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Fountain J, Pandey A, Nayak S, Bajaj P, Wang H, Kumar V, Chitikineni A, Abbas H, Scully B, Kemerait R, Pandey M, Guo B, Varshney R. Transcriptional responses of toxigenic and atoxigenic isolates of Aspergillus flavus to oxidative stress in aflatoxin-conducive and non-conducive media. WORLD MYCOTOXIN J 2020. [DOI: 10.3920/wmj2020.2566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aflatoxin production by isolates of Aspergillus flavus varies, ranging from highly toxigenic to completely atoxigenic. Several mechanisms have been identified which regulate aflatoxin production including medium carbon source and oxidative stress. In recent studies, aflatoxin production has been implicated in partially ameliorating oxidative stress in A. flavus. To better understand the role of aflatoxin production in oxidative stress responses, a selection of toxigenic and atoxigenic isolates of A. flavus with moderate to high oxidative stress tolerance were exposed to increasing concentrations of H2O2 in both aflatoxin-conducive and non-conducive media. Mycelial mats were collected for global transcriptome sequencing followed by differential expression, functional prediction, and weighted co-expression analyses. Oxidative stress and medium carbon source had a significant effect on the expression of several secondary metabolite gene clusters including those for aflatoxin, aflatrem, aflavarin, cyclopiazonic acid, and kojic acid. Atoxigenic biological control isolates showed less differential expression under stress than other atoxigenic isolates suggesting expression profiles may be useful in screening. Increasing stress also resulted in regulation of SakA/Hog1 and MpkA MAP kinase signalling pathways pointing to their potential roles in regulating oxidative stress responses. Their expression was also influenced by medium carbon source. These results suggest that aflatoxin production along with that of other mycotoxins may occur as part of a concerted coping mechanism for oxidative stress and its effects in the environment. This mechanism is also regulated by availability of simple sugars and glycolytic compounds for their biosynthesis.
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Affiliation(s)
- J.C. Fountain
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Starkville, MS 39762, USA
| | - A.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - S.N. Nayak
- Department of Biotechnology, University of Agricultural Sciences, Dharwad, Karnataka 580005, India
| | - P. Bajaj
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H. Wang
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - V. Kumar
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - A. Chitikineni
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H.K. Abbas
- USDA-ARS, Biological Control of Pests Research Unit, Stoneville, MS, USA
| | - B.T. Scully
- USDA-ARS, National Horticultural Research Laboratory, Fort Pierce, FL, USA
| | - R.C. Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - M.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - B. Guo
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
| | - R.K. Varshney
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
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Fountain J, Pandey A, Nayak S, Bajaj P, Wang H, Kumar V, Chitikineni A, Abbas H, Scully B, Kemerait R, Pandey M, Guo B, Varshney R. Transcriptional responses of toxigenic and atoxigenic isolates of Aspergillus flavus to oxidative stress in aflatoxin-conducive and non-conducive media. WORLD MYCOTOXIN J 2020. [DOI: 10.3920/wmj2020.test2566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aflatoxin production by isolates of Aspergillus flavus varies, ranging from highly toxigenic to completely atoxigenic. Several mechanisms have been identified which regulate aflatoxin production including medium carbon source and oxidative stress. In recent studies, aflatoxin production has been implicated in partially ameliorating oxidative stress in A. flavus. To better understand the role of aflatoxin production in oxidative stress responses, a selection of toxigenic and atoxigenic isolates of A. flavus with moderate to high oxidative stress tolerance were exposed to increasing concentrations of H2O2 in both aflatoxin-conducive and non-conducive media. Mycelial mats were collected for global transcriptome sequencing followed by differential expression, functional prediction, and weighted co-expression analyses. Oxidative stress and medium carbon source had a significant effect on the expression of several secondary metabolite gene clusters including those for aflatoxin, aflatrem, aflavarin, cyclopiazonic acid, and kojic acid. Atoxigenic biological control isolates showed less differential expression under stress than other atoxigenic isolates suggesting expression profiles may be useful in screening. Increasing stress also resulted in regulation of SakA/Hog1 and MpkA MAP kinase signalling pathways pointing to their potential roles in regulating oxidative stress responses. Their expression was also influenced by medium carbon source. These results suggest that aflatoxin production along with that of other mycotoxins may occur as part of a concerted coping mechanism for oxidative stress and its effects in the environment. This mechanism is also regulated by availability of simple sugars and glycolytic compounds for their biosynthesis.
