Evaluation of Selected Genotypes of Soybean for Resistance to Phakopsora pachyrhizi

2009 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
S. Li ◽  
L. D. Young
Keyword(s):  
Rust Fungus ◽  
Soybean Rust ◽  
Information Network ◽  
Phakopsora Pachyrhizi ◽  
Sources Of Resistance ◽  
Plant Introductions ◽  
Severity Rating ◽  
Resistant Lines ◽  
Lesion Type ◽  
Glycine Max L

Soybean rust, caused by Phakopsora pachyrhizi Syd. & P. Syd., is one of the most destructive diseases of soybean [Glycine max (L.) Merr.] worldwide. To identify sources of resistance to domestic soybean rust fungus populations for plant breeding, our strategy has been to evaluate soybean lines that were previously identified as resistant to foreign isolates. In this study, two sets of plant introductions (PI) were evaluated using P. pachyrhizi urediniospores collected in Mississippi in 2006. The first set of PIs contained 10 lines previously identified as resistant in Paraguay, four PIs with known single genes for resistance to P. pachyrhizi, and Freedom and Williams 82 as susceptible checks. The second set included 17 lines that were selected based on information from Germplasm Resources Information Network (GRIN) and susceptible Williams 82. PI567102B was one of the most resistant lines to a Mississippi bulk isolate of P. pachyrhizi with the lowest severity rating, no sporulation, and red-brown lesion type. Accepted for publication 25 April 2009. Published 15 June 2009.

scholarly journals Models and applications for risk assessment and prediction of Asian soybean rust epidemics

2006 ◽  
Vol 31 (6) ◽  
pp. 533-544 ◽  
Author(s):  
Emerson M. Del Ponte ◽  
Cláudia V. Godoy ◽  
Marcelo G. Canteri ◽  
Erlei M. Reis ◽  
X.B. Yang
Keyword(s):  
Disease Modeling ◽  
Weather Conditions ◽  
Epidemiological Studies ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Spatial And Temporal Scales ◽  
Asian Soybean Rust ◽  
New Development ◽  
Glycine Max L ◽  
Favorable Weather

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.

scholarly journals Adult Plant Evaluation of Soybean Accessions for Resistance to Phakopsora pachyrhizi in the Field and Greenhouse in Paraguay

Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 96-105 ◽  
Author(s):  
M. R. Miles ◽  
W. Morel ◽  
J. D. Ray ◽  
J. R. Smith ◽  
R. D. Frederick ◽  
...  
Keyword(s):  
Field Trial ◽  
Field Experiments ◽  
Field Evaluation ◽  
Soybean Rust ◽  
Adult Plant ◽  
Phakopsora Pachyrhizi ◽  
Sources Of Resistance ◽  
Plant Evaluation ◽  
Maturity Groups

Five hundred thirty soybean accessions from maturity groups (MG) III through IX were evaluated for resistance to Phakopsora pachyrhizi in a replicated field trial at Centro Regional de Investigación Agrícola in Capitán Miranda, Itapúa, Paraguay during the 2005–06 season. Soybean rust severities of individual accessions ranged from 0% (resistant) to 30.0% (susceptible). In MG III and IV, the most resistant accessions were PI 506863, PI 567341, and PI 567351B, with severities less than 1.2%. In MG V, the most resistant accessions were PI 181456, PI 398288, PI 404134B, and PI 507305, with severities less than 0.3%. In MG VI, the most resistant accessions were PI 587886, PI 587880A, and PI 587880B, with severities less than 0.3%. In MG VII and VIII, the most resistant were PI 587905 and PI 605779E, with severities less than 1.0%. In MG IX, the most resistant accessions were PI 594754, PI 605833, PI 576102B, and PI 567104B, with severities less than 1.0%. The resistance in 10 selected accessions from MG VI, VII, VIII, and XI was confirmed in subsequent greenhouse and field experiments where severities of 0.4% or less and reddish-brown lesions with sporulation levels less than 3.0 were observed. These accessions, with low severities in the adult plant field evaluation, may be new sources of resistance to P. pachyrhizi.

scholarly journals The Importance of Phenolic Metabolism to Limit the Growth of Phakopsora pachyrhizi

2009 ◽  
Vol 99 (12) ◽  
pp. 1412-1420 ◽  
Author(s):  
Anatoliy V. Lygin ◽  
Shuxian Li ◽  
Ramya Vittal ◽  
Jack M. Widholm ◽  
Glen L. Hartman ◽  
...  
Keyword(s):  
Protective Role ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Phenolic Metabolism ◽  
Rust Infection ◽  
Resistant Lines ◽  
Significant Difference ◽  
Soybean Genotypes ◽  
Soybean Leaves

Understanding the metabolic responses of the plant to a devastating foliar disease, soybean rust, caused by Phakopsora pachyrhizi, will assist in development of cultivars resistant to soybean rust. In this study, differences in phenolic metabolism were analyzed between inoculated and noninoculated plants using two susceptible and three resistant soybean genotypes with known resistance genes. Rust infection resulted in increased accumulation of isoflavonoids and flavonoids in leaves of all soybean genotypes tested. Although the soybean phytoalexin glyceollin was not detected in leaves of uninfected plants, accumulation of this compound at marked levels occurred in rust-infected leaves, being substantially higher in genotypes with a red-brown resistant reaction. In addition, there was inhibition of P. pachyrhizi spore germination by glyceollin, formononetin, quercetin, and kaempferol. However, there was no correlation between concentrations of flavonoids quercetin and kaempferol and rust-induced isoflavonoid formononetin in soybean leaves and rust resistance. Lignin synthesis also increased in all inoculated soybean genotypes whereas there was no significant difference in all noninoculated soybean genotypes. Cell wall lignification was markedly higher in inoculated resistant lines compared with inoculated susceptible lines, indicating a possible protective role of lignin in rust infection development.

scholarly journals Transgenic Suppression of Cell Death Limits Penetration Success of the Soybean Rust Fungus Phakopsora pachyrhizi into Epidermal Cells of Barley

2009 ◽  
Vol 99 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Caroline Hoefle ◽  
Marco Loehrer ◽  
Ulrich Schaffrath ◽  
Markus Frank ◽  
Holger Schultheiss ◽  
...  
Keyword(s):  
Cell Death ◽  
Epidermal Cell ◽  
Plant Cell Wall ◽  
Rust Fungus ◽  
Mesophyll Cell ◽  
Epidermal Cells ◽  
Plant Diseases ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Hypersensitive Cell Death

The basidiomycete Phakopsora pachyrhizi (P. pachyrhizi) causes Asian soybean rust, one of the most devastating plant diseases on soybean. When inoculated on the nonhost barley P. pachyrhizi caused only very small necrotic spots, typical for an incompatible interaction, which involves a hypersensitive cell death reaction. A microscopic inspection of the interaction of barley with P. pachyrhizi revealed that the fungus germinated on barley and formed functional appressoria on epidermal cells. The fungus attempted to directly penetrate through periclinal cell walls but often failed, arrested in plant cell wall appositions that stained positively for callose. Penetration resistance depends on intact ROR1(REQUIRED FOR mlo-SPECIFIED RESISTANCE 1) and ROR2 genes of barley. If the fungus succeeded in penetration, epidermal cell death took place. Dead epidermal cells did not generally restrict fungal development but allowed for mesophyll invasion, which was followed by mesophyll cell death and fungal arrest. Transient or stable over expression of the barley cell death suppressor BAX inhibitor-1 reduced both epidermal cell death and fungal penetration success. Data suggest that P. pachyrhizi provokes a programmed cell death facilitating fungal entry into epidermal cells of barley.

scholarly journals Suppression or Activation of Immune Responses by Predicted Secreted Proteins of the Soybean Rust Pathogen Phakopsora pachyrhizi

2018 ◽  
Vol 31 (1) ◽  
pp. 163-174 ◽  
Author(s):  
Mingsheng Qi ◽  
James P. Grayczyk ◽  
Janina M. Seitz ◽  
Youngsill Lee ◽  
Tobias I. Link ◽  
...  
Keyword(s):  
Immune Responses ◽  
Crop Production ◽  
Rust Fungus ◽  
Functional Characterization ◽  
Rust Fungi ◽  
Effector Proteins ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Immune Systems ◽  
Rust Pathogen

Rust fungi, such as the soybean rust pathogen Phakopsora pachyrhizi, are major threats to crop production. They form specialized haustoria that are hyphal structures intimately associated with host-plant cell membranes. These haustoria have roles in acquiring nutrients and secreting effector proteins that manipulate host immune systems. Functional characterization of effector proteins of rust fungi is important for understanding mechanisms that underlie their virulence and pathogenicity. Hundreds of candidate effector proteins have been predicted for rust pathogens, but it is not clear how to prioritize these effector candidates for further characterization. There is a need for high-throughput approaches for screening effector candidates to obtain experimental evidence for effector-like functions, such as the manipulation of host immune systems. We have focused on identifying effector candidates with immune-related functions in the soybean rust fungus P. pachyrhizi. To facilitate the screening of many P. pachyrhizi effector candidates (named PpECs), we used heterologous expression systems, including the bacterial type III secretion system, Agrobacterium infiltration, a plant virus, and a yeast strain, to establish an experimental pipeline for identifying PpECs with immune-related functions and establishing their subcellular localizations. Several PpECs were identified that could suppress or activate immune responses in nonhost Nicotiana benthamiana, N. tabacum, Arabidopsis, tomato, or pepper plants.

scholarly journals Differential Response of Common Bean Cultivars to Phakopsora pachyrhizi

Plant Disease ◽  
2007 ◽  
Vol 91 (6) ◽  
pp. 698-704 ◽  
Author(s):  
M. R. Miles ◽  
M. A. Pastor-Corrales ◽  
G. L. Hartman ◽  
R. D. Frederick
Keyword(s):  
Common Bean ◽  
Single Gene ◽  
The United States ◽  
Differential Response ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Bean Rust ◽  
Lesion Type ◽  
Lower Severity ◽  
The Common

Soybean rust (Phakopsora pachyrhizi) has been reported on common bean (Phaseolus vulgaris) in Asia, South Africa, and the United States. However, there is little information on the interaction of individual isolates of Phakopsora pachyrhizi with common bean germplasm. A set of 16 common bean cultivars with known genes for resistance to Uromyces appendiculatus, the causal agent of common bean rust, three soybean accessions that were sources of the single gene resistance to P. pachyrhizi, and the moderately susceptible soybean ‘Ina’ were evaluated using seedlings inoculated with six isolates of P. pachyrhizi. Among the common bean cultivars, Aurora, Compuesto Negro Chimaltenango, and Pinto 114, were the most resistant to all six P. pachyrhizi isolates, with lower severity, less sporulation, and consistent reddish-brown (RB) lesions associated with resistance in soybean. A differential response was observed among the common bean cultivars, with a cultivar-isolate interaction for both severity and sporulation levels, as well as the presence or absence of the RB lesion type. This differential response was independent of the known genes that condition resistance to U. appendiculatus, suggesting that resistance to P. pachyrhizi was independent of resistance to U. appendiculatus.

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