scholarly journals Rathayibacter toxicus, Other Rathayibacter Species Inducing Bacterial Head Blight of Grasses, and the Potential for Livestock Poisonings

2017 ◽  
Vol 107 (7) ◽  
pp. 804-815 ◽  
Author(s):  
Timothy D. Murray ◽  
Brenda K. Schroeder ◽  
William L. Schneider ◽  
Douglas G. Luster ◽  
Aaron Sechler ◽  
...  
Keyword(s):  
United States ◽  
Infected Plant ◽  
Extracellular Polysaccharide ◽  
Toxin Production ◽  
The United States ◽  
Diagnostic Methods ◽  
Extracellular Polysaccharides ◽  
Head Blight ◽  
Dry Conditions ◽  
Infected Plant Material

Rathayibacter toxicus, a Select Agent in the United States, is one of six recognized species in the genus Rathayibacter and the best known due to its association with annual ryegrass toxicity, which occurs only in parts of Australia. The Rathayibacter species are unusual among phytopathogenic bacteria in that they are transmitted by anguinid seed gall nematodes and produce extracellular polysaccharides in infected plants resulting in bacteriosis diseases with common names such as yellow slime and bacterial head blight. R. toxicus is distinguished from the other species by producing corynetoxins in infected plants; toxin production is associated with infection by a bacteriophage. These toxins cause grazing animals feeding on infected plants to develop convulsions and abnormal gate, which is referred to as “staggers,” and often results in death of affected animals. R. toxicus is the only recognized Rathayibacter species to produce toxin, although reports of livestock deaths in the United States suggest a closely related toxigenic species may be present. A closely related but undescribed species, Rathayibacter sp. EV, originally isolated from Ehrharta villosa var. villosa in South Africa, is suspected of producing toxin. Many of the diseases caused by Rathayibacter species occur in arid areas and the extracellular polysaccharide they produce is believed to aid in their survival between crops. For example, R. “agropyri” was isolated from infected plant material after being stored for 50 years in a herbarium. Similarly, the anguinid vectors associated with these bacteria form seed galls in infected plants and are capable of surviving for very long periods of time under dry conditions. The addition of R. toxicus to the list of Select Agents has raised concern over its potential introduction and a realization that current diagnostic methods are inadequate to distinguish among Rathayibacter species. In addition, little is known about the Rathayibacter species and their seed gall nematode vectors present in the United States.

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy

Science ◽  
2021 ◽  
Vol 371 (6536) ◽  
pp. eaax9050
Author(s):  
Steffen Breinlinger ◽  
Tabitha J. Phillips ◽  
Brigette N. Haram ◽  
Jan Mareš ◽  
José A. Martínez Yerena ◽  
...  
Keyword(s):  
United States ◽  
Aquatic Vegetation ◽  
Southeastern United States ◽  
Hydrilla Verticillata ◽  
Toxin Production ◽  
The United States ◽  
Biosynthetic Gene Cluster ◽  
Biosynthetic Gene ◽  
Bald Eagles ◽  
Cyanobacterial Species

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata. Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola. We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors—especially bromide availability—that promote toxin production.

scholarly journals A Unified Effort to Fight an Enemy of Wheat and Barley: Fusarium Head Blight

Plant Disease ◽  
2012 ◽  
Vol 96 (12) ◽  
pp. 1712-1728 ◽  
Author(s):  
Marcia McMullen ◽  
Gary Bergstrom ◽  
Erick De Wolf ◽  
Ruth Dill-Macky ◽  
Don Hershman ◽  
...  
Keyword(s):  
United States ◽  
Fusarium Head Blight ◽  
Great Plains ◽  
Plant Disease ◽  
Management Strategies ◽  
The United States ◽  
Export Market ◽  
Northern Great Plains ◽  
Head Blight ◽  
Food And Feed

Wheat and barley are critical food and feed crops around the world. Wheat is grown on more land area worldwide than any other crop. In the United States, production of wheat and barley contributes to domestic food and feed use, and contributes to the export market and balance of trade. Fifteen years ago, Plant Disease published a feature article titled “Scab of wheat and barley: A re-emerging disease of devastating impact”. That article described the series of severe Fusarium head blight (FHB) epidemics that occurred in the United States and Canada, primarily from 1991 through 1996, with emphasis on the unparalleled economic and sociological impacts caused by the 1993 FHB epidemic in spring grains in the Northern Great Plains region. Earlier publications had dealt with the scope and damage caused by this disease in the United States, Canada, Europe, and China. Reviews published after 1997 further described this disease and its impact on North American grain production in the 1990s. This article reviews the disease and documents the information on U.S. FHB epidemics since 1997. The primary goal of this article is to summarize a sustained, coordinated, and collaborative research program that was put in place shortly after the 1993 epidemic, a program intended to quickly lead to improved management strategies and outreach implementation. This program serves as a model to deal with other emerging plant disease threats.

