1
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Grünwald NJ, Bock CH, Chang JH, De Souza AA, Ponte EMD, du Toit LJ, Dorrance AE, Dung J, Gent D, Goss EM, Lowe-Power TM, Madden LV, Martin FN, McDowell J, Naegele RP, Potnis N, Quesada-Ocampo LM, Sundin GW, Thiessen L, Vinatzer BA, Zeng Q. Open Access and Reproducibility in Plant Pathology Research: Guidelines and Best Practices. Phytopathology 2024:PHYTO12230483IA. [PMID: 38330057 DOI: 10.1094/phyto-12-23-0483-ia] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
The landscape of scientific publishing is experiencing a transformative shift toward open access, a paradigm that mandates the availability of research outputs such as data, code, materials, and publications. Open access provides increased reproducibility and allows for reuse of these resources. This article provides guidance for best publishing practices of scientific research, data, and associated resources, including code, in The American Phytopathological Society journals. Key areas such as diagnostic assays, experimental design, data sharing, and code deposition are explored in detail. This guidance aligns with that observed by other leading journals. We hope the information assembled in this paper will raise awareness of best practices and enable greater appraisal of the true effects of biological phenomena in plant pathology.
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Affiliation(s)
- Niklaus J Grünwald
- U.S. Department of Agriculture-Agricultural Research Service, Horticultural Crops Disease and Pest Management Research Unit, Corvallis, OR 97331, U.S.A
| | - Clive H Bock
- U.S. Department of Agriculture-Agricultural Research Service, Southeastern Fruit and Tree Nut Research Station, Byron, GA 31008, U.S.A
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A
| | | | - Emerson M Del Ponte
- Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil
| | - Lindsey J du Toit
- Department of Plant Pathology, Washington State University, Mount Vernon, WA 98273, U.S.A
| | - Anne E Dorrance
- Department of Plant Pathology, College of Food, Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH 44691, U.S.A
| | - Jeremiah Dung
- Department of Botany and Plant Pathology, Central Oregon Agricultural Research and Extension Center, Oregon State University, Madras, OR 97741, U.S.A
| | - David Gent
- U.S. Department of Agriculture-Agricultural Research Service, Forage Seed and Cereal Research Unit, Corvallis, OR 97331, U.S.A
| | - Erica M Goss
- Department of Plant Pathology and Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, U.S.A
| | - Tiffany M Lowe-Power
- Department of Plant Pathology, University of California Davis, Davis, CA 95616, U.S.A
| | - Laurence V Madden
- Department of Plant Pathology, College of Food, Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH 44691, U.S.A
| | - Frank N Martin
- U.S. Department of Agriculture-Agricultural Research Service, Crop Protection and Improvement Research Center, Salinas, CA 93905, U.S.A
| | - John McDowell
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, U.S.A
| | - Rachel P Naegele
- U.S. Department of Agriculture-Agricultural Research Service, Sugarbeet and Bean Research Unit, East Lansing, MI 48824, U.S.A
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, U.S.A
| | - Lina M Quesada-Ocampo
- Department of Entomology and Plant Pathology and NC Plant Sciences Initiative, North Carolina State University, Raleigh, NC 27606, U.S.A
| | - George W Sundin
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Lindsey Thiessen
- Domestic and Emergency Scientific Support, U.S. Department of Agriculture-Animal & Plant Health Inspection Service-Plant Protection and Quarantine, Raleigh, NC 27606, U.S.A
| | - Boris A Vinatzer
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, U.S.A
| | - Quan Zeng
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06511, U.S.A
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2
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Rott P, Grinstead S, Dallot S, Foster ZSL, Daugrois JH, Fernandez E, Kaye CJ, Hendrickson L, Hu X, Adhikari B, Malapi M, Grünwald NJ, Roumagnac P, Mollov D. Genetic Diversity, Evolution, and Diagnosis of Sugarcane Yellow Leaf Virus from 19 Sugarcane-Producing Locations Worldwide. Plant Dis 2023; 107:3437-3447. [PMID: 37079008 DOI: 10.1094/pdis-10-22-2405-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Sugarcane yellow leaf virus (SCYLV), the causal agent of yellow leaf, has been reported in an increasing number of sugarcane-growing locations since its first report in the 1990s in Brazil, Florida, and Hawaii. In this study, the genetic diversity of SCYLV was investigated using the genome coding sequence (5,561 to 5,612 nt) of 109 virus isolates from 19 geographical locations, including 65 new isolates from 16 geographical regions worldwide. These isolates were distributed in three major phylogenetic lineages (BRA, CUB, and REU), except for one isolate from Guatemala. Twenty-two recombination events were identified among the 109 isolates of SCYLV, thus confirming that recombination was a significant driving force in the genetic diversity and evolution of this virus. No temporal signal was found in the genomic sequence dataset, most likely because of the short temporal window of the 109 SCYLV isolates (1998 to 2020). Among 27 primers reported in the literature for the detection of the virus by RT-PCR, none matched 100% with all 109 SCYLV sequences, suggesting that the use of some primer pairs may not result in the detection of all virus isolates. Primers YLS111/YLS462, which were the first primer pair used by numerous research organizations to detect the virus by RT-PCR, failed to detect isolates belonging to the CUB lineage. In contrast, primer pair ScYLVf1/ScYLVr1 efficiently detected isolates of all three lineages. Continuous pursuit of knowledge of SCYLV genetic variability is therefore critical for effective diagnosis of yellow leaf, especially in virus-infected and mainly asymptomatic sugarcane plants.
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Affiliation(s)
- Philippe Rott
- CIRAD, UMR PHIM, 34398 Montpellier, France
- PHIM Plant Health Institute, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Sam Grinstead
- National Germplasm Resources Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A
| | - Sylvie Dallot
- CIRAD, UMR PHIM, 34398 Montpellier, France
- PHIM Plant Health Institute, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Zachary S L Foster
- Horticultural Crops Disease and Pest Management Research Unit, USDA-ARS, Corvallis, OR 97330, U.S.A
| | - Jean H Daugrois
- CIRAD, UMR PHIM, 34398 Montpellier, France
- PHIM Plant Health Institute, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Emmanuel Fernandez
- CIRAD, UMR PHIM, 34398 Montpellier, France
- PHIM Plant Health Institute, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | | | | | - Xiaojun Hu
- Plant Germplasm Quarantine Program, USDA-APHIS, Beltsville, MD 20705, U.S.A
| | - Bishwo Adhikari
- Plant Germplasm Quarantine Program, USDA-APHIS, Beltsville, MD 20705, U.S.A
| | - Martha Malapi
- Plant Germplasm Quarantine Program, USDA-APHIS, Beltsville, MD 20705, U.S.A
| | - Niklaus J Grünwald
- Horticultural Crops Disease and Pest Management Research Unit, USDA-ARS, Corvallis, OR 97330, U.S.A
| | - Philippe Roumagnac
- CIRAD, UMR PHIM, 34398 Montpellier, France
- PHIM Plant Health Institute, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Dimitre Mollov
- Horticultural Crops Disease and Pest Management Research Unit, USDA-ARS, Corvallis, OR 97330, U.S.A
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3
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Sparks AH, Ponte EMD, Alves KS, Foster ZSL, Grünwald NJ. Openness and Computational Reproducibility in Plant Pathology: Where We Stand and a Way Forward. Phytopathology 2023; 113:1159-1170. [PMID: 36624724 DOI: 10.1094/phyto-10-21-0430-per] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Open research practices have been highlighted extensively during the last 10 years in many fields of scientific study as essential standards needed to promote transparency and reproducibility of scientific results. Scientific claims can only be evaluated based on how protocols, materials, equipment, and methods were described; data were collected and prepared; and analyses were conducted. Openly sharing protocols, data, and computational code is central to current scholarly dissemination and communication, but in many fields, including plant pathology, adoption of these practices has been slow. We randomly selected 450 articles published from 2012 to 2021 across 21 journals representative of the plant pathology discipline and assigned them scores reflecting their openness and computational reproducibility. We found that most of the articles did not follow protocols for open science and failed to share data or code in a reproducible way. We propose that use of open-source tools facilitates computationally reproducible work and analyses, benefitting not just readers but the authors as well. Finally, we provide ideas and suggest tools to promote open, reproducible computational research practices among plant pathologists. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Adam H Sparks
- Department of Primary Industries and Regional Development, Perth, WA 6000, Australia
- University of Southern Queensland, Centre for Crop Health, Toowoomba, Qld 4350, Australia
| | | | - Kaique S Alves
- Departmento de Fitopatologia, Universidade Federal de Viçosa, Brazil
| | - Zachary S L Foster
- Horticultural Crops Disease and Pest Management Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
| | - Niklaus J Grünwald
- Horticultural Crops Disease and Pest Management Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
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4
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Iruegas-Bocardo F, Weisberg AJ, Riutta ER, Kilday K, Bonkowski JC, Creswell T, Daughtrey ML, Rane K, Grünwald NJ, Chang JH, Putnam ML. Whole Genome Sequencing-Based Tracing of a 2022 Introduction and Outbreak of Xanthomonas hortorum pv. pelargonii. Phytopathology 2023; 113:975-984. [PMID: 36515656 DOI: 10.1094/phyto-09-22-0321-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Globalization has made agricultural commodities more accessible, available, and affordable. However, their global movement increases the potential for invasion by pathogens and necessitates development and implementation of sensitive, rapid, and scalable surveillance methods. Here, we used 35 strains, isolated by multiple diagnostic laboratories, as a case study for using whole genome sequence data in a plant disease diagnostic setting. Twenty-seven of the strains were isolated in 2022 and identified as Xanthomonas hortorum pv. pelargonii. Eighteen of these strains originated from material sold by a plant breeding company that had notified clients following a release of infected geranium cuttings. Analyses of whole genome sequences revealed epidemiological links among the 27 strains from different growers that confirmed a common source of the outbreak and uncovered likely secondary spread events within facilities that housed plants originating from different plant breeding companies. Whole genome sequencing data were also analyzed to reveal how preparatory and analytical methods can impact conclusions on outbreaks of clonal pathogenic strains. The results demonstrate the potential power of using whole genome sequencing among a network of diagnostic labs and highlight how sharing such data can help shorten response times to mitigate outbreaks more expediently and precisely than standard methods.
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Affiliation(s)
| | - Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Elizabeth R Riutta
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Kameron Kilday
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - John C Bonkowski
- Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907
| | - Tom Creswell
- Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907
| | - Margery L Daughtrey
- Long Island Horticultural Research and Extension Center, Cornell University, Riverhead, NY 11901
| | - Karen Rane
- Department of Entomology, University of Maryland, College Park, MD 20742
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97331
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Melodie L Putnam
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
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5
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Kronmiller BA, Feau N, Shen D, Tabima JF, Ali SS, Armitage AD, Arredondo F, Bailey BA, Bollmann SR, Dale A, Harrison RJ, Hrywkiw K, Kasuga T, McDougal R, Nellist CF, Panda P, Tripathy S, Williams NM, Ye W, Wang Y, Hamelin RC, Grünwald NJ. Comparative Genomic Analysis of 31 Phytophthora Genomes Reveals Genome Plasticity and Horizontal Gene Transfer. Mol Plant Microbe Interact 2023; 36:26-46. [PMID: 36306437 DOI: 10.1094/mpmi-06-22-0133-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Phytophthora species are oomycete plant pathogens that cause great economic and ecological impacts. The Phytophthora genus includes over 180 known species, infecting a wide range of plant hosts, including crops, trees, and ornamentals. We sequenced the genomes of 31 individual Phytophthora species and 24 individual transcriptomes to study genetic relationships across the genus. De novo genome assemblies revealed variation in genome sizes, numbers of predicted genes, and in repetitive element content across the Phytophthora genus. A genus-wide comparison evaluated orthologous groups of genes. Predicted effector gene counts varied across Phytophthora species by effector family, genome size, and plant host range. Predicted numbers of apoplastic effectors increased as the host range of Phytophthora species increased. Predicted numbers of cytoplasmic effectors also increased with host range but leveled off or decreased in Phytophthora species that have enormous host ranges. With extensive sequencing across the Phytophthora genus, we now have the genomic resources to evaluate horizontal gene transfer events across the oomycetes. Using a machine-learning approach to identify horizontally transferred genes with bacterial or fungal origin, we identified 44 candidates over 36 Phytophthora species genomes. Phylogenetic reconstruction indicates that the transfers of most of these 44 candidates happened in parallel to major advances in the evolution of the oomycetes and Phytophthora spp. We conclude that the 31 genomes presented here are essential for investigating genus-wide genomic associations in genus Phytophthora. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Brent A Kronmiller
- Center for Quantitative Life Sciences, Oregon State University, Corvallis, OR, U.S.A
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - Nicolas Feau
- Department of Forest and Conservation Sciences, The University of British Columbia, Vancouver, Canada
| | - Danyu Shen
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
| | - Javier F Tabima
- Department of Biology, Clark University, Worcester, MA, U.S.A
| | - Shahin S Ali
- Sustainable Perennial Crops Laboratory, Northeast Area, USDA/ARS, Beltsville Agricultural Research Center-West, Beltsville, MD, U.S.A
| | - Andrew D Armitage
- Natural Resources Institute, University of Greenwich, Chatham Maritime, U.K
| | - Felipe Arredondo
- Center for Quantitative Life Sciences, Oregon State University, Corvallis, OR, U.S.A
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - Bryan A Bailey
- Sustainable Perennial Crops Laboratory, Northeast Area, USDA/ARS, Beltsville Agricultural Research Center-West, Beltsville, MD, U.S.A
| | - Stephanie R Bollmann
- Department of Integrative Biology, Oregon State University, Corvallis, OR, U.S.A
| | - Angela Dale
- Department of Forest and Conservation Sciences, The University of British Columbia, Vancouver, Canada
- SC-New Construction Materials, FPInnovations, Vancouver, V6T 1Z4, Canada
| | | | - Kelly Hrywkiw
- Department of Forest and Conservation Sciences, The University of British Columbia, Vancouver, Canada
| | - Takao Kasuga
- Crops Pathology and Genetics Research Unit, Agricultural Research Service, United States Department of Agriculture, Davis, CA, U.S.A
| | - Rebecca McDougal
- Scion (Zealand Forest Research Institute), 49 Sala Street, Te Papa Tipu Innovation Park, Private Bag 3020, Rotorua, New Zealand
| | | | - Preeti Panda
- The New Zealand Institute for Plant and Food Research Ltd, 74 Gerald Street, Lincoln, 7608, New Zealand
| | | | - Nari M Williams
- Scion (Zealand Forest Research Institute), 49 Sala Street, Te Papa Tipu Innovation Park, Private Bag 3020, Rotorua, New Zealand
- Department of Pathogen Ecology and Control, Plant and Food Research, Private Bag 1401, Havelock North, New Zealand
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
| | - Richard C Hamelin
- Department of Forest and Conservation Sciences, The University of British Columbia, Vancouver, Canada
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada
- Département des sciences du bois et de la forêt, Faculté de Foresterie et Géographie, Université Laval, Québec, Canada
| | - Niklaus J Grünwald
- Horticultural Crop Research Unit, United States Department of Agriculture, Agricultural Research Service, Corvallis, OR, U.S.A
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6
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LeBoldus JM, Navarro SM, Kline N, Ritokova G, Grünwald NJ. Repeated Emergence of Sudden Oak Death in Oregon: Chronology, Impact, and Management. Plant Dis 2022; 106:3013-3021. [PMID: 35486603 DOI: 10.1094/pdis-02-22-0294-fe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It has been two decades since the first detection of the sudden oak death pathogen Phytophthora ramorum in Oregon forests. Although the epidemic was managed since its first discovery in 2001, at least three invasions of three separate variants (clonal lineages), NA1, EU1, and NA2, are documented to have occurred to date. Control of this epidemic has cost over US$32 million from 2001 to 2020. This is dwarfed by the predicted cost of the closure to the Coos Bay export terminal, estimated at $58 million per year, if the epidemic was allowed to spread unchecked. Management efforts in Oregon have reduced inoculum and limited the spread of the pathogen. An outreach and citizen scientist program has been piloted to help in early detection efforts and search for disease-resistant tanoak. This feature article documents the repeated emergence, impact, costs, and lessons learned from managing this devastating invasive pathogen.
