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Reid D. Frederick - One of the best experts on this subject based on the ideXlab platform.
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registration of eight Soybean germplasm lines resistant to Soybean Rust
Journal of Plant Registrations, 2014Co-Authors: Brian W Diers, Glen L Hartman, Reid D. Frederick, Kiseung Kim, Jair Rogerio Unfried, Sarah Schultz, T R CaryAbstract:Soybean Rust (SBR; caused by Sydow) is a threat to Soybean [ (L.) Merr.] production worldwide. Although SBR has not caused widespread damage in North America, the crop is still threatened by the disease because most cultivars in production are susceptible. We backcrossed the SBR-resistance genes , , (Hyuuga), and into the maturity group (MG) II experimental line LD01-7323 and the MG IV cultivar LD00-3309 to develop Midwest-adapted Soybean germplasm with SBR resistance. The backcross lines were tested for SBR resistance in greenhouse tests and for agronomic traits in multilocation field tests. The four MG II Soybean germplasm lines LD10-30052 (Reg. No. GP-383, PI 668384), LD10-14321 (Reg. No. GP- 384, PI 668385), LD10-14284 (Reg. No. GP- 385, PI 668386), and LD09-16057 (Reg. No. GP- 386, PI 668387) and the four MG IV germplasm lines LD10-14205 (Reg. No. GP- 389, PI 668390), LD10-13091 (Reg. No. GP- 387, PI 668388), LD10-14274 (Reg. No. GP- 388, PI 668389), and 08RST5-10 (Reg. No. GP- 390, PI 668391) developed through these efforts were released by the Illinois Agricultural Experiment Station in April 2012. The lines carry SBR resistance genes and are indistinguishable from the recurrent parents for morphological traits and, with only a few exceptions, are not significantly different than their recurrent parents for agronomic traits including seed yield. These lines should be useful to Soybean breeders who wish to develop Rust-resistant cultivars.
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identification of a new Soybean Rust resistance gene in pi 567102b
Theoretical and Applied Genetics, 2012Co-Authors: James R Smith, Jeffery D Ray, Reid D. FrederickAbstract:Soybean Rust (SBR) caused by Phakopsora pachyrhizi Syd. and P. Syd. is one of the most economically important diseases of Soybean (Glycine max (L.) Merr.). Durable resistance to P. pachyrhizi is the most effective long-term strategy to control SBR. The objective of this study was to investigate the genetics of resistance to P. pachyrhizi in Soybean accession PI 567102B. This accession was previously identified as resistant to SBR in Paraguay and to P. pachyrhizi isolates from seven states in the USA (Alabama, Florida, Georgia, Louisiana, Mississippi, South Carolina, and Texas). Analysis of two independent populations, one in which F2 phenotypes were inferred from F2-derived F3 (F2:3) families and the other in which F2 plants had phenotypes measured directly, showed that the resistance in PI 567102B was controlled by a single dominant gene. Two different isolates (MS06-1 and LA04-1) at different locations (Stoneville, MS and Ft. Detrick, MD) were used to independently assay the two populations. Linkage analysis of both populations indicated that the resistance locus was located on chromosome 18 (formerly linkage group G), but at a different location than either Rpp1 or Rpp4, which were previously mapped to this linkage group. Therefore, the SBR resistance in PI 567102B appeared to be conditioned by a previously unreported locus, with an underlying single dominant gene inferred. We propose this gene to be designated Rpp6. Incorporating Rpp6 into improved Soybean cultivars may have wide benefits as PI 567102B has been shown to provide resistance to P. pachyrhizi isolates from Paraguay and the US.
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identification of a second asian Soybean Rust resistance gene in hyuuga Soybean
Phytopathology, 2011Co-Authors: Mandy D Kendrick, Reid D. Frederick, Donna K Harris, Roger H Boerma, David L Hyten, Perry B Cregan, Kerry F PedleyAbstract:ABSTRACT 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. Three isolates elicited different responses from Soybean accessions PI 462312 (Ankur) (Rpp3) and PI 506764 (Hyuuga) (Rpp?[Hyuuga]). In all, 11 of the new accessions yielded responses identical to either PI 462312 or Hyuuga and 1 of the new accessions, PI 417089B (Kuro daizu), differed from all others. Additional screening of Hyuuga-derived recombinant inbred lines ind...
