scholarly journals Populations of Phytophthora rubi Show Little Differentiation and High Rates of Migration Among States in the Western United States

2018 ◽  
Vol 31 (6) ◽  
pp. 614-622 ◽  
Author(s):  
Javier F. Tabima ◽  
Michael D. Coffey ◽  
Inga A. Zazada ◽  
Niklaus J. Grünwald
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Root Rot ◽  
Genotyping By Sequencing ◽  
The United States ◽  
Western United States ◽  
Lineage Sorting ◽  
Phytophthora Root Rot ◽  
Agricultural Ecosystems ◽  
Low Genetic Diversity

Population genetics is a powerful tool to understand patterns and evolutionary processes that are involved in plant-pathogen emergence and adaptation to agricultural ecosystems. We are interested in studying the population dynamics of Phytophthora rubi, the causal agent of Phytophthora root rot in raspberry. P. rubi is found in the western United States, where most of the fresh and processed raspberries are produced. We used genotyping-by-sequencing to characterize genetic diversity in populations of P. rubi sampled in the United States and other countries. Our results confirm that P. rubi is a monophyletic species with complete lineage sorting from its sister taxon P. fragariae. Overall, populations of P. rubi show low genetic diversity across the western United States. Demographic analyses suggest that populations of P. rubi from the western United States are the source of pathogen migration to Europe. We found no evidence for population differentiation at a global or regional (western United States) level. Finally, our results provide evidence of migration from California and Oregon into Washington. This report provides new insights into the evolution and structure of global and western United States populations of the raspberry pathogen P. rubi, indicating that human activity might be involved in moving the pathogen among regions and fields.

scholarly journals Contrasting Patterns of Genetic Diversity and Population Structure of Armillaria mellea sensu stricto in the Eastern and Western United States

2010 ◽  
Vol 100 (7) ◽  
pp. 708-718 ◽  
Author(s):  
Kendra Baumgartner ◽  
Renaud Travadon ◽  
Johann Bruhn ◽  
Sarah E. Bergemann
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Population Structure ◽  
Los Angeles ◽  
The United States ◽  
Sensu Stricto ◽  
Western United States ◽  
Eastern United States ◽  
Armillaria Mellea ◽  
Genetic Pools

Armillaria mellea infects hundreds of plant species in natural and managed ecosystems throughout the Northern hemisphere. Previously reported nuclear genetic divergence between eastern and western U.S. isolates is consistent with the disjunct range of A. mellea in North America, which is restricted mainly to both coasts of the United States. We investigated patterns of population structure and genetic diversity of the eastern (northern and southern Appalachians, Ozarks, and western Great Lakes) and western (Berkeley, Los Angeles, St. Helena, and San Jose, CA) regions of the United States. In total, 156 diploid isolates were genotyped using 12 microsatellite loci. Absence of genetic differentiation within either eastern subpopulations (θST = –0.002, P = 0.5 ) or western subpopulations (θST = 0.004, P = 0.3 ) suggests that spore dispersal within each region is sufficient to prevent geographic differentiation. In contrast to the western United States, our finding of more than one genetic cluster of isolates within the eastern United States (K = 3), revealed by Bayesian assignment of multilocus genotypes in STRUCTURE and confirmed by genetic multivariate analyses, suggests that eastern subpopulations are derived from multiple founder sources. The existence of amplifiable and nonamplifiable loci and contrasting patterns of genetic diversity between the two regions demonstrate that there are two geographically isolated, divergent genetic pools of A. mellea in the United States.

Races of Phytophthora sojae on Soybean in Illinois

2000 ◽  
Vol 1 (1) ◽  
pp. 32
Author(s):  
R. A. Leitz ◽  
G. L. Hartman ◽  
W. L. Pedersen ◽  
C. D. Nickell
Keyword(s):  
United States ◽  
Glycine Max ◽  
Root Rot ◽  
The United States ◽  
Phytophthora Sojae ◽  
Phytophthora Root Rot ◽  
Glycine Max L

Phytophthora root rot of soybean (Glycine max (L.) Merr.), caused by Phytophthora sojae M. J. Kauffmann & J. W. Gerdemann, has been isolated throughout the soybean-producing regions of the United States. Posted 3 June 2000.