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Affiliation(s)
- Jared M LeBoldus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
- Forest Engineering, Resources and Management Department, Oregon State University, Corvallis, OR
| | | | - Norma Kline
- Forest Engineering, Resources and Management Department, Oregon State University, Corvallis, OR
| | | | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR
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7
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Hamelin RC, Bilodeau GJ, Heinzelmann R, Hrywkiw K, Capron A, Dort E, Dale AL, Giroux E, Kus S, Carleson NC, Grünwald NJ, Feau N. Genomic biosurveillance detects a sexual hybrid in the sudden oak death pathogen. Commun Biol 2022; 5:477. [PMID: 35589982 PMCID: PMC9120034 DOI: 10.1038/s42003-022-03394-w] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 04/21/2022] [Indexed: 11/24/2022] Open
Abstract
Invasive exotic pathogens pose a threat to trees and forest ecosystems worldwide, hampering the provision of essential ecosystem services such as carbon sequestration and water purification. Hybridization is a major evolutionary force that can drive the emergence of pathogens. Phytophthora ramorum, an emergent pathogen that causes the sudden oak and larch death, spreads as reproductively isolated divergent clonal lineages. We use a genomic biosurveillance approach by sequencing genomes of P. ramorum from survey and inspection samples and report the discovery of variants of P. ramorum that are the result of hybridization via sexual recombination between North American and European lineages. We show that these hybrids are viable, can infect a host and produce spores for long-term survival and propagation. Genome sequencing revealed genotypic combinations at 54,515 single nucleotide polymorphism loci not present in parental lineages. More than 6,000 of those genotypes are predicted to have a functional impact in genes associated with host infection, including effectors, carbohydrate-active enzymes and proteases. We also observed post-meiotic mitotic recombination that could generate additional genotypic and phenotypic variation and contribute to homoploid hybrid speciation. Our study highlights the importance of plant pathogen biosurveillance to detect variants, including hybrids, and inform management and control. Genome sequencing of isolates of the pathogen responsible for sudden oak death in the United States and sudden larch death in Europe reveal hybridisation between European and American lineages.
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Affiliation(s)
- Richard C Hamelin
- The Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada.
| | | | - Renate Heinzelmann
- The Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada.,Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Kelly Hrywkiw
- The Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Arnaud Capron
- The Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Erika Dort
- The Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Angela L Dale
- New Construction Materials, FPInnovations, Vancouver, BC, Canada
| | - Emilie Giroux
- Ottawa Plant Laboratory, Canadian Food Inspection Agency, Ottawa, ON, Canada
| | - Stacey Kus
- New Construction Materials, FPInnovations, Vancouver, BC, Canada
| | - Nick C Carleson
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Niklaus J Grünwald
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.,Horticultural Crops Research Unit, USDA ARS, Corvallis, OR, USA
| | - Nicolas Feau
- The Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada.
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8
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Peterson EK, Grünwald NJ, Parke JL. Risk of Epidemic Development in Nurseries from Soil Inoculum of Phytophthora ramorum. Phytopathology 2022; 112:1046-1054. [PMID: 34664977 DOI: 10.1094/phyto-06-21-0245-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Soilborne inoculum arising from buried, infested leaf debris may contribute to the persistence of Phytophthora ramorum at recurrently positive nurseries. To initiate new epidemics, inoculum must not only survive but also produce sporangia during times conducive to infection at the soil surface. To assess this risk, we performed two year-long experiments in a soil plot at the National Ornamentals Research Site at Dominican University of California. Inoculated rhododendron leaf disks were buried at a depth of 5 or 15 cm in the early summer of 2014 or 2015. Inoculum was baited at the soil surface with noninfested leaf disks (2014 only) and then retrieved to assess pathogen viability and sporulation capacity every 5 weeks. Two 14-week-long trials were conducted in 2016. We were able to consistently culture P. ramorum over all time periods. Soil incubation rapidly reduced the capacity of inoculum to sporulate, especially at 5 cm; however, sporulation capacity increased with the onset of seasonally cooler temperatures. P. ramorum was baited most frequently between November and January, especially from inoculum buried at 5 cm 1 day before the baiting period; in January we also baited P. ramorum from inoculum buried at 15 cm the previous June. We validate prior observations that P. ramorum poses a greater risk after exposure to cooler temperatures and provide evidence that infested leaf debris plays a role in the perpetuation of P. ramorum in nurseries. This work provides novel insights into the survival and epidemic behavior of P. ramorum in nursery soils.
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Affiliation(s)
- Ebba K Peterson
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Niklaus J Grünwald
- Horticultural Crops Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97331
| | - Jennifer L Parke
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
- Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331
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9
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Mestas A, Weiland JE, Scagel CF, Grünwald NJ, Davis EA, Mitchell JN, Beck BR. Is Disease Induced by Flooding Representative of Nursery Conditions in Rhododendrons Infected with Phytophthora cinnamomi or P. plurivora? Plant Dis 2022; 106:1157-1166. [PMID: 34784743 DOI: 10.1094/pdis-06-21-1340-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The degree of flooding commonly used to induce disease in Phytophthora root rot studies rarely occurs in container nurseries. Instead, over-irrigation and poor drainage result in plants periodically sitting in shallow pools of water. Rhododendron plants were grown in a noninfested substrate or substrate infested with Phytophthora cinnamomi or P. plurivora to determine whether root rot induced by flooding represents disease that occurs under simulated nursery conditions when plants are in a shallow pool of water (saucers), or are allowed to freely drain and maintained at ∼75% container capacity (CC). Generally P. cinnamomi caused more disease than P. plurivora, and all water treatments were conducive to root rot. In experiment 1, the amount of disease caused by flooding was similar to that in the saucer treatment (75% CC not tested) while in experiment 2, flooding often caused more rapid and severe disease than the saucer or 75% CC treatment. Pathogens differed in their response to water treatments. P. cinnamomi caused more disease in treatments with >90% substrate moisture for either a short (flood) or long duration (saucer), while P. plurivora was less capable of causing disease when soil moisture was maintained >90% than when substrate moisture was maintained at a more moderate level (flood, 75% CC). Our results indicate that it is not necessary to flood plants to induce disease under experimental conditions and that disease induced by flooding can represent disease in container nurseries when containers are in pools of water or maintained at ∼75% CC. In addition, our results suggest that P. cinnamomi is a more aggressive pathogen than P. plurivora in nursery conditions where drainage is poor; however, both species are capable of causing a similar amount of disease under more typical irrigation management.
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Affiliation(s)
- Angie Mestas
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Jerry E Weiland
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Carolyn F Scagel
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Niklaus J Grünwald
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - E Anne Davis
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Jesse N Mitchell
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Bryan R Beck
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
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10
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Affiliation(s)
- Nicholas C Carleson
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - Caroline M Press
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR, U.S.A
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR, U.S.A
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Peterson EK, Sondreli KL, Reeser P, Navarro SM, Nichols C, Wiese R, Fieland V, Grünwald NJ, LeBoldus JM. First report of the NA2 clonal lineage of the sudden oak death pathogen, Phytophthora ramorum, infecting tanoak in Oregon forests. Plant Dis 2022; 106:2537. [PMID: 35147452 DOI: 10.1094/pdis-10-21-2152-pdn] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Phytophthora ramorum Werres, de Cock & Man in't Veld, causal agent of sudden oak death (SOD) and ramorum leaf blight, is comprised of four clonal lineages in its invasive ranges of North America and Europe (Grünwald et al. 2012, Van Poucke et al. 2012). Of these, three - the NA1, NA2, and EU1 lineages - are found in U.S. nurseries, but only two, the NA1 and EU1 lineages, have been found infecting trees in North American forests (Grünwald et al. 2012, 2016). In the spring of 2021, tanoak (Notholithocarpus densiflorus Manos, Cannon & Oh) displaying symptoms consistent with SOD were detected north of Port Orford (Curry County, Oregon). Symptoms were canopy dieback and blackened petiole and stem lesions on tanoak sprouts. The pathogen isolated on PAR (CMA plus 200 ml/L ampicillin, 10 mg/L rifamycin, 66.7 mg/L PCNB) selective media was determined to be P. ramorum based on characteristic morphology of hyphae, sporangia, and chlamydospores (Werres et al. 2001). Positive identification as P. ramorum was obtained with a lineage-specific LAMP assay targeting an NA2 orphan gene, indicating the presence of the NA2 lineage. NA2 was confirmed by sequencing a portion of the cellulose binding elicitor lectin (CBEL) gene using CBEL5U and CBEL6L primers (Gagnon et al. 2014). Sequences (GenBank accessions MZ733981 and MZ733982) were aligned against reference sequences for all lineages (Gagnon et al. 2014) confirming the presence of NA2. Lineage determination as NA2 was further confirmed at eleven SSR loci (ILVOPrMS145, PrMS39, PrMS9C3, ILVOPrMS79, KI18, KI64, PrMS45, PrMS6, ILVOPrMS131, KI82ab, and PrMS43) using the methods of Kamvar et al. (2015). We completed Koch's postulates using potted tanoaks, wound-inoculated at the midpoint of 1-year old stems with either hyphal plugs or non-colonized agar (n=4 per treatment). Tanoaks were maintained in a growth chamber (20°C-day / 18°C-night temperatures) with regular watering and an 18-photoperiod using F32T8 fluorescent bulbs (Phillips, Eindhoven, The Netherlands). After 7 days, brown to black lesions 1.2 to 2.9 cm in length were observed on the inoculated stems, from which P. ramorum was subsequently re-isolated; no symptoms were observed on the controls, and no pathogens were recovered when plating the wound sites in PAR. This is the first detection of the NA2 lineage causing disease in forests worldwide. The outbreak was found on private and public lands in forests typical to the SOD outbreak in Oregon (mixed conifer and tanoak), and was 33 km north of the closest known P. ramorum infestation. Follow-up ground surveys on adjacent lands have identified over 100 P. ramorum-positive tanoak trees, from which additional NA2 isolates have been recovered from bole cankers. NA2 is thought to be more aggressive than the NA1 lineage (Elliott et al. 2011), which has been present in Curry County since the mid-1990s (Goheen et al. 2017). Eradication of the NA2 lineage is being pursued to slow its further spread and prevent overlap with existing NA1 and EU1 populations. The repeated introductions of novel lineages into the western United States native plant communities highlights the vulnerability of this region to Phytophthora establishment, justifying continued monitoring for P. ramorum in nurseries and forests. References • Elliott, M, et al. 2011. For. Path. 41:7. https://doi.org/10.1111/j.1439-0329.2009.00627.x • Gagnon, M.-C., et al. 2014. Can. J. Plant Pathol. 36:367. https://doi.org/10.1080/07060661.2014.924999 • Goheen, E.M., et al. 2017. For. Phytophthoras 7:45. https://doi: 10.5399/osu/fp.7.1.4030 • Grünwald, N. J., et al. 2012. Trends Microbiol. 20:131. https://doi.org/10.1016/j.tim.2011.12.006 • Grünwald, N. J., et al. 2016. Plant Dis. 100:1024. https://doi.org/10.1094/PDIS-10-15-1169-PDN • Kamvar, Z.N. et al. 2015. Phytopath. 105:982. https://doi.org/10.1094/PHYTO-12-14-0350-FI • Van Poucke, K., et al. 2012. Fungal Biol. 116:1178. https://doi.org/10.1016/j.funbio.2012.09.003 • Werres, S., et al. 2001. Mycol. Res. 105: 1155. https://doi.org/10.1016/S0953-7562(08)61986-3.
