scholarly journals First Report of Asian Soybean Rust Caused by Phakopsora pachyrhizi on Kudzu in South Africa

Plant Disease ◽  
2007 ◽  
Vol 91 (10) ◽  
pp. 1364-1364 ◽  
Author(s):  
Z. A. Pretorius ◽  
B. Visser ◽  
P. J. du Preez
Keyword(s):  
South Africa ◽  
Dna Analysis ◽  
Elisa Test ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Asian Soybean Rust ◽  
Test Kit ◽  
Kwazulu Natal

Asian soybean rust was first reported on soybean in South Africa (SA) in 2001 (3). The disease has occurred in all ensuing seasons, particularly in the humid, eastern production regions, causing significant losses in soybean fields not protected by fungicides. In April 2005, rust-infected Pueraria lobata (kudzu) was detected near Nelspruit, Mpumalanga, SA. At this location (25°20′41″S, 30°43′30″E), kudzu plants occurred abundantly on road sides, edges of pine plantations, and in natural vegetation. Most vines were infected, with abaxial surfaces of older leaves often showing 100% severity. Following inoculation with rust spores collected from kudzu, soybean line PI200492 (Rpp1) produced tan lesions typical of a susceptible reaction for Asian soybean rust. PI230970 (Rpp2), PI462312 (Rpp3), and PI459025 (Rpp4) showed red-brown lesions typical of a resistant reaction. Using Ppm1/Ppa2 and Ppm1/Ppm2 primer combinations, the amplification profiles of the internal transcribed spacer region (1) of rust DNA extracted from primary leaves of line PI200492 infected with spores collected from kudzu positively identified the pathogen as Phakopsora pachyrhizi. The Ppm1/Pme2 primer combination specific for P. meibomiae (1) did not yield an amplification product. The Qualiplate ELISA test kit (EnviroLogix Inc., Portland, ME) verified the identification of P. pachyrhizi on an original kudzu sample as well as the leaf material used for DNA analysis. A survey of kudzu at the Nelspruit site during July 2005 confirmed the presence of the pathogen during the offseason for soybean. At that time, incidence of kudzu rust remained high, but few leaves showed high severity. The susceptibility of kudzu to Asian soybean rust has been reported in controlled infection studies in SA (2). To our knowledge, this is the first report of P. pachyrhizi causing rust on a large, naturally occurring kudzu population in SA. References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) A. Nunkumar. M.Sc. thesis. University of KwaZulu-Natal, South Africa, 2006. (3) Z. A. Pretorius et al. Plant Dis. 85:1288, 2001.

scholarly journals First Report of Asian Soybean Rust Caused by Phakopsora pachyrhizi from Mexico

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1260-1260 ◽  
Author(s):  
A. Cárcamo Rodríguez ◽  
J. Aguilar Rios ◽  
J. R. Hernández
Keyword(s):  
Plant Protection ◽  
Soybean Rust ◽  
Thin Wall ◽  
Phakopsora Pachyrhizi ◽  
First Report ◽  
The North ◽  
San Luis ◽  
Asian Soybean Rust ◽  
Glycine Max L ◽  
Voucher Specimens

Leaves of soybean (Glycine max (L.) Merr.; Fabaceae) cv. Huasteca 400, with conspicuous chlorotic spots and associated hypophyllous cinnamon-brown sori, were collected in commercial soybean plantings in Ébano and Tamuín in the state of San Luis de Potosí, Mexico on 26 October 2005. Uredinia, Malupa-type, are mostly hypophyllous, minute, pulverulent, cinnamon-brown, scattered or in groups, subepidermal becoming erumpent, cone like, surrounded by paraphyses; paraphyses are cylindric to clavate, 25 to 50 × 6 to 14 μm, colorless to yellow brownish with wall thickened at the apex. Urediniospores are obovoid to broadly ellipsoidal, measuring 18 to 37 × 15 to 24 μm, and have a minutely echinulate thin wall, hyaline to pale yellowish brown. This morphology is typical of Phakopsora pachyrhizi Syd. & P. Syd. and P. meibomiae (Arthur) Arthur. DNA was extracted from leaves containing sori with the PureLink Plant DNA Reagent (Invitrogen, Carlsbad, CA), and the identity of P. pachyrhizi was confirmed by the polymerase chain reaction protocol (1) with Ppa1/Ppa2 primers at the National Phytosanitary Reference Center of Mexico. The morphological and molecular diagnosis and presence of P. pachyrhizi in Mexico was officially communicated by the North American Plant Protection Organization (NAPPO) on 16 February 2006. Asian soybean rust was reported for the first time in North America in 2004 (2). To our knowledge, this the first report of P. pachyrhizi in Mexico. Voucher specimens have been placed in the USDA National Fungus Collection as BPI 871130, BPI 871131, and BPI 871132. Images and a complete description of Asian soybean rust can be viewed at http://nt.arsgrin.gov/taxadescriptions/factsheets/index.cfm?thisapp=Phakopsorapachyr hizi . References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) R. W. Schneider et al. Plant Dis. 89:774, 2005.

scholarly journals First Report of Soybean Rust (Phakopsora pachyrhizi) on Florida Beggarweed (Desmodium tortuosum) in Alabama

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1374-1374 ◽  
Author(s):  
M. A. Delaney ◽  
E. J. Sikora ◽  
D. P. Delaney ◽  
M. E. Palm ◽  
J. S. Haudenshield ◽  
...  
Keyword(s):  
Agricultural Research ◽  
Soybean Rust ◽  
Molecular Diagnostic ◽  
Phakopsora Pachyrhizi ◽  
Rna Sequences ◽  
Diagnostic Laboratory ◽  
First Report ◽  
Test Kit ◽  
Hot Weather ◽  
Strip Test

Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi, was detected on Florida Beggarweed (Desmodium tortuosum) for the first time in Alabama in November, 2009. The pathogen was not observed in 2010 or 2011, probably because of the exceptionally dry, hot weather in the region. The pathogen was observed on multiple mature leaves of plants, evenly distributed through a field at the Wiregrass Research and Extension Center in Headland, Alabama, located in the southeast region of the state. Florida Beggarweed can serve as an overwintering host for SBR. Symptoms on leaves were consistent with SBR symptoms previously described on soybeans (1). Sori in multiple pustules were observed on the undersurface of the leaves. Urediniospores and paraphyses were observed microscopically and identified as P. pachyrhizi. Symptomatic leaves from 20 plants were analyzed using an Envirologix monoclonal antibody strip test kit at the Auburn University Plant Diagnostic Laboratory. A subsample of 20 plants were positive for the pathogen. Representative symptomatic leaves were sent to the USDA Molecular Diagnostic Laboratory in Beltsville, Maryland, for confirmation. DNA was extracted from sori aseptically removed from leaves using a Qiagen DNeasy Plant Mini Kit, and amplified with primers Ppa1 and NL4. The resulting partial ITS2 and 28S ribosomal RNA sequences were 100% identical to GenBank entry DQ354537. Voucher specimens were deposited in the USDA Agricultural Research Service, National Fungus Collection (BPI). To our knowledge, this is the first report of the disease on Florida Beggarweed in Alabama. References: (1) A. Carcamo Rodriguez et al. Plant Dis. 90:1260, 2006. (2) R. D. Frederick et al. Phytopathology 92:217, 2002.

scholarly journals First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Dry Beans in South Africa

Plant Disease ◽  
2005 ◽  
Vol 89 (2) ◽  
pp. 206-206 ◽  
Author(s):  
E. D. du Preez ◽  
N. C. van Rij ◽  
K. F. Lawrance ◽  
M. R. Miles ◽  
R. D. Frederick
Keyword(s):  
South Africa ◽  
Agricultural Research ◽  
Disease Incidence ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Dry Beans ◽  
Alternate Host ◽  
Internal Transcribed Spacer Region ◽  
Dry Bean ◽  
Fluorescent Polymerase Chain Reaction

During April 2004, a 150-m2 dry bean (Phaseolus vulgaris) plot growing adjacent to rust-infected soybean (Glycine max) at Cedara Agricultural Research Farm (29°32′S 30°16′E) was observed to be infected with two distinct rust types. Common bean rust (caused by Uromyces appendiculatus) with reddish brown uredinia and black telia was readily identified. A second rust with smaller sporulating uredinia (1.0 to 1.5 mm2), which were gray in appearance, was also found. Visual rust severity on the dry bean plants, which were in mid pod-fill, was high (approximately 30 to 40% disease incidence). Twenty plants were examined and observed to be infected with both rusts. With microscopic examination of no fewer than 20 leaves per plant, the urediniospores from the smaller lesions were determined to be morphologically similar to Phakopsora pachyrhizi (3). Real-time fluorescent polymerase chain reaction assays on six leaves and sequence analysis of the nuclear ribosomal internal transcribed spacer region 2 (1) verified the identity of the urediniospores as P. pachyrhizi. Although P. vulgaris is a known host of P. pachyrhizi, to our knowledge this is the first time since the arrival of soybean rust in 2001 that P. pachyrhizi has been observed on an alternate host plant in South Africa (2). Since dry beans are grown all year in frost-free areas, the implications are that dry beans may serve as an important overwintering host and source of inoculum for seasonal soybean rust outbreaks. References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) Z. A. Pretorius et al. Plant Dis. 85:1288, 2001. (3) J. B. Sinclair and G. L. Hartman. Soybean Rust. Pages 25–26 in: Compendium of Soybean Diseases, 4th ed. G. L. Hartman et al. eds. The American Phytopathological Society, St. Paul, MN, 1999.

Asian Soybean Rust Caused by Phakopsora pachyrhizi on Soybean and Kudzu in Florida

2005 ◽  
Vol 6 (1) ◽  
pp. 9 ◽  
Author(s):  
Philip F. Harmon ◽  
M. Timur Momol ◽  
J. J. Marois ◽  
Hank Dankers ◽  
Carrie L. Harmon
Keyword(s):  
Light Microscopy ◽  
Dna Extraction ◽  
Pcr Amplification ◽  
Initial Diagnosis ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
First Report ◽  
Asian Soybean Rust ◽  
Rust Diseases ◽  
Amplification Protocol

Asian soybean rust caused by Phakopsora pachyrhizi was found on soybean and kudzu in Florida in November of 2004. The initial diagnosis of soybean rust was based on observations of symptoms and urediniospores. The two species of Phakopsora that cause rust diseases on soybean, P. pachyrhizi and P. meibomiae, cannot be differentiated with light microscopy. A rapid DNA extraction and PCR amplification protocol discriminated between the two species. The sequence of the amplified DNA product confirmed this first report of P. pachyrhizi in Florida. Accepted for publication 9 May 2005. Published 13 June 2005.

scholarly journals Asian Soybean Rust: Incidence, Severity, and Morphological Characterization of Phakopsora pachyrhizi (Uredinia and Telia) in Argentina

Plant Disease ◽  
2005 ◽  
Vol 89 (1) ◽  
pp. 109-109 ◽  
Author(s):  
M. A. Carmona ◽  
M. E. Gally ◽  
S. E. Lopez
Keyword(s):  
Morphological Characterization ◽  
Northern Region ◽  
Soybean Rust ◽  
Limited Area ◽  
Growth Stages ◽  
Phakopsora Pachyrhizi ◽  
First Report ◽  
Telial Stage ◽  
Asian Soybean Rust

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is the most destructive disease of soybean (Glycine max) in many areas of the world. ASR was first detected in Argentina during 2002 in a limited area in the northern region of the country (2). During the 2004 growing season, P. pachyrhizi spread rapidly throughout most soybean growing areas of northwestern and northeastern Argentina. ASR was also was found in some fields in Entre Ríos and Santa Fe provinces. In all areas, symptoms were expressed late in the 2004 season (growth stages R5.5 to R7) and yield losses were minimal. The objectives of this study were to quantify P. pachyrhizi infection in the canopy and morphologically characterize the fungus from fields where it had been previously detected by polymerase chain reaction (PCR) (3). Incidence (percentage of plants affected) and severity (percentage of leaf area affected, including chlorosis) were visually estimated for 10 plants arbitrarily collected (April 2004) from each of three fields located in Charata (Chacabuco), Chaco Province (Sample 1, collected in the R6 stage), La Paloma (Moreno), Santiago del Estero Province (Sample 2, stage R6 to R7), and Tolloche (Anta), Salta Province (Sample 3, stage R5.5). Disease assessments were made for the lower, middle, and upper canopy from 15 leaves per plant. The number of pustules per cm2 and uredinia per lesion were recorded from the undersides of central leaflets for each trifoliolate observed. Tissue sections were made to observe fructifications of P. pachyrhizi. Incidence of affected plants was 100% in all fields. Disease severity for Sample 1 was 45% (range 30 to 60%), 20% (10 to 30%), and 10% (5 to 20%) for the lower, middle, and upper canopy, respectively; for Sample 2: 60% (30 to 80%), 40% (25 to 50%), and 25% (15 to 40%) for the lower, middle, and upper canopy, respectively; and for Sample 3: 25% (10 to 50%), 15% (10 to 20%), and 10% (5 to 15%) for the lower, middle, and upper canopy, respectively. The number of pustules per cm2 for Sample 1 was 156/cm2 (range 88 to 200); Sample 2: 172/cm2 (128 to 232); and Sample 3: 120/cm2 (72 to 232). The number of uredinia per lesion for Sample 1 was 6 per lesion (range 1 to 15); Sample 2: 5.5 per lesion (1 to 13), and Sample 3: 2.8 per lesion (1 to 5). The two spore types that were commonly observed were urediniospores and teliospores. Telia were found on infected leaves mixed with uredinia in every sample. Urediniospores measured 16 to 22 μm (mean 18.5 μm) × 25 to 30 μm (mean 27 μm). Teliospores measured 8 to 11 μm (mean 9 μm) × 19 to 27 μm (mean 23.8 μm). Spores sizes are in the range described by Ono et al. (1). To our knowledge, this is the first report of epidemiological and morphological characterization of ASR in Argentina and the first report of the telial stage of P. pachyrhizi on soybean in South America. References: (1) Y. Ono et al. Mycol. Res. 96:825, 1992. (2) R. L. Rossi. Plant Dis 87:102, 2003. (3) SINAVIMO, Sistema Nacional Argentino de Vigilancia y Monitoreo de plagas. Roya de la soja: Resultados de la campaña 2003-2004. On-line publication. SENASA, 2004.

scholarly journals First Report of Asian Soybean Rust Caused by Phakopsora pachyrhizi in Puerto Rico

Plant Disease ◽  
2013 ◽  
Vol 97 (10) ◽  
pp. 1378-1378 ◽  
Author(s):  
C. Estévez de Jensen ◽  
C. L. Harmon ◽  
A. Vitoreli
Keyword(s):  
Puerto Rico ◽  
Light Microscope ◽  
Soybean Rust ◽  
Pathogenicity Test ◽  
Phakopsora Pachyrhizi ◽  
Specific Primers ◽  
First Report ◽  
Asian Soybean Rust ◽  
Species Specific ◽  
Pcr Test

Sentinel plots for monitoring Asian soybean rust (ASR) caused by Phakopsora pachyrhizi Syd. were initiated in 2005 at Isabela (EEI), Adjuntas (EEA), and Juana Diaz (EEJD) experiment stations. Until 2009, no signs or symptoms of ASR were observed in soybean (Glycine max [L.] Merr.) or common bean (Phaseolus vulgaris L.). These sites were found to be negative for the occurrence of ASR based on PCR with specific primers Ppa1 and Ppa2 (2). However, P. meibomiae, the cause of American soybean rust (AmSR) endemic to this region, was found in Adjuntas naturally infecting numerous wild and cultivated legumes, particularly Lablab purpureus (3). Symptoms of AmSR in L. purpureus appeared as reddish-brown spots on the underside of the leaves with three to four uredia per lesion. On February 12, 2011, leaf samples of soybean in beginning pod-fill (R5) and beginning-maturity (R8) growth stages were collected in a winter nursery at EEI and found to have small brown specks with chlorotic haloes on the underside of the leaves and leaf sections from symptomatic areas indicated an abundance of uredinia. Under the light microscope, urediniospores observed at 40× were morphologically similar to Phakopsora spp. Total DNA was extracted from leaf discs using the Qiagen DNeasy Plant Mini Kit following the methods of Frederick et al. (2). Detection of ASR pathogen was achieved via PCR amplification with Ppa1 and Ppa2 primers that are specific for P. pachyrhizi Syd. After sequencing the amplicon, BLAST analysis of the internal transcribed spacer (ITS) region of the ribosomal RNA genes indicated 100% identity with known P. pachyrhizi sequences in GenBank. The sequence of isolate P. pachyrhizi EEI-2011 was submitted to GenBank as JX994293. No amplification was observed after PCR with species-specific primers Pme1 and Pme2 specific for P. meibomiae (Arthur) Arthur. L. purpureus collected from EEA and Utuado only appears to be infected by P. meibomiae and no mixed infections with P. pachyrhizi were apparent, based on the PCR test. Leaf samples from EEI were sent to the UF Plant Diagnostic Center in Gainesville, FL, where quantitative PCR with primers Ppa1 and Ppa2 confirmed the presence of P. pachyrhizi; while P. meibomiae was not detected with primers Pme1 and Pme2. Pathogenicity tests were conducted on the soybean cv. Williams with isolate EEI-2011. Fifteen-day-old soybean plants were inoculated by attaching an infected and sporulating 1 cm2 piece of soybean leaf from EEI-2011 with an average of 4.5 × 105 urediniospores per cm2 (1). Inoculated plants were placed in a growth chamber at 20°C night and 28°C day temperatures, 80% humidity, and a 12-h light photoperiod. Small reddish brown spots with chlorotic haloes developed 4 to 6 days after inoculation and tan lesions appeared 10 to 15 days later. Mature tan lesions developed in 2 weeks with an average of 2.4 uredinia/lesion. Urediniospores were observed with light microscope and these were morphologically similar to those spores observed in the original diseased samples. Another PCR test confirmed P. pachyrhizi after amplification with the species-specific primers. The pathogenicity test was repeated twice with the same cultivar. To our knowledge, this is the first report of ASR in Puerto Rico and this finding will have implications as another overwintering site for Asian soybean rust in the Caribbean region. References: (1) C. Estévez de Jensen et al. J. Agric. Univ. P.R. 93:125, 2009. (2) R. D. Frederick et al. Phytopathology 92:217, 2002. (3) B. Vega and C. Estévez de Jensen. J. Agric. Univ. P.R. 94:211, 2010.

scholarly journals First Report of Asian Soybean Rust Caused by Phakopsora pachyrhizi on Soybean in Alabama

Plant Disease ◽  
2006 ◽  
Vol 90 (1) ◽  
pp. 112-112 ◽  
Author(s):  
J. M. Mullen ◽  
E. J. Sikora ◽  
J. M. McKemy ◽  
M. E. Palm ◽  
L. Levy ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Rust Disease ◽  
First Report ◽  
Leaf Spots ◽  
Asian Soybean Rust ◽  
Leaf Surfaces ◽  
Soybean Leaves

On November 4, 2004, soybean leaves (Glycine max (L.) Merr) were submitted to the Auburn University Plant Diagnostic Lab by a State Department of Agriculture and Industries Inspector. Samples were collected from an 80-ha field of soybean plants in a late-reproductive-growth stage in Mobile County, Alabama. Under microscopic examination, leaves showed rust pustules in advanced stages of development with urediniospores and sori characteristic of Phakopsora spp. Uredinia were ostiolate in small, brown, angular leaf spots (2 to 3 mm) on lower leaf surfaces. Urediniospores were pale yellow-to-white, globose or ovate, 20 to 40 × 15 to 25 μm. In a subsequent visit to the field, symptoms and signs of the rust disease were observed on plants bordering the edge of the field since the majority of plants were senescent. Tan lesions on lower leaf surfaces contained small pustules surrounded by a small zone of slightly discolored necrotic tissue. Masses of tan spores covered the lower leaf surface pustules. Leaves were mailed overnight to the USDA National Identification Services (Mycology) Laboratory in Beltsville, MD. The fungal structures were confirmed to be a Phakopsora sp., and the sample was forwarded to the USDA National Plant Germplasm and Biotechnology Laboratory in Beltsville, MD. DNA was extracted from leaf pieces containing sori using the Qiagen DNeasy Plant Mini kit (Qiagen, Valencia, CA). Phakopsora pachyrhizi was detected using a real-time polymerase chain reaction (PCR) protocol (1) performed in a Cepheid SmartCycler (Sunnyvale, CA). The PCR master mix was modified to include OmniMix beads (Cepheid). The field and microscopic suspect diagnosis of P. pachyrhizi was confirmed officially by APHIS on November 18, 2004. This was the fourth USDA official confirmation of Asian soybean rust in the continental United States during 2004, and to our knowledge, this is the first report of the disease in Alabama. This report helps confirm that early occurrences of Asian soybean rust in the United States were present in other areas in addition to the first reported finding in Louisiana (2). References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) R. W. Schneider et al. Plant Dis. 89:774, 2005.

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