scholarly journals Resistance in Winter Wheat Lines to Initial Infection and Spread Within Spikes by Deoxynivalenol and Nivalenol Chemotypes of Fusarium graminearum

Plant Disease ◽  
2011 ◽  
Vol 95 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Peter Horevaj ◽  
Liane R. Gale ◽  
Eugene A. Milus
Keyword(s):  
United States ◽  
Winter Wheat ◽  
Fusarium Graminearum ◽  
The United States ◽  
Blight Resistance ◽  
Head Blight ◽  
Initial Infection ◽  
Additional Information ◽  
Progress Curve ◽  
Wheat Lines

Head blight of wheat in the United States is caused primarily by the deoxynivalenol (DON)-producing chemotype of Fusarium graminearum. However, the discovery of the nivalenol (NIV) chemotype of F. graminearum in Louisiana and Arkansas necessitates having resistance in wheat to both chemotypes. The objectives of this research were to quantify resistance of selected winter wheat lines to initial infection and pathogen spread within spikes, to determine whether wheat lines selected for resistance to the DON chemotype also have resistance to the NIV chemotype, and to improve the methods for quantifying resistance to initial infection. A susceptible check (Coker 9835) and 15 winter wheat lines, which are adapted to the southeastern United States and possess diverse sources of head blight resistance, were evaluated for head blight resistance in a series of greenhouse and growth-chamber experiments. Significant levels of resistance to both initial infection and spread within a spike were found among the lines, and lines with resistance to isolates of the DON chemotype had even higher levels of resistance to isolates of the NIV chemotype. Quantifying resistance to initial infection was improved by standardizing the inoculum and environmental conditions. Additional information related to resistance to spread within a spike was obtained by calculating the area under the disease progress curve from 7 to 21 days after inoculation.

scholarly journals Field Testing Peach Rootstocks for Resistance to Armillaria Root Rot

HortScience ◽  
2001 ◽  
Vol 36 (1) ◽  
pp. 101-103 ◽  
Author(s):  
T.G. Beckman ◽  
P.L. Pusey
Keyword(s):  
United States ◽  
Root Rot ◽  
Tree Mortality ◽  
Prunus Persica ◽  
Infected Plant ◽  
Field Testing ◽  
The United States ◽  
Peach Tree ◽  
Armillaria Root Rot ◽  
Peach Rootstocks

Armillaria root rot is the second leading cause of peach tree mortality (after peach tree short life) in the southeastern United States. Currently, there are no commercially available rootstocks for peach with proven resistance to this pathogen in the United States. Since 1983, we have been screening rootstock candidates for resistance to Armillaria utilizing naturally infected field sites. Inoculation of peach [Prunus persica (L.) Batsch], plum (P. cerasifera J.F. Ehrh., P. munsoniana F.W. Wight & Hedr., P. salicina Lindl. or P. angustifolia Marsh.) × peach and plum × plum hybrid rootstocks with infected plant tissue (such as acorns, Quercus sp.) prior to planting has provided a significantly increased infection and mortality of candidate rootstock lines in comparison with sole reliance on natural inoculum on an infested site.

scholarly journals Trichothecene Genotype of Fusarium graminearum Isolates from Soybean (Glycine max) Seedling and Root Diseases in the United States

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 1012-1012 ◽  
Author(s):  
M. L. Ellis ◽  
G. P. Munkvold
Keyword(s):  
United States ◽  
North America ◽  
Fusarium Graminearum ◽  
Root Rot ◽  
Elongation Factor ◽  
Host Shift ◽  
The United States ◽  
Sensu Stricto ◽  
Head Blight ◽  
The Third