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Affiliation(s)
- Ebba K Peterson
- Oregon State University, 2694, Botany and Plant Pathology, Corvallis, Oregon, United States;
| | - Kelsey Liann Sondreli
- Oregon State University, 2694, Botany & Plant Pathology, Corvallis, Oregon, United States;
| | - Paul Reeser
- Oregon State University, 2694, Botany and Plant Pathology, Corvallis, Oregon, United States;
| | - Sarah M Navarro
- United States Department of Agriculture Forest Service Pacific Northwest Region, 114606, State and Private Forests, Forest Health Protection, Portland, Oregon, United States;
| | - Casara Nichols
- Oregon Department of Forestry, 260065, Salem, Oregon, United States;
| | - Randall Wiese
- Oregon Department of Forestry, Salem, Oregon, United States;
| | - Valerie Fieland
- Oregon State University, 2694, Botany and Plant Pathology, Corvallis, Oregon, United States;
| | - Niklaus J Grünwald
- USDA Agricultural Research Service, 17123, Horticultural Crops Research Lab, Corvallis, Oregon, United States;
| | - Jared M LeBoldus
- Oregon State University, 2694, Botany and Plant Pathology, Corvallis, Oregon, United States
- Oregon State University, 2694, Forest Engineering, Resources and Management, Corvallis, Oregon, United States;
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12
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Weisberg AJ, Miller M, Ream W, Grünwald NJ, Chang JH. Diversification of plasmids in a genus of pathogenic and nitrogen-fixing bacteria. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200466. [PMID: 34839700 PMCID: PMC8628075 DOI: 10.1098/rstb.2020.0466] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Members of the agrobacteria-rhizobia complex (ARC) have multiple and diverse plasmids. The extent to which these plasmids are shared and the consequences of their interactions are not well understood. We extracted over 4000 plasmid sequences from 1251 genome sequences and constructed a network to reveal interactions that have shaped the evolutionary histories of oncogenic virulence plasmids. One newly discovered type of oncogenic plasmid is a mosaic with three incomplete, but complementary and partially redundant virulence loci. Some types of oncogenic plasmids recombined with accessory plasmids or acquired large regions not known to be associated with pathogenicity. We also identified two classes of partial virulence plasmids. One class is potentially capable of transforming plants, but not inciting disease symptoms. Another class is inferred to be incomplete and non-functional but can be found as coresidents of the same strain and together are predicted to confer pathogenicity. The modularity and capacity for some plasmids to be transmitted broadly allow them to diversify, convergently evolve adaptive plasmids and shape the evolution of genomes across much of the ARC. This article is part of the theme issue 'The secret lives of microbial mobile genetic elements'.
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Affiliation(s)
- Alexandra J. Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Marilyn Miller
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Walt Ream
- Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA
| | - Niklaus J. Grünwald
- Horticultural Crops Research Laboratory, United States Department of Agriculture and Agricultural Research Service, Corvallis, OR 97330, USA
| | - Jeff H. Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
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13
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Weisberg AJ, Grünwald NJ, Savory EA, Putnam ML, Chang JH. Genomic Approaches to Plant-Pathogen Epidemiology and Diagnostics. Annu Rev Phytopathol 2021; 59:311-332. [PMID: 34030448 DOI: 10.1146/annurev-phyto-020620-121736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Diseases have a significant cost to agriculture. Findings from analyses of whole-genome sequences show great promise for informing strategies to mitigate risks from diseases caused by phytopathogens. Genomic approaches can be used to dramatically shorten response times to outbreaks and inform disease management in novel ways. However, the use of these approaches requires expertise in working with big, complex data sets and an understanding of their pitfalls and limitations to infer well-supported conclusions. We suggest using an evolutionary framework to guide the use of genomic approaches in epidemiology and diagnostics of plant pathogens. We also describe steps that are necessary for realizing these as standard approaches in disease surveillance.
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Affiliation(s)
- Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA;
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, Oregon 97331, USA
| | | | - Melodie L Putnam
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA;
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA;
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14
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Shakya SK, Grünwald NJ, Fieland VJ, Knaus BJ, Weiland JE, Maia C, Drenth A, Guest DI, Liew ECY, Crane C, Chang TT, Fu CH, Minh Chi N, Quang Thu P, Scanu B, von Stowasser ES, Durán Á, Horta Jung M, Jung T. Phylogeography of the wide-host range panglobal plant pathogen Phytophthora cinnamomi. Mol Ecol 2021; 30:5164-5178. [PMID: 34398981 DOI: 10.1111/mec.16109] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 06/09/2021] [Accepted: 07/28/2021] [Indexed: 12/27/2022]
Abstract
Various hypotheses have been proposed regarding the origin of the plant pathogen Phytophthora cinnamomi. P. cinnamomi is a devastating, highly invasive soilborne pathogen associated with epidemics of agricultural, horticultural and forest plantations and native ecosystems worldwide. We conducted a phylogeographic analysis of populations of this pathogen sampled in Asia, Australia, Europe, southern and northern Africa, South America, and North America. Based on genotyping-by-sequencing, we observed the highest genotypic diversity in Taiwan and Vietnam, followed by Australia and South Africa. Mating type ratios were in equal proportions in Asia as expected for a sexual population. Simulations based on the index of association suggest a partially sexual, semi-clonal mode of reproduction for the Taiwanese and Vietnamese populations while populations outside of Asia are clonal. Ancestral area reconstruction provides new evidence supporting Taiwan as the ancestral area, given our sample, indicating that this region might be near or at the centre of origin for this pathogen as speculated previously. The Australian and South African populations appear to be a secondary centre of diversity following migration from Taiwan or Vietnam. Our work also identified two panglobal, clonal lineages PcG1-A2 and PcG2-A2 of A2 mating type found on all continents. Further surveys of natural forests across Southeast Asia are needed to definitively locate the actual centre of origin of this important plant pathogen.
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Affiliation(s)
- Shankar K Shakya
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Niklaus J Grünwald
- Horticultural Crop Research Unit, United States Department of Agriculture, Agricultural Research Service, Corvallis, Oregon, USA
| | - Valerie J Fieland
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Brian J Knaus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Jerry E Weiland
- Horticultural Crop Research Unit, United States Department of Agriculture, Agricultural Research Service, Corvallis, Oregon, USA
| | - Cristiana Maia
- Centre of Marine Sciences (CCMAR), Faculty of Sciences and Technology, University of Algarve, Faro, Portugal
| | - André Drenth
- Centre for Horticultural Science, The University of Queensland, Ecosciences Precinct, Brisbane, Queensland, Australia
| | - David I Guest
- Sydney Institute of Agriculture, School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
| | - Edward C Y Liew
- Research Centre for Ecosystem Resilience, Australian Institute of Botanical Science, The Royal Botanic Gardens and Domain Trust, Sydney, NSW, Australia
| | - Colin Crane
- Vegetation Health Service, Kensington, Washington, Australia
| | - Tun-Tschu Chang
- Forest Protection Division, Taiwan Forestry Research Institute, Taipei, Taiwan
| | - Chuen-Hsu Fu
- Forest Protection Division, Taiwan Forestry Research Institute, Taipei, Taiwan
| | - Nguyen Minh Chi
- Forest Protection Research Centre, Vietnamese Academy of Forest Sciences, Hanoi, Vietnam
| | - Pham Quang Thu
- Forest Protection Research Centre, Vietnamese Academy of Forest Sciences, Hanoi, Vietnam
| | - Bruno Scanu
- Department of Agricultural Sciences, University of Sassari, Sassari, Italy
| | - Eugenio Sanfuentes von Stowasser
- Laboratorio de Patología Forestal, Facultad Ciencias Forestales y Centro de Biotecnología, Universidad de Concepción, Concepción, Chile
| | - Álvaro Durán
- Bioforest S.A., Casilla 70-C, Concepción, Chile.,Research and Development, Asia Pacific Resources International Limited, Pangkalan Kerinci, Indonesia
| | - Marilia Horta Jung
- Phytophthora Research Centre, Department of Forest Protection and Wildlife Management, Mendel University in Brno, Brno, Czech Republic
| | - Thomas Jung
- Phytophthora Research Centre, Department of Forest Protection and Wildlife Management, Mendel University in Brno, Brno, Czech Republic
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Weiland JE, Scagel CF, Grünwald NJ, Davis EA, Beck BR. Phytophthora Species Differ in Response to Phosphorous Acid and Mefenoxam for the Management of Phytophthora Root Rot in Rhododendron. Plant Dis 2021; 105:1505-1514. [PMID: 33337240 DOI: 10.1094/pdis-09-20-1960-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Phytophthora root rot, caused by many soilborne Phytophthora spp., is a significant disease affecting the $42 million rhododendron nursery industry. Rhododendron growers have increasingly reported failure by two systemic fungicides, phosphorous acid and mefenoxam, to adequately control root rot. Both fungicides may be applied as a foliar spray or soil drench but it is unknown how application method, fungicide chemistry, or pathogen diversity affects disease control. Therefore, two experiments were conducted to (i) determine whether differences in application method or fungicide chemistry affect control of root rot caused by P. cinnamomi and P. plurivora and (ii) evaluate the sensitivity of Phytophthora spp. and isolates from the rhododendron industry to each fungicide. Results demonstrated that soil drenches of either fungicide were more effective than foliar sprays for control of P. cinnamomi but were ineffective for P. plurivora. Furthermore, Phytophthora spp. and isolates varied in sensitivity to phosphorous acid and mefenoxam, and there were multiple fungicide-insensitive isolates, especially within P. plurivora. Differences in sensitivity were also observed among isolates from different nurseries and production systems, with some nurseries having less sensitive isolates than others and with container systems generally having less sensitive isolates than field systems. Our results provide three potential reasons for why fungicide control of Phytophthora root rot might fail: (i) the fungicide can be applied to the wrong portion of the plant for optimal control, (ii) there are differences in fungicide sensitivity among soilborne Phytophthora spp. and isolates infecting rhododendron, and (iii) fungicide-insensitive isolates are present in the rhododendron nursery industry.
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Affiliation(s)
- Jerry E Weiland
- United States Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Laboratory, 3420 NW Orchard Avenue, Corvallis, OR 97330
| | - Carolyn F Scagel
- United States Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Laboratory, 3420 NW Orchard Avenue, Corvallis, OR 97330
| | - Niklaus J Grünwald
- United States Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Laboratory, 3420 NW Orchard Avenue, Corvallis, OR 97330
| | - E Anne Davis
- United States Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Laboratory, 3420 NW Orchard Avenue, Corvallis, OR 97330
| | - Bryan R Beck
- United States Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Laboratory, 3420 NW Orchard Avenue, Corvallis, OR 97330
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16
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Block M, Knaus BJ, Wiseman MS, Grünwald NJ, Gent DH. Development of a Diagnostic Assay for Race Differentiation of Podosphaera macularis. Plant Dis 2021; 105:965-971. [PMID: 32915117 DOI: 10.1094/pdis-06-20-1289-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Hop powdery mildew (caused by Podosphaera macularis) was confirmed in the Pacific Northwest in 1996. Before 2012, the most common race of P. macularis was able to infect plants that possessed powdery mildew resistance based on the R-genes Rb, R3, and R5. After 2012, two additional races of P. macularis were discovered that can overcome the resistance gene R6 and the partial resistance found in the cultivar Cascade. These three races now occur throughout the region, which can complicate management and research efforts because of uncertainty on which race(s) may be present in the region and able to infect susceptible hop genotypes. Current methods for determining the races of P. macularis are labor intensive, costly, and typically require more than 14 days to obtain results. We sought to develop a molecular assay to differentiate races of the fungus possessing virulence on plants with R6, referred to as V6-virulent, from other races. The transcriptomes of 46 isolates of P. macularis were sequenced to identify loci and variants unique to V6 isolates. Fourteen primer pairs were designed for 10 candidate loci that contained single nucleotide polymorphisms (SNP) and short insertion-deletion polymorphisms. Two differentially labeled locked nucleic acid probes were designed for a contig that contained a conserved SNP associated with V6-virulence. The resulting duplexed real-time PCR assay was validated against 46 V6 and 54 non-V6 P. macularis isolates collected from the United States and Europe. The assay had perfect discrimination of V6-virulence among isolates of P. macularis originating from the western U.S. but failed to predict V6-virulence in three isolates collected from Europe. The specificity of the assay was tested with different species of powdery mildew fungi and other microorganisms associated with hop. Weak nonspecific amplification occurred with powdery mildew fungi collected from Vitis vinifera, Fragaria sp., and Zinnia sp.; however, nonspecification amplification is not a concern when differentiating pathogen race from colonies on hop. The assay has practical applications in hop breeding, epidemiological studies, and other settings where rapid confirmation of pathogen race is needed.