Exploring origins, invasion history and genetic diversity ofImperata cylindrica(L.) P. Beauv. (Cogongrass) in the United States using genotyping by sequencing

2015 ◽  
Vol 24 (9) ◽  
pp. 2177-2193 ◽  
Author(s):  
A. Millie Burrell ◽  
Alan E. Pepper ◽  
George Hodnett ◽  
John A. Goolsby ◽  
William A. Overholt ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Genotyping By Sequencing ◽  
The United States ◽  
Invasion History

Writing Time in Metaphors

2018 ◽  
Author(s):  
Jennifer J. Smith
Keyword(s):  
United States ◽  
The United States ◽  
Western United States ◽  
Entire System ◽  
Language And Culture ◽  
Space Race ◽  
Do So

Coherence of place often exists alongside irregularities in time in cycles, and chapter three turns to cycles linked by temporal markers. Ray Bradbury’s The Martian Chronicles (1950) follows a linear chronology and describes the exploration, conquest, and repopulation of Mars by humans. Conversely, Louise Erdrich’s Love Medicine (1984) jumps back and forth across time to narrate the lives of interconnected families in the western United States. Bradbury’s cycle invokes a confluence of historical forces—time as value-laden, work as a calling, and travel as necessitating standardized time—and contextualizes them in relation to anxieties about the space race. Erdrich’s cycle invokes broader, oppositional conceptions of time—as recursive and arbitrary and as causal and meaningful—to depict time as implicated in an entire system of measurement that made possible the destruction and exploitation of the Chippewa people. Both volumes understand the United States to be preoccupied with imperialist impulses. Even as they critique such projects, they also point to the tenacity with which individuals encounter these systems, and they do so by creating “interstitial temporalities,” which allow them to navigate time at the crossroads of language and culture.

scholarly journals Dermacentor variabilis is the Predominant Dermacentor spp. (Acari: Ixodidae) Feeding on Dogs and Cats Throughout the United States

2021 ◽  
Author(s):  
Kathryn T Duncan ◽  
Meriam N Saleh ◽  
Kellee D Sundstrom ◽  
Susan E Little
Keyword(s):  
United States ◽  
Spotted Fever ◽  
Rocky Mountain ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Western United States ◽  
Its2 Region ◽  
Rrna Gene ◽  
Rocky Mountain Spotted Fever ◽  
Dermacentor Albipictus

Abstract Throughout North America, Dermacentor spp. ticks are often found feeding on animals and humans, and are known to transmit pathogens, including the Rocky Mountain spotted fever agent. To better define the identity and distribution of Dermacentor spp. removed from dogs and cats in the United States, ticks submitted from 1,457 dogs (n = 2,924 ticks) and 137 cats (n = 209 ticks) from veterinary practices in 44/50 states from February 2018-January 2020 were identified morphologically (n = 3,133); the identity of ticks from regions where Dermacentor andersoni (Stiles) have been reported, and a subset of ticks from other regions, were confirmed molecularly through amplification and sequencing of the ITS2 region and a 16S rRNA gene fragment. Of the ticks submitted, 99.3% (3,112/3,133) were Dermacentor variabilis (Say), 0.4% (12/3,133) were D. andersoni, and 0.3% (9/3,133) were Dermacentor albipictus (Packard). While translocation of pets prior to tick removal cannot be discounted, the majority (106/122; 87%) of Dermacentor spp. ticks removed from dogs and cats in six Rocky Mountain states (Montana, Idaho, Wyoming, Nevada, Utah, and Colorado) were D. variabilis, suggesting this species may be more widespread in the western United States than is currently recognized, or that D. andersoni, if still common in the region, preferentially feeds on hosts other than dogs and cats. Together, these data support the interpretation that D. variabilis is the predominant Dermacentor species found on pets throughout the United States, a finding that may reflect recent shifts in tick distribution.

scholarly journals Molecular Analysis of a Plum pox virus W Isolate in Plum Germplasm Hand Carried into the USA from the Ukraine Shows a Close Relationship to a Latvian Isolate

Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Vessela Mavrodieva ◽  
Delano James ◽  
Karen Williams ◽  
Sarika Negi ◽  
Aniko Varga ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
The United States ◽  
Common Source ◽  
Plum Pox Virus ◽  
High Genetic Diversity ◽  
Close Relationship ◽  
The Usa ◽  
Sequence Identities ◽  
Germplasm Accessions