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analysis of the complete mitochondrial genome sequences of the Soybean Rust pathogens phakopsora pachyrhizi and p meibomiae
Mycologia, 2010Co-Authors: Christine L. Stone, Martha Lucia Posada Buitrago, Jeffrey L Boore, Reid D. FrederickAbstract:The mitochondrial (mt) genomes of two Soybean Rust pathogens, Phakopsora pachyrhizi and P. meibomiae, have been sequenced. The mt genome of P. pachyrhizi is a circular 31 825-bp molecule with a mean GC content of 34.6%, while P. meibomiae possesses a 32 520-bp circular molecule with a mean GC content of 34.9%. Both mt genomes contain the genes encoding ATP synthase subunits 6, 8 and 9 (atp6, atp8 and atp9), cytochrome oxidase subunits I, II and III (cox1, cox2 and cox3), apocytochrome b (cob), reduced nicotinamide adenine dinucleotide ubiquinone oxidoreductase subunits (nad1, nad2, nad3, nad4, nad4L, nad5 and nad6), the large and small mt ribosomal RNA genes, one ORF coding for a ribosomal protein (rps3), and a set of 24 tRNA genes that recognize codons for all amino acids. The order of the protein-coding genes and tRNA is identical in the two Phakopsora species, and all genes are transcribed from the same DNA strand clockwise. Introns were identified in the cox1, cob and rnl genes of both species, with t...
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international fungicide efficacy trials for the management of Soybean Rust
Plant Disease, 2007Co-Authors: M R Miles, Reid D. Frederick, C Levy, W Morel, T A Mueller, Todd A Steinlage, Glen L HartmanAbstract:ABSTRACT The efficacy of fungicides in managing Soybean Rust was evaluated in 12 environments in South America and southern Africa over three growing seasons from 2002 to 2005. There were differences in final Soybean Rust severity, defoliation, and yield among the treatments at most locations. In locations where Soybean Rust was not severe, all the fungicides evaluated reduced severity. In locations where Soybean Rust was severe, applications of triazole and triazole + strobilurin fungicides resulted in lower severity and higher yields compared with other fungicides. The strobilurin fungicides provided the highest yields in many locations; however, severity tended to be higher than that of the triazole fungicides. There also were differences in yield and severity between the trials with two and three applications of several fungicides, with three applications resulting in less severe Soybean Rust and higher yields. However, the third application of tebuconazole, tetraconazole, and the mixtures containing ...
Glen L Hartman - One of the best experts on this subject based on the ideXlab platform.
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effect of selected biopesticides in reducing Soybean Rust phakopsora pachyrhizi development
Plant Disease, 2019Co-Authors: M Twizeyimana, Glen L HartmanAbstract:The intensive use of fungicides in controlling Soybean Rust (SBR), a damaging foliar fungal disease of Soybean caused by the obligate fungus Phakopsora pachyrhizi, may have accelerated the insensit...
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from select agent to an established pathogen the response to phakopsora pachyrhizi Soybean Rust in north america
Phytopathology, 2015Co-Authors: Heather Y Kelly, James J. Marois, David L. Wright, Scott A. Isard, R. W. Schneider, Nicholas S Dufault, David R Walker, Loren J Giesler, Glen L HartmanAbstract:The pathogen causing Soybean Rust, Phakopsora pachyrhizi, was first described in Japan in 1902. The disease was important in the Eastern Hemisphere for many decades before the fungus was reported in Hawaii in 1994, which was followed by reports from countries in Africa and South America. In 2004, P. pachyrhizi was confirmed in Louisiana, making it the first report in the continental United States. Based on yield losses from countries in Asia, Africa, and South America, it was clear that this pathogen could have a major economic impact on the yield of 30 million ha of Soybean in the United States. The response by agencies within the United States Department of Agriculture, industry, Soybean check-off boards, and universities was immediate and complex. The impacts of some of these activities are detailed in this review. The net result has been that the once dreaded disease, which caused substantial losses in other parts of the world, is now better understood and effectively managed in the United States. The disease continues to be monitored yearly for changes in spatial and temporal distribution so that Soybean growers can continue to benefit by knowing where Soybean Rust is occurring during the growing season.