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Affiliation(s)
- Mary Block
- Oregon State University, Department of Crop and Soil Science, Corvallis, OR 97331
| | - Brian J Knaus
- Oregon State University, Department of Horticulture, Corvallis, OR 97331
| | - Michele S Wiseman
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331
| | - Niklaus J Grünwald
- U.S. Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Unit, Corvallis, OR 97330
| | - David H Gent
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331
- U.S. Department of Agriculture-Agricultural Research Service, Forage Seed and Cereal Research Unit, Corvallis, OR 97331
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17
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Carleson NC, Daniels HA, Reeser PW, Kanaskie A, Navarro SM, LeBoldus JM, Grünwald NJ. Novel Introductions and Epidemic Dynamics of the Sudden Oak Death Pathogen Phytophthora ramorum in Oregon Forests. Phytopathology 2021; 111:731-740. [PMID: 33021878 DOI: 10.1094/phyto-05-20-0164-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Sudden oak death caused by Phytophthora ramorum has been actively managed in Oregon since the early 2000s. To date, this epidemic has been driven mostly by the NA1 clonal lineage of P. ramorum, but an outbreak of the EU1 lineage has recently emerged. Here, we contrast the population dynamics of the NA1 outbreak first reported in 2001 to the outbreak of the EU1 lineage first detected in 2015. We performed tests to determine whether any of the lineages were introduced more than once. Infested regions of the forest were sampled between 2013 and 2018 (n = 903), and strains were genotyped at 15 microsatellite loci. Most genotypes observed were transient, with 272 of 358 unique genotypes emerging during one year and disappearing the next year. The diversity of EU1 was very low and isolates were spatially clustered (less than 8 km apart), suggesting a single EU1 introduction. Some forest isolates are genetically similar to isolates collected from a local nursery in 2012, suggesting the introduction of EU1 from this nursery or simultaneous introduction to both the nursery and latently into the forest. In contrast, the older NA1 populations were more polymorphic and spread more than 30 km2. A principal component analysis supported two to four independent NA1 introductions. The NA1 and EU1 epidemics infest the same area but show disparate demographics because of the initial introductions of the lineages spaced 10 years apart. Comparing these epidemics provides novel insight regarding patterns of emergence of clonal pathogens in forest ecosystems.
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Affiliation(s)
- Nicholas C Carleson
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
| | - Hazel A Daniels
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
| | - Paul W Reeser
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
| | | | | | - Jared M LeBoldus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
- Forest Engineering, Resources and Management Department, Oregon State University, Corvallis, OR
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR
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Garbelotto M, Dovana F, Schmidt D, Chee C, Lee C, Fieland V, Grünwald NJ, Valachovic Y. First reports of Phytophthora ramorum clonal lineages NA1 and EU1 causing Sudden Oak Death on tanoaks in Del Norte County, California. Plant Dis 2021; 105:2737. [PMID: 33461317 DOI: 10.1094/pdis-12-20-2633-pdn] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A year of forest health surveys has led to the first detection of Phytophthora ramorum in Del Norte County followed by the first wildland detection of the EU1 clonal lineage (Grunwald et al. 2009) of this pathogen in California. In July 2019, leaves were sampled from two tanoaks (Notholithocarpus densiflorus) and 16 California bay laurels (Umbellularia californica) in Jedediah Smith State Park in Del Norte County, the northernmost coastal County of California. Leaves displayed lesions normally associated with Sudden Oak Death (SOD) caused by P. ramorum and were discovered during the citizen science-based survey known as SOD Blitz (Meentemeyer et al. 2015). Samples were surface sterilized using 75% Ethanol and plated on PARPH-V8 agar (Jeffers and Martin 1986). After plating, DNA was extracted and amplified using two P. ramorum-specific assays (Hayden et al. 2006, Kroon et al. 2004). Leaves from two tanoaks exhibiting twig die-back had typical SOD lesions along the midvein, gave positive PCR results and yielded cultures with colony morphology, sporangia and chlamydospores typical of the NA1 lineage of P. ramorum originally isolated in California from tanoaks and coast live oaks (Quercus agrifolia) (Rizzo et al. 2002). The ITS locus and a portion of the Cox-1 locus were sequenced from DNA extracts of each culture using primers DC6-ITS4 (Bonants et al. 2004) and COXF4N-COXR4N (Kroon et al. 2004), respectively. ITS sequences (GB MN540639-40) were typical of P. ramorum and Cox-1 sequences (GB MN540142-3) perfectly matched the Cox-1 sequence of the NA1 lineage (GB DQ832718) (Kroon et al. 2004). Microsatellite alleles were generated as described in Croucher et al. (2013) for the two Del Norte cultures and for eight P. ramorum cultures, representative of the four main multilocus genotypes (MLGs) present in California, namely c1 (Santa Cruz/Commercial Nurseries), c3 (San Francisco Bay Area), c2 (Monterey County), and c4 (Humboldt County) (Croucher et al. 2013). The two Del Norte MLGs were identical to one another and most similar to MLG c1, with a single repeat difference at a single locus. SSR results suggest the inoculum source may not be from Humboldt County, neighboring to the South, but from a yet unidentified outbreak, possibly associated with ornamental plants. Jedediah Smith State Park was surveyed for 12 months following the initial detection, however the pathogen has yet to be re-isolated in that location. In July 2020, SOD symptomatic leaves from two tanoak trees exhibiting twig cankers were collected 8 Km north of Jedediah Smith State Park, where three additional tanoak trees displayed rapidly browned dead canopies consistent with late stage SOD. Leaves were processed as above. Colonies from these samples produced chlamydospores and sporangia typical of P. ramorum on PARPH-V8 agar, but displayed a growth rate faster than that of NA1 genotypes and were characterized by aerial hyphae, overall resembling the morphology of EU1 lineage colonies (Brasier 2003). The EU1 lineage was confirmed by the perfect match of the sequence of a portion of the Cox-1 gene (GB MW349116-7) with the Cox-1 sequence of EU1 genotypes (GB EU124926). The EU1 clonal lineage has been previously isolated from tanoaks in Oregon forests, approximately 55 Km to the North (Grünwald et al. 2016), but this is the first report for California wildlands and will require containment and government regulations. It is unknown whether the EU1 strains in Del Norte County originated from Oregon forests or elsewhere.
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Affiliation(s)
| | - Francesco Dovana
- University of California Berkeley, 1438, ESMP, Berkeley, California, United States;
| | - Douglas Schmidt
- University of California Berkeley, 1438, Environmental Science, Policy, and Management, Berkeley, California, United States;
| | - Cameron Chee
- University of California Berkeley, 1438, ESMP, Berkeley, California, United States;
| | - Chris Lee
- California Department of Forestry and Fire Protection, Fortuna, California, United States;
| | - Valerie Fieland
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, Oregon, United States;
| | - Niklaus J Grünwald
- USDA ARS, Horticultural Crops Research Lab, 3420 NW Orcahrd Ave., Corvallis, Oregon, United States, 97330;
| | - Yana Valachovic
- University of California Cooperative Extension Humboldt and Del Norte, Arcata, California, United States;
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19
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Grünwald NJ. Entering the international year of fruits and vegetables: tradeoffs between food production and the environment. CABI Agric Biosci 2021; 2:2. [PMID: 33748771 PMCID: PMC7809233 DOI: 10.1186/s43170-021-00023-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Niklaus J. Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Services, Corvallis, OR USA
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20
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Abstract
Phylogeography combines geographic information with phylogenetic and population genomic approaches to infer the evolutionary history of a species or population in a geographic context. This approach has been instrumental in understanding the emergence, spread, and evolution of a range of plant pathogens. In particular, phylogeography can address questions about where a pathogen originated, whether it is native or introduced, and when and how often introductions occurred. We review the theory, methods, and approaches underpinning phylogeographic inference and highlight applications providing novel insights into the emergence and spread of select pathogens. We hope that this review will be useful in assessing the power, pitfalls, and opportunities presented by various phylogeographic approaches.
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Affiliation(s)
- David A Rasmussen
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC
| | - Niklaus J Grünwald
- Horticultural Crops Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR
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21
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Weldon WA, Knaus BJ, Grünwald NJ, Havill JS, Block MH, Gent DH, Cadle-Davidson LE, Gadoury DM. Transcriptome-Derived Amplicon Sequencing Markers Elucidate the U.S. Podosphaera macularis Population Structure Across Feral and Commercial Plantings of Humulus lupulus. Phytopathology 2021; 111:194-203. [PMID: 33044132 DOI: 10.1094/phyto-07-20-0299-fi] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Obligately biotrophic plant pathogens pose challenges in population genetic studies due to their genomic complexities and elaborate culturing requirements with limited biomass. Hop powdery mildew (Podosphaera macularis) is an obligately biotrophic ascomycete that threatens sustainable hop production. P. macularis populations of the Pacific Northwest (PNW) United States differ from those of the Midwest and Northeastern United States, lacking one of two mating types needed for sexual recombination and harboring two strains that are differentially aggressive on the cultivar Cascade and able to overcome the Humulus lupulus R-gene R6 (V6), respectively. To develop a high-throughput marker platform for tracking the flow of genotypes across the United States and internationally, we used an existing transcriptome of diverse P. macularis isolates to design a multiplex of 54 amplicon sequencing markers, validated across a panel of 391 U.S. samples and 123 international samples. The results suggest that P. macularis from U.S. commercial hop yards form one population closely related to P. macularis of the United Kingdom, while P. macularis from U.S. feral hop locations grouped with P. macularis of Eastern Europe. Included in this multiplex was a marker that successfully tracked V6-virulence in 65 of 66 samples with a confirmed V6-phenotype. A new qPCR assay for high-throughput genotyping of P. macularis mating type generated the highest resolution distribution map of P. macularis mating type to date. Together, these genotyping strategies enable the high-throughput and inexpensive tracking of pathogen spread among geographical regions from single-colony samples and provide a roadmap to develop markers for other obligate biotrophs.
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Affiliation(s)
- William A Weldon
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Brian J Knaus
- Department of Botany and Plant Pathology, Corvallis, OR 97331
| | - Niklaus J Grünwald
- U.S. Department of Agriculture-Agricultural Research Service Horticultural Crops Research Unit, Corvallis, OR 97330
| | - Joshua S Havill
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108
| | - Mary H Block
- Department of Botany and Plant Pathology, Corvallis, OR 97331
| | - David H Gent
- U.S. Department of Agriculture-Agricultural Research Service Forage Seed and Cereal Research Unit, Corvallis, OR 97331
| | - Lance E Cadle-Davidson
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
- U.S. Department of Agriculture-Agricultural Research Service Grape Genetics Research Unit, Geneva, NY 14456
| | - David M Gadoury
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
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22
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Tabima JF, Gonen L, Gómez-Gallego M, Panda P, Grünwald NJ, Hansen EM, McDougal R, LeBoldus JM, Williams NM. Molecular Phylogenomics and Population Structure of Phytophthora pluvialis. Phytopathology 2021; 111:108-115. [PMID: 33048632 DOI: 10.1094/phyto-06-20-0232-fi] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Phytophthora pluvialis is an oomycete that was first isolated from soil, water, and tree foliage in mixed Douglas-fir-tanoak forests of the U.S. Pacific Northwest (PNW). It was then identified as the causal agent of red needle cast of radiata pine (Pinus radiata) in New Zealand (NZ). Genotyping-by-sequencing was used to obtain 1,543 single nucleotide polymorphisms across 145 P. pluvialis isolates to characterize the population structure in the PNW and NZ. We tested the hypothesis that P. pluvialis was introduced to NZ from the PNW using genetic distance measurements and population structure analyses among locations between countries. The low genetic distance, population heterozygosity, and lack of geographic structure in NZ suggest a single colonization event from the United States followed by clonal expansion in NZ. The PNW Coast Range was proposed as a presumptive center of origin of the currently known distribution of P. pluvialis based on its geographic range and position as the central cluster in a minimum spanning network. The Coastal cluster of isolates were located at the root of every U.S. cluster and emerged earlier than all NZ clusters. The Coastal cluster had the highest degree of heterozygosity (Hs = 0.254) and median pairwise genetic distance (0.093) relative to any other cluster. Finally, the rapid host diversification between closely related isolates of P. pluvialis in NZ indicate that this pathogen has the potential to infect a broader range of hosts than is currently recognized.