Four of 19 Prunus germplasm accessions hand carried from the Ukraine into the United States without authorization were found to be infected with Plum pox virus (PPV). Of the three isolates characterized, isolates UKR 44189 and UKR 44191 were confirmed to be isolates of PPV strain W, and UKR 44188 was confirmed to be an isolate of PPV strain D. UKR 44189 and UKR 44191 are very closely related to the PPV strain W isolate LV-145bt (HQ670748) from Latvia. Nucleotide and amino acid sequence identities between these three isolates were greater than 99%. This indicates that the isolates are very closely related and likely originated from a common source. The high genetic diversity among PPV-W strain isolates allowed the identification of potential recombination events between PPV isolates. It appears also that GF 305 peach and Prunus tomentosa are not hosts for the PPV isolate UKR 44189.

scholarly journals A Climatology of 500-hPa Closed Lows in the Northeastern Pacific Ocean, 1948–2011

2014 ◽  
Vol 53 (6) ◽  
pp. 1578-1592 ◽  
Author(s):  
Nina S. Oakley ◽  
Kelly T. Redmond
Keyword(s):  
United States ◽  
Pacific Ocean ◽  
Interannual Variability ◽  
West Coast ◽  
The United States ◽  
Western United States ◽  
The West ◽  
Reanalysis Dataset ◽  
The Pacific ◽  
Northeastern Pacific

AbstractThe northeastern Pacific Ocean is a preferential location for the formation of closed low pressure systems. These slow-moving, quasi-barotropic systems influence vertical stability and sustain a moist environment, giving them the potential to produce or affect sustained precipitation episodes along the west coast of the United States. They can remain motionless or change direction and speed more than once and thus often pose difficult forecast challenges. This study creates an objective climatological description of 500-hPa closed lows to assess their impacts on precipitation in the western United States and to explore interannual variability and preferred tracks. Geopotential height at 500 hPa from the NCEP–NCAR global reanalysis dataset was used at 6-h and 2.5° × 2.5° resolution for the period 1948–2011. Closed lows displayed seasonality and preferential durations. Time series for seasonal and annual event counts were found to exhibit strong interannual variability. Composites of the tracks of landfalling closed lows revealed preferential tracks as the features move inland over the western United States. Correlations of seasonal event totals for closed lows with ENSO indices, the Pacific decadal oscillation (PDO), and the Pacific–North American (PNA) pattern suggested an above-average number of events during the warm phase of ENSO and positive PDO and PNA phases. Precipitation at 30 U.S. Cooperative Observer stations was attributed to closed-low events, suggesting 20%–60% of annual precipitation along the West Coast may be associated with closed lows.

Genetic Diversity of Wild Oat (Avena fatua)Populations from China and the United States

Weed Science ◽  
2007 ◽  
Vol 55 (2) ◽  
pp. 95-101 ◽  
Author(s):  
Runzhi Li ◽  
Shiwen Wang ◽  
Liusheng Duan ◽  
Zhaohu Li ◽  
Michael J. Christoffers ◽  
...  
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Gene Diversity ◽  
Genetic Relationships ◽  
The United States ◽  
Mantel Test ◽  
Wild Oat ◽  
Chinese Populations ◽  
Nei's Distance ◽  
The Impact

Weed genetic diversity is important for understanding the ability of weeds to adapt to different environments and the impact of herbicide selection on weed populations. Genetic diversity within and among six wild oat populations in China varying in herbicide selection pressure and one population in North Dakota were surveyed using 64 polymorphic alleles resulting from 25 microsatellite loci. Mean Nei's gene diversity (h) for six wild oat populations from China was between 0.17 and 0.21, and total diversity (HT) was 0.23. A greater proportion of this diversity, however, was within (Hs= 0.19) rather than among (Gst= 0.15) populations. For the wild oat population from the United States,h= 0.24 andHT= 0.24 were comparable to the values for the six populations from China. Cluster analysis divided the seven populations into two groups, where one group was the United States population and the other group included the six Chinese populations. The genetic relationships among six populations from China were weakly correlated with their geographic distribution (r= 0.22) using the Mantel test. Minimal difference in gene diversity and small genetic distance (Nei's distance 0.07 or less) among six populations from China are consistent with wide dispersal of wild oat in the 1980s. Our results indicate that the wild oat populations in China are genetically diverse at a level similar to North America, and the genetic diversity of wild oat in the broad spatial scale is not substantially changed by environment, agronomic practices, or herbicide usage.

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