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registration of eight Soybean germplasm lines resistant to Soybean Rust
Journal of Plant Registrations, 2014Co-Authors: Brian W Diers, Glen L Hartman, Reid D. Frederick, Kiseung Kim, Jair Rogerio Unfried, Sarah Schultz, T R CaryAbstract:Soybean Rust (SBR; caused by Sydow) is a threat to Soybean [ (L.) Merr.] production worldwide. Although SBR has not caused widespread damage in North America, the crop is still threatened by the disease because most cultivars in production are susceptible. We backcrossed the SBR-resistance genes , , (Hyuuga), and into the maturity group (MG) II experimental line LD01-7323 and the MG IV cultivar LD00-3309 to develop Midwest-adapted Soybean germplasm with SBR resistance. The backcross lines were tested for SBR resistance in greenhouse tests and for agronomic traits in multilocation field tests. The four MG II Soybean germplasm lines LD10-30052 (Reg. No. GP-383, PI 668384), LD10-14321 (Reg. No. GP- 384, PI 668385), LD10-14284 (Reg. No. GP- 385, PI 668386), and LD09-16057 (Reg. No. GP- 386, PI 668387) and the four MG IV germplasm lines LD10-14205 (Reg. No. GP- 389, PI 668390), LD10-13091 (Reg. No. GP- 387, PI 668388), LD10-14274 (Reg. No. GP- 388, PI 668389), and 08RST5-10 (Reg. No. GP- 390, PI 668391) developed through these efforts were released by the Illinois Agricultural Experiment Station in April 2012. The lines carry SBR resistance genes and are indistinguishable from the recurrent parents for morphological traits and, with only a few exceptions, are not significantly different than their recurrent parents for agronomic traits including seed yield. These lines should be useful to Soybean breeders who wish to develop Rust-resistant cultivars.
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interaction of Soybean and phakopsora pachyrhizi the cause of Soybean Rust
Cab Reviews: Perspectives in Agriculture Veterinary Science Nutrition and Natural Resources, 2011Co-Authors: Glen L Hartman, M R Miles, Curtis B. Hill, M Twizeyimana, Ranajit BandyopadhyayAbstract:Soybean Rust, caused by Phakopsora pachyrhizi Syd., is a major disease limiting Soybean [Glycine max (L.) Merr.] production in many areas of the world. Yield losses of up to 80% have been reported in experimental plots in Taiwan. Although the disease is not always yield limiting, it has the potential under conducive conditions to cause major losses in most Soybean-producing countries in the world. The threat of P. pachyrhizi to Soybean production in the Western Hemisphere began in Paraguay in 2001, where the disease was found in a limited number of Soybean fields in the Parana River basin bordering Brazil. Later, in 2004, P. pachyrhizi was found in the continental USA. There are approximately 150 species in 53 genera the family Fabaceae known to be hosts of P. pachyrhizi. Approximately 120 of the known hosts occur in North and Central America and could become important in the epidemiology of the disease, serving as a bridge or overwintering host between Soybean crops. The interaction between Soybean genotypes and P. pachyrhizi isolates appears to follow gene-for-gene theory, with resistance genes controlling resistance to specific pathotypes. In addition to Soybean, pathotype-specific resistance has also been found in a number of perennial Glycine species. Dominant genes controlling pathotypespecific resistance to Soybean Rust have been identified and mapped to five loci in the Soybean genome, with multiple alleles at four loci. Many of the resistance genes have become ineffective over time in different geographic areas following their deployment into Soybean production. The search for more durable Soybean Rust resistance will include research on non-host and/or engineered resistance.
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dynamics of Soybean Rust epidemics in sequential plantings of Soybean cultivars in nigeria
Plant Disease, 2011Co-Authors: M Twizeyimana, Glen L Hartman, P S Ojiambo, Ranajit BandyopadhyayAbstract:Abstract Soybean Rust, caused by Phakopsora pachyrhizi, is an important foliar disease of Soybean. Disease severity is dependent on several environmental factors, although the precise nature of most of these factors under field conditions is not known. To help understand the environmental factors that affect disease development, Soybean Rust epidemics were studied in Nigeria by sequentially planting an early-maturing, highly susceptible cultivar, TGx 1485-1D, and a late-maturing, moderately susceptible cultivar, TGx 1448-2E, at 30- to 45-day intervals from August 2004 to September 2006. Within each planting date, disease onset occurred earlier on TGx 1485-1D than on TGx 1448-2E, and Rust onset was at least 20 days earlier on Soybean planted between August and October than on Soybean planted between November and April. The logistic model provided a better description of the temporal increase in Rust severity than the Gompertz model. Based on the logistic model, the highest absolute rates of disease increas...