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Affiliation(s)
- Javier F Tabima
- Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, OR 97331, U.S.A
- Department of Biology, Clark University, The Lasry Center for Bioscience, Worcester, MA 01610, U.S.A
| | - Lilah Gonen
- Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, OR 97331, U.S.A
| | - Mireia Gómez-Gallego
- New Zealand Forest Research Institute (Scion), 49 Sala Street, Te Papa Tipu Innovation Park, Private Bag 3020, Rotorua 3046, New Zealand
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, 750 07 Uppsala, Sweden
- UMR IAM-Interactions Arbres-Microorganismes, Université de Lorraine, INRAE, Nancy 54000, France
| | - Preeti Panda
- New Zealand Forest Research Institute (Scion), 49 Sala Street, Te Papa Tipu Innovation Park, Private Bag 3020, Rotorua 3046, New Zealand
- Department of Pathogen Ecology and Control, Plant and Food Research, Private Bag 1401, Havelock North 4130, New Zealand
| | - Niklaus J Grünwald
- USDA Agricultural Research Service, Horticultural Research Unit, 3420 NW Orchard Ave., Corvallis, OR 97331, U.S.A
| | - Everett M Hansen
- Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, OR 97331, U.S.A
| | - Rebecca McDougal
- New Zealand Forest Research Institute (Scion), 49 Sala Street, Te Papa Tipu Innovation Park, Private Bag 3020, Rotorua 3046, New Zealand
| | - Jared M LeBoldus
- Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, OR 97331, U.S.A
- Department of Forest Engineering, Resources and Management, Oregon State University, Peavy Forest Science Center, Corvallis, OR 97331, U.S.A
| | - Nari M Williams
- New Zealand Forest Research Institute (Scion), 49 Sala Street, Te Papa Tipu Innovation Park, Private Bag 3020, Rotorua 3046, New Zealand
- Department of Pathogen Ecology and Control, Plant and Food Research, Private Bag 1401, Havelock North 4130, New Zealand
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23
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Weisberg AJ, Davis EW, Tabima J, Belcher MS, Miller M, Kuo CH, Loper JE, Grünwald NJ, Putnam ML, Chang JH. Unexpected conservation and global transmission of agrobacterial virulence plasmids. Science 2020; 368:368/6495/eaba5256. [PMID: 32499412 DOI: 10.1126/science.aba5256] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/28/2020] [Accepted: 04/27/2020] [Indexed: 12/21/2022]
Abstract
The accelerated evolution and spread of pathogens are threats to host species. Agrobacteria require an oncogenic Ti or Ri plasmid to transfer genes into plants and cause disease. We developed a strategy to characterize virulence plasmids and applied it to analyze hundreds of strains collected between 1927 and 2017, on six continents and from more than 50 host species. In consideration of prior evidence for prolific recombination, it was surprising that oncogenic plasmids are descended from a few conserved lineages. Characterization of a hierarchy of features that promote or constrain plasticity allowed inference of the evolutionary history across the plasmid lineages. We uncovered epidemiological patterns that highlight the importance of plasmid transmission in pathogen diversification as well as in long-term persistence and the global spread of disease.
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Affiliation(s)
- Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Edward W Davis
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97331, USA
| | - Javier Tabima
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Michael S Belcher
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Marilyn Miller
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Joyce E Loper
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97331, USA.,Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR 97331, USA
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR 97331, USA
| | - Melodie L Putnam
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA. .,Molecular and Cellular Biology Program, Oregon State University, Corvallis, OR 97331, USA.,Center for Genome Research and Biocomputing (CGRB), Oregon State University, Corvallis, OR 97331, USA
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24
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Weiland JE, Scagel CF, Grünwald NJ, Davis EA, Beck BR, Foster ZSL, Fieland VJ. Soilborne Phytophthora and Pythium Diversity From Rhododendron in Propagation, Container, and Field Production Systems of the Pacific Northwest. Plant Dis 2020; 104:1841-1850. [PMID: 32370604 DOI: 10.1094/pdis-08-19-1672-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Rhododendron root rot is a severe disease that causes significant mortality in rhododendrons. Information is needed about the incidence and identity of soilborne Phytophthora and Pythium species causing root rot in Pacific Northwest nurseries in order to better understand the disease etiology and to optimize disease control strategies. The last survey focusing solely on soilborne oomycete pathogens in rhododendron production was conducted in 1974. Since then, advances in pathogen identification have occurred, new species may have been introduced, pathogen communities may have shifted, and little is known about Pythium species affecting this crop. Therefore, a survey of root-infecting Phytophthora and Pythium species was conducted at seven nurseries from 2013 to 2017 to (i) document the incidence of root rot damage at each nursery and stage of production, (ii) identify soilborne oomycetes infecting rhododendron, and (iii) determine whether there are differences in pathogen diversity among nurseries and production systems. Rhododendrons from propagation, container, and field systems were sampled and Phytophthora and Pythium species were isolated from the roots and collar region. Root rot was rarely evident in propagation systems, which were dominated by Pythium species. However, severe root rot was much more common in container and field systems where the genus Phytophthora was also more prevalent, suggesting that Phytophthora species are the primary cause of severe root rot and that most contamination by these pathogens comes in after the propagation stage. In total, 20 Pythium species and 11 Phytophthora species were identified. Pythium cryptoirregulare, Pythium aff. macrosporum, Phytophthora plurivora, and Phytophthora cinnamomi were the most frequently isolated species and the results showed that Phytophthora plurivora has become much more common than in the past. Phytophthora diversity was also greater in field systems than in propagation or container systems. Risks for Phytophthora contamination were commonly observed during the survey and included placement of potting media in direct contact with field soil, the presence of dead plants that could serve as continuous sources of inoculum, and the presence of excess water as a result of poor drainage, overirrigation, or malfunctioning irrigation equipment. In the past, research on disease development and root rot disease control in rhododendron focused almost exclusively on Phytophthora cinnamomi. More research is needed on both of these topics for the other root-infecting species identified in this survey.
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Affiliation(s)
- Jerry E Weiland
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture Agricultural Research Service, Corvallis, OR 97330
| | - Carolyn F Scagel
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture Agricultural Research Service, Corvallis, OR 97330
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture Agricultural Research Service, Corvallis, OR 97330
| | - E Anne Davis
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture Agricultural Research Service, Corvallis, OR 97330
| | - Bryan R Beck
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture Agricultural Research Service, Corvallis, OR 97330
| | - Zachary S L Foster
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331
| | - Valerie J Fieland
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331
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25
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Gent DH, Claassen BJ, Gadoury DM, Grünwald NJ, Knaus BJ, Radišek S, Weldon W, Wiseman MS, Wolfenbarger SN. Population Diversity and Structure of Podosphaera macularis in the Pacific Northwestern United States and Other Populations. Phytopathology 2020; 110:1105-1116. [PMID: 32091314 DOI: 10.1094/phyto-12-19-0448-r] [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] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Powdery mildew, caused by Podosphaera macularis, is one of the most important diseases of hop. The disease was first reported in the Pacific Northwestern United States, the primary hop-growing region in this country, in the mid-1990s. More recently, the disease has reemerged in newly planted hopyards of the eastern United States, as hop production has expanded to meet demands of local craft brewers. The spread of strains virulent on previously resistant cultivars, the paucity of available fungicides, and the potential introduction of the MAT1-2 mating type to the western United States, all threaten sustainability of hop production. We sequenced the transcriptome of 104 isolates of P. macularis collected throughout the western United States, eastern United States, and Europe to quantify genetic diversity of pathogen populations and elucidate the possible origins of pathogen populations in the western United States. Discriminant analysis of principal components grouped isolates within three to five geographic populations, dependent on stringency of grouping criteria. Isolates from the western United States were phenotyped and categorized into one of three pathogenic races based on disease symptoms generated on differential cultivars. Western U.S. populations were clonal, irrespective of pathogenic race, and grouped with isolates originating from Europe. Isolates originating from wild hop plants in the eastern United States were genetically differentiated from all other populations, whereas isolates from cultivated hop plants in the eastern United States mostly grouped with isolates originating from the west, consistent with origins from nursery sources. Mating types of isolates originating from cultivated western and eastern U.S. hop plants were entirely MAT1-1. In contrast, a 1:1 ratio of MAT1-1 and MAT1-2 was observed with isolates sampled from wild plants or Europe. Within the western United States a set of highly differentiated loci were identified in P. macularis isolates associated with virulence to the powdery mildew R-gene R6. The weight of genetic and phenotypic evidence suggests a European origin of the P. macularis populations in the western United States, followed by spread of the pathogen from the western United States to re-emergent production regions in the eastern United States. Furthermore, R6 compatibility appears to have been selected from an extant isolate within the western United States. Greater emphasis on sanitation measures during propagation and quarantine policies should be considered to limit further spread of novel genotypes of the pathogen, both between and within production areas.
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Affiliation(s)
- David H Gent
- U.S. Department of Agriculture-Agricultural Research Service, Forage Seed and Cereal Research Unit, Corvallis, OR 97331, U.S.A
| | - Briana J Claassen
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331, U.S.A
| | - David M Gadoury
- Plant Pathology and Plant-Microbe Biology Section, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, U.S.A
| | - Niklaus J Grünwald
- U.S. Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Unit, Corvallis, OR 97330, U.S.A
| | - Brian J Knaus
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331, U.S.A
| | | | - William Weldon
- Plant Pathology and Plant-Microbe Biology Section, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, U.S.A
| | - Michele S Wiseman
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331, U.S.A
| | - Sierra N Wolfenbarger
- Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331, U.S.A
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26
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Adams TM, Armitage AD, Sobczyk MK, Bates HJ, Tabima JF, Kronmiller BA, Tyler BM, Grünwald NJ, Dunwell JM, Nellist CF, Harrison RJ. Genomic Investigation of the Strawberry Pathogen Phytophthora fragariae Indicates Pathogenicity Is Associated With Transcriptional Variation in Three Key Races. Front Microbiol 2020; 11:490. [PMID: 32351458 PMCID: PMC7174552 DOI: 10.3389/fmicb.2020.00490] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 03/06/2020] [Indexed: 01/08/2023] Open
Abstract
The oomycete Phytophthora fragariae is a highly destructive pathogen of cultivated strawberry (Fragaria × ananassa), causing the root rotting disease, "red core". The host-pathogen interaction has a well described gene-for-gene resistance relationship, but to date neither candidate avirulence nor resistance genes have been identified. We sequenced a set of American, Canadian, and United Kingdom isolates of known race type, along with three representatives of the closely related pathogen of the raspberry (Rubus idaeus), P. rubi, and found a clear population structure, with a high degree of nucleotide divergence seen between some race types and abundant private variation associated with race types 4 and 5. In contrast, between isolates defined as United Kingdom races 1, 2, and 3 (UK1-2-3) there was no evidence of gene loss or gain; or the presence of insertions/deletions (INDELs) or Single Nucleotide Polymorphisms (SNPs) within or in proximity to putative pathogenicity genes could be found associated with race variation. Transcriptomic analysis of representative UK1-2-3 isolates revealed abundant expression variation in key effector family genes associated with pathogen race; however, further long read sequencing did not reveal any long range polymorphisms to be associated with avirulence to race UK2 or UK3 resistance, suggesting either control in trans or other stable forms of epigenetic modification modulating gene expression. This work reveals the combined power of population resequencing to uncover race structure in pathosystems and in planta transcriptomic analysis to identify candidate avirulence genes. This work has implications for the identification of putative avirulence genes in the absence of associated expression data and points toward the need for detailed molecular characterisation of mechanisms of effector regulation and silencing in oomycete plant pathogens.
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Affiliation(s)
- Thomas M. Adams
- Department of Genetics, Genomics and Breeding, NIAB EMR, Kent, United Kingdom
- School of Agriculture, Policy and Development, University of Reading, Reading, United Kingdom
| | - Andrew D. Armitage
- Department of Genetics, Genomics and Breeding, NIAB EMR, Kent, United Kingdom
| | - Maria K. Sobczyk
- Department of Genetics, Genomics and Breeding, NIAB EMR, Kent, United Kingdom
| | - Helen J. Bates
- Department of Genetics, Genomics and Breeding, NIAB EMR, Kent, United Kingdom
| | - Javier F. Tabima
- Department of Botany and Plant Pathology, Center for Genome Biology and Biocomputing, Oregon State University, Corvallis, OR, United States
| | - Brent A. Kronmiller
- Center for Genome Biology and Biocomputing, Oregon State University, Corvallis, OR, United States
| | - Brett M. Tyler
- Department of Botany and Plant Pathology, Center for Genome Biology and Biocomputing, Oregon State University, Corvallis, OR, United States
- Center for Genome Biology and Biocomputing, Oregon State University, Corvallis, OR, United States
| | - Niklaus J. Grünwald
- Horticultural Crops Research Unit, Agricultural Research Service, United States Department of Agriculture, Corvallis, OR, United States
| | - Jim M. Dunwell
- School of Agriculture, Policy and Development, University of Reading, Reading, United Kingdom
| | | | - Richard J. Harrison
- Department of Genetics, Genomics and Breeding, NIAB EMR, Kent, United Kingdom
- NIAB Cambridge Crop Research, NIAB, Cambridge, United Kingdom
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27
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Diao Y, Larsen MM, Kamvar ZN, Zhang C, Li S, Wang W, Lin D, Peng Q, Knaus BJ, Foster ZSL, Grünwald NJ, Liu X. Genetic Differentiation and Clonal Expansion of Chinese Botrytis cinerea Populations from Tomato and Other Crops in China. Phytopathology 2020; 110:428-439. [PMID: 31454305 DOI: 10.1094/phyto-09-18-0347-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Botrytis cinerea is an important pathogen of vegetable and fruit crops but little is known about its population structure and genetics in China. We hypothesized that the geographic populations of B. cinerea in China would be genetically differentiated by host, geographic location, and/or year. In this study, we collected 393 B. cinerea isolates representing 28 populations from tomato, cherry, and nectarine from 2006 to 2014 in China. The isolates were analyzed using 14 microsatellite markers, including six new markers that provided more genotyping power than the eight previously published loci. We also investigated the B. cinerea population structure and inferred its mode of reproduction and dispersal based on genotype data. High genotypic diversity was detected in all populations, and clonal reproduction was dominant. Southern China populations harbored more genotypes than northern populations. Differentiation by host plant was evident. Between 2011 and 2012, genotypes changed only slightly among years for Liaoning populations, but they changed substantially among years for the Shanghai and Fujian populations. Clonal dispersal was detected and the farthest dispersal distance was estimated to be about 1,717 km. Two high-frequency genotypes were widely distributed in more than 10 populations and across several years. Our results provide useful, novel information for plant breeding programs and control of B. cinerea in China.