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Affiliation(s)
- J.C. Fountain
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Starkville, MS 39762, USA
| | - A.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - S.N. Nayak
- Department of Biotechnology, University of Agricultural Sciences, Dharwad, Karnataka 580005, India
| | - P. Bajaj
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H. Wang
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - V. Kumar
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - A. Chitikineni
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - H.K. Abbas
- USDA-ARS, Biological Control of Pests Research Unit, Stoneville, MS, USA
| | - B.T. Scully
- USDA-ARS, National Horticultural Research Laboratory, Fort Pierce, FL, USA
| | - R.C. Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, USA
| | - M.K. Pandey
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
| | - B. Guo
- USDA-ARS, Crop Protection and Management Research Unit, Tifton, GA 31793, USA
| | - R.K. Varshney
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, Telangana 502324, India
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Marasigan K, Toews M, Kemerait R, Abney MR, Culbreath A, Srinivasan R. Evaluation of Alternatives to an Organophosphate Insecticide with Selected Cultural Practices: Effects on Thrips, Frankliniella fusca, and Incidence of Spotted Wilt in Peanut Farmscapes. J Econ Entomol 2018; 111:1030-1041. [PMID: 29635299 DOI: 10.1093/jee/toy079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Indexed: 06/08/2023]
Abstract
Peanut growers use a combination of tactics to manage spotted wilt disease caused by thrips-transmitted Tomato spotted wilt virus (TSWV). They include planting TSWV-resistant cultivars, application of insecticides, and various cultural practices. Two commonly used insecticides against thrips are aldicarb and phorate. Both insecticides exhibit broad-spectrum toxicity. Recent research has led to the identification of potential alternatives to aldicarb and phorate. In this study, along with reduced-risk, alternative insecticides, we evaluated the effect of conventional versus strip tillage; single versus twin row seeding pattern; and 13 seed/m versus 20 seed/m on thips density, feeding injury, and spotted wilt incidence. Three field trials were conducted in Georgia in 2012 and 2013. Thrips counts, thrips feeding injuriy, and incidence of spotted wilt were less under strip tillage than under conventional tillage. Reduced feeding injury from thrips was observed on twin-row plots compared with single-row plots. Thrips counts, thrips feeding injury, and incidence of spotted wilt did not vary by seeding rate. Yield from twin-row plots was greater than yield from single-row plots only in 2012. Yield was not affected by other cultural practices. Alternative insecticides, including imidacloprid and spinetoram, were as effective as phorate in suppressing thrips and reducing incidence of spotted wilt in conjunction with cultural practices. Results suggest that cultural practices and reduced-risk insecticides (alternatives to aldicarb and phorate) can effectively suppress thrips and incidence of spotted wilt in peanut.
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Affiliation(s)
- K Marasigan
- Department of Entomology, University of Georgia, Tifton, GA
| | - M Toews
- Department of Entomology, University of Georgia, Tifton, GA
| | - R Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA
| | - M R Abney
- Department of Entomology, University of Georgia, Tifton, GA
| | - A Culbreath
- Department of Plant Pathology, University of Georgia, Tifton, GA
| | - R Srinivasan
- Department of Entomology, University of Georgia, Tifton, GA
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Marasigan K, Toews M, Kemerait R, Abney MR, Culbreath A, Srinivasan R. Evaluation of Alternatives to Carbamate and Organophosphate Insecticides Against Thrips and Tomato Spotted Wilt Virus in Peanut Production. J Econ Entomol 2016; 109:544-57. [PMID: 26637534 DOI: 10.1093/jee/tov336] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Thrips are important pests of peanut. They cause severe feeding injuries on peanut foliage in the early season. They also transmit Tomato spotted wilt virus (TSWV), which causes spotted wilt disease. At-plant insecticides and cultivars that exhibit field resistance to TSWV are often used to manage thrips and spotted wilt disease. Historically, peanut growers used the broad-spectrum insecticides aldicarb (IRAC class 1A; Temik) and phorate (IRAC class 1B; Thimet) for managing thrips and thereby reducing TSWV transmission. Aldicarb has not been produced since 2011 and its usage in peanut will be legally phased out in 2018; therefore, identification of alternative chemistries is critical for thrips and spotted wilt management. Here, eight alternative insecticides, with known thrips activity, were evaluated in field trials conducted from 2011 through 2013. In addition, different application methods of alternatives were also evaluated. Imidacloprid (Admire Pro), thiamethoxam (Actara), spinetoram (Radiant), and cyantraniliprole (Exirel) were as effective as aldicarb and phorate in suppressing thrips, but none of the insecticides significantly suppressed spotted wilt incidence. Nevertheless, greenhouse assays demonstrated that the same alternative insecticides were effective in suppressing thrips feeding and reducing TSWV transmission. Spotted wilt incidence in the greenhouse was more severe (∼80%) than in the field (5–25%). In general, field resistance to TSWV in cultivars only marginally influenced spotted wilt incidence. Results suggest that effective management of thrips using alternative insecticides and subsequent feeding reduction could improve yields under low to moderate virus pressure.