R. W. Schneider - One of the best experts on this subject based on the ideXlab platform.
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from select agent to an established pathogen the response to phakopsora pachyrhizi Soybean Rust in north america
Phytopathology, 2015Co-Authors: Heather Y Kelly, James J. Marois, David L. Wright, Scott A. Isard, R. W. Schneider, Nicholas S Dufault, David R Walker, Loren J Giesler, Glen L HartmanAbstract:The pathogen causing Soybean Rust, Phakopsora pachyrhizi, was first described in Japan in 1902. The disease was important in the Eastern Hemisphere for many decades before the fungus was reported in Hawaii in 1994, which was followed by reports from countries in Africa and South America. In 2004, P. pachyrhizi was confirmed in Louisiana, making it the first report in the continental United States. Based on yield losses from countries in Asia, Africa, and South America, it was clear that this pathogen could have a major economic impact on the yield of 30 million ha of Soybean in the United States. The response by agencies within the United States Department of Agriculture, industry, Soybean check-off boards, and universities was immediate and complex. The impacts of some of these activities are detailed in this review. The net result has been that the once dreaded disease, which caused substantial losses in other parts of the world, is now better understood and effectively managed in the United States. The disease continues to be monitored yearly for changes in spatial and temporal distribution so that Soybean growers can continue to benefit by knowing where Soybean Rust is occurring during the growing season.
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effects of simplicillium lanosoniveum on phakopsora pachyrhizi the Soybean Rust pathogen and its use as a biological control agent
Phytopathology, 2012Co-Authors: C L Robertson, N A Ward, Ashok Kumar Chanda, R. W. SchneiderAbstract:The fungus Simplicillium lanosoniveum was isolated from Soybean leaves infected with Phakopsora pachyrhizi, the Soybean Rust pathogen, in Louisiana and Florida. The fungus did not grow or become established on leaf surfaces until uredinia erupted, but when Soybean Rust signs and symptoms were evident, S. lanosoniveum colonized leaves within 3 days and sporulated within 4 days. Development of new uredinia was suppressed by about fourfold when S. lanosoniveum colonized uredinia. In the presence of S. lanosoniveum, uredinia became increasingly red-brown, and urediniospores turned brown and germinated at very low rates. Assays using quantitative real time polymerase chain reaction revealed that the fungus colonized leaf surfaces when plants were infected with P. pachyrhizi, either in a latent stage of infection or when symptoms were present. However, when plants were inoculated before infection, there was no increase of DNA of S. lanosoniveum, suggesting that the pathogen must be present in order for the antagonist to become established on Soybean leaf surfaces. We documented significantly lower amounts of DNA of P. pachyrhizi and lower disease severity when Soybean leaves were colonized with S. lanosoniveum. These studies documented the mycophilic and disease-suppressive nature of S. lanosoniveum.
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colonization of Soybean Rust sori by simplicillium lanosoniveum
Fungal Ecology, 2011Co-Authors: N A Ward, R. W. Schneider, M C AimeAbstract:Abstract In 2007, we isolated a filamentous fungus inhabiting sori of Soybean Rust ( Phakopsora pachyrhizi ) on Soybean collected from Louisiana and Florida. This fungus was identified as Simplicillium lanosoniveum on the basis of ITS sequence data and morphological traits. S. lanosoniveum was found coiling within sori and around urediniospores. It showed a trophic attraction to Rust sori, extending from sorus to sorus. It was not isolated from healthy leaf surfaces or within lesions of other diseases, nor was it isolated from commercial Soybean fields where fungicides are routinely applied for control of diseases. Herein, we document for the first time the association between P. pachyrhizi and S. lanosoniveum .