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Affiliation(s)
- Yongzhao Diao
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China 100193
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97330, U.S.A
| | - Meredith M Larsen
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
| | - Zhian N Kamvar
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97330, U.S.A
| | - Can Zhang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China 100193
| | - Shuo Li
- China Animal Disease Control Center, Beijing, China 100125
| | - Weizhen Wang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China 100193
| | - Dong Lin
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China 100193
| | - Qin Peng
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China 100193
| | - Brian J Knaus
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
| | - Zachary S L Foster
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97330, U.S.A
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
| | - Xili Liu
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China 100193
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28
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Dung JKS, Knaus BJ, Fellows HLS, Grünwald NJ, Vining KJ. Genetic Diversity of Verticillium dahliae Isolates From Mint Detected with Genotyping by Sequencing. Phytopathology 2019; 109:1966-1974. [PMID: 31246137 DOI: 10.1094/phyto-12-18-0475-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Verticillium wilt is the most important disease threatening the commercial production of mint grown for essential oil. An important long-term goal for mint breeders is the production of cultivars with resistance to Verticillium wilt. Before that can be accomplished, a better understanding of the genetic variation within and among populations of Verticillium dahliae is needed. We characterized the extent of phenotypic and genetic diversity present in contemporary and archival populations of V. dahliae from mint fields in Oregon and other production regions of the United States using genotyping by sequencing, PCR assays for mating type and pathogenic race, vegetative compatibility group (VCG) tests, and aggressiveness assays. We report that the population in the Pacific Northwest can be described as one common genetic group and four relatively rare genetic groups. Eighty-three percent of the isolates belonged to VCG2B, and all isolates possessed the MAT1-2 idiomorph and were characterized as pathogenic race 2. These results indicate low levels of genetic diversity and a negligible risk of sexual recombination in populations of this host-adapted pathogen population. Knowledge of the genetic structure of V. dahliae in the Pacific Northwest will inform breeders about the diversity of pathogenicity factors that may need to be considered in their breeding programs.
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Affiliation(s)
- Jeremiah K S Dung
- Central Oregon Agricultural Research and Extension Center, Madras, OR 97741
| | - Brian J Knaus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Henry L S Fellows
- Department of Horticulture, Oregon State University, Corvallis, OR 97331
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture Agricultural Research Service, Corvallis, OR 97331
| | - Kelly J Vining
- Department of Horticulture, Oregon State University, Corvallis, OR 97331
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29
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Abstract
Downy mildew of grape caused by Plasmopara viticola is a global pathogen of economic importance to commercial viticulture. In contrast to populations in the northern hemisphere, few studies have investigated the population biology, genetic diversity, and origin of the pathogen in Australian production systems. DNA was extracted from 381 P. viticola samples from Vitis vinifera and alternate hosts collected via fresh and herbarium leaves from populations within Australia and Whatman FTA cards from North America, Brazil, and Uruguay. A total of 32 DNA samples were provided from a French population. The populations were genotyped using 16 polymorphic microsatellite markers. Representative samples from within Australia, Brazil, and Uruguay were also genotyped to determine which of the cryptic species (clades) within the P. viticola species complex were present. Our findings suggest the Australian and South American populations of P. viticola are more closely related to the European population than the North American population, the reported source of origin of the pathogen. The Western Australian population had similarities to the South Australian population, and the tight clustering of samples suggests a single introduction into Western Australia. P. viticola clade aestivalis was the only clade detected in Australian and South American populations. Analysis of the Western Australian population suggests that it is reproducing clonally, but additional research is required to determine the mechanism as to how this is occurring.
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Affiliation(s)
- Andrew S Taylor
- Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia
- Department of Primary Industries and Regional Development, Bunbury, Western Australia 6230, Australia
| | - Brian J Knaus
- Horticultural Crops Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
| | - Niklaus J Grünwald
- Horticultural Crops Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330, U.S.A
| | - Treena Burgess
- Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia
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Franić I, Prospero S, Hartmann M, Allan E, Auger-Rozenberg MA, Grünwald NJ, Kenis M, Roques A, Schneider S, Sniezko R, Williams W, Eschen R. Are traded forest tree seeds a potential source of nonnative pests? Ecol Appl 2019; 29:e01971. [PMID: 31302945 DOI: 10.1002/eap.1971] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 06/04/2019] [Accepted: 06/14/2019] [Indexed: 06/10/2023]
Abstract
The international seed trade is considered relatively safe from a phytosanitary point of view and is therefore less regulated than trade in other plants for planting. However, the pests carried by traded seeds are not well known. We assessed insects and fungi in 58 traded seed lots of 11 gymnosperm and angiosperm tree species from North America, Europe, and Asia. Insects were detected by X-raying and molecular methods. The fungal community was characterized using high-throughput sequencing (HTS) and by growing fungi on non-selective agar. About 30% of the seed lots contained insect larvae. Gymnosperms contained mostly hymenopteran (Megastigmus spp.) and dipteran (Cecidomyiidae) larvae, while angiosperms contained lepidopteran (Cydia latiferreana) and coleopteran (Curculio spp.) larvae. HTS indicated the presence of fungi in all seed lots and fungi grew on non-selective agar from 96% of the seed lots. Fungal abundance and diversity were much higher than insect diversity and abundance, especially in angiosperm seeds. Almost 50% of all fungal exact sequence variants (ESVs) found in angiosperms were potential pathogens, in comparison with around 30% of potentially pathogenic ESVs found in gymnosperms. The results of this study indicate that seeds may pose a greater risk of pest introduction than previously believed or accounted for. A rapid risk assessment suggests that only a small number of species identified in this study is of phytosanitary concern. However, more research is needed to enable better risk assessment, especially to increase knowledge about the potential for transmission of fungi to seedlings and the host range and impact of identified species.
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Affiliation(s)
- Iva Franić
- CABI, Delémont, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Simone Prospero
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Martin Hartmann
- Institute of Agricultural Sciences, ETH Zürich, Zürich, Switzerland
| | - Eric Allan
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | | | | | | | | | - Salome Schneider
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Richard Sniezko
- Dorena Genetic Resource Center, USDA Forest Service, Cottage Grove, Oregon , 97424, USA
| | - Wyatt Williams
- Private Forests Division, Oregon Department of Forestry, Salem, Oregon, 97310, USA
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31
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Gent DH, Adair N, Knaus BJ, Grünwald NJ. Genotyping-by-Sequencing Reveals Fine-Scale Differentiation in Populations of Pseudoperonospora humuli. Phytopathology 2019; 109:1801-1810. [PMID: 31199202 DOI: 10.1094/phyto-12-18-0485-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pseudoperonospora humuli is the causal agent of downy mildew of hop, one of the most important diseases of this plant and a limiting factor for production of susceptible cultivars in certain environments. The degree of genetic diversity and population differentiation within and among P. humuli populations at multiple spatial scales was quantified using genotyping-by-sequencing to test the hypothesis that populations of P. humuli have limited genetic diversity but are differentiated at the scale of individual hop yards. Hierarchical sampling was conducted to collect isolates from three hop yards in Oregon, plants within these yards, and infected shoots within heavily diseased plants. Additional isolates also were collected broadly from other geographic regions and from the two previously described clades of the sister species, P. cubensis. Genotyping of these 240 isolates produced a final quality-filtered data set of 216 isolates possessing 25,227 variants. Plots of G'ST values indicated that the majority of variants had G'ST values near 0 and were scattered randomly across contig positions. However, there was a subset of variants that were highly differentiated (G'ST > 0.3) and reproducible when genotyped independently. Within P. humuli, there was evidence of genetic differentiation at the level of hop yards and plants within yards; 19.8% of the genetic variance was associated with differences among yards and 20.3% of the variance was associated with plants within the yard. Isolates of P. humuli were well differentiated from two isolates of P. cubensis representative of the two clades of this organism. There was strong evidence of linkage disequilibrium in variant loci, consistent with nonrandom assortment of alleles expected from inbreeding and/or asexual recombination. Mantel tests found evidence that the genetic distance between isolates collected from heavily diseased plants within a hop yard was associated with the physical distance of the plants from which the isolates were collected. The sum of the data presented here indicates that populations of P. humuli are consistent with a clonal or highly inbred genetic structure with a small, yet significant differentiation of populations among yards and plants within yards. Fine-scale genetic differentiation at the yard and plant scales may point to persistence of founder genotypes associated with planting material, and chronic, systemic infection of hop plants by P. humuli. More broadly, genotyping-by-sequencing appears to have sufficient resolution to identify rare variants that differentiate subpopulations within organisms with limited genetic variability.
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Affiliation(s)
- David H Gent
- Forage Seed and Cereal Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97331
| | - Nanci Adair
- Forage Seed and Cereal Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Corvallis, OR 97331
| | - Brian J Knaus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
| | - Niklaus J Grünwald
- U.S. Department of Agriculture-Agricultural Research Service, Horticultural Crops Research Unit, Corvallis, OR 97330
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32
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Tabima JF, Grünwald NJ. effectR: An Expandable R Package to Predict Candidate RxLR and CRN Effectors in Oomycetes Using Motif Searches. Mol Plant Microbe Interact 2019; 32:1067-1076. [PMID: 30951442 DOI: 10.1094/mpmi-10-18-0279-ta] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Effectors are small, secreted proteins that facilitate infection of host plants by all major groups of plant pathogens. Effector protein identification in oomycetes relies on identification of open reading frames with certain amino acid motifs among additional minor criteria. To date, identification of effectors relies on custom scripts to identify motifs in candidate open reading frames. Here, we developed the R package effectR, which provides a convenient tool for rapid prediction of effectors in oomycete genomes, or with custom scripts for any genome, in a reproducible way. The effectR package relies on a combination of regular expressions statements and hidden Markov model approaches to predict candidate RxLR and crinkler effectors. Other custom motifs for novel effectors can easily be implemented and added to package updates. The effectR package has been validated with published oomycete genomes. This package provides a convenient tool for wet lab researchers interested in reproducible identification of candidate effectors in oomycete genomes.
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Affiliation(s)
- Javier F Tabima
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, OR 97330, U.S.A
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33
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Tabima JF, Grünwald NJ. effectR: An Expandable R Package to Predict Candidate RxLR and CRN Effectors in Oomycetes Using Motif Searches. Mol Plant Microbe Interact 2019; 32:1067-1076. [PMID: 30951442 DOI: 10.1101/398404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Effectors are small, secreted proteins that facilitate infection of host plants by all major groups of plant pathogens. Effector protein identification in oomycetes relies on identification of open reading frames with certain amino acid motifs among additional minor criteria. To date, identification of effectors relies on custom scripts to identify motifs in candidate open reading frames. Here, we developed the R package effectR, which provides a convenient tool for rapid prediction of effectors in oomycete genomes, or with custom scripts for any genome, in a reproducible way. The effectR package relies on a combination of regular expressions statements and hidden Markov model approaches to predict candidate RxLR and crinkler effectors. Other custom motifs for novel effectors can easily be implemented and added to package updates. The effectR package has been validated with published oomycete genomes. This package provides a convenient tool for wet lab researchers interested in reproducible identification of candidate effectors in oomycete genomes.
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Affiliation(s)
- Javier F Tabima
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, OR 97330, U.S.A
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Abstract
The sudden oak and sudden larch death pathogen Phytophthora ramorum emerged simultaneously in the United States on oak and in Europe on Rhododendron in the 1990s. This pathogen has had a devastating impact on larch plantations in the United Kingdom as well as mixed conifer and oak forests in the Western United States. Since the discovery of this pathogen, a large body of research has provided novel insights into the emergence, epidemiology, and genetics of this pandemic. Genetic and genomic resources developed for P. ramorum have been instrumental in improving our understanding of the epidemiology, evolution, and ecology of this disease. The recent reemergence of EU1 in the United States and EU2 in Europe and the discovery of P. ramorum in Asia provide renewed impetus for research on the sudden oak death pathogen.
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Affiliation(s)
- Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, Oregon 97330, USA;
| | - Jared M LeBoldus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA
- Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, OR 97331-5704, USA
| | - Richard C Hamelin
- Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Faculté de Foresterie et de Géomatique, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec G1V 0A6, Canada
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35
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Carleson NC, Fieland VJ, Scagel CF, Weiland JE, Grünwald NJ. Population Structure of Phytophthora plurivora on Rhododendron in Oregon Nurseries. Plant Dis 2019; 103:1923-1930. [PMID: 31140922 DOI: 10.1094/pdis-12-18-2187-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Phytophthora plurivora is a recently described plant pathogen, formerly recognized as P. citricola. Recent sampling of Pacific Northwest nurseries frequently encountered this pathogen, and it has been shown to be among the most damaging Phytophthora pathogens on ornamentals. We characterized the population structure of P. plurivora in a survey of four Oregon nurseries across three different counties with focus on Rhododendron hosts. Isolates were identified to the species level by Sanger sequencing and/or a PCR-RFLP assay of the internal transcribed spacer (ITS) region. We used genotyping-by-sequencing to determine genetic diversity. Variants were called de novo, resulting in 284 high-quality variants for 61 isolates after stringent filtering. Based on Fst and AMOVA, populations were moderately differentiated among nurseries. Overall, population structure suggested presence of one dominant clonal lineage in all nurseries, as well as isolates of cryptic diversity mostly found in one nursery. Within the clonal lineage, there was a broad range of sensitivity to mefenoxam and phosphorous acid. Sensitivity of the two fungicides was correlated. P. plurivora was previously assumed to spread clonally, and the low genotypic diversity observed within and among isolates corroborated this hypothesis. The broad range of fungicide sensitivity within the P. plurivora population found in PNW nurseries has implications for managing disease caused by this important nursery pathogen. These findings provide the first perspective into P. plurivora population structure and phenotypic plasticity in Pacific Northwest nurseries.