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Sikora EJ, Allen TW, Wise KA, Bergstrom G, Bradley CA, Bond J, Brown-Rytlewski D, Chilvers M, Damicone J, DeWolf E, Dorrance A, Dufault N, Esker P, Faske TR, Giesler L, Goldberg N, Golod J, Gómez IRG, Grau C, Grybauskas A, Franc G, Hammerschmidt R, Hartman GL, Henn RA, Hershman D, Hollier C, Isakeit T, Isard S, Jacobsen B, Jardine D, Kemerait R, Koenning S, Langham M, Malvick D, Markell S, Marois JJ, Monfort S, Mueller D, Mueller J, Mulrooney R, Newman M, Osborne L, Padgett GB, Ruden BE, Rupe J, Schneider R, Schwartz H, Shaner G, Singh S, Stromberg E, Sweets L, Tenuta A, Vaiciunas S, Yang XB, Young-Kelly H, Zidek J. A Coordinated Effort to Manage Soybean Rust in North America: A Success Story in Soybean Disease Monitoring. Plant Dis 2014; 98:864-875. [PMID: 30708845 DOI: 10.1094/pdis-02-14-0121-fe] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Existing crop monitoring programs determine the incidence and distribution of plant diseases and pathogens and assess the damage caused within a crop production region. These programs have traditionally used observed or predicted disease and pathogen data and environmental information to prescribe management practices that minimize crop loss. Monitoring programs are especially important for crops with broad geographic distribution or for diseases that can cause rapid and great economic losses. Successful monitoring programs have been developed for several plant diseases, including downy mildew of cucurbits, Fusarium head blight of wheat, potato late blight, and rusts of cereal crops. A recent example of a successful disease-monitoring program for an economically important crop is the soybean rust (SBR) monitoring effort within North America. SBR, caused by the fungus Phakopsora pachyrhizi, was first identified in the continental United States in November 2004. SBR causes moderate to severe yield losses globally. The fungus produces foliar lesions on soybean (Glycine max) and other legume hosts. P. pachyrhizi diverts nutrients from the host to its own growth and reproduction. The lesions also reduce photosynthetic area. Uredinia rupture the host epidermis and diminish stomatal regulation of transpiration to cause tissue desiccation and premature defoliation. Severe soybean yield losses can occur if plants defoliate during the mid-reproductive growth stages. The rapid response to the threat of SBR in North America resulted in an unprecedented amount of information dissemination and the development of a real-time, publicly available monitoring and prediction system known as the Soybean Rust-Pest Information Platform for Extension and Education (SBR-PIPE). The objectives of this article are (i) to highlight the successful response effort to SBR in North America, and (ii) to introduce researchers to the quantity and type of data generated by SBR-PIPE. Data from this system may now be used to answer questions about the biology, ecology, and epidemiology of an important pathogen and disease of soybean.