Fusarium graminearum is an economically important pathogen that causes Fusarium head blight of wheat, barley, and oat, and Gibberella ear and stalk rot of maize. More recently, F. graminearum was reported as a soybean seedling and root pathogen in North America (1,5), causing seed decay, damping-off, and brown to reddish-brown root rot symptoms. Type B trichothecene mycotoxins are commonly produced by F. graminearum, which can be categorized into three trichothecene genotypes; those that produce 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), or nivalenol (NIV). The 15-ADON genotype is dominant in populations from small grains and maize in North America (4), but the 3-ADON genotype has recently been found (4). F. graminearum was known as a pathogen of wheat and maize in North America for over a century before it was reported as a soybean pathogen. Therefore, we hypothesized that recent reports on soybean could be associated with the appearance of the 3-ADON genotype. The objective of this research was to determine the trichothecene genotype of F. graminearum isolates from soybean in the United States. Thirty-eight isolates from soybean were evaluated. Twenty-seven isolates came from a 3-year survey for Fusarium root rot from 2007 to 2009 in Iowa. Other isolates (Ahmad Fakhoury, Southern Illinois University, Carbondale) were collected from soybean seedlings during a multi-state survey in 2012, and included three isolates from Illinois, three from Indiana, and five from Nebraska. Species identification and lineage of F. graminearum were confirmed by sequencing the translation elongation factor gene (EF1-α) using EF-1H and EF-2T primers. A maximum likelihood analysis of the EF1-α, including voucher strains from nine lineages of F. graminearum (2), placed all 38 isolates into lineage 7, F. graminearum sensu stricto (representative GenBank accessions KJ415349 to KJ415352). To determine the trichothecene genotype of each isolate we used three multiplex PCR assays. The first two assays targeted a portion of trichothecene biosynthesis genes Tri3 and Tri12 (4), while the third assay targeted portions of the Tri3, Tri5, and Tri7 genes (3). The PCR for the first two assays was conducted as described by Ward et al. (4) using four sets of primers: 3CON, 3NA, 3D15A, and 3D3A; and 12CON, 12NF, 12-15F, and 12-3F for the Tri3 and Tri12 genes, respectively. The PCR for the third assay was conducted as described by Quarta et al. (3) using the following primers: Tri3F971, Tri3F1325, Tri3R1679, Tri7F340, Tri7R965, 3551H, and 4056H. The amplification products were analyzed by gel electrophoresis. All 38 isolates produced amplicons consistent with the 15-ADON genotype; ~610 and 670 bp for the Tri3 and Tri12 genes, respectively (4), and two amplicons of ~708 and 525 bp for the Tri3/Tri5 genes (3). Our results indicated that the dominant trichothecene genotype among isolates of F. graminearum from soybean is 15-ADON, and the introduction of 3-ADON isolates does not explain the recent host shift of F. graminearum to soybean in North America. To our knowledge, this is the first assessment of trichothecene genotypes in F. graminearum populations from soybean from the United States. References: (1) K. E. Broders et al. Plant Dis. 91:1155, 2007. (2) K. O'Donnell et al. Fungal Gen. Biol. 41:600, 2004. (3) A. Quarta et al. FEMS Microbiol. Lett. 259:7, 2006. (4) T. D. Ward et al. Fungal Gen. Biol. 45:473, 2008. (5) A. G. Zue et al. Can. J. Plant Pathol. 29:35, 2007.

Mechanisms Associated with Daytime and Nighttime Heat Waves over the Contiguous United States

2020 ◽  
Vol 59 (11) ◽  
pp. 1865-1882
Author(s):  
Natalie P. Thomas ◽  
Michael G. Bosilovich ◽  
Allison B. Marquardt Collow ◽  
Randal D. Koster ◽  
Siegfried D. Schubert ◽  
...  
Keyword(s):  
United States ◽  
Human Health ◽  
Heat Wave ◽  
Heat Waves ◽  
The United States ◽  
Daily Maximum ◽  
Local Threshold ◽  
Dry Conditions ◽  
Heat And Moisture ◽  
Climate Events

AbstractHeat waves are extreme climate events that have the potential to cause immense stress on human health, agriculture, and energy systems, so understanding the processes leading to their onset is crucial. There is no single accepted definition for heat waves, but they are generally described as a sustained amount of time over which temperature exceeds a local threshold. Multiple different temperature variables are potentially relevant, because high values of both daily maximum and minimum temperatures can be detrimental to human health. In this study, we focus explicitly on the different mechanisms associated with summertime heat waves manifested during daytime hours versus nighttime hours over the contiguous United States. Heat waves are examined using the National Aeronautics and Space Administration Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). Over 1980–2018, the increase in the number of heat-wave days per summer was generally stronger for nighttime heat-wave days than for daytime heat-wave days, with localized regions of significant positive trends. Processes linked with daytime and nighttime heat waves are identified through composite analysis of precipitation, soil moisture, clouds, humidity, and fluxes of heat and moisture. Daytime heat waves are associated with dry conditions, reduced cloud cover, and increased sensible heating. Mechanisms leading to nighttime heat waves differ regionally across the United States, but they are typically associated with increased clouds, humidity, and/or low-level temperature advection. In the midwestern United States, enhanced moisture is transported from the Gulf of Mexico during nighttime heat waves.

scholarly journals Current methods of laboratory diagnosis of Chlamydia trachomatis infections.