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Affiliation(s)
- Nicholas C Carleson
- 1Department of Botany & Plant Pathology, Oregon State University, Corvallis, OR
| | - Valerie J Fieland
- 1Department of Botany & Plant Pathology, Oregon State University, Corvallis, OR
| | - Carolyn F Scagel
- 2Horticultural Crops Research Unit, United States Department of Agriculture, Agricultural Research Service, Corvallis, OR
| | - Jerry E Weiland
- 2Horticultural Crops Research Unit, United States Department of Agriculture, Agricultural Research Service, Corvallis, OR
| | - Niklaus J Grünwald
- 2Horticultural Crops Research Unit, United States Department of Agriculture, Agricultural Research Service, Corvallis, OR
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36
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Martin FN, Zhang Y, Cooke DEL, Coffey MD, Grünwald NJ, Fry WE. Insights into evolving global populations of Phytophthora infestans via new complementary mtDNA haplotype markers and nuclear SSRs. PLoS One 2019; 14:e0208606. [PMID: 30601865 PMCID: PMC6314598 DOI: 10.1371/journal.pone.0208606] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 11/20/2018] [Indexed: 01/08/2023] Open
Abstract
In many parts of the world the damaging potato late blight pathogen, Phytophthora infestans, is spread as a succession of clonal lineages. The discrimination of genetic diversity within such evolving populations provides insights into the processes generating novel lineages and the pathways and drivers of pathogen evolution and dissemination at local and global scales. This knowledge, in turn, helps optimise management practices. Here we combine two key methods for dissecting mitochondrial and nuclear diversity and resolve intra and inter-lineage diversity of over 100 P. infestans isolates representative of key clonal lineages found globally. A novel set of PCR primers that amplify five target regions are provided for mitochondrial DNA sequence analysis. These five loci increased the number of mtDNA haplotypes resolved from four with the PCR RFLP method to 37 (17, 6, 8 and 4 for Ia, Ib, IIa, and IIb haplotypes, respectively, plus 2 Herb-1 haplotypes). As with the PCR RFLP method, two main lineages, I and II were defined. Group I contained 25 mtDNA haplotypes that grouped broadly according to the Ia and Ib types and resolved several sub-clades amongst the global sample. Group II comprised two distinct clusters with four haplotypes corresponding to the RFLP type IIb and eight haplotypes resolved within type IIa. The 12-plex SSR assay revealed 90 multilocus genotypes providing accurate discrimination of dominant clonal lineages and other genetically diverse isolates. Some association of genetic diversity and geographic region of contemporary isolates was observed; US and Mexican isolates formed a loose grouping, distinct from isolates from Europe, South America and other regions. Diversity within clonal lineages was observed that varied according to the age of the clone. In combination, these fine-scale nuclear and maternally inherited mitochondrial markers enabled a greater level of discrimination among isolates than previously available and provided complementary perspectives on evolutionary questions relating to the diversity, phylogeography and the origins and spread of clonal lineages of P. infestans.
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Affiliation(s)
- Frank N. Martin
- USDA-ARS, Crop Improvement and Protection Research Unit, Salinas, California, United States of America
| | - Yonghong Zhang
- Plant Pathology and Microbiology Department, University of California, Riverside, California, United States of America
| | | | - Mike D. Coffey
- USDA-ARS, Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America
| | - Niklaus J. Grünwald
- USDA-ARS, Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America
| | - William E. Fry
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York, United States of America
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Weiland JE, Scagel CF, Grünwald NJ, Davis EA, Beck BR, Fieland VJ. Variation in Disease Severity Caused by Phytophthora cinnamomi, P. plurivora, and Pythium cryptoirregulare on Two Rhododendron Cultivars. Plant Dis 2018; 102:2560-2570. [PMID: 30346246 DOI: 10.1094/pdis-04-18-0666-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Rhododendrons are an important crop in the ornamental nursery industry, but are prone to Phytophthora root rot. Phytophthora root rot is a continuing issue on rhododendrons despite decades of research. Several Phytophthora species are known to cause root rot, but most research has focused on P. cinnamomi, and comparative information on pathogenicity is limited for other commonly encountered oomycetes, including Phytophthora plurivora and Pythium cryptoirregulare. In this study, three isolates each of P. cinnamomi, P. plurivora, and Py. cryptoirregulare were used to inoculate rhododendron cultivars Cunningham's White and Yaku Princess at two different inoculum levels. All three species caused disease, especially at the higher inoculum level. P. cinnamomi and P. plurivora were the most aggressive pathogens, causing severe root rot, whereas Py. cryptoirregulare was a weak pathogen that only caused mild disease. Within each pathogen species, isolate had no influence on disease. Both P. cinnamomi and P. plurivora caused more severe disease on Cunningham's White than on Yaku Princess, suggesting that the relative resistance and susceptibility among rhododendron cultivars might be similar for both pathogens. Reisolation of P. cinnamomi and P. plurivora was also greater from plants exhibiting aboveground symptoms of wilting and plant death and belowground symptoms of root rot than from those without symptoms. Results show that both P. cinnamomi and P. plurivora, but not Py. cryptoirregulare, are important pathogens causing severe root rot in rhododendron. This study establishes the risks for disease resulting from low and high levels of inoculum for each pathogen. Further research is needed to evaluate longer term risks associated with low inoculum levels on rhododendron health and to explore whether differences among pathogen species affect disease control.
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Affiliation(s)
- Jerry E Weiland
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Carolyn F Scagel
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Niklaus J Grünwald
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - E Anne Davis
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Bryan R Beck
- U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR 97330
| | - Val J Fieland
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
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Bollmann SR, Press CM, Tyler BM, Grünwald NJ. Expansion and Divergence of Argonaute Genes in the Oomycete Genus Phytophthora. Front Microbiol 2018; 9:2841. [PMID: 30555430 PMCID: PMC6284064 DOI: 10.3389/fmicb.2018.02841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 11/05/2018] [Indexed: 01/17/2023] Open
Abstract
Modulation of gene expression through RNA interference is well conserved in eukaryotes and is involved in many cellular processes. In the oomycete Phytophthora, research on the small RNA machinery and function has started to reveal potential roles in the pathogen, but much is still unknown. We examined Argonaute (AGO) homologs within oomycete genome sequences, especially among Phytophthora species, to gain a clearer understanding of the evolution of this well-conserved protein family. We identified AGO homologs across many representative oomycete and stramenopile species, and annotated representative homologs in P. sojae. Furthermore, we demonstrate variable transcript levels of all identified AGO homologs in comparison to previously identified Dicer-like (DCL) and RNA-dependent RNA polymerase (RDR) homologs. Our phylogenetic analysis further refines the relationship of the AGO homologs in oomycetes and identifies a conserved tandem duplication of AGO homologs in a subset of Phytophthora species.
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Affiliation(s)
- Stephanie R Bollmann
- Horticultural Crop Research Unit, Agricultural Research Service, United States Department of Agriculture, Corvallis, OR, United States
| | - Caroline M Press
- Horticultural Crop Research Unit, Agricultural Research Service, United States Department of Agriculture, Corvallis, OR, United States
| | - Brett M Tyler
- Department of Botany and Plant Pathology, Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, United States
| | - Niklaus J Grünwald
- Horticultural Crop Research Unit, Agricultural Research Service, United States Department of Agriculture, Corvallis, OR, United States
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Shakya SK, Larsen MM, Cuenca-Condoy MM, Lozoya-Saldaña H, Grünwald NJ. Variation in Genetic Diversity of Phytophthora infestans Populations in Mexico from the Center of Origin Outwards. Plant Dis 2018; 102:1534-1540. [PMID: 30673430 DOI: 10.1094/pdis-11-17-1801-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Toluca valley, located in central Mexico, is thought to be the center of origin of the potato late blight pathogen Phytophthora infestans. We characterized over 500 individuals of P. infestans sampled from populations with a geographical distance of more than 400 km in six regions adjacent to the Toluca valley in three states including Michoacán, Mexico, and Tlaxcala. Our sampling occurred on a predominant east to west gradient and showed significant genetic differentiation. The most western sampling location found in Michoacán was most differentiated from the other populations. Populations from San Gerónimo, Juchitepec, and Tlaxcala clustered together and appeared to be in linkage equilibrium. This work provides a finer understanding of gradients of genetic diversity in populations of P. infestans at the center of origin.
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Affiliation(s)
- Shankar K Shakya
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
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Arsenault-Labrecque G, Sonah H, Lebreton A, Labbé C, Marchand G, Xue A, Belzile F, Knaus BJ, Grünwald NJ, Bélanger RR. Stable predictive markers for Phytophthora sojae avirulence genes that impair infection of soybean uncovered by whole genome sequencing of 31 isolates. BMC Biol 2018; 16:80. [PMID: 30049268 PMCID: PMC6060493 DOI: 10.1186/s12915-018-0549-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 07/19/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The interaction between oomycete plant pathogen Phytophthora sojae and soybean is characterized by the presence of avirulence (Avr) genes in P. sojae, which encode for effectors that trigger immune responses and resistance in soybean via corresponding resistance genes (Rps). A recent survey highlighted a rapid diversification of P. sojae Avr genes in soybean fields and the need to deploy new Rps genes. However, the full genetic diversity of P. sojae isolates remains complex and dynamic and is mostly characterized on the basis of phenotypic associations with differential soybean lines. RESULTS We sequenced the genomes of 31 isolates of P. sojae, representing a large spectrum of the pathotypes found in soybean fields, and compared all the genetic variations associated with seven Avr genes (1a, 1b, 1c, 1d, 1k, 3a, 6) and how the derived haplotypes matched reported phenotypes in 217 interactions. We discovered new variants, copy number variations and some discrepancies with the virulence of previously described isolates with Avr genes, notably with Avr1b and Avr1c. In addition, genomic signatures revealed 11.5% potentially erroneous phenotypes. When these interactions were re-phenotyped, and the Avr genes re-sequenced over time and analyzed for expression, our results showed that genomic signatures alone accurately predicted 99.5% of the interactions. CONCLUSIONS This comprehensive genomic analysis of seven Avr genes of P. sojae in a population of 31 isolates highlights that genomic signatures can be used as accurate predictors of phenotypes for compatibility with Rps genes in soybean. Our findings also show that spontaneous mutations, often speculated as a source of aberrant phenotypes, did not occur within the confines of our experiments and further suggest that epigenesis or gene silencing do not account alone for previous discordance between genotypes and phenotypes. Furthermore, on the basis of newly identified virulence patterns within Avr1c, our results offer an explanation why Rps1c has failed more rapidly in the field than the reported information on virulence pathotypes.
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Affiliation(s)
| | - Humira Sonah
- Département de Phytologie, Université Laval, Québec, QC Canada
| | | | - Caroline Labbé
- Département de Phytologie, Université Laval, Québec, QC Canada
| | | | - Allen Xue
- Agriculture and Agri-Food Canada, Ontario, ON Canada
| | | | - Brian J. Knaus
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR USA
| | - Niklaus J. Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR USA
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41
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Tabima JF, Coffey MD, Zazada IA, Grünwald NJ. Populations of Phytophthora rubi Show Little Differentiation and High Rates of Migration Among States in the Western United States. Mol Plant Microbe Interact 2018; 31:614-622. [PMID: 29451433 DOI: 10.1094/mpmi-10-17-0258-r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Population genetics is a powerful tool to understand patterns and evolutionary processes that are involved in plant-pathogen emergence and adaptation to agricultural ecosystems. We are interested in studying the population dynamics of Phytophthora rubi, the causal agent of Phytophthora root rot in raspberry. P. rubi is found in the western United States, where most of the fresh and processed raspberries are produced. We used genotyping-by-sequencing to characterize genetic diversity in populations of P. rubi sampled in the United States and other countries. Our results confirm that P. rubi is a monophyletic species with complete lineage sorting from its sister taxon P. fragariae. Overall, populations of P. rubi show low genetic diversity across the western United States. Demographic analyses suggest that populations of P. rubi from the western United States are the source of pathogen migration to Europe. We found no evidence for population differentiation at a global or regional (western United States) level. Finally, our results provide evidence of migration from California and Oregon into Washington. This report provides new insights into the evolution and structure of global and western United States populations of the raspberry pathogen P. rubi, indicating that human activity might be involved in moving the pathogen among regions and fields.