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Affiliation(s)
- E J Sikora
- Department of Entomology and Plant Pathology, Auburn University, Auburn 36849
| | - T W Allen
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Delta Research and Extension Center, Mississippi State University, Stoneville 38776
| | - K A Wise
- Department of Botany and Plant Pathology, Purdue University, West Lafayette 47907
| | - G Bergstrom
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca 14853
| | - C A Bradley
- Department of Crop Sciences, University of Illinois, Urbana 61801
| | - J Bond
- Department of Plant, Soil, and Agricultural Systems, Southern Illinois University, Carbondale 62901
| | - D Brown-Rytlewski
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing 48824
| | - M Chilvers
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing 48824
| | - J Damicone
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater 74078
| | - E DeWolf
- Department of Plant Pathology, Kansas State University, Manhattan 66506
| | - A Dorrance
- Department of Plant Pathology, The Ohio State University, Wooster 44691
| | - N Dufault
- Department of Plant Pathology, University of Florida, Gainesville 32611
| | - P Esker
- Escuela de Agronomia, Universidad de Costa Rica, San José, Costa Rica 10111
| | - T R Faske
- Department of Plant Pathology, University of Arkansas Lonoke Research and Extension Center, Lonoke 72086
| | - L Giesler
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln 68508
| | - N Goldberg
- Department of Plant Sciences, New Mexico State University, Las Cruces 88003
| | - J Golod
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park 16802
| | - I R G Gómez
- Sistema Nacional de Vigilancia Epidemiologica Fitosanitaria, Centro Nacional de Referenceia Fitosanitaria, Col. Del Carmen, Coyoacan, Mexico
| | - C Grau
- Department of Plant Pathology, University of Wisconsin, Madison 53706
| | - A Grybauskas
- Department of Plant Science and Landscape Management, University of Maryland, College Park 20742
| | | | - R Hammerschmidt
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing 48824
| | - G L Hartman
- United States Department of Agriculture/Agricultural Research Service, Urbana 61801
| | - R A Henn
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State 39762
| | - D Hershman
- Department of Plant Pathology, University of Kentucky Research and Education Center, Princeton 42445
| | - C Hollier
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803
| | - T Isakeit
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station 77843
| | - S Isard
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park 16802
| | - B Jacobsen
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman 59717
| | - D Jardine
- Department of Plant Pathology, Kansas State University, Manhattan 66506
| | - R Kemerait
- Department of Plant Pathology, University of Georgia, Tifton 31793
| | - S Koenning
- Department of Plant Pathology, North Carolina State University, Raleigh 27695
| | - M Langham
- Department of Plant Science, South Dakota State University, Brookings 57007
| | - D Malvick
- Department of Plant Pathology, University of Minnesota, St. Paul 55108
| | - S Markell
- Department of Plant Pathology, North Dakota State University, Fargo 58108
| | - J J Marois
- Department of Plant Pathology, University of Florida, Gainesville 32611
| | - S Monfort
- Edisto Research and Education Center, Clemson University, Blackville 29817
| | - D Mueller
- Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011
| | - J Mueller
- Edisto Research and Education Center, Clemson University, Blackville 29817
| | - R Mulrooney
- Department of Plant and Soil Science, University of Delaware, Newark 19716
| | - M Newman
- BASF Corporation, Jackson, TN 38301
| | | | - G B Padgett
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803
| | - B E Ruden
- South Dakota Wheat Growers Association, Aberdeen 57401
| | - J Rupe
- Department of Plant Pathology, University of Arkansas, Fayetteville 72701
| | - R Schneider
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803
| | - H Schwartz
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins 80523
| | - G Shaner
- Department of Botany and Plant Pathology, Purdue University, West Lafayette 47907
| | - S Singh
- Department of Plant, Soil and Entomological Sciences, University of Idaho, Kimberly 83341
| | - E Stromberg
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061
| | - L Sweets
- Division of Plant Sciences, University of Missouri, Columbia 65211
| | - A Tenuta
- Ontario Ministry of Agriculture and Food, and Ministry of Rural Affairs, Ridgetown, Ontario, Canada, NOP2CO
| | - S Vaiciunas
- New Jersey Department of Agriculture, Trenton 08625
| | - X B Yang
- Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011
| | - H Young-Kelly