1997 ◽  
Vol 10 (1) ◽  
pp. 160-184 ◽  
Author(s):  
C M Black
Keyword(s):  
United States ◽  
Chlamydia Trachomatis ◽  
Reproductive Tract ◽  
Dna Amplification ◽  
Laboratory Diagnosis ◽  
The United States ◽  
Diagnostic Methods ◽  
Sexually Transmitted ◽  
Immunodeficiency Virus ◽  
Diagnostic Technologies

Infections caused by Chlamydia trachomatis are probably the most common sexually transmitted diseases in the United States. Commonly unrecognized and often inadequately treated, chlamydial infections can ascend the reproductive tract and cause pelvic inflammatory disease, which often results in the devastating consequences of infertility, ectopic pregnancy, or chronic pelvic pain. C. trachomatis infections are also known to increase the risk for human immunodeficiency virus infection. The obligate intracellular life cycle of C. trachomatis has traditionally required laboratory diagnostic tests that are technically demanding, labor-intensive, expensive, and difficult to access. In spite of these historical challenges, however, laboratory diagnosis of C. trachomatis has been a rapidly advancing area in which there is presently a wide array of commercial diagnostic technologies, costs, manufacturers. This review describes and compares the diagnostic methods for C. trachomatis infection that are currently approved for use in the United States, including the newest DNA amplification technologies which are yet to be licensed for commercial use. Issues to consider in selecting a test for purposes of screening versus diagnosis based on prevalence, performance, legal, social, and cost issues are also discussed.

scholarly journals Nivalenol-Type Populations of Fusarium graminearum and F. asiaticum Are Prevalent on Wheat in Southern Louisiana

2011 ◽  
Vol 101 (1) ◽  
pp. 124-134 ◽  
Author(s):  
Liane Rosewich Gale ◽  
Stephen A. Harrison ◽  
Todd J. Ward ◽  
Kerry O'Donnell ◽  
Eugene A. Milus ◽  
...  
Keyword(s):  
United States ◽  
North Carolina ◽  
Fusarium Graminearum ◽  
Gulf Coast ◽  
Pcr Primers ◽  
The United States ◽  
Sensu Stricto ◽  
Head Blight ◽  
Trichothecene Mycotoxin ◽  
Southern Louisiana

U.S. populations of the Fusarium graminearum clade cause head blight on wheat and barley and usually contaminate grain with the trichothecene mycotoxin deoxynivalenol (DON). Recently, however, individual nivalenol (NIV)-type isolates from the United States were described that belonged to either the newly described species F. gerlachii or the genetically distinct Gulf Coast population of F. graminearum sensu stricto (s.s.). Here, we describe the discovery of NIV-type F. graminearum s.s. populations that were found in high proportion (79%) among isolates from small-grain-growing regions of Louisiana. We genotyped 237 isolates from Louisiana with newly developed polymerase chain reaction (PCR) restriction fragment length polymorphism markers and multiplex PCR primers that distinguish among the three trichothecene types: the two DON types (15ADON and 3ADON) and NIV. These isolates were compared with 297 isolates from 11 other U.S. states, predominantly from the Midwest. Using Bayesian-model-based clustering, we discovered a southern Louisiana population of F. graminearum s.s. that was genetically distinct from the previously recognized pathogen population in the Midwest (MW15ADON population). Population membership was correlated with trichothecene type. Most isolates from the southern Louisiana population were of the NIV type, while the majority of the isolates from the Midwest were of the 15ADON type. A smaller proportion of isolates from Louisiana belonged to the previously described Gulf Coast population that was mostly of the 3ADON type. The NIV type was also identified in collections from Arkansas (12%), North Carolina (40%), and Missouri (2%), with the collections from Arkansas and North Carolina being small and unrepresentative. F. asiaticum was detected from the two southern Louisiana parishes Acadia and Alexandria. All identified 41 F. asiaticum isolates were of the NIV type. Greenhouse tests indicated that U.S. NIV types accumulated four times less trichothecene toxin than DON types on inoculated wheat. This is the first report of NIV-type populations of F. graminearum s. s. and F. asiaticum in the United States.

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