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first report of Soybean Rust caused by phakopsora pachyrhizi in the continental united states
Plant Disease, 2005Co-Authors: R. W. Schneider, J. R. Hernández, Mary E. Palm, J. M. Mckemy, Laurene Levy, Clayton A. Hollier, H. K. Whitam, R DevriespatersonAbstract:Asian Soybean Rust, caused by Phakopsora pachyrhizi Sydow, has been known to occur in the eastern hemisphere for nearly a century. More recently, it was reported from Hawaii in 1994, eastern and so...
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First Report of Soybean Rust Caused by Phakopsora pachyrhizi in the Continental United States.
Plant disease, 2005Co-Authors: R. W. Schneider, J. R. Hernández, Mary E. Palm, J. M. Mckemy, Laurene Levy, Clayton A. Hollier, H. K. Whitam, R. Devries-patersonAbstract:Asian Soybean Rust, caused by Phakopsora pachyrhizi Sydow, has been known to occur in the eastern hemisphere for nearly a century. More recently, it was reported from Hawaii in 1994, eastern and southern Africa from 1996-1998, Nigeria in 2001, and Brazil and Paraguay in 2002. Aerobiological models suggested that urediniospores of the pathogen would be disseminated on wind currents to the continental United States in association with tropical storms if the disease became established north of the equator during hurricane season (U.S. Soybean Rust Detection and Aerobiological Modeling online publication at www.aphis.usda.gov/ppq/ ep/Soybean_Rust/). Since Soybean Rust was observed at approximately 5°N latitude in South America before several hurricanes impacted the continental United States in September 2004, it seems likely that the introduction was associated with at least one of these tropical storms, especially hurricane Ivan. Symptoms of the disease were first observed on Soybean (Glycine max (L.) Merr.)...
X. B. Yang - One of the best experts on this subject based on the ideXlab platform.
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estimation of Soybean Rust uredospore terminal velocity dry deposition and the wet deposition associated with rainfall
European Journal of Plant Pathology, 2009Co-Authors: Xun Li, X. B. Yang, Janyou MoAbstract:Using models from atmospheric chemistry and physics, this study examined the wet deposition of single uredospores of Soybean Rust caused by Phakopsora pachyrhizi associated with rainfall and its importance compared with dry deposition. First, a measurement of the terminal velocity of freshly collected P. pachyrhizi uredospores was conducted in Nanning, China. The observed terminal velocities associated with different sizes of the uredospore clumps were fitted by negative exponential models. The average terminal velocity of single uredospores (0.0187 m s−1) determined by the fitted models was used to estimate the dry deposition. The wet deposition of single uredospores associated with different rainfall rates was determined numerically using coupled models, in which raindrop capture efficiency of uredospores was based on Slinn’s semi-empirical model. The results showed that at a rainfall rate of 0.5 mm h−1, wet deposition can remove 50% of the single uredospores in the air within 1 h. If the rainfall rate is 5 mm h−1, 10 min is sufficient to remove 50% of the uredospores. The dry deposition of the single uredospores was estimated with simplified scenarios: i.e., assuming the uredospore cloud was continuously from 1,000 to 2,000 m in height above a field with a uniform concentration. In the first 16 h, almost no uredospores reached the ground, while the wet deposition caused by 2 mm h−1 rainfall within 30 min was even much greater than dry deposition of 24 h duration. The comparisons indicated that the wet deposition of Soybean Rust uredospores was much more efficient than the dry deposition.
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similarity pattern and grouping of Soybean fungal diseases in the united states implications for the risk of Soybean Rust
Plant Disease, 2009Co-Authors: X. B. YangAbstract:Ten biological or ecological characteristics of pathogens/diseases were used to quantitatively describe 34 Soybean (Glycine max) fungal diseases in the United States. These characteristics included optimal temperatures for disease development, host ranges, characteristics of disease cycle, and the pathogens' survival capacity. Gower's general similarity coefficients for pairs of diseases were determined and used in principal coordinate analysis (PCoA) to project the diseases into a two-dimensional space, in which significant patterns were identified for some of the characteristic variables, e.g., means of pathogen dispersal. Similarity coefficients indicated that Soybean Rust (Phakopsora pachyrhizi) resembled Soybean downy mildew (Peronospora manshurica) and Leptosphaerulina leaf spot (Leptosphaerulina trifolii). Cluster analysis with multiscale bootstrapping identified two major clusters with high significance level (P > 0.95). In a loose cluster (P = 0.86), Soybean Rust was grouped with brown spot (Septoria glycines), frogeye leaf spot (Cercospora sojina), Phyllosticta leaf spot (Phyllosticta sojicola), purple seed stain (Cercospora kikuchii), downy mildew, and Leptosphaerulina leaf spot. Estimated Soybean yield losses in the United States from 1996 to 2005 and the geographical distribution information of the diseases in this cluster implied that the potential geographical distribution range of Soybean Rust may include most U.S. Soybean production regions and that yield losses would be light in the north but moderate in the south if environmental conditions are conducive.
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models and applications for risk assessment and prediction of asian Soybean Rust epidemics
Fitopatologia Brasileira, 2006Co-Authors: E M Del Ponte, C V Godoy, Marcelo Giovanetti Canteri, Erlei Melo Reis, X. B. YangAbstract:Asian Rust of Soybean [Glycine max (L.) Merril] is one of the most important fungal diseases of this crop worldwide. The recent introduction of Phakopsora pachyrhizi Syd. & P. Syd in the Americas represents a major threat to Soybean production in the main growing regions, and significant losses have already been reported. P. pachyrhizi is extremely aggressive under favorable weather conditions, causing rapid plant defoliation. Epidemiological studies, under both controlled and natural environmental conditions, have been done for several decades with the aim of elucidating factors that affect the disease cycle as a basis for disease modeling. The recent spread of Asian Soybean Rust to major production regions in the world has promoted new development, testing and application of mathematical models to assess the risk and predict the disease. These efforts have included the integration of new data, epidemiological knowledge, statistical methods, and advances in computer simulation to develop models and systems with different spatial and temporal scales, objectives and audience. In this review, we present a comprehensive discussion on the models and systems that have been tested to predict and assess the risk of Asian Soybean Rust. Limitations, uncertainties and challenges for modelers are also discussed.
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predicting severity of asian Soybean Rust epidemics with empirical rainfall models
Phytopathology, 2006Co-Authors: E M Del Ponte, C V Godoy, X. B. YangAbstract:Del Ponte, E. M., Godoy, C. V., Li, X., and Yang, X. B. 2006. Predicting severity of Asian Soybean Rust epidemics with empirical rainfall models. Phytopathology 96:797-803. Although Asian Soybean Rust occurs in a broad range of environmental conditions, the most explosive and severe epidemics have been reported in seasons with warm temperature and abundant moisture. Associations between weather and epidemics have been reported previously, but attempts to identify the major factors and model these relationships with field data have been limited to specific locations. Using data from 2002–03 to 2004–05 from 34 field experiments at 21 locations in Brazil that represented all major Soybean production areas, we attempted to identify weather variables using a 1-month time window following disease detection to develop simple models to predict final disease severity. Four linear models were identified, and these models explained 85 to 93% of variation in disease severity. Temperature variables had lower correlation with disease severity compared with rainfall, and had minimal predictive value for final disease severity. A curvilinear relationship was observed between 1 month of accumulated rainfall and final disease severity, and a quadratic response model using this variable had the lowest prediction error. Linear response models using only rainfall or number of rainy days in the 1-month period tended to overestimate disease for severity <30%. The study highlights the importance of rainfall in influencing Soybean Rust epidemics in Brazil, as well as its potential use to provide quantitative risk assessments and seasonal forecasts for Soybean Rust, especially for regions where temperature is not a limiting factor for disease development. Additional keywords: modeling, Phakopsora pachyrhizi.
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long term prediction of Soybean Rust entry into the continental united states
Plant Disease, 2006Co-Authors: Zaitao Pan, X. B. Yang, S Pivonia, Lulin Xue, R Pasken, John O RoadsAbstract:This special report demonstrates the feasibility of long-term prediction of intercontinental dispersal of Phakopsora pachyrhizi spores, the causal agent of the devastating Asian Soybean Rust (SBR) that invaded the continental United States in 2004. The climate-dispersion integrated model system used for the prediction is the combination of the particle transport and dispersion model (HYSPLIT_4) with the regional climate prediction model (MM5). The integrated model system predicts the trajectory and concentration of P. pachyrhizi spores based on three-dimensional wind advection and turbulent transport while incorporating simple viability criteria for aerial spores. The weather input of the model system is from a seasonal global climate prediction. The spore source strength and distribution were estimated from detected SBR disease severity and spread. The model system was applied to the known P. pachyrhizi spore dispersal between and within continents while focusing on the disease entry into the United States. Prediction validation using confirmed disease activity demonstrated that the model predicted the 2004 U.S. entry months in advance and reasonably forecast disease spread from the south coast states in the 2005 growing season. The model also simulated the dispersal from Africa to South America and from southern South America to Columbia across the equator. These validations indicate that the integrated model system, when furnished with detailed source distribution, can be a useful tool for P. pachyrhizi and possibly other airborne pathogen prediction.
Kerry F Pedley - One of the best experts on this subject based on the ideXlab platform.
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discovery of a seventh rpp Soybean Rust resistance locus in Soybean accession pi 605823
Theoretical and Applied Genetics, 2018Co-Authors: Silas P. Childs, Kerry F Pedley, James W. Buck, Zachary R King, David Walker, Donna K Harris, Roger H BoermaAbstract:A novel Rpp gene from PI 605823 for resistance to Phakopsora pachyrhizi was mapped on chromosome 19. Soybean Rust, caused by the obligate biotrophic fungal pathogen Phakopsora pachyrhizi Syd. & P. Syd, is a disease threat to Soybean production in regions of the world with mild winters. Host plant resistance conditioned by resistance to P. pachyrhizi (Rpp) genes has been found in numerous Soybean accessions, and at least 10 Rpp genes or alleles have been mapped to six genetic loci. Identifying additional disease-resistance genes will facilitate development of Soybean cultivars with durable resistance. PI 605823, a plant introduction from Vietnam, was previously identified as resistant to US populations of P. pachyrhizi in greenhouse and field trials. In this study, bulked segregant analysis using an F2 population derived from ‘Williams 82’ × PI 605823 identified a genomic region associated with resistance to P. pachyrhizi isolate GA12, which had been collected in the US State of Georgia in 2012. To further map the resistance locus, linkage mapping was carried out using single-nucleotide polymorphism markers and phenotypic data from greenhouse assays with an F2:3 population derived from Williams 82 × PI 605823 and an F4:5 population derived from ‘5601T’ × PI 605823. A novel resistance gene, Rpp7, was mapped to a 154-kb interval (Gm19: 39,462,291–39,616,643 Glyma.Wm82.a2) on chromosome 19 that is different from the genomic locations of any previously reported Rpp genes. This new gene could be incorporated into elite breeding lines to help provide more durable resistance to Soybean Rust.
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a small cysteine rich protein from the asian Soybean Rust fungus phakopsora pachyrhizi suppresses plant immunity
PLOS Pathogens, 2016Co-Authors: Tobias Link, Kerry F Pedley, Manuel Muller, Daniela Hirschburger, Ramesh N Pudake, E J Braun, Ralf T Voegele, Thomas J Baum, Steven A WhithamAbstract:The Asian Soybean Rust fungus, Phakopsora pachyrhizi, is an obligate biotrophic pathogen causing severe Soybean disease epidemics. Molecular mechanisms by which P. pachyrhizi and other Rust fungi interact with their host plants are poorly understood. The genomes of all Rust fungi encode many small, secreted cysteine-rich proteins (SSCRP). While these proteins are thought to function within the host, their roles are completely unknown. Here, we present the characterization of P. pachyrhizi effector candidate 23 (PpEC23), a SSCRP that we show to suppress plant immunity. Furthermore, we show that PpEC23 interacts with Soybean transcription factor GmSPL12l and that Soybean plants in which GmSPL12l is silenced have constitutively active immunity, thereby identifying GmSPL12l as a negative regulator of Soybean defenses. Collectively, our data present evidence for a virulence function of a Rust SSCRP and suggest that PpEC23 is able to suppress Soybean immune responses and physically interact with Soybean transcription factor GmSPL12l, a negative immune regulator.
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identification of a second asian Soybean Rust resistance gene in hyuuga Soybean
Phytopathology, 2011Co-Authors: Mandy D Kendrick, Reid D. Frederick, Donna K Harris, Roger H Boerma, David L Hyten, Perry B Cregan, Kerry F PedleyAbstract:ABSTRACT 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. Three isolates elicited different responses from Soybean accessions PI 462312 (Ankur) (Rpp3) and PI 506764 (Hyuuga) (Rpp?[Hyuuga]). In all, 11 of the new accessions yielded responses identical to either PI 462312 or Hyuuga and 1 of the new accessions, PI 417089B (Kuro daizu), differed from all others. Additional screening of Hyuuga-derived recombinant inbred lines ind...
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functional analysis of the asian Soybean Rust resistance pathway mediated by rpp2
Molecular Plant-microbe Interactions, 2011Co-Authors: Ajay Kumar Pandey, Kerry F Pedley, Chunling Yang, Chunquan Zhang, John H Hill, Michelle A Graham, Heidi D Horstman, Yeunsook Lee, Olga A Zabotina, Steven A WhithamAbstract:Asian Soybean Rust is an aggressive foliar disease caused by the obligate biotrophic fungus Phakopsora pachyrhizi. On susceptible plants, the pathogen penetrates and colonizes leaf tissue, resulting in the formation of necrotic lesions and the development of numerous uredinia. The Soybean Rpp2 gene confers resistance to specific isolates of P. pachyrhizi. Rpp2-mediated resistance limits the growth of the pathogen and is characterized by the formation of reddish-brown lesions and few uredinia. Using virus-induced gene silencing, we screened 140 candidate genes to identify those that play a role in Rpp2 resistance toward P. pachyrhizi. Candidate genes included putative orthologs to known defense-signaling genes, transcription factors, and genes previously found to be upregulated during the Rpp2 resistance response. We identified 11 genes that compromised Rpp2-mediated resistance when silenced, including GmEDS1, GmNPR1, GmPAD4, GmPAL1, five predicted transcription factors, an O-methyl transferase, and a cytochrome P450 monooxygenase. Together, our results provide new insight into the signaling and biochemical pathways required for resistance against P. pachyrhizi.
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identification and analyses of candidate genes for rpp4 mediated resistance to asian Soybean Rust in Soybean
Plant Physiology, 2009Co-Authors: Jenelle D F Meyer, Kerry F Pedley, R V Abdelnoor, Danielle C G Silva, Chunling Yang, Chunquan Zhang, Martijn Van De Mortel, John H Hill, Randy C Shoemaker, Steven A WhithamAbstract:Asian Soybean Rust is a formidable threat to Soybean (Glycine max) production in many areas of the world, including the United States. Only five sources of resistance have been identified (Resistance to Phakopsora pachyrhizi1 [Rpp1], Rpp2, Rpp3, Rpp4, and Rpp5). Rpp4 was previously identified in the resistant genotype PI459025B and mapped within 2 centimorgans of Satt288 on Soybean chromosome 18 (linkage group G). Using simple sequence repeat markers, we developed a bacterial artificial chromosome contig for the Rpp4 locus in the susceptible cv Williams82 (Wm82). Sequencing within this region identified three Rpp4 candidate disease resistance genes (Rpp4C1-Rpp4C3 [Wm82]) with greatest similarity to the lettuce (Lactuca sativa) RGC2 family of coiled coil-nucleotide binding site-leucine rich repeat disease resistance genes. Constructs containing regions of the Wm82 Rpp4 candidate genes were used for virus-induced gene silencing experiments to silence resistance in PI459025B, confirming that orthologous genes confer resistance. Using primers developed from conserved sequences in the Wm82 Rpp4 candidate genes, we identified five Rpp4 candidate genes (Rpp4C1-Rpp4C5 [PI459025B]) from the resistant genotype. Additional markers developed from the Wm82 Rpp4 bacterial artificial chromosome contig further defined the region containing Rpp4 and eliminated Rpp4C1 (PI459025B) and Rpp4C3 (PI459025B) as candidate genes. Sequencing of reverse transcription-polymerase chain reaction products revealed that Rpp4C4 (PI459025B) was highly expressed in the resistant genotype, while expression of the other candidate genes was nearly undetectable. These data support Rpp4C4 (PI459025B) as the single candidate gene for Rpp4-mediated resistance to Asian Soybean Rust.