- Department of Entomology and Plant Pathology, University of Tennessee West Tennessee Research and Education Center, Jackson 38301
| | - J Zidek
- ZedX Incorporated, Bellefonte, PA 16823
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Dolezal W, Tiwari K, Kemerait R, Kichler J, Sapp P, Pataky J. An Unusual Occurrence of Southern Rust, Caused by Rpp9-virulent Puccinia polysora, on Corn in Southwestern Georgia. Plant Dis 2009; 93:676. [PMID: 30764419 DOI: 10.1094/pdis-93-6-0676a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Southern rust, caused by Puccinia polysora Underw., occurs frequently on corn (Zea mays) grown in subtropical or tropical regions. When conditions are favorable, southern rust also occurs in temperate climates of the central and southern United States although the fungus does not survive on corn crop residue and must be introduced to temperate regions each growing season. Several single, dominant, resistance genes, designated as Rpp genes, convey hypersensitive, chlorotic fleck reactions when challenged with avirulent isolates of P. polysora (1). Rpp resistance prevents or limits the formation of uredinia. The Rpp9 gene has been used successfully in North America in the past 20 years to control southern rust even though the gene has been ineffective in other parts of the world (e.g., Africa and Hawaii) because of the prevalence of virulent races. During the past 3 years, Rpp9 virulence has occurred in the western hemisphere (e.g., Brazil, Mexico, Nebraska, and Texas), but prior to 2008, uredinia were not observed east of the Mississippi River on corn with the Rpp9 gene. A few uredinia were observed on corn with the Rpp9 gene in eastern Nebraska in 2006 and near Victoria, TX in 2007 (W. Dolezal, personal observation). In July of 2008, a virulent isolate of P. polysora was confirmed from Grady County, GA on corn lines with the Rpp9 gene including the original source of this resistance gene, Boesman yellow flint, which is PI 186208 (3). In August of 2008, isolates of P. polysora were collected from severely infected corn hybrids with Rpp9 grown in Macon County, GA. Rust samples from hybrids without Rpp genes also were collected in Burke County, GA where Rpp-resistant corn was asymptomatic. In greenhouse trials, corn lines with and without the Rpp9 gene were inoculated with urediniospores from collections from Burke and Macon counties and Illinois. Rust infection types (1) were scored 18 to 25 days after inoculation. The Macon County isolate produced type 1 and 2 infections (small uredinia surrounded by necrotic or chlorotic tissue) on Oh43Rpp9 and W64aRpp9 and type 4 infections (large, sporulating uredinia) on two versions of a commercial hybrid with and without the Rpp9 gene and on Va59 (which carries an Rpp gene different from Rpp9). The Burke County isolate and an isolate from Illinois collected in 2001 produced type 0 infections (chlorotic flecks) on all of these lines except the non-Rpp version of the commercial hybrid which had a type 4 reaction. To our knowledge, Rpp9-virulent isolates of P. polysora have not been reported from the continental United States for nearly 50 years. In the late 1950s and early 1960s, A. L. Robert (2) collected isolates of P. polysora from throughout the world and observed multiple races on a set of host differentials that is no longer available. A. L. Robert's collection included an isolate from Georgia that was virulent on PI 186208. Commercial hybrids containing the Rpp9 gene may continue to be resistant throughout most of North America if previously common Rpp9-avirulent isolates of P. polysora are prevalent, but those hybrids should be carefully monitored for infection by newly introduced Rpp9-virulent isolates. References: (1) A. L. Hooker. Page 207 in: The Cereal Rusts. Vol. II. Academic Press, San Diego, 1985. (2) A. L. Robert. Phytopathology 52:1010, 1962. (3) A. J. Ullstrup. Phytopathology 55:425, 1965.
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Affiliation(s)
- W Dolezal
- Pioneer Hi-Bred International, Inc., Johnston, IA 50131
| | - K Tiwari
- Pioneer Hi-Bred International, Inc., Cairo, GA 39828
| | - R Kemerait
- University of Georgia, Department of Plant Pathology, Tifton 31793
| | - J Kichler
- University of Georgia, Cooperative Extension, Oglethorpe 31068
| | - P Sapp
- University of Georgia, Cooperative Extension, Waynesboro 30830
| | - J Pataky
- University of Illinois, Department of Crop Science, Urbana 61801
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Sconyers L, Kemerait R, Brock J, Phillips D. Asian Soybean Rust Development in 2005: A Perspective from the Southeastern United States. ACTA ACUST UNITED AC 2006. [DOI: 10.1094/apsnetfeatures-2006-0106] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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