultural Experiment Station Research Reports

The effect of soybean planting date on the severity of sudden death syndrome (SDS) and yield were evaluated in two studies at the Kansas River Valley Experiment Field in 2015. One study was established to promote SDS and the other to minimize SDS. In both studies the severity of SDS was greatest with the earlier planting dates, except for the more tolerant variety. The yield was greatest with the earlier planting date, except for the most susceptible variety. The severity of SDS was not as great as had been observed in previous years.


Interaction Between Seed Treatment And Variety On Sudden Death Syndrome Symptoms And Soybean Yield, Eric Adee 2016 Kansas State University

Interaction Between Seed Treatment And Variety On Sudden Death Syndrome Symptoms And Soybean Yield, Eric Adee

Kansas Agricultural Experiment Station Research Reports

Sudden Death Syndrome (SDS) is a soybean disease that perennially limits yields in the Kansas River Valley (KRV). The presence of soybean cyst nematode (SCN) and saturated soils has been implicated in contributing to the severity of the disease. Selecting varieties with some degree of tolerance to SDS has been the primary cultural practice to reduce yield loss to SDS. Another tool to reduce yield loss to SDS has been made available to growers with the release of ILeVO seed treatment from Bayer CropScience (Research Triangle Park, NC). The potential benefit of ILeVO on varieties with different levels of tolerance ...


Corn Following Corn In 2008, Mahdi Al-Kaisi, Roger W. Elmore, Antonio P. Mallarino, Palle Pedersen, Alison E. Robertson, John E. Sawyer, Jon J. Tollefson 2016 Iowa State University

Corn Following Corn In 2008, Mahdi Al-Kaisi, Roger W. Elmore, Antonio P. Mallarino, Palle Pedersen, Alison E. Robertson, John E. Sawyer, Jon J. Tollefson

John E. Sawyer

Corn following corn is in rough shape in areas across Iowa. Many wonder what is happening. The crop’s condition in general is not normal for this time of year. For example, last Sunday the USDA rated this year’s Iowa corn crop as 54 percent in ‘Good’ to ‘Excellent’ condition and 15 percent is ‘Poor’ or ‘Very Poor.’ Last year 72 percent was rated ‘Good’ to ‘Excellent’ and 5 percent was in ‘Poor’ or ‘Very Poor’ condition during the same week. Average plant height as of Sunday was 24 inches compared to 40 inches at end of the same ...


Corn Field Guide, Lori Abendroth, Roger Elmore, Robert G. Hartzler, Clarke McGrath, Daren S. Mueller, Gary P. Munkvold, Richard Pope, Marlin E. Rice, Alison E. Robertson, John E. Sawyer, Kristine J. P. Schaefer, Jon James Tollefson, Gregory L. Tylka 2016 Iowa State University

Corn Field Guide, Lori Abendroth, Roger Elmore, Robert G. Hartzler, Clarke Mcgrath, Daren S. Mueller, Gary P. Munkvold, Richard Pope, Marlin E. Rice, Alison E. Robertson, John E. Sawyer, Kristine J. P. Schaefer, Jon James Tollefson, Gregory L. Tylka

John E. Sawyer

A reference for identifying diseases, insect pests, and disorders of corn.


Development Of Cold Hardy, Large Patch Resistant Zoysiagrass Cultivars For The Transition Zone, Mingying Xiang, J. Fry, M. Kennelly 2016 Kansas State University, Manhattan

Development Of Cold Hardy, Large Patch Resistant Zoysiagrass Cultivars For The Transition Zone, Mingying Xiang, J. Fry, M. Kennelly

Kansas Agricultural Experiment Station Research Reports

TAES 5645, a Z. japonica genotype that exhibited resistance to large patch in preliminary studies, was used as a breeding parent and crossed with 22 cold hardy zoysiagrasses, resulting in 985 progeny. These progeny were evaluated for cold hardiness and agronomic traits (establishment rate, overall quality, spring greenup, leaf texture, and genetic color) in Manhattan, KS; West Lafayette, IN; and Dallas, TX; from 2012 to 2014. From this work, 60 progeny were identified for further evaluation in larger plots. During the 2015-2016 establishment year, experimental line 6102-47 showed good vigor and spring green up rate, which is comparable to ‘Meyer ...


Preventative Control Of Brown Patch With Select Fungicides, E. Alderman, J. Reeves, J. Hoyle 2016 Kansas State University

Preventative Control Of Brown Patch With Select Fungicides, E. Alderman, J. Reeves, J. Hoyle

Kansas Agricultural Experiment Station Research Reports

Preventative applications of Velista and Heritage Action fungicides will decrease the percentage of brown patch observed in a perennial stand of tall fescue.


The Genetics, Pathology, And Molecular Biology Of T-Cytoplasm Male Sterility In Maize, Roger P. Wise, Charlotte R. Bronson, Patrick S. Schnable, Harry T. Horner 2016 United States Department of Agriculture

The Genetics, Pathology, And Molecular Biology Of T-Cytoplasm Male Sterility In Maize, Roger P. Wise, Charlotte R. Bronson, Patrick S. Schnable, Harry T. Horner

Harry Horner

This chapter reviews the genetics, pathology, and molecular biology of T-cytoplasm male sterility in maize. The chapter discusses the role of cytoplasmic male sterility systems in facilitating the production of hybrid seeds. The effects of widespread planting of T-cytoplasm maize on the severe 1970 epidemic and effect of a mitochondria1 gene on disease susceptibility and male sterility are discussed. It also discusses the involvement of nuclear cytoplasmic interactions in restoration of cms-T, the perspectives of cms-T researchers, and future directions. In cms-T plants, male sterility is associated with premature breakdown of the mitochondria-rich, tapetal cell layer of the anther; this ...


The Preparation Of Carbon-Metal Replicas For The Study Of Carboniferous Coal Ball Fossils: Replication And Cleaning Procedures, Sam W. Rosso, M. Glenn Williams, Harry T. Horner, James Moreland 2016 University of Southern Mississippi

The Preparation Of Carbon-Metal Replicas For The Study Of Carboniferous Coal Ball Fossils: Replication And Cleaning Procedures, Sam W. Rosso, M. Glenn Williams, Harry T. Horner, James Moreland

Harry Horner

In the early stages of a previous study of fossil spores of Botryopteris globosa and B. americana from the Carboniferous (Phillips & Rosso, 1970), considerable difficulty was encountered in replicating and cleaning spore materials and associ- ated debris from the carbon-platinum spore replicas. After numerous attempts to clean these carbon films, the techniques presented in this paper proved ef- ficient and reliable for transmission electron microscope examination of Botry- opteris spores found in calcified coal ball fossils.


Developmental Aspects Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Robert E. Whitmoyer, Harry T. Horner 2016 Iowa State University

Developmental Aspects Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Robert E. Whitmoyer, Harry T. Horner

Harry Horner

The ontogeny and biological activity of bacterial leaf nodules in Psychotria bacteriophila were studied. The acridine-orange fluorescence method coupled with ribonuclease extractions showed that young and developing nodules were rich in ribonucleic acid (RNA), whereas nodules in older leaves displayed less RNA fluorescence, and nodules in leaves near absciscion did not fluoresce. Fluorescence was attributed to normal and dividing ribosome-rich bacteria. As nodules age, the bacterial population becomes crowded, and de- generating bacteria appear. The latter become a membrane mass which fills the nodule network, replacing the bacteria. The loss of fluorescence is therefore correlated with bacterial cell degeneration. These ...


Development And Structure Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Nels R. Lersten, Harry T. Horner 2016 Iowa State University

Development And Structure Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Nels R. Lersten, Harry T. Horner

Harry Horner

The development and mature structure of bacterial leaf nodules in Psychotria bacteriophila were studied by using light and electron microscopy. Bacteria in mucilage surrounding the shoot apex pass through certain stomates in leaf primordia into the substomatal chamber. These chambers enlarge and become nodules as the young leaves grow out of the apical region. Surrounding mesophyll cells grow into each nodule and form a cellular reticulum whose interstices are occupied by bacteria. Each intrusive mesophyll cell wall is unusually thick and continually supplemented by vesicles originating from dictyosomes. The gram-negative bacteria are often surrounded by capsules. Nodule bacteria contain several ...


The Capacity Of Switchgrass (Panicum Virgatum) To Degrade Atrazine In A Phytoremediation Setting., Ian J. Murphy, Joel R. Coats 2016 Iowa State University

The Capacity Of Switchgrass (Panicum Virgatum) To Degrade Atrazine In A Phytoremediation Setting., Ian J. Murphy, Joel R. Coats

Joel R. Coats

Atrazine is a widely used herbicide in agriculture. Non-point source contamination of groundwater and drinking water may pose a significant threat to humans, wildlife, and the environment. Phytoremediation may provide a cost-effective strategy for reducing non-point source contamination of atrazine from agricultural runoff. Previous studies have shown that the rhizosphere of the native prairie grass, switchgrass (Panicum virgatum) is capable of enhancing the degradation of atrazine in soils. Biodegradation also may occur within the plant biomass; however, the extent to which this occurs has not been studied. We hypothesize that switchgrass has the capacity to degrade atrazine in vivo, in ...


Fate Of Atrazine In Switchgrass-Soil Column System., Vurtice C. Albright III, Ian J. Murphy, Jennifer A. Anderson, Joel R. Coats 2016 Iowa State University

Fate Of Atrazine In Switchgrass-Soil Column System., Vurtice C. Albright Iii, Ian J. Murphy, Jennifer A. Anderson, Joel R. Coats

Joel R. Coats

Atrazine, a broad-leaf herbicide, has been used widely to control weeds in corn and other crops for several decades and its extensive used has led to widespread contamination of soils and water bodies. Phytoremediation with switchgrass and other native prairie grasses is one strategy that has been suggested to lessen the impact of atrazine in the environment. The goal of this study is to characterize: (1) the uptake of atrazine into above-ground switchgrass biomass; and (2) the degradation and transformation of atrazine over time. A fate study was performed using mature switchgrass columns treated with an artificially-created agricultural runoff containing ...


The Phenolic Monoterpenoid Carvacrol Inhibits The Binding Of Nicotine To The Housefly Nicotinic Acetylcholine Receptor, Fan Tong, Aaron D. Gross, Marc C. Dolan, Joel R. Coats 2016 University of Florida

The Phenolic Monoterpenoid Carvacrol Inhibits The Binding Of Nicotine To The Housefly Nicotinic Acetylcholine Receptor, Fan Tong, Aaron D. Gross, Marc C. Dolan, Joel R. Coats

Joel R. Coats

Background

The phenolic monoterpenoid carvacrol, which is found in many plant essential oils (thyme, oregano and Alaska yellow cedar), is highly active against pest arthropods, but its mechanisms of action are not fully understood. Here, carvacrol is shown to bind in a membrane preparation containing insect nicotinic acetylcholine receptors (nAChRs). [14C]-Nicotine binding assays with Musca domestica (housefly) nAChRs were used in this study to demonstrate carvacrol's binding to nAChRs, thereby acting as a modulator of the receptors.

Results

Carvacrol showed a concentration-dependent inhibition of [14C]-nicotine binding in a membrane preparation of housefly heads containing nAChRs ...


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