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Affiliation(s)
- Javier F Tabima
- 1 Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A
| | - Michael D Coffey
- 2 Department of Plant Pathology and Microbiology, UC Riverside, Riverside, CA 92521, U.S.A.; and
| | - Inga A Zazada
- 3 Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, OR 97330, U.S.A
| | - Niklaus J Grünwald
- 3 Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, OR 97330, U.S.A
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42
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Chang JH, Putnam ML, Grünwald NJ, Savory EA, Fuller SL, Weisberg AJ. Response to comments on "Evolutionary transitions between beneficial and phytopathogenic Rhodococcus challenge disease management". eLife 2018; 7:35852. [PMID: 29737968 PMCID: PMC5951679 DOI: 10.7554/elife.35852] [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] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 04/13/2018] [Indexed: 11/26/2022] Open
Abstract
Randall et al., 2018 and Vereecke, 2018 have raised concerns about a paper we published (Savory et al., 2017). Here, we respond to those concerns.
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Affiliation(s)
- Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States.,Center for Genome Research and Biocomputing, Oregon State University, Corvallis, United States.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, United States
| | - Melodie L Putnam
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Niklaus J Grünwald
- Department of Agriculture, Agricultural Research Service, Corvallis, United States
| | - Elizabeth A Savory
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Skylar L Fuller
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, United States
| | - Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
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43
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Abstract
Inference of copy number variation presents a technical challenge because variant callers typically require the copy number of a genome or genomic region to be known a priori. Here we present a method to infer copy number that uses variant call format (VCF) data as input and is implemented in the R package vcfR. This method is based on the relative frequency of each allele (in both genic and non-genic regions) sequenced at heterozygous positions throughout a genome. These heterozygous positions are summarized by using arbitrarily sized windows of heterozygous positions, binning the allele frequencies, and selecting the bin with the greatest abundance of positions. This provides a non-parametric summary of the frequency that alleles were sequenced at. The method is applicable to organisms that have reference genomes that consist of full chromosomes or sub-chromosomal contigs. In contrast to other software designed to detect copy number variation, our method does not rely on an assumption of base ploidy, but instead infers it. We validated these approaches with the model system of Saccharomyces cerevisiae and applied it to the oomycete Phytophthora infestans, both known to vary in copy number. This functionality has been incorporated into the current release of the R package vcfR to provide modular and flexible methods to investigate copy number variation in genomic projects.
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Affiliation(s)
- Brian J Knaus
- Horticultural Crops Research Unit, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR, United States
| | - Niklaus J Grünwald
- Horticultural Crops Research Unit, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR, United States
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44
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Savory EA, Fuller SL, Weisberg AJ, Thomas WJ, Gordon MI, Stevens DM, Creason AL, Belcher MS, Serdani M, Wiseman MS, Grünwald NJ, Putnam ML, Chang JH. Correction: Evolutionary transitions between beneficial and phytopathogenic Rhodococcus challenge disease management. eLife 2018. [PMID: 29533183 PMCID: PMC5849409 DOI: 10.7554/elife.36350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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45
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Abstract
The taxa R package provides a set of tools for defining and manipulating taxonomic data. The recent and widespread application of DNA sequencing to community composition studies is making large data sets with taxonomic information commonplace. However, compared to typical tabular data, this information is encoded in many different ways and the hierarchical nature of taxonomic classifications makes it difficult to work with. There are many R packages that use taxonomic data to varying degrees but there is currently no cross-package standard for how this information is encoded and manipulated. We developed the R package taxa to provide a robust and flexible solution to storing and manipulating taxonomic data in R and any application-specific information associated with it. Taxa provides parsers that can read common sources of taxonomic information (taxon IDs, sequence IDs, taxon names, and classifications) from nearly any format while preserving associated data. Once parsed, the taxonomic data and any associated data can be manipulated using a cohesive set of functions modeled after the popular R package dplyr. These functions take into account the hierarchical nature of taxa and can modify the taxonomy or associated data in such a way that both are kept in sync. Taxa is currently being used by the metacoder and taxize packages, which provide broadly useful functionality that we hope will speed adoption by users and developers.
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Affiliation(s)
- Zachary S L Foster
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | | | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR, 97330, USA
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46
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Savory EA, Fuller SL, Weisberg AJ, Thomas WJ, Gordon MI, Stevens DM, Creason AL, Belcher MS, Serdani M, Wiseman MS, Grünwald NJ, Putnam ML, Chang JH. Evolutionary transitions between beneficial and phytopathogenic Rhodococcus challenge disease management. eLife 2017; 6:30925. [PMID: 29231813 PMCID: PMC5726852 DOI: 10.7554/elife.30925] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/03/2017] [Indexed: 02/02/2023] Open
Abstract
Understanding how bacteria affect plant health is crucial for developing sustainable crop production systems. We coupled ecological sampling and genome sequencing to characterize the population genetic history of Rhodococcus and the distribution patterns of virulence plasmids in isolates from nurseries. Analysis of chromosome sequences shows that plants host multiple lineages of Rhodococcus, and suggested that these bacteria are transmitted due to independent introductions, reservoir populations, and point source outbreaks. We demonstrate that isolates lacking virulence genes promote beneficial plant growth, and that the acquisition of a virulence plasmid is sufficient to transition beneficial symbionts to phytopathogens. This evolutionary transition, along with the distribution patterns of plasmids, reveals the impact of horizontal gene transfer in rapidly generating new pathogenic lineages and provides an alternative explanation for pathogen transmission patterns. Results also uncovered a misdiagnosed epidemic that implicated beneficial Rhodococcus bacteria as pathogens of pistachio. The misdiagnosis perpetuated the unnecessary removal of trees and exacerbated economic losses. All organisms live in a world teeming with bacteria. Some bacteria are beneficial and, for example, provide their hosts with nutrients. Others cause harm, for example, by stealing nutrients and causing disease. Many bacteria can also gain DNA from other bacteria, and the genes encoded within the new DNA can help them to live with other organisms. This can start the bacteria on an evolutionary path to becoming beneficial or harmful. Rhodococcus are bacteria that live in association with many species of plants, including trees. Most are harmless but some cause disease. Plants infected with harmful Rhodococcus can show deformed growth, which causes major losses to the nursery industry. Savory, Fuller, Weisberg et al. set out to understand how disease-causing Rhodococcus are introduced into nurseries, if they are transferred between nurseries, whether they persist in nurseries, and how to limit their spread. It turns out that harmless Rhodococcus are beneficial to plants. However, if these harmless bacteria gain a certain DNA molecule – called a virulence plasmid – they can convert into harmful bacteria. Further analysis showed that some nurseries repeatedly acquired the harmful bacteria. The pattern of affected nurseries suggested that some might have purchased diseased plants from a common provider. In other cases, the sources remained a mystery. Savory et al. also report that, contrary to previous findings, there is no evidence to support the diagnosis that Rhodococcus without a virulence plasmid are responsible for an unusual growth problem that has plagued the pistachio industry. In recent years, this incorrect diagnosis led to trees being unnecessarily destroyed, worsening the economic losses. These findings suggest that genes moving between bacteria can dramatically change how those bacteria interact with the organisms in which they live. It needs to be shown whether this is an exceptional process, unique to only certain groups of bacteria, or if it is more widespread in nature. These findings could inform future disease management strategies to better protect agricultural systems.
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Affiliation(s)
- Elizabeth A Savory
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Skylar L Fuller
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, United States
| | - Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - William J Thomas
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Michael I Gordon
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Danielle M Stevens
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Allison L Creason
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, United States
| | - Michael S Belcher
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Maryna Serdani
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Michele S Wiseman
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, United States Department of Agriculture and Agricultural Research Service, Corvallis, United States
| | - Melodie L Putnam
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, United States.,Molecular and Cellular Biology Program, Oregon State University, Corvallis, United States.,Center for Genome Research, Oregon State University, Corvallis, United States
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47
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Tabima JF, Kronmiller BA, Press CM, Tyler BM, Zasada IA, Grünwald NJ. Whole Genome Sequences of the Raspberry and Strawberry Pathogens Phytophthora rubi and P. fragariae. Mol Plant Microbe Interact 2017; 30:767-769. [PMID: 28682157 DOI: 10.1094/mpmi-04-17-0081-a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Phytophthora rubi and P. fragariae are two closely related oomycete plant pathogens that exhibit strong morphological and physiological similarities but are specialized to infect different hosts of economic importance, namely, raspberry and strawberry. Here, we report the draft genome sequences of these two Phytophthora species as a first step toward understanding the genomic processes underlying plant host adaptation in these pathogens.
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Affiliation(s)
- Javier F Tabima
- 1 Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, U.S.A
| | - Brent A Kronmiller
- 2 Center for Genome Biology and Biocomputing (CGRB), Oregon State University; and
| | - Caroline M Press
- 3 Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, OR, 97330, U.S.A
| | - Brett M Tyler
- 1 Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, U.S.A
- 2 Center for Genome Biology and Biocomputing (CGRB), Oregon State University; and
| | - Inga A Zasada
- 3 Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, OR, 97330, U.S.A
| | - Niklaus J Grünwald
- 3 Horticultural Crops Research Laboratory, USDA-ARS, Corvallis, OR, 97330, U.S.A
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48
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Abstract
Population genetic analysis is a powerful tool to understand how pathogens emerge and adapt. However, determining the genetic structure of populations requires complex knowledge on a range of subtle skills that are often not explicitly stated in book chapters or review articles on population genetics. What is a good sampling strategy? How many isolates should I sample? How do I include positive and negative controls in my molecular assays? What marker system should I use? This review will attempt to address many of these practical questions that are often not readily answered from reading books or reviews on the topic, but emerge from discussions with colleagues and from practical experience. A further complication for microbial or pathogen populations is the frequent observation of clonality or partial clonality. Clonality invariably makes analyses of population data difficult because many assumptions underlying the theory from which analysis methods were derived are often violated. This review provides practical guidance on how to navigate through the complex web of data analyses of pathogens that may violate typical population genetics assumptions. We also provide resources and examples for analysis in the R programming environment.
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Affiliation(s)
- N J Grünwald
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
| | - S E Everhart
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
| | - B J Knaus
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
| | - Z N Kamvar
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
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49
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Gagnon MC, Feau N, Dale AL, Dhillon B, Hamelin RC, Brasier CM, Grünwald NJ, Brière SC, Bilodeau GJ. Development and Validation of Polymorphic Microsatellite Loci for the NA2 Lineage of Phytophthora ramorum from Whole Genome Sequence Data. Plant Dis 2017; 101:666-673. [PMID: 30678572 DOI: 10.1094/pdis-11-16-1586-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [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
Phytophthora ramorum is the causal agent of sudden oak death and sudden larch death, and is also responsible for causing ramorum blight on woody ornamental plants. Many microsatellite markers are available to characterize the genetic diversity and population structure of P. ramorum. However, only two markers are polymorphic in the NA2 lineage, which is predominant in Canadian nurseries. Microsatellite motifs were mined from whole-genome sequence data of six P. ramorum NA2 isolates. Of the 43 microsatellite primer pairs selected, 13 loci displayed different allele sizes among the four P. ramorum lineages, 10 loci displayed intralineage variation in the EU1, EU2, and/or NA1 lineages, and 12 microsatellites displayed polymorphism in the NA2 lineage. Genotyping of 272 P. ramorum NA2 isolates collected in nurseries in British Columbia, Canada, from 2004 to 2013 revealed 12 multilocus genotypes (MLGs). One MLG was dominant when examined over time and across sampling locations, and only a few mutations separated the 12 MLGs. The NA2 population observed in Canadian nurseries also showed no signs of sexual recombination, similar to what has been observed in previous studies. The markers developed in this study can be used to assess P. ramorum inter- and intralineage genetic diversity and generate a better understanding of the population structure and migration patterns of this important plant pathogen, especially for the lesser-characterized NA2 lineage.
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Affiliation(s)
| | - Nicolas Feau
- Faculty of Forestry, University of British Columbia (UBC), Vancouver, BC, Canada
| | - Angela L Dale
- Faculty of Forestry, University of British Columbia (UBC), Vancouver, BC, Canada
| | - Braham Dhillon
- UBC and Department of Plant Pathology, University of Arkansas, Fayetteville
| | - Richard C Hamelin
- UBC and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada
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50
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Wang J, Fernández‐Pavía SP, Larsen MM, Garay‐Serrano E, Gregorio‐Cipriano R, Rodríguez‐Alvarado G, Grünwald NJ, Goss EM. High levels of diversity and population structure in the potato late blight pathogen at the Mexico centre of origin. Mol Ecol 2017; 26:1091-1107. [DOI: 10.1111/mec.14000] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 12/11/2016] [Accepted: 12/21/2016] [Indexed: 01/15/2023]
Affiliation(s)
- Jianan Wang
- Department of Plant Pathology and Emerging Pathogens Institute University of Florida Gainesville FL 32611 USA
| | - Sylvia P. Fernández‐Pavía
- Laboratorio de Patología Vegetal Universidad Michoacana de San Nicolás de Hidalgo IIAF Tarímbaro Michoacán 58880 México
| | | | - Edith Garay‐Serrano
- Laboratorio de Patología Vegetal Universidad Michoacana de San Nicolás de Hidalgo IIAF Tarímbaro Michoacán 58880 México
| | - Rosario Gregorio‐Cipriano
- Laboratorio de Patología Vegetal Universidad Michoacana de San Nicolás de Hidalgo IIAF Tarímbaro Michoacán 58880 México
| | - Gerardo Rodríguez‐Alvarado
- Laboratorio de Patología Vegetal Universidad Michoacana de San Nicolás de Hidalgo IIAF Tarímbaro Michoacán 58880 México
| | | | - Erica M. Goss
- Department of Plant Pathology and Emerging Pathogens Institute University of Florida Gainesville FL 32611 USA
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