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Gouveia C, Santos RB, Paiva-Silva C, Buchholz G, Malhó R, Figueiredo A. The pathogenicity of Plasmopara viticola: a review of evolutionary dynamics, infection strategies and effector molecules. BMC PLANT BIOLOGY 2024; 24:327. [PMID: 38658826 PMCID: PMC11040782 DOI: 10.1186/s12870-024-05037-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 04/17/2024] [Indexed: 04/26/2024]
Abstract
Oomycetes are filamentous organisms that resemble fungi in terms of morphology and life cycle, primarily due to convergent evolution. The success of pathogenic oomycetes lies in their ability to adapt and overcome host resistance, occasionally transitioning to new hosts. During plant infection, these organisms secrete effector proteins and other compounds during plant infection, as a molecular arsenal that contributes to their pathogenic success. Genomic sequencing, transcriptomic analysis, and proteomic studies have revealed highly diverse effector repertoires among different oomycete pathogens, highlighting their adaptability and evolution potential.The obligate biotrophic oomycete Plasmopara viticola affects grapevine plants (Vitis vinifera L.) causing the downy mildew disease, with significant economic impact. This disease is devastating in Europe, leading to substantial production losses. Even though Plasmopara viticola is a well-known pathogen, to date there are scarce reviews summarising pathogenicity, virulence, the genetics and molecular mechanisms of interaction with grapevine.This review aims to explore the current knowledge of the infection strategy, lifecycle, effector molecules, and pathogenicity of Plasmopara viticola. The recent sequencing of the Plasmopara viticola genome has provided new insights into understanding the infection strategies employed by this pathogen. Additionally, we will highlight the contributions of omics technologies in unravelling the ongoing evolution of this oomycete, including the first in-plant proteome analysis of the pathogen.
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Affiliation(s)
- Catarina Gouveia
- Biosystems and Integrative Sciences Institute (BioISI), Faculty of Science, University of Lisbon, Lisboa, Portugal
| | - Rita B Santos
- Biosystems and Integrative Sciences Institute (BioISI), Faculty of Science, University of Lisbon, Lisboa, Portugal
| | - Catarina Paiva-Silva
- Biosystems and Integrative Sciences Institute (BioISI), Faculty of Science, University of Lisbon, Lisboa, Portugal
| | - Günther Buchholz
- RLP AgroScience/AlPlanta-Institute for Plant Research, Neustadt an Der Weinstrasse, Germany
| | - Rui Malhó
- Biosystems and Integrative Sciences Institute (BioISI), Faculty of Science, University of Lisbon, Lisboa, Portugal
| | - Andreia Figueiredo
- Biosystems and Integrative Sciences Institute (BioISI), Faculty of Science, University of Lisbon, Lisboa, Portugal.
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2
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Johnson ET, Lyon R, Zaitlin D, Khan AB, Jairajpuri MA. A comparison of transporter gene expression in three species of Peronospora plant pathogens during host infection. PLoS One 2023; 18:e0285685. [PMID: 37262030 DOI: 10.1371/journal.pone.0285685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 04/28/2023] [Indexed: 06/03/2023] Open
Abstract
Protein transporters move essential metabolites across membranes in all living organisms. Downy mildew causing plant pathogens are biotrophic oomycetes that transport essential nutrients from their hosts to grow. Little is known about the functions and gene expression levels of membrane transporters produced by downy mildew causing pathogens during infection of their hosts. Approximately 170-190 nonredundant transporter genes were identified in the genomes of Peronospora belbahrii, Peronospora effusa, and Peronospora tabacina, which are specialized pathogens of basil, spinach, and tobacco, respectively. The largest groups of transporter genes in each species belonged to the major facilitator superfamily, mitochondrial carriers (MC), and the drug/metabolite transporter group. Gene expression of putative Peronospora transporters was measured using RNA sequencing data at two time points following inoculation onto leaves of their hosts. There were 16 transporter genes, seven of which were MCs, expressed in each Peronospora species that were among the top 45 most highly expressed transporter genes 5-7 days after inoculation. Gene transcripts encoding the ADP/ATP translocase and the mitochondrial phosphate carrier protein were the most abundant mRNAs detected in each Peronospora species. This study found a number of Peronospora genes that are likely critical for pathogenesis and which might serve as future targets for control of these devastating plant pathogens.
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Affiliation(s)
- Eric T Johnson
- United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Crop Bioprotection Unit, Peoria, Illinois, United States of America
| | - Rebecca Lyon
- United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Crop Bioprotection Unit, Peoria, Illinois, United States of America
| | - David Zaitlin
- Kentucky Tobacco Research & Development Center, University of Kentucky, Lexington, Kentucky, United States of America
| | - Abdul Burhan Khan
- Department of Biosciences, Jamia Millia Islamia University, New Delhi, India
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Fletcher K, Martin F, Isakeit T, Cavanaugh K, Magill C, Michelmore R. The genome of the oomycete Peronosclerospora sorghi, a cosmopolitan pathogen of maize and sorghum, is inflated with dispersed pseudogenes. G3 (BETHESDA, MD.) 2023; 13:jkac340. [PMID: 36592124 PMCID: PMC9997571 DOI: 10.1093/g3journal/jkac340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 11/14/2022] [Accepted: 12/05/2022] [Indexed: 01/03/2023]
Abstract
Several species in the oomycete genus Peronosclerospora cause downy mildew on maize and can result in significant yield losses in Asia. Bio-surveillance of these pathogens is a high priority to prevent epidemics on maize in the United States and consequent damage to the US economy. The unresolved taxonomy and dearth of molecular resources for Peronosclerospora spp. hinder these efforts. P. sorghi is a pathogen of sorghum and maize with a global distribution, for which limited diversity has been detected in the southern USA. We characterized the genome, transcriptome, and mitogenome of an isolate, representing the US pathotype 6. The highly homozygous genome was assembled using 10× Genomics linked reads and scaffolded using Hi-C into 13 chromosomes. The total assembled length was 303.2 Mb, larger than any other oomycete previously assembled. The mitogenome was 38 kb, similar in size to other oomycetes, although it had a unique gene order. Nearly 20,000 genes were annotated in the nuclear genome, more than described for other downy mildew causing oomycetes. The 13 chromosomes of P. sorghi were highly syntenic with the 17 chromosomes of Peronospora effusa with conserved centromeric regions and distinct chromosomal fusions. The increased assembly size and gene count of P. sorghi is due to extensive retrotransposition, resulting in putative pseudogenization. Ancestral genes had higher transcript abundance and were enriched for differential expression. This study provides foundational resources for analysis of Peronosclerospora and comparisons to other oomycete genera. Further genomic studies of global Peronosclerospora spp. will determine the suitability of the mitogenome, ancestral genes, and putative pseudogenes for marker development and taxonomic relationships.
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Affiliation(s)
- Kyle Fletcher
- The Genome Center, University of California, Davis, CA 95616, USA
| | - Frank Martin
- U.S. Department of Agriculture–Agriculture Research Service, Salinas, CA, 93905, USA
| | - Thomas Isakeit
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Keri Cavanaugh
- The Genome Center, University of California, Davis, CA 95616, USA
| | - Clint Magill
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Richard Michelmore
- The Genome Center, University of California, Davis, CA 95616, USA
- Departments of Plant Sciences, Molecular & Cellular Biology, Medical Microbiology & Immunology, University of California, Davis, CA 95616, USA
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4
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Combier M, Evangelisti E, Piron MC, Schornack S, Mestre P. Candidate effector proteins from the oomycetes Plasmopara viticola and Phytophthora parasitica share similar predicted structures and induce cell death in Nicotiana species. PLoS One 2022; 17:e0278778. [PMID: 36459530 PMCID: PMC9718384 DOI: 10.1371/journal.pone.0278778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/22/2022] [Indexed: 12/04/2022] Open
Abstract
Effector proteins secreted by plant pathogens are essential for infection. Cytoplasmic RXLR effectors from oomycetes are characterized by the presence of RXLR and EER motifs that are frequently linked to WY- and/or LWY-domains, folds that are exclusive to this effector family. A related family of secreted candidate effector proteins, carrying WY-domains and the EER motif but lacking the canonical RXLR motif, has recently been described in oomycetes and is mainly found in downy mildew pathogens. Plasmopara viticola is an obligate biotrophic oomycete causing grapevine downy mildew. Here we describe a conserved Pl. viticola secreted candidate non-RXLR effector protein with cell death-inducing activity in Nicotiana species. A similar RXLR effector candidate from the broad host range oomycete pathogen Phytophthora parasitica also induces cell death in Nicotiana. Through comparative tertiary structure modelling, we reveal that both proteins are predicted to carry WY- and LWY-domains. Our work supports the presence of LWY-domains in non-RXLR effectors and suggests that effector candidates with similar domain architecture may exert similar activities.
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Affiliation(s)
- Maud Combier
- SVQV, UMR-A 1131, Université de Strasbourg, INRAE, Colmar, France
| | - Edouard Evangelisti
- Sainsbury Laboratory (SLCU), University of Cambridge, Cambridge, United Kingdom
| | | | - Sebastian Schornack
- Sainsbury Laboratory (SLCU), University of Cambridge, Cambridge, United Kingdom
| | - Pere Mestre
- SVQV, UMR-A 1131, Université de Strasbourg, INRAE, Colmar, France
- * E-mail:
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5
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Rollano-Peñaloza OM, Palma-Encinas V, Widell S, Mollinedo P, Rasmusson AG. The Disease Progression and Molecular Defense Response in Chenopodium Quinoa Infected with Peronospora Variabilis, the Causal Agent of Quinoa Downy Mildew. PLANTS (BASEL, SWITZERLAND) 2022; 11:2946. [PMID: 36365398 PMCID: PMC9654897 DOI: 10.3390/plants11212946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 10/05/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
Downy mildew disease, caused by the biotrophic oomycete Peronospora variabilis, is the largest threat to the cultivation of quinoa (Chenopodium quinoa Willd.) in the Andean highlands, and occurs worldwide. However, so far, no molecular study of the quinoa-Peronospora interaction has been reported. Here, we developed tools to study downy mildew disease in quinoa at the gene expression level. P. variabilis was isolated and maintained, allowing the study of downy mildew disease progression in two quinoa cultivars under controlled conditions. Quinoa gene expression changes induced by P. variabilis were analyzed by qRT-PCR, for quinoa homologues of A. thaliana pathogen-associated genes. Overall, we observed a slower disease progression and higher tolerance in the quinoa cultivar Kurmi than in the cultivar Maniqueña Real. The quinoa orthologs of putative defense genes such as the catalase CqCAT2 and the endochitinase CqEP3 showed no changes in gene expression. In contrast, quinoa orthologs of other defense response genes such as the transcription factor CqWRKY33 and the chaperone CqHSP90 were significantly induced in plants infected with P. variabilis. These genes could be used as defense response markers to select quinoa cultivars that are more tolerant to P. variabilis infection.
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Affiliation(s)
- Oscar M. Rollano-Peñaloza
- Department of Biology, Lund University, SE-223 62 Lund, Sweden
- Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, La Paz P.O. Box 12958, Bolivia
| | - Valeria Palma-Encinas
- Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, La Paz P.O. Box 12958, Bolivia
| | - Susanne Widell
- Department of Biology, Lund University, SE-223 62 Lund, Sweden
| | - Patricia Mollinedo
- Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, La Paz P.O. Box 12958, Bolivia
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6
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Winkworth RC, Neal G, Ogas RA, Nelson BCW, McLenachan PA, Bellgard SE, Lockhart PJ. Comparative analyses of complete Peronosporaceae (Oomycota) mitogenome sequences - insights into structural evolution and phylogeny. Genome Biol Evol 2022; 14:6568501. [PMID: 35420669 PMCID: PMC9020773 DOI: 10.1093/gbe/evac049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2022] [Indexed: 11/14/2022] Open
Abstract
Members of the Peronosporaceae (Oomycota, Chromista), which currently consists of 25 genera and approximately 1000 recognised species, are responsible for disease on a wide range of plant hosts. Molecular phylogenetic analyses over the last two decades have improved our understanding of evolutionary relationships within Peronosporaceae. To date, 16 numbered and three named clades have been recognised; it is clear from these studies that the current taxonomy does not reflect evolutionary relationships. Whole organelle genome sequences are an increasingly important source of phylogenetic information, and in this study we present comparative and phylogenetic analyses of mitogenome sequences from 15 of the 19 currently recognized clades of Peronosporaceae, including 44 newly assembled sequences. Our analyses suggest strong conservation of mitogenome size and gene content across Peronosporaceae but, as previous studies have suggested, limited conservation of synteny. Specifically, we identified 28 distinct syntenies amongst the 71 examined isolates. Moreover, 19 of the isolates contained inverted or direct repeats, suggesting repeated sequences may be more common than previously thought. In terms of phylogenetic relationships, our analyses of 34 concatenated mitochondrial gene sequences resulted in a topology that was broadly consistent with previous studies. However, unlike previous studies concatenated mitochondrial sequences provided strong support for higher level relationships within the family.
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Affiliation(s)
- Richard C Winkworth
- Bio-Protection Research Centre, Massey University, Palmerston North, New Zealand.,School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Grace Neal
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Raeya A Ogas
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Briana C W Nelson
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | | | - Stanley E Bellgard
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
| | - Peter J Lockhart
- Bio-Protection Research Centre, Massey University, Palmerston North, New Zealand.,School of Natural Sciences, Massey University, Palmerston North, New Zealand
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7
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Nowicki M, Hadziabdic D, Trigiano RN, Runge F, Thines M, Boggess SL, Ristaino J, Spring O. Microsatellite Markers from Peronospora tabacina, the Cause of Blue Mold of Tobacco, Reveal Species Origin, Population Structure, and High Gene Flow. PHYTOPATHOLOGY 2022; 112:422-434. [PMID: 34058860 DOI: 10.1094/phyto-03-21-0092-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Peronospora tabacina is an obligate parasite that causes blue mold of tobacco. The pathogen reproduces primarily by sporangia, whereas the sexual oospores are rarely observed. A collection of 122 isolates of P. tabacina was genotyped using nine microsatellites to assess the population structure of individuals from subpopulations collected from central, southern, and western Europe; the Middle East; Central America; North America; and Australia. Genetic variations among the six subpopulations accounted for ∼8% of the total variation, including moderate levels of genetic differentiation, high gene flow among these subpopulations, and a positive correlation between geographic and genetic distance (r = 0.225; P < 0.001). Evidence of linkage disequilibrium (P < 0.001) showed that populations contained partially clonal subpopulations but that subpopulations from Australia and Mediterranean Europe did not. High genetic variation and population structure among samples could be explained by continuous gene flow across continents via infected transplant exchange and/or long-distance dispersal of sporangia via wind currents. This study analyzed the most numerous P. tabacina collection and allowed conclusions regarding the migration, mutation, and evolutionary history of this obligate biotrophic oomycete. The evidence pointed to the species origin in Australia and identified intracontinental and intercontinental migration patterns of this important pathogen.[Formula: see text] Copyright © 2022 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)
- Marcin Nowicki
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37996-4560, U.S.A
| | - Denita Hadziabdic
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37996-4560, U.S.A
| | - Robert N Trigiano
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37996-4560, U.S.A
| | - Fabian Runge
- Institute of Botany 210, University of Hohenheim, D-70593 Stuttgart, Germany
- Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, D-60325 Frankfurt am Main, Germany
| | - Marco Thines
- Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, D-60325 Frankfurt am Main, Germany
- Department of Life Sciences, Institute of Ecology, Evolution and Diversity, Goethe University Frankfurt, D-60323 Frankfurt am Main, Germany
| | - Sarah L Boggess
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37996-4560, U.S.A
| | - Jean Ristaino
- Department of Entomology and Plant Pathology, Emerging Plant Disease and Global Food Security Cluster, North Carolina State University, Raleigh 27650, U.S.A
| | - Otmar Spring
- Institute of Botany 210, University of Hohenheim, D-70593 Stuttgart, Germany
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8
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Purayannur S, Gent DH, Miles TD, Radišek S, Quesada‐Ocampo LM. The hop downy mildew pathogen Pseudoperonospora humuli. MOLECULAR PLANT PATHOLOGY 2021; 22:755-768. [PMID: 33942461 PMCID: PMC8232024 DOI: 10.1111/mpp.13063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/29/2021] [Accepted: 03/14/2021] [Indexed: 06/12/2023]
Abstract
UNLABELLED Pseudoperonospora humuli is an obligate biotrophic oomycete that causes downy mildew, one of the most devastating diseases of cultivated hop, Humulus lupulus. Downy mildew occurs in all production areas of the crop in the Northern Hemisphere and Argentina. The pathogen overwinters in hop crowns and roots, and causes considerable crop loss. Downy mildew is managed by sanitation practices, planting of resistant cultivars, and fungicide applications. However, the scarcity of sources of host resistance and fungicide resistance in pathogen populations complicates disease management. This review summarizes the current knowledge on the symptoms of the disease, life cycle, virulence factors, and management of hop downy mildew, including various forecasting systems available in the world. Additionally, recent developments in genomics and effector discovery, and the future prospects of using such resources in successful disease management are also discussed. TAXONOMY Class: Oomycota; Order: Peronosporales; Family: Peronosporaceae; Genus: Pseudoperonospora; Species: Pseudoperonospora humuli. DISEASE SYMPTOMS The disease is characterized by systemically infected chlorotic shoots called "spikes". Leaf symptoms and signs include angular chlorotic lesions and profuse sporulation on the abaxial side of the leaf. Under severe disease pressure, dark brown discolouration or lesions are observed on cones. Infected crowns have brown to black streaks when cut open. Cultivars highly susceptible to crown rot may die at this phase of the disease cycle without producing shoots. However, foliar symptoms may not be present on plants with systemically infected root systems. INFECTION PROCESS Pathogen mycelium overwinters in buds and crowns, and emerges on infected shoots in spring. Profuse sporulation occurs on infected tissues and sporangia are released and dispersed by air currents. Under favourable conditions, sporangia germinate and produce biflagellate zoospores that infect healthy tissue, thus perpetuating the infection cycle. Though oospores are produced in infected tissues, their role in the infection cycle is not defined. CONTROL Downy mildew on hop is managed by a combination of sanitation practices and timely fungicide applications. Forecasting systems are used to time fungicide applications for successful management of the disease. USEFUL WEBSITES: https://content.ces.ncsu.edu/hop-downy-mildew (North Carolina State University disease factsheet), https://www.canr.msu.edu/resources/michigan-hop-management-guide (Michigan Hop Management Guide), http://uspest.org/risk/models (Oregon State University Integrated Plant Protection Center degree-day model for hop downy mildew), https://www.usahops.org/cabinet/data/Field-Guide.pdf (Field Guide for Integrated Pest Management in Hops).
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Affiliation(s)
- Savithri Purayannur
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | - David H. Gent
- US Department of Agriculture‐Agricultural Research Service, Forage Seed and Cereal Research Unit, and Department of Botany and Plant PathologyOregon State UniversityCorvallisOregonUSA
| | - Timothy D. Miles
- Department of Plant, Soil and Microbial SciencesMichigan State UniversityEast LansingMichiganUSA
| | - Sebastjan Radišek
- Plant Protection DepartmentDiagnostics LaboratorySlovenian Institute for Hop Research and BrewingŽalecSlovenia
| | - Lina M. Quesada‐Ocampo
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
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Fantastic Downy Mildew Pathogens and How to Find Them: Advances in Detection and Diagnostics. PLANTS 2021; 10:plants10030435. [PMID: 33668762 PMCID: PMC7996204 DOI: 10.3390/plants10030435] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/11/2021] [Accepted: 02/15/2021] [Indexed: 12/26/2022]
Abstract
Downy mildews affect important crops and cause severe losses in production worldwide. Accurate identification and monitoring of these plant pathogens, especially at early stages of the disease, is fundamental in achieving effective disease control. The rapid development of molecular methods for diagnosis has provided more specific, fast, reliable, sensitive, and portable alternatives for plant pathogen detection and quantification than traditional approaches. In this review, we provide information on the use of molecular markers, serological techniques, and nucleic acid amplification technologies for downy mildew diagnosis, highlighting the benefits and disadvantages of the technologies and target selection. We emphasize the importance of incorporating information on pathogen variability in virulence and fungicide resistance for disease management and how the development and application of diagnostic assays based on standard and promising technologies, including high-throughput sequencing and genomics, are revolutionizing the development of species-specific assays suitable for in-field diagnosis. Our review provides an overview of molecular detection technologies and a practical guide for selecting the best approaches for diagnosis.
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10
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Abstract
AbstractPeronospora belbahrii is one of the most destructive downy mildew diseases that has emerged throughout the past two decades. Due to the lack of quarantine regulations and its possible seed-borne nature, it has spread globally and is now present in most areas in which basil is produced. While most obligate biotrophic, plant parasitic oomycetes are highly host-specific, there are a few that have a wider host range, e.g. Albugo candida, Bremia tulasnei, and Pseudoperonospora cubensis. Recently, it was shown that Peronospora belbahrii is able to infect Rosmarinus, Nepetia, and Micromeria in Israel in cross-infection trials, hinting an extended host range for also this pathogen. In this study, a newly occurring downy mildew pathogen on lavender was investigated with respect to its morphology and phylogeny, and it is shown that it belongs to Peronospora belbahrii as well. Thus, it seems that Peronospora belbahrii is currently extending its host range to additional members of the tribe Mentheae and Ocimeae. Therefore, it seems advisable to scrutinise all commonly used members of these tribes in order to avoid further spread of virulent genotypes.
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11
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Wood KJ, Nur M, Gil J, Fletcher K, Lakeman K, Gann D, Gothberg A, Khuu T, Kopetzky J, Naqvi S, Pandya A, Zhang C, Maisonneuve B, Pel M, Michelmore R. Effector prediction and characterization in the oomycete pathogen Bremia lactucae reveal host-recognized WY domain proteins that lack the canonical RXLR motif. PLoS Pathog 2020; 16:e1009012. [PMID: 33104763 PMCID: PMC7644090 DOI: 10.1371/journal.ppat.1009012] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 11/05/2020] [Accepted: 09/29/2020] [Indexed: 12/11/2022] Open
Abstract
Pathogens that infect plants and animals use a diverse arsenal of effector proteins to suppress the host immune system and promote infection. Identification of effectors in pathogen genomes is foundational to understanding mechanisms of pathogenesis, for monitoring field pathogen populations, and for breeding disease resistance. We identified candidate effectors from the lettuce downy mildew pathogen Bremia lactucae by searching the predicted proteome for the WY domain, a structural fold found in effectors that has been implicated in immune suppression as well as effector recognition by host resistance proteins. We predicted 55 WY domain containing proteins in the genome of B. lactucae and found substantial variation in both sequence and domain architecture. These candidate effectors exhibit several characteristics of pathogen effectors, including an N-terminal signal peptide, lineage specificity, and expression during infection. Unexpectedly, only a minority of B. lactucae WY effectors contain the canonical N-terminal RXLR motif, which is a conserved feature in the majority of cytoplasmic effectors reported in Phytophthora spp. Functional analysis of 21 effectors containing WY domains revealed 11 that elicited cell death on wild accessions and domesticated lettuce lines containing resistance genes, indicative of recognition of these effectors by the host immune system. Only two of the 11 recognized effectors contained the canonical RXLR motif, suggesting that there has been an evolutionary divergence in sequence motifs between genera; this has major consequences for robust effector prediction in oomycete pathogens.
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Affiliation(s)
- Kelsey J. Wood
- The Genome Center, University of California, Davis, Davis, California, United States of America
- Integrative Genetics & Genomics Graduate Group, University of California, Davis, Davis, California, United States of America
| | - Munir Nur
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Juliana Gil
- The Genome Center, University of California, Davis, Davis, California, United States of America
- Plant Pathology Graduate Group, University of California, Davis, Davis, California, United States of America
| | - Kyle Fletcher
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | | | - Dasan Gann
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Ayumi Gothberg
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Tina Khuu
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Jennifer Kopetzky
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Sanye Naqvi
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Archana Pandya
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Chi Zhang
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | | | | | - Richard Michelmore
- The Genome Center, University of California, Davis, Davis, California, United States of America
- Departments of Plant Sciences, Molecular & Cellular Biology, Medical Microbiology & Immunology, University of California, Davis, Davis, California, United States of America
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12
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Purayannur S, Cano LM, Bowman MJ, Childs KL, Gent DH, Quesada-Ocampo LM. The Effector Repertoire of the Hop Downy Mildew Pathogen Pseudoperonospora humuli. Front Genet 2020; 11:910. [PMID: 32849854 PMCID: PMC7432248 DOI: 10.3389/fgene.2020.00910] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/22/2020] [Indexed: 01/18/2023] Open
Abstract
Pseudoperonospora humuli is an obligate biotrophic oomycete that causes downy mildew (DM), one of the most destructive diseases of cultivated hop that can lead to 100% crop loss in susceptible cultivars. We used the published genome of P. humuli to predict the secretome and effectorome and analyze the transcriptome variation among diverse isolates and during infection of hop leaves. Mining the predicted coding genes of the sequenced isolate OR502AA of P. humuli revealed a secretome of 1,250 genes. We identified 296 RXLR and RXLR-like effector-encoding genes in the secretome. Among the predicted RXLRs, there were several WY-motif-containing effectors that lacked canonical RXLR domains. Transcriptome analysis of sporangia from 12 different isolates collected from various hop cultivars revealed 754 secreted proteins and 201 RXLR effectors that showed transcript evidence across all isolates with reads per kilobase million (RPKM) values > 0. RNA-seq analysis of OR502AA-infected hop leaf samples at different time points after infection revealed highly expressed effectors that may play a relevant role in pathogenicity. Quantitative RT-PCR analysis confirmed the differential expression of selected effectors. We identified a set of P. humuli core effectors that showed transcript evidence in all tested isolates and elevated expression during infection. These effectors are ideal candidates for functional analysis and effector-assisted breeding to develop DM resistant hop cultivars.
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Affiliation(s)
- Savithri Purayannur
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - Liliana M. Cano
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
- Indian River Research and Education Center, Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Fort Pierce, FL, United States
| | - Megan J. Bowman
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
- Ball Horticultural Company, West Chicago, IL, United States
| | - Kevin L. Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - David H. Gent
- United States Department of Agriculture-Agricultural Research Service, Forage Seed and Cereal Research Unit, Oregon State University, Corvallis, OR, United States
| | - Lina M. Quesada-Ocampo
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
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13
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Klein J, Neilen M, van Verk M, Dutilh BE, Van den Ackerveken G. Genome reconstruction of the non-culturable spinach downy mildew Peronospora effusa by metagenome filtering. PLoS One 2020; 15:e0225808. [PMID: 32396560 PMCID: PMC7217449 DOI: 10.1371/journal.pone.0225808] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 04/24/2020] [Indexed: 01/27/2023] Open
Abstract
Peronospora effusa (previously known as P. farinosa f. sp. spinaciae, and here referred to as Pfs) is an obligate biotrophic oomycete that causes downy mildew on spinach (Spinacia oleracea). To combat this destructive many disease resistant cultivars have been bred and used. However, new Pfs races rapidly break the employed resistance genes. To get insight into the gene repertoire of Pfs and identify infection-related genes, the genome of the first reference race, Pfs1, was sequenced, assembled, and annotated. Due to the obligate biotrophic nature of this pathogen, material for DNA isolation can only be collected from infected spinach leaves that, however, also contain many other microorganisms. The obtained sequences can, therefore, be considered a metagenome. To filter and obtain Pfs sequences we utilized the CAT tool to taxonomically annotate ORFs residing on long sequences of a genome pre-assembly. This study is the first to show that CAT filtering performs well on eukaryotic contigs. Based on the taxonomy, determined on multiple ORFs, contaminating long sequences and corresponding reads were removed from the metagenome. Filtered reads were re-assembled to provide a clean and improved Pfs genome sequence of 32.4 Mbp consisting of 8,635 scaffolds. Transcript sequencing of a range of infection time points aided the prediction of a total of 13,277 gene models, including 99 RxLR(-like) effector, and 14 putative Crinkler genes. Comparative analysis identified common features in the predicted secretomes of different obligate biotrophic oomycetes, regardless of their phylogenetic distance. Their secretomes are generally smaller, compared to hemi-biotrophic and necrotrophic oomycete species. We observe a reduction in proteins involved in cell wall degradation, in Nep1-like proteins (NLPs), proteins with PAN/apple domains, and host translocated effectors. The genome of Pfs1 will be instrumental in studying downy mildew virulence and for understanding the molecular adaptations by which new isolates break spinach resistance.
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Affiliation(s)
- Joël Klein
- Department of Biology, Plant-Microbe Interactions, Utrecht University, Utrecht, The Netherlands
| | - Manon Neilen
- Department of Biology, Plant-Microbe Interactions, Utrecht University, Utrecht, The Netherlands
| | - Marcel van Verk
- Department of Biology, Plant-Microbe Interactions, Utrecht University, Utrecht, The Netherlands
- Crop Data Science, KeyGene, Wageningen, The Netherlands
| | - Bas E. Dutilh
- Department of Biology, Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, The Netherlands
| | - Guido Van den Ackerveken
- Department of Biology, Plant-Microbe Interactions, Utrecht University, Utrecht, The Netherlands
- * E-mail:
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14
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Natesan K, Park JY, Kim CW, Park DS, Kwon YS, Back CG, Cho H. High-Quality Genome Assembly of Peronospora destructor, the Causal Agent of Onion Downy Mildew. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:718-720. [PMID: 32237963 DOI: 10.1094/mpmi-10-19-0280-a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Peronospora destructor is an obligate biotrophic oomycete that causes downy mildew on onion (Allium cepa). Onion is an important crop worldwide, but its production is affected by this pathogen. We sequenced the genome of P. destructor using the PacBio sequencing platform, and de novo assembly resulted in 74 contigs with a total contig size of 29.3 Mb and 48.48% GC content. Here, we report the first high-quality genome sequence of P. destructor and its comparison with the genome assemblies of other oomycetes. The genome is a very useful resource to serve as a reference for analysis of P. destructor isolates and for comparative genomic studies of the biotrophic oomycetes.
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Affiliation(s)
- Karthi Natesan
- National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Republic of Korea
| | - Ji Yeon Park
- National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Republic of Korea
| | - Cheol-Woo Kim
- National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju 55365, Republic of Korea
| | - Dong Suk Park
- National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Republic of Korea
| | - Young-Seok Kwon
- National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju 55365, Republic of Korea
| | - Chang-Gi Back
- National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju 55365, Republic of Korea
| | - Heejung Cho
- National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Republic of Korea
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15
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Thines M, Sharma R, Rodenburg SYA, Gogleva A, Judelson HS, Xia X, van den Hoogen J, Kitner M, Klein J, Neilen M, de Ridder D, Seidl MF, van den Ackerveken G, Govers F, Schornack S, Studholme DJ. The Genome of Peronospora belbahrii Reveals High Heterozygosity, a Low Number of Canonical Effectors, and TC-Rich Promoters. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:742-753. [PMID: 32237964 DOI: 10.1094/mpmi-07-19-0211-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Along with Plasmopara destructor, Peronosopora belbahrii has arguably been the economically most important newly emerging downy mildew pathogen of the past two decades. Originating from Africa, it has started devastating basil production throughout the world, most likely due to the distribution of infested seed material. Here, we present the genome of this pathogen and results from comparisons of its genomic features to other oomycetes. The assembly of the nuclear genome was around 35.4 Mbp in length, with an N50 scaffold length of around 248 kbp and an L50 scaffold count of 46. The circular mitochondrial genome consisted of around 40.1 kbp. From the repeat-masked genome, 9,049 protein-coding genes were predicted, out of which 335 were predicted to have extracellular functions, representing the smallest secretome so far found in peronosporalean oomycetes. About 16% of the genome consists of repetitive sequences, and, based on simple sequence repeat regions, we provide a set of microsatellites that could be used for population genetic studies of P. belbahrii. P. belbahrii has undergone a high degree of convergent evolution with other obligate parasitic pathogen groups, reflecting its obligate biotrophic lifestyle. Features of its secretome, signaling networks, and promoters are presented, and some patterns are hypothesized to reflect the high degree of host specificity in Peronospora species. In addition, we suggest the presence of additional virulence factors apart from classical effector classes that are promising candidates for future functional studies.
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Affiliation(s)
- Marco Thines
- Institute of Ecology, Evolution and Diversity, Goethe University, Max-von-Laue-Str. 9, 60323 Frankfurt (Main), Germany
- Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325 Frankfurt (Main), Germany
- Integrative Fungal Research (IPF) and Translational Biodiversity Genomics (TBG), Georg-Voigt-Str. 14-16, 60325 Frankfurt (Main), Germany
| | - Rahul Sharma
- Institute of Ecology, Evolution and Diversity, Goethe University, Max-von-Laue-Str. 9, 60323 Frankfurt (Main), Germany
- Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325 Frankfurt (Main), Germany
- Integrative Fungal Research (IPF) and Translational Biodiversity Genomics (TBG), Georg-Voigt-Str. 14-16, 60325 Frankfurt (Main), Germany
| | - Sander Y A Rodenburg
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
- Bioinformatics Group, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Anna Gogleva
- University of Cambridge, Sainsbury Laboratory, 47 Bateman Street, Cambridge, CB2 1LR, U.K
| | - Howard S Judelson
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521 U.S.A
| | - Xiaojuan Xia
- Institute of Ecology, Evolution and Diversity, Goethe University, Max-von-Laue-Str. 9, 60323 Frankfurt (Main), Germany
- Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325 Frankfurt (Main), Germany
| | - Johan van den Hoogen
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Miloslav Kitner
- Department of Botany, Faculty of Science, Palacký University Olomouc, Šlechtitelů 27, 78371 Olomouc, Czech Republic
| | - Joël Klein
- Plant-Microbe Interactions, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Manon Neilen
- Plant-Microbe Interactions, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Dick de Ridder
- Bioinformatics Group, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Michael F Seidl
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Guido van den Ackerveken
- Plant-Microbe Interactions, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Francine Govers
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Sebastian Schornack
- University of Cambridge, Sainsbury Laboratory, 47 Bateman Street, Cambridge, CB2 1LR, U.K
| | - David J Studholme
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, U.K
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16
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Abstract
The oomycetes are a class of ubiquitous, filamentous microorganisms that include some of the biggest threats to global food security and natural ecosystems. Within the oomycete class are highly diverse species that infect a broad range of animals and plants. Some of the most destructive plant pathogens are oomycetes, such as Phytophthora infestans, the agent of potato late blight and the cause of the Irish famine. Recent years have seen a dramatic increase in the number of sequenced oomycete genomes. Here we review the latest developments in oomycete genomics and some of the important insights that have been gained. Coupled with proteomic and transcriptomic analyses, oomycete genome sequences have revealed tremendous insights into oomycete biology, evolution, genome organization, mechanisms of infection, and metabolism. We also present an updated phylogeny of the oomycete class using a phylogenomic approach based on the 65 oomycete genomes that are currently available.
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Affiliation(s)
- Jamie McGowan
- Genome Evolution Laboratory, Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland; Kathleen Lonsdale Institute for Human Health Research, Maynooth University, Maynooth, County Kildare, Ireland
| | - David A Fitzpatrick
- Genome Evolution Laboratory, Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland; Kathleen Lonsdale Institute for Human Health Research, Maynooth University, Maynooth, County Kildare, Ireland.
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17
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Genome-Wide Analysis of Cyclophilin Proteins in 21 Oomycetes. Pathogens 2019; 9:pathogens9010024. [PMID: 31888032 PMCID: PMC7168621 DOI: 10.3390/pathogens9010024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/12/2019] [Accepted: 12/20/2019] [Indexed: 12/20/2022] Open
Abstract
Cyclophilins (CYPs), a highly-conserved family of proteins, belong to a subgroup of immunophilins. Ubiquitous in eukaryotes and prokaryotes, CYPs have peptidyl-prolyl cis–trans isomerase (PPIase) activity and have been implicated as virulence factors in plant pathogenesis by oomycetes. We identified 16 CYP orthogroups from 21 diverse oomycetes. Each species was found to encode 15 to 35 CYP genes. Three of these orthogroups contained proteins with signal peptides at the N-terminal end, suggesting a role in secretion. Multidomain analysis revealed five conserved motifs of the CYP domain of oomycetes shared with other eukaryotic PPIases. Expression analysis of CYP proteins in different asexual life stages of the hemibiotrophic Phytophthora infestans and the biotrophic Plasmopara halstedii demonstrated distinct expression profiles between life stages. In addition to providing detailed comparative information on the CYPs in multiple oomycetes, this study identified candidate CYP effectors that could be the foundation for future studies of virulence.
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18
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Rahman A, Góngora-Castillo E, Bowman MJ, Childs KL, Gent DH, Martin FN, Quesada-Ocampo LM. Genome Sequencing and Transcriptome Analysis of the Hop Downy Mildew Pathogen Pseudoperonospora humuli Reveal Species-Specific Genes for Molecular Detection. PHYTOPATHOLOGY 2019; 109:1354-1366. [PMID: 30939079 DOI: 10.1094/phyto-11-18-0431-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pseudoperonospora humuli is an obligate oomycete pathogen of hop (Humulus lupulus) that causes downy mildew, an important disease in most production regions in the Northern Hemisphere. The pathogen can cause a systemic infection in hop, overwinter in the root system, and infect propagation material. Substantial yield loss may occur owing to P. humuli infection of strobiles (seed cones), shoots, and cone-bearing branches. Fungicide application and cultural practices are the primary methods to manage hop downy mildew. However, effective, sustainable, and cost-effective management of downy mildew can be improved by developing early detection systems to inform on disease risk and timely fungicide application. However, no species-specific diagnostic assays or genomic resources are available for P. humuli. The genome of the P. humuli OR502AA isolate was partially sequenced using Illumina technology and assembled with ABySS. The assembly had a minimum scaffold length of 500 bp and an N50 (median scaffold length of the assembled genome) of 19.2 kbp. A total number of 18,656 genes were identified using MAKER standard gene predictions. Additionally, transcriptome assemblies were generated using RNA-seq and Trinity for seven additional P. humuli isolates. Bioinformatics analyses of next generation sequencing reads of P. humuli and P. cubensis (a closely related sister species) identified 242 candidate species-specific P. humuli genes that could be used as diagnostic molecular markers. These candidate genes were validated using polymerase chain reaction against a diverse collection of isolates from P. humuli, P. cubensis, and other oomycetes. Overall, four diagnostic markers were found to be uniquely present in P. humuli. These candidate markers identified through comparative genomics can be used for pathogen diagnostics in propagation material, such as rhizomes and vegetative cuttings, or adapted for biosurveillance of airborne sporangia, an important source of inoculum in hop downy mildew epidemics.
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Affiliation(s)
- A Rahman
- 1Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695-7613, U.S.A
| | - E Góngora-Castillo
- 1Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695-7613, U.S.A
- 2Department of Biotechnology, Yucatan Center for Scientific Research, 97205 Mérida, Yucatán, México
| | - M J Bowman
- 3Department of Plant Biology, Michigan State University, East Lansing, MI 48823, U.S.A
| | - K L Childs
- 3Department of Plant Biology, Michigan State University, East Lansing, MI 48823, U.S.A
| | - D H Gent
- 4Forage Seed and Cereal Research Unit, U.S. Department of Agriculture-Agricultural Research Service and Oregon State University, Corvallis 97331, OR, U.S.A
| | - F N Martin
- 5Crop Improvement and Protection Research Station, U.S. Department of Agriculture-Agricultural Research Service, Salinas, CA 93905, U.S.A
| | - L M Quesada-Ocampo
- 1Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695-7613, U.S.A
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19
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Combier M, Evangelisti E, Piron MC, Rengel D, Legrand L, Shenhav L, Bouchez O, Schornack S, Mestre P. A secreted WY-domain-containing protein present in European isolates of the oomycete Plasmopara viticola induces cell death in grapevine and tobacco species. PLoS One 2019; 14:e0220184. [PMID: 31356604 PMCID: PMC6663016 DOI: 10.1371/journal.pone.0220184] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/10/2019] [Indexed: 01/02/2023] Open
Abstract
Plasmopara viticola is a biotrophic oomycete pathogen causing grapevine downy mildew. We characterized the repertoire of P. viticola effector proteins which may be translocated into plants to support the disease. We found several secreted proteins that contain canonical dEER motifs and conserved WY-domains but lack the characteristic RXLR motif reported previously from oomycete effectors. We cloned four candidates and showed that one of them, Pv33, induces plant cell death in grapevine and Nicotiana species. This activity is dependent on the nuclear localization of the protein. Sequence similar effectors were present in seven European, but in none of the tested American isolates. Together our work contributes a new type of conserved P. viticola effector candidates.
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Affiliation(s)
- Maud Combier
- SVQV, Université de Strasbourg, INRA, Colmar, France
| | - Edouard Evangelisti
- University of Cambridge, Sainsbury Laboratory (SLCU), Cambridge, United Kingdom
| | | | - David Rengel
- LIPM Laboratoire des Interactions Plantes-Microorganismes, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France
| | - Ludovic Legrand
- LIPM Laboratoire des Interactions Plantes-Microorganismes, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France
| | - Liron Shenhav
- University of Cambridge, Sainsbury Laboratory (SLCU), Cambridge, United Kingdom
| | | | - Sebastian Schornack
- University of Cambridge, Sainsbury Laboratory (SLCU), Cambridge, United Kingdom
| | - Pere Mestre
- SVQV, Université de Strasbourg, INRA, Colmar, France
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20
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Dussert Y, Mazet ID, Couture C, Gouzy J, Piron MC, Kuchly C, Bouchez O, Rispe C, Mestre P, Delmotte F. A High-Quality Grapevine Downy Mildew Genome Assembly Reveals Rapidly Evolving and Lineage-Specific Putative Host Adaptation Genes. Genome Biol Evol 2019; 11:954-969. [PMID: 30847481 PMCID: PMC6660063 DOI: 10.1093/gbe/evz048] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2019] [Indexed: 02/06/2023] Open
Abstract
Downy mildews are obligate biotrophic oomycete pathogens that cause devastating plant diseases on economically important crops. Plasmopara viticola is the causal agent of grapevine downy mildew, a major disease in vineyards worldwide. We sequenced the genome of Pl. viticola with PacBio long reads and obtained a new 92.94 Mb assembly with high contiguity (359 scaffolds for a N50 of 706.5 kb) due to a better resolution of repeat regions. This assembly presented a high level of gene completeness, recovering 1,592 genes encoding secreted proteins involved in plant–pathogen interactions. Plasmopara viticola had a two-speed genome architecture, with secreted protein-encoding genes preferentially located in gene-sparse, repeat-rich regions and evolving rapidly, as indicated by pairwise dN/dS values. We also used short reads to assemble the genome of Plasmopara muralis, a closely related species infecting grape ivy (Parthenocissus tricuspidata). The lineage-specific proteins identified by comparative genomics analysis included a large proportion of RxLR cytoplasmic effectors and, more generally, genes with high dN/dS values. We identified 270 candidate genes under positive selection, including several genes encoding transporters and components of the RNA machinery potentially involved in host specialization. Finally, the Pl. viticola genome assembly generated here will allow the development of robust population genomics approaches for investigating the mechanisms involved in adaptation to biotic and abiotic selective pressures in this species.
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Affiliation(s)
- Yann Dussert
- SAVE, INRA, Bordeaux Sciences Agro, Villenave d'Ornon, France
| | | | - Carole Couture
- SAVE, INRA, Bordeaux Sciences Agro, Villenave d'Ornon, France
| | - Jérôme Gouzy
- LIPM, INRA, Université de Toulouse, CNRS, Castanet-Tolosan, France
| | | | - Claire Kuchly
- US 1426 GeT-PlaGe, Genotoul, INRA, Castanet-Tolosan, France
| | | | | | - Pere Mestre
- SVQV, INRA, Université de Strasbourg, Colmar, France
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21
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Kandel SL, Mou B, Shishkoff N, Shi A, Subbarao KV, Klosterman SJ. Spinach Downy Mildew: Advances in Our Understanding of the Disease Cycle and Prospects for Disease Management. PLANT DISEASE 2019; 103:791-803. [PMID: 30939071 DOI: 10.1094/pdis-10-18-1720-fe] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Downy mildew on spinach is caused by Peronospora effusa, an oomycete pathogen that poses a challenge to spinach production worldwide, especially in organic production. Following infection, P. effusa produces abundant amounts of asexual sporangia. Sporangia become windborne and initiate new infections locally or distantly, leading to widespread epidemics. Oospores produced from the union of opposite mating types have been observed within infected leaves and seeds and may remain viable for many years. Sexual reproduction increases the genetic diversity of P. effusa through sexual recombination, and thus, the movement of oospores on seed has likely fueled the rapid explosion of new pathotypes in different regions of the world over the past 20 years. This review summarizes recent advances in spinach downy mildew research, especially in light of the findings of oospores in contemporary commercial spinach seed lots as well as their germination. Knowledge of the role of the oospores and other aspects of the disease cycle can directly translate into new and effective disease management strategies.
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Affiliation(s)
- Shyam L Kandel
- 1 USDA-ARS Crop Improvement and Protection Research Unit, Salinas, CA 93905
| | - Beiquan Mou
- 1 USDA-ARS Crop Improvement and Protection Research Unit, Salinas, CA 93905
| | - Nina Shishkoff
- 2 USDA-ARS Foreign Disease Weed Science Research Unit, Frederick, MD 21702
| | - Ainong Shi
- 3 Department of Horticulture, University of Arkansas, Fayetteville, AR; and
| | - Krishna V Subbarao
- 4 Department of Plant Pathology, University of California-Davis, Salinas, CA
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22
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The fungal ribonuclease-like effector protein CSEP0064/BEC1054 represses plant immunity and interferes with degradation of host ribosomal RNA. PLoS Pathog 2019; 15:e1007620. [PMID: 30856238 PMCID: PMC6464244 DOI: 10.1371/journal.ppat.1007620] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 04/15/2019] [Accepted: 02/06/2019] [Indexed: 01/08/2023] Open
Abstract
The biotrophic fungal pathogen Blumeria graminis causes the powdery mildew disease of cereals and grasses. We present the first crystal structure of a B. graminis effector of pathogenicity (CSEP0064/BEC1054), demonstrating it has a ribonuclease (RNase)-like fold. This effector is part of a group of RNase-like proteins (termed RALPHs) which comprise the largest set of secreted effector candidates within the B. graminis genomes. Their exceptional abundance suggests they play crucial functions during pathogenesis. We show that transgenic expression of RALPH CSEP0064/BEC1054 increases susceptibility to infection in both monocotyledonous and dicotyledonous plants. CSEP0064/BEC1054 interacts in planta with the pathogenesis-related protein PR10. The effector protein associates with total RNA and weakly with DNA. Methyl jasmonate (MeJA) levels modulate susceptibility to aniline-induced host RNA fragmentation. In planta expression of CSEP0064/BEC1054 reduces the formation of this RNA fragment. We propose CSEP0064/BEC1054 is a pseudoenzyme that binds to host ribosomes, thereby inhibiting the action of plant ribosome-inactivating proteins (RIPs) that would otherwise lead to host cell death, an unviable interaction and demise of the fungus. Powdery mildews are common plant diseases which affect important crop plants including cereals such as wheat and barley. The fungi that cause this disease are obligate biotrophs: they have an absolute requirement for living host cells which they penetrate with feeding structures called haustoria. These fungi must be highly effective at avoiding immune recognition which would lead to death of the host cell and the pathogen. We assume they do this by delivering effector proteins to the host. While several hundred secreted effectors have been described in cereal powdery mildews, it is unknown how they work. Here, we use X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy to determine the structure and interactions of the effector CSEP0064/BEC1054, representative of the largest class of effectors resembling fungal RNases. We find that this effector binds nucleic acids. Expression of the effector in plants increases susceptibility to infection. Moreover, transgenic CSEP0064/BEC1054 expression in wheat inhibits the degradation of host ribosomal RNA induced by ribosome-inactivating proteins (RIPs). We propose a novel mechanism of action for the RNase-like effectors in powdery mildews: they may act as pseudoenzymes to inhibit the host RIPs, known components of plant immune responses that lead to host cell death.
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Dussert Y, Mazet ID, Couture C, Gouzy J, Piron MC, Kuchly C, Bouchez O, Rispe C, Mestre P, Delmotte F. A High-Quality Grapevine Downy Mildew Genome Assembly Reveals Rapidly Evolving and Lineage-Specific Putative Host Adaptation Genes. Genome Biol Evol 2019. [PMID: 30847481 DOI: 10.1101/350041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023] Open
Abstract
Downy mildews are obligate biotrophic oomycete pathogens that cause devastating plant diseases on economically important crops. Plasmopara viticola is the causal agent of grapevine downy mildew, a major disease in vineyards worldwide. We sequenced the genome of Pl. viticola with PacBio long reads and obtained a new 92.94 Mb assembly with high contiguity (359 scaffolds for a N50 of 706.5 kb) due to a better resolution of repeat regions. This assembly presented a high level of gene completeness, recovering 1,592 genes encoding secreted proteins involved in plant-pathogen interactions. Plasmopara viticola had a two-speed genome architecture, with secreted protein-encoding genes preferentially located in gene-sparse, repeat-rich regions and evolving rapidly, as indicated by pairwise dN/dS values. We also used short reads to assemble the genome of Plasmopara muralis, a closely related species infecting grape ivy (Parthenocissus tricuspidata). The lineage-specific proteins identified by comparative genomics analysis included a large proportion of RxLR cytoplasmic effectors and, more generally, genes with high dN/dS values. We identified 270 candidate genes under positive selection, including several genes encoding transporters and components of the RNA machinery potentially involved in host specialization. Finally, the Pl. viticola genome assembly generated here will allow the development of robust population genomics approaches for investigating the mechanisms involved in adaptation to biotic and abiotic selective pressures in this species.
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Affiliation(s)
- Yann Dussert
- SAVE, INRA, Bordeaux Sciences Agro, Villenave d'Ornon, France
| | | | - Carole Couture
- SAVE, INRA, Bordeaux Sciences Agro, Villenave d'Ornon, France
| | - Jérôme Gouzy
- LIPM, INRA, Université de Toulouse, CNRS, Castanet-Tolosan, France
| | | | - Claire Kuchly
- US 1426 GeT-PlaGe, Genotoul, INRA, Castanet-Tolosan, France
| | | | | | - Pere Mestre
- SVQV, INRA, Université de Strasbourg, Colmar, France
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Liu L, Xu L, Jia Q, Pan R, Oelmüller R, Zhang W, Wu C. Arms race: diverse effector proteins with conserved motifs. PLANT SIGNALING & BEHAVIOR 2019; 14:1557008. [PMID: 30621489 PMCID: PMC6351098 DOI: 10.1080/15592324.2018.1557008] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Effector proteins play important roles in the infection by pathogenic oomycetes and fungi or the colonization by endophytic and mycorrhizal fungi. They are either translocated into the host plant cells via specific translocation mechanisms and function in the host's cytoplasm or nucleus, or they reside in the apoplast of the plant cells and act at the extracellular host-microbe interface. Many effector proteins possess conserved motifs (such as the RXLR, CRN, LysM, RGD, DELD, EAR, RYWT, Y/F/WXC or CFEM motifs) localized in their N- or C-terminal regions. Analysis of the functions of effector proteins, especially so-called "core effectors", is crucial for the understanding of pathogenicity/symbiosis mechanisms and plant defense strategies, and helps to develop breeding strategies for pathogen-resistant cultivars, and to increase crop yield and quality as well as abiotic stress resistance. This review summarizes current knowledge about these effector proteins with the conversed motifs and their involvement in pathogenic or mutualistic plant/fungal interactions.
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Affiliation(s)
- Liping Liu
- College of Horticulture & Gardening, Yangtze University, Jingzhou, China
| | - Le Xu
- Hubei Collaborative Innovation Center for Grain Industry/Research Center of Crop Stresses Resistance Technologies, Yangtze University, Jingzhou, China
| | - Qie Jia
- College of Horticulture & Gardening, Yangtze University, Jingzhou, China
| | - Rui Pan
- Hubei Collaborative Innovation Center for Grain Industry/Research Center of Crop Stresses Resistance Technologies, Yangtze University, Jingzhou, China
| | - Ralf Oelmüller
- Plant Physiology, Matthias-Schleiden-Institute for Genetics, Bioinformatics and Molecular Botany, Faculty of Biological Science, Friedrich-Schiller-University Jena, Jena, Germany
| | - Wenying Zhang
- Hubei Collaborative Innovation Center for Grain Industry/Research Center of Crop Stresses Resistance Technologies, Yangtze University, Jingzhou, China
- CONTACT Wenying Zhang Hubei Collaborative Innovation Center for Grain Industry/Research Center of Crop Stresses Resistance Technologies, Yangtze University, Jingzhou 434025, China; Chu Wu College of Horticulture & Gardening, Yangtze University, Jingzhou 434025, China
| | - Chu Wu
- College of Horticulture & Gardening, Yangtze University, Jingzhou, China
- Institute of Plant Ecology and Environmental Restoration, Yangtze University, Jingzhou, China
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25
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Fletcher K, Klosterman SJ, Derevnina L, Martin F, Bertier LD, Koike S, Reyes-Chin-Wo S, Mou B, Michelmore R. Comparative genomics of downy mildews reveals potential adaptations to biotrophy. BMC Genomics 2018; 19:851. [PMID: 30486780 PMCID: PMC6264045 DOI: 10.1186/s12864-018-5214-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 10/31/2018] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Spinach downy mildew caused by the oomycete Peronospora effusa is a significant burden on the expanding spinach production industry, especially for organic farms where synthetic fungicides cannot be deployed to control the pathogen. P. effusa is highly variable and 15 new races have been recognized in the past 30 years. RESULTS We virulence phenotyped, sequenced, and assembled two isolates of P. effusa from the Salinas Valley, California, U.S.A. that were identified as race 13 and 14. These assemblies are high quality in comparison to assemblies of other downy mildews having low total scaffold count (784 & 880), high contig N50s (48 kb & 52 kb), high BUSCO completion and low BUSCO duplication scores and share many syntenic blocks with Phytophthora species. Comparative analysis of four downy mildew and three Phytophthora species revealed parallel absences of genes encoding conserved domains linked to transporters, pathogenesis, and carbohydrate activity in the biotrophic species. Downy mildews surveyed that have lost the ability to produce zoospores have a common loss of flagella/motor and calcium domain encoding genes. Our phylogenomic data support multiple origins of downy mildews from hemibiotrophic progenitors and suggest that common gene losses in these downy mildews may be of genes involved in the necrotrophic stages of Phytophthora spp. CONCLUSIONS We present a high-quality draft genome of Peronospora effusa that will serve as a reference for Peronospora spp. We identified several Pfam domains as under-represented in the downy mildews consistent with the loss of zoosporegenesis and necrotrophy. Phylogenomics provides further support for a polyphyletic origin of downy mildews.
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Affiliation(s)
- Kyle Fletcher
- The Genome Center, Genome and Biomedical Sciences Facility, University of California, 451 East Health Sciences Drive, Davis, CA 95616 USA
| | - Steven J. Klosterman
- United States Department of Agriculture, Agricultural Research Service, Salinas, CA 93905 USA
| | - Lida Derevnina
- The Genome Center, Genome and Biomedical Sciences Facility, University of California, 451 East Health Sciences Drive, Davis, CA 95616 USA
- Present Address: The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH UK
| | - Frank Martin
- United States Department of Agriculture, Agricultural Research Service, Salinas, CA 93905 USA
| | - Lien D. Bertier
- The Genome Center, Genome and Biomedical Sciences Facility, University of California, 451 East Health Sciences Drive, Davis, CA 95616 USA
| | - Steven Koike
- UC Davis Cooperative Extension Monterey County, Salinas, CA 93901 USA
- Present Address: TriCal Diagnostics, Hollister, CA 95023 USA
| | - Sebastian Reyes-Chin-Wo
- The Genome Center, Genome and Biomedical Sciences Facility, University of California, 451 East Health Sciences Drive, Davis, CA 95616 USA
| | - Beiquan Mou
- United States Department of Agriculture, Agricultural Research Service, Salinas, CA 93905 USA
| | - Richard Michelmore
- The Genome Center, Genome and Biomedical Sciences Facility, University of California, 451 East Health Sciences Drive, Davis, CA 95616 USA
- Departments of Plant Sciences, Molecular & Cellular Biology, Medical Microbiology & Immunology, University of California, Davis, 95616 USA
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26
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Subbarao CS, Anchieta A, Ochoa L, Dhar N, Kunjeti SG, Subbarao KV, Klosterman SJ. Detection of Latent Peronospora effusa Infections in Spinach. PLANT DISEASE 2018; 102:1766-1771. [PMID: 30125212 DOI: 10.1094/pdis-12-17-1956-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Downy mildew disease of spinach, caused by Peronospora effusa, is managed in conventional fields by a combination of host resistance and scheduled fungicide applications. Fungicides are currently applied to prevent downy mildew epidemics regardless of the infection status of spinach crops. A more streamlined approach would be to develop methods to target either latent infections for fungicide application in conventional production systems or to hasten harvest in organic production. In this study, conventional polymerase chain reaction (PCR) was applied to detect P. effusa DNA in symptomless spinach leaves in three spatially and temporally separated field plots, each containing four 2-m beds, 35 m in length. Spinach leaves were sampled weekly at 3-m intervals at 48 locations throughout each plot. Initial samples were asymptomatic and yet PCR enabled detection of P. effusa DNA extracted from sampled spinach leaves. Detection of latent downy mildew infection in spinach leaves was confirmed by PCR as early as 7 days prior to symptom development. The limit of pathogen DNA detection in spinach leaves was calculated at 10 pg using the conventional PCR approach. Quantitative PCR with TaqMan methodology revealed the presence of inhibitors from spinach leaf DNA extracts and affected amplification efficiencies, but not when diluted, enabling detection of P. effusa DNA at a concentration of <0.1 pg. In conclusion, detection of latent infections may enable management decisions for earlier-than-normal harvest of infected, symptomless organic crops, and for timing fungicide applications on symptomless plants in conventional production.
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Affiliation(s)
| | - Amy Anchieta
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Salinas, CA 93905
| | - Lorena Ochoa
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Salinas, CA 93905
| | - Nikhilesh Dhar
- Department of Plant Pathology, University of California, Davis, c/o U.S. Agricultural Research Station, Salinas 93905
| | - Sridhara G Kunjeti
- Department of Plant Pathology, University of California, Davis, c/o U.S. Agricultural Research Station, Salinas 93905
| | - Krishna V Subbarao
- Department of Plant Pathology, University of California, Davis, c/o U.S. Agricultural Research Station, Salinas 93905
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Gómez-Zeledón J, Spring O. Up-regulated RxLR effector genes of Plasmopara viticola in synchronized host-free stages and infected leaves of hosts with different susceptibility. Fungal Biol 2018; 122:1125-1133. [PMID: 30449350 DOI: 10.1016/j.funbio.2018.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 11/17/2022]
Abstract
Fast recognition of host signals and early activation of infection mechanisms in Plasmopara viticola are decisive for successful infestation of Vitis vinifera. To better understand interactive processes at the first front line of combat between the pathogen and its host, a specific pre-infective stage was generated in a host-free system. Zoospore encystment was triggered within minutes after treatment with CaCl2. Subsequently, high rates of germ tube formation occurred in a synchronized manner. This method was employed to compare development-related gene expression in strains of different virulence. Soon after germination, spores showed strong up-regulation of two effector genes, PvRxLR18 and PvRxLR28, particularly in the high virulence strain. On infected grapevine leaf-discs of cultivars with different susceptibility, a similar up-regulation was found at 6 hours post inoculation (hpi). This effect was much more evident in the high virulence than in the low virulence strain and was significantly higher on leaves of the tolerant cultivar Regent than on Müller-Thurgau. In addition, PvRxLR67 was up-regulated 24 hpi in the high virulence strain indicating that different effectors are active in later infection stages. Differences in the expression pattern of RxLR effector genes between the two strains corroborated with infection symptoms visible by sporulation.
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Affiliation(s)
| | - Otmar Spring
- Institute of Botany, University of Hohenheim, 70593, Stuttgart, BW, Germany.
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28
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Bourret TB, Choudhury RA, Mehl HK, Blomquist CL, McRoberts N, Rizzo DM. Multiple origins of downy mildews and mito-nuclear discordance within the paraphyletic genus Phytophthora. PLoS One 2018. [PMID: 29529094 PMCID: PMC5846723 DOI: 10.1371/journal.pone.0192502] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Phylogenetic relationships between thirteen species of downy mildew and 103 species of Phytophthora (plant-pathogenic oomycetes) were investigated with two nuclear and four mitochondrial loci, using several likelihood-based approaches. Three Phytophthora taxa and all downy mildew taxa were excluded from the previously recognized subgeneric clades of Phytophthora, though all were strongly supported within the paraphyletic genus. Downy mildews appear to be polyphyletic, with graminicolous downy mildews (GDM), brassicolous downy mildews (BDM) and downy mildews with colored conidia (DMCC) forming a clade with the previously unplaced Phytophthora taxon totara; downy mildews with pyriform haustoria (DMPH) were placed in their own clade with affinities to the obligate biotrophic P. cyperi. Results suggest the recognition of four additional clades within Phytophthora, but few relationships between clades could be resolved. Trees containing all twenty extant downy mildew genera were produced by adding partial coverage of seventeen additional downy mildew taxa; these trees supported the monophyly of the BDMs, DMCCs and DMPHs but suggested that the GDMs are paraphyletic in respect to the BDMs or polyphyletic. Incongruence between nuclear-only and mitochondrial-only trees suggests introgression may have occurred between several clades, particularly those containing biotrophs, questioning whether obligate biotrophic parasitism and other traits with polyphyletic distributions arose independently or were horizontally transferred. Phylogenetic approaches may be limited in their ability to resolve some of the complex relationships between the "subgeneric" clades of Phytophthora, which include twenty downy mildew genera and hundreds of species.
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Affiliation(s)
- Tyler B. Bourret
- Department of Plant Pathology, University of California, Davis, Davis, California, United States of America
- * E-mail:
| | - Robin A. Choudhury
- Plant Pathology Department, University of Florida, Gainesville, Florida, United States of America
| | - Heather K. Mehl
- Department of Plant Pathology, University of California, Davis, Davis, California, United States of America
| | - Cheryl L. Blomquist
- California Department of Food and Agriculture, Sacramento, California, United States of America
| | - Neil McRoberts
- Department of Plant Pathology, University of California, Davis, Davis, California, United States of America
| | - David M. Rizzo
- Department of Plant Pathology, University of California, Davis, Davis, California, United States of America
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29
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Crandall SG, Rahman A, Quesada-Ocampo LM, Martin FN, Bilodeau GJ, Miles TD. Advances in Diagnostics of Downy Mildews: Lessons Learned from Other Oomycetes and Future Challenges. PLANT DISEASE 2018; 102:265-275. [PMID: 30673522 DOI: 10.1094/pdis-09-17-1455-fe] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Downy mildews are plant pathogens that damage crop quality and yield worldwide. Among the most severe and notorious crop epidemics of downy mildew occurred on grapes in the mid-1880s, which almost destroyed the wine industry in France. Since then, there have been multiple outbreaks on sorghum and millet in Africa, tobacco in Europe, and recent widespread epidemics on lettuce, basil, cucurbits, and spinach throughout North America. In the mid-1970s, loss of corn to downy mildew in the Philippines was estimated at US$23 million. Today, crops that are susceptible to downy mildews are worth at least $7.5 billion of the United States' economy. Although downy mildews cause devastating economic losses in the United States and globally, this pathogen group remains understudied because they are difficult to culture and accurately identify. Early detection of downy mildews in the environment is critical to establish pathogen presence and identity, determine fungicide resistance, and understand how pathogen populations disperse. Knowing when and where pathogens emerge is also important for identifying critical control points to restrict movement and to contain populations. Reducing the spread of pathogens also decreases the likelihood of sexual recombination events and discourages the emergence of novel virulent strains. A major challenge in detecting downy mildews is that they are obligate pathogens and thus cannot be cultured in artificial media to identify and maintain specimens. However, advances in molecular detection techniques hold promise for rapid and in some cases, relatively inexpensive diagnosis. In this article, we discuss recent advances in diagnostic tools that can be used to detect downy mildews. First, we briefly describe downy mildew taxonomy and genetic loci used for detection. Next, we review issues encountered when identifying loci and compare various traditional and novel platforms for diagnostics. We discuss diagnosis of downy mildew traits and issues to consider when detecting this group of organisms in different environments. We conclude with challenges and future directions for successful downy mildew detection.
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Affiliation(s)
- Sharifa G Crandall
- California State University Monterey Bay, School of Natural Sciences, Seaside, CA, 93955
| | - Alamgir Rahman
- North Carolina State University, Department of Plant Pathology, Raleigh, NC, 27695
| | | | - Frank N Martin
- USDA-ARS, Crop Improvement and Protection Research Unit, Salinas, CA, 93905
| | | | - Timothy D Miles
- California State University Monterey Bay, School of Natural Sciences, Seaside, CA, 93955
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30
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Blanco-Meneses M, Carbone I, Ristaino JB. Population structure and migration of the Tobacco Blue Mold Pathogen, Peronospora tabacina, into North America and Europe. Mol Ecol 2018; 27:737-751. [PMID: 29218863 DOI: 10.1111/mec.14453] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 10/13/2017] [Accepted: 11/08/2017] [Indexed: 11/28/2022]
Abstract
Tobacco blue mold, caused by Peronospora tabacina, is an oomycete plant pathogen that causes yearly epidemics in tobacco (Nicotiana tabacum) in the United States and Europe. The genetic structure of P. tabacina was examined to understand genetic diversity, population structure and patterns of migration. Two nuclear loci, Igs2 and Ypt1, and one mitochondrial locus, cox2, were amplified, cloned and sequenced from fifty-four isolates of P. tabacina from the United States, Central America-Caribbean-Mexico (CCAM), Europe and the Middle East (EULE). Cloned sequences from the three genes showed high genetic variability across all populations. Nucleotide diversity and the population mean mutation parameter per site (Watterson's theta) were higher in EULE and CCAM and lower in U.S. POPULATIONS Neutrality tests were significant and the equilibrium model of neutral evolution was rejected, indicating an excess of recent mutations or rare alleles. Hudson's Snn tests were performed to examine population subdivision and gene flow among populations. An isolation-with-migration analysis (IM) supported the hypothesis of long-distance migration of P. tabacina from the Caribbean region, Florida and Texas into other states in the United States. Within the European populations, the model documented migration from North Central Europe into western Europe and Lebanon, and migration from western Europe into Lebanon. The migration patterns observed support historical observations about the first disease introductions and movement in Europe. The models developed are applicable to other aerial dispersed emerging pathogens and document that high-evolutionary-risk plant pathogens can move over long distances to cause disease due to their large effective population size, population expansion and dispersal.
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Affiliation(s)
| | - Ignazio Carbone
- Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Jean B Ristaino
- Department of Entomology and Plant Pathology, NC State University, Raleigh, NC, USA
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31
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Abstract
A high-quality, annotated genome assembly is the foundation for many downstream studies. However, obtaining such an assembly is a complex, reiterative process that requires the assimilation of high-quality data and combines different approaches and data types. While some software packages incorporating multiple steps of genome assembly are commercially available, they may not be flexible enough to be routinely applied to all organisms, particularly to nonmodel species such as pathogenic oomycetes and fungi. If researchers understand and apply the most appropriate, currently available tools for each step, it is possible to customize parameters and optimize results for their organism of study. Based on our experience of de novo assembly and annotation of several oomycete species, this chapter provides a modular workflow from processing of raw reads, to initial assembly generation, through optimization, chromosome-scale scaffolding and annotation, outlining input and output data as well as examples and alternative software used for each step. The accompanying Notes provide background information for each step as well as alternative options. The final result of this workflow could be an annotated, high-quality, validated, chromosome-scale assembly or a draft assembly of sufficient quality to meet specific needs of a project.
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Affiliation(s)
- Kyle Fletcher
- The Genome Center, Genome and Biomedical Sciences Facility, University of California, Davis, CA, USA
| | - Richard Michelmore
- The Genome Center, Genome and Biomedical Sciences Facility, University of California, Davis, CA, USA.
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32
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Kobayashi M, Hiraka Y, Abe A, Yaegashi H, Natsume S, Kikuchi H, Takagi H, Saitoh H, Win J, Kamoun S, Terauchi R. Genome analysis of the foxtail millet pathogen Sclerospora graminicola reveals the complex effector repertoire of graminicolous downy mildews. BMC Genomics 2017; 18:897. [PMID: 29166857 PMCID: PMC5700566 DOI: 10.1186/s12864-017-4296-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 11/13/2017] [Indexed: 11/30/2022] Open
Abstract
Background Downy mildew, caused by the oomycete pathogen Sclerospora graminicola, is an economically important disease of Gramineae crops including foxtail millet (Setaria italica). Plants infected with S. graminicola are generally stunted and often undergo a transformation of flower organs into leaves (phyllody or witches’ broom), resulting in serious yield loss. To establish the molecular basis of downy mildew disease in foxtail millet, we carried out whole-genome sequencing and an RNA-seq analysis of S. graminicola. Results Sequence reads were generated from S. graminicola using an Illumina sequencing platform and assembled de novo into a draft genome sequence comprising approximately 360 Mbp. Of this sequence, 73% comprised repetitive elements, and a total of 16,736 genes were predicted from the RNA-seq data. The predicted genes included those encoding effector-like proteins with high sequence similarity to those previously identified in other oomycete pathogens. Genes encoding jacalin-like lectin-domain-containing secreted proteins were enriched in S. graminicola compared to other oomycetes. Of a total of 1220 genes encoding putative secreted proteins, 91 significantly changed their expression levels during the infection of plant tissues compared to the sporangia and zoospore stages of the S. graminicola lifecycle. Conclusions We established the draft genome sequence of a downy mildew pathogen that infects Gramineae plants. Based on this sequence and our transcriptome analysis, we generated a catalog of in planta-induced candidate effector genes, providing a solid foundation from which to identify the effectors causing phyllody. Electronic supplementary material The online version of this article (10.1186/s12864-017-4296-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Yukie Hiraka
- Iwate Biotechnology Research Center, Iwate, Japan
| | - Akira Abe
- Iwate Biotechnology Research Center, Iwate, Japan
| | | | | | | | | | - Hiromasa Saitoh
- Iwate Biotechnology Research Center, Iwate, Japan.,Department of Molecular Microbiology, Tokyo University of Agriculture, Tokyo, Japan
| | - Joe Win
- The Sainsbury Laboratory, Norwich, UK
| | | | - Ryohei Terauchi
- Iwate Biotechnology Research Center, Iwate, Japan. .,Kyoto University, Kyoto, Japan.
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33
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Wallace EC, Quesada-Ocampo LM. Analysis of microsatellites from the transcriptome of downy mildew pathogens and their application for characterization of Pseudoperonospora populations. PeerJ 2017; 5:e3266. [PMID: 28480143 PMCID: PMC5417063 DOI: 10.7717/peerj.3266] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/02/2017] [Indexed: 12/17/2022] Open
Abstract
Downy mildew pathogens affect several economically important crops worldwide but, due to their obligate nature, few genetic resources are available for genomic and population analyses. Draft genomes for emergent downy mildew pathogens such as the oomycete Pseudoperonospora cubensis, causal agent of cucurbit downy mildew, have been published and can be used to perform comparative genomic analysis and develop tools such as microsatellites to characterize pathogen population structure. We used bioinformatics to identify 2,738 microsatellites in the P. cubensis predicted transcriptome and evaluate them for transferability to the hop downy mildew pathogen, Pseudoperonospora humuli, since no draft genome is available for this species. We also compared the microsatellite repertoire of P. cubensis to that of the model organism Hyaloperonospora arabidopsidis, which causes downy mildew in Arabidopsis. Although trends in frequency of motif-type were similar, the percentage of SSRs identified from P. cubensis transcripts differed significantly from H. arabidopsidis. The majority of a subset of microsatellites selected for laboratory validation (92%) produced a product in P. cubensis isolates, and 83 microsatellites demonstrated transferability to P. humuli. Eleven microsatellites were found to be polymorphic and consistently amplified in P. cubensis isolates. Analysis of Pseudoperonospora isolates from diverse hosts and locations revealed higher diversity in P. cubensis compared to P. humuli isolates. These microsatellites will be useful in efforts to better understand relationships within Pseudoperonospora species and P. cubensis on a population level.
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Affiliation(s)
- Emma C. Wallace
- Department of Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - Lina M. Quesada-Ocampo
- Department of Plant Pathology, North Carolina State University, Raleigh, NC, United States
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34
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Yin L, An Y, Qu J, Li X, Zhang Y, Dry I, Wu H, Lu J. Genome sequence of Plasmopara viticola and insight into the pathogