Isozyme structure of Peridermium harknessii in the western United States

1991 ◽  
Vol 69 (11) ◽  
pp. 2434-2441 ◽  
Author(s):  
D. R. Vogler ◽  
B. B. Kinloch Jr. ◽  
F. W. Cobb Jr. ◽  
T. L. Popenuck
Keyword(s):  
United States ◽  
Sierra Nevada ◽  
Rust Fungus ◽  
Western United States ◽  
Population Genetic Study ◽  
Coastal Forests ◽  
Low Frequencies ◽  
Heterozygous Condition ◽  
Pinus Spp ◽  
Pine Species

We conducted a population genetic study of the western gall rust fungus (Peridermium harknessii) using isozymes as genetic markers. Electrophoresis of 341 single-gall aeciospore isolates collected from several pine species revealed that western gall rust is comprised of two distinct zymodemes (multilocus electrophoretic types) in the western United States. Within zymodemes, all 15 loci studied were monomorphic (0.95 criterion), although variants were found at low frequencies (≤ 0.03) at 3 loci. Zymodeme I was characterized by single bands, indicating homozygosity at all loci; it consisted of isolates from all pine species and environments studied, including the Pacific Coast and Cascade Ranges and the Sierra Nevada and Rocky Mountains. Zymodeme II, which was absent from coastal forests, was characterized by double or triple bands at 6 of 15 loci. The additional bands were interpreted as products of alternative alleles in heterozygous condition; isozyme phenotypes at the other nine loci were identical to those of zymodeme I. Presumed heterozygotes were fixed within zymodeme II, and homozygotes of alleles unique to this zymodeme were not found. Generally, all isolates sampled from a forest stand were in the same zymodeme, and when isolates from both zymodemes were found in the same location, recombinant genotypes between zymodemes were not observed. Such extreme disequilibrium is inconsistent with sexual reproduction, indicating that P. harknessii is asexual. Key words: western gall rust, Pinus spp., genetic variation.

scholarly journals Influence of Atmospheric Rivers on Mountain Snowpack in the Western United States

2018 ◽  
Vol 31 (24) ◽  
pp. 9921-9940 ◽  
Author(s):  
N. Goldenson ◽  
L. R. Leung ◽  
C. M. Bitz ◽  
E. Blanchard-Wrigglesworth
Keyword(s):  
United States ◽  
Sierra Nevada ◽  
Snow Water Equivalent ◽  
Region Of Interest ◽  
Internal Variability ◽  
Western United States ◽  
Historical Period ◽  
Atmospheric Rivers ◽  
Atmospheric River ◽  
The Impact

In the coastal mountains of western North America, most extreme precipitation is associated with atmospheric rivers (ARs), narrow bands of moisture originating in the tropics. Here we quantify how interannual variability in atmospheric rivers influences snowpack in the western United States in observations and a model. We simulate the historical climate with the Model for Prediction Across Scales (MPAS) with physics from the Community Atmosphere Model, version 5 [CAM5 (MPAS-CAM5)], using prescribed sea surface temperatures. In the global variable-resolution domain, regional refinement (at ~30 km) is applied to our region of interest and upwind over the northeast Pacific. To better characterize internal variability, we conduct simulations with three ensemble members over 30 years of the historical period. In the Cascade Range, with some exceptions, winters with more atmospheric river days are associated with less snowpack. In California’s Sierra Nevada, winters with more ARs are associated with greater snowpack. The slope of the linear regression of observed snow water equivalent (SWE) on reanalysis-based AR count has the same sign as that arrived at using the model, but is statistically significant in observations only for California. In spring, internal variance plays an important role in determining whether atmospheric river days appear to be associated with greater or less snowpack. The cumulative (winter through spring) number of atmospheric river days, on the other hand, has a relationship with spring snowpack, which is consistent across ensemble members. Thus, the impact of atmospheric rivers on winter snowpack has a greater influence on spring snowpack than spring atmospheric rivers in the model for both regions and in California consistently in observations.

scholarly journals Virulence Characterization of Wheat Stripe Rust Fungus Puccinia striiformis f. sp. tritici in Ethiopia and Evaluation of Ethiopian Wheat Germplasm for Resistance to Races of the Pathogen from Ethiopia and the United States

Plant Disease ◽  
2017 ◽  
Vol 101 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Anmin Wan ◽  
Kebede T. Muleta ◽  
Habtemariam Zegeye ◽  
Bekele Hundie ◽  
Michael O. Pumphrey ◽  
...  
Keyword(s):  
United States ◽  
Stripe Rust ◽  
Puccinia Striiformis ◽  
Rust Fungus ◽  
Single Gene ◽  
The United States ◽  
Wheat Cultivars ◽  
Low Frequencies ◽  
Additional Information

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most important diseases of wheat in Ethiopia. In total, 97 isolates were recovered from stripe rust samples collected in Ethiopia in 2013 and 2014. These isolates were tested on a set of 18 Yr single-gene differentials for characterization of races and 7 supplementary differentials for additional information of virulence. Of 18 P. striiformis f. sp. tritici races identified, the 5 most predominant races were PSTv-105 (21.7%), PSTv-106 (17.5%), PSTv-107 (11.3%), PSTv-76 (10.3%), and PSTv-41 (6.2%). High frequencies (>40%) were detected for virulence to resistance genes Yr1, Yr2, Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, Yr27, Yr28, Yr31, Yr43, Yr44, YrExp2, and YrA. Low frequencies (<40%) were detected for virulence to Yr10, Yr24, Yr32, YrTr1, Hybrid 46, and Vilmorin 23. None of the isolates were virulent to Yr5, Yr15, YrSP, and YrTye. Among the six collection regions, Arsi Robe and Tiyo had the highest virulence diversities, followed by Bekoji, while Bale and Holeta had the lowest. Evaluation of 178 Ethiopian wheat cultivars and landraces with two of the Ethiopian races and three races from the United States indicated that the Ethiopian races were more virulent on the germplasm than the predominant races of the United States. Thirteen wheat cultivars or landraces that were resistant or moderately resistant to all five tested races should be useful for breeding wheat cultivars with resistance to stripe rust in both countries.

Contemporary uplift of the Sierra Nevada, western United States, from GPS and InSAR measurements

Geology ◽  
2012 ◽  
Vol 40 (7) ◽  
pp. 667-670 ◽  
Author(s):  
W. C. Hammond ◽  
G. Blewitt ◽  
Z. Li ◽  
H.-P. Plag ◽  
C. Kreemer
Keyword(s):  
United States ◽  
Sierra Nevada ◽  
Western United States

scholarly journals Races of Puccinia striiformis f. sp. tritici in the United States in 2011 and 2012 and Comparison with Races in 2010

Plant Disease ◽  
2016 ◽  
Vol 100 (5) ◽  
pp. 966-975 ◽  
Author(s):  
Anmin Wan ◽  
Xianming Chen ◽  
Jonathan Yuen
Keyword(s):  
United States ◽  
Stripe Rust ◽  
Resistance Genes ◽  
Puccinia Striiformis ◽  
Single Gene ◽  
Durable Resistance ◽  
The United States ◽  
Western United States ◽  
Adult Plant ◽  
Low Frequencies

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most important diseases on wheat in the United States. In 2011, severe wheat stripe rust caused extensive application of fungicides in the western United States, and the disease was more widespread and caused more yield loss in the eastern United States in 2012. In this study, we characterized virulences and identified races of P. striiformis f. sp. tritici by testing the stripe rust samples collected throughout the United States in 2011 and 2012 on a set of 18 Yr single-gene differentials. In 2011, 35 races were identified from 349 viable samples collected from 19 states of the United States and Ontario province of Canada, with PSTv-11 (35.5%), PSTv-37 (12.6%), PSTv-14 (11.8%), PSTv-4 (5.4%), and PSTv-34 (3.4%) as the top five predominant races. In 2012, 23 races were identified from 341 viable samples collected from 24 states of the United States and Ontario of Canada, with PSTv-37 (47.5%), PSTv-11 (11.7%), PSTv-14 (10.0%), PSTv-52 (9.4%), and PSTv-48 (4.4%) as the top five predominant races. Nationally, PSTv-37, PSTv-52, and PSTv-34 were most widely distributed, while PSTv-11, PSTv-14, PSTv-4, and PSTv-48 were mostly detected in the western United States. High frequencies (>80%) were detected for virulences to Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr44, and YrExp2; moderate frequencies (20 to 80%) for virulences to Yr1, Yr43, YrTr1, and YrTye; low frequencies (<10%) for virulences to Yr10, Yr24, Yr32, and YrSP; and virulences to Yr5 and Yr15 were not detected, indicating that these two genes are still effective against the P. striiformis f. sp. tritici population in the United States. Both positive and negative associations were identified between some of the virulences. In total, 55 races identified from 2010 to 2012 in the United States were clustered into two major virulence groups, and dynamics of predominant races and virulence frequencies for the 3 years were presented and discussed. This information is useful for making decisions when screening wheat germplasm for developing stripe-rust-resistant wheat cultivars and managing the disease by growing cultivars with adequate and durable resistance. The severe epidemics and the occurrence of the large number of races in the 3 years indicate that efforts should be made to use diverse resistance genes, especially to combine effective all-stage resistance genes with genes for high-temperature adult-plant resistance.

scholarly journals Assessing differences in snowmelt-dependent hydrologic projections using CMIP3 and CMIP5 climate forcing data for the western United States

2015 ◽  
Vol 47 (2) ◽  
pp. 483-500 ◽  
Author(s):  
Darren L. Ficklin ◽  
Sally L. Letsinger ◽  
Iris T. Stewart ◽  
Edwin P. Maurer
Keyword(s):  
United States ◽  
River Basin ◽  
Sierra Nevada ◽  
General Circulation ◽  
Coupled Model ◽  
Circulation Model ◽  
Western United States ◽  
Recent Climate ◽  
High Emission ◽  
And Shifts

Most recent climate change impact studies are using Coupled Model Intercomparison Project Phase 5 (CMIP5) projections to replace older generation CMIP3 projections. Here we evaluate whether differences between projections based on comparable high emission pathways of a seven-member general circulation model CMIP3 versus CMIP5 ensemble change our understanding of the expected hydrologic impacts. This work focuses on the important snowmelt-dominated mountain runoff-generating regions of the western United States (WUS; Upper Colorado River Basin (UCRB), Columbia River Basin (CRB), and Sierra Nevada (SN) Basins). Significant declines in snowmelt, and shifts in streamflow timing owing to warmer, wetter CMIP5 projections match or exceed those based on CMIP3 throughout the WUS. CMIP3- and CMIP5-based projections, while generally in agreement about hydroclimatic changes, differ in some important aspects for key regions. The most important is the UCRB, where CMIP5-based projections suggest increases in future streamflows. Comparable hydrologic projections result from similar underlying climate signals in CMIP3 and CMIP5 output for the CRB and SN, suggesting that previous work completed in these basins based on CMIP3 projections is likely still useful. However, UCRB hydrologic projections based on CMIP5 output suggest that a re-evaluation of future impacts on water resources is warranted.

scholarly journals First Report of Rust Caused by Puccinia allii on Wild Garlic in California

Plant Disease ◽  
2001 ◽  
Vol 85 (12) ◽  
pp. 1290-1290 ◽  
Author(s):  
S. T. Koike ◽  
R. F. Smith
Keyword(s):  
United States ◽  
Allium Sativum ◽  
Rust Fungus ◽  
Morphological Characteristics ◽  
Western United States ◽  
Rust Disease ◽  
Perennial Weed ◽  
First Report ◽  
Wild Garlic ◽  
Puccinia Allii

Wild garlic (Allium vineale) is a bulbous perennial weed that was introduced from Europe and is now established throughout the eastern and much of the western United States. In 2001, wild garlic plants growing in Monterey County, CA were infected with a rust fungus. Uredinia and telia were present on leaves, resulting in small (2 to 5 mm long) lesions; however, leaf dieback and other symptoms were not observed. The orange urediniospores were spherical to ellipsoidal, echinulate, and mea-sured 26 to 30 × 25 to 28 μm. Telia were black in mass and divided into locules by fused paraphyses. Teliospores were located within the locules and were brown, smooth-walled, two-celled, and measured 40 to 50 × 17 to 20 μm. Teliospore pedicels were hyaline, usually fractured, and measured 3 to 15 μm. One-celled mesospores were not observed. Based on these morphological characteristics, the pathogen was identified as Puccinia allii (1,2). To our knowledge, this is the first report of rust caused by P. allii on wild garlic in California. Because of this finding, an experiment was designed to determine whether wild garlic could be a source of rust inoculum for commercial allium crops. Wild garlic bulbs were planted in 4-in. pots (10 cm square) and grown in a greenhouse. At the 4- to 5-leaf stage the plants were transplanted in a garlic (Allium sativum) cultivar trial that had been inoculated with an isolate of P. allii from garlic. When plants were evaluated 2 months later, uredinia and telia were observed on the wild garlic plants, and the fungus was confirmed to be P. allii. Wild garlic, therefore, could be a source of overwintered inocula for the rust disease that occurs on commercial garlic and onion (A. cepa) in California (2). References: (1) D. M. Jennings et al. Mycol. Res. 94:83, 1990. (2) S. T. Koike et al. Plant Dis. 85:585, 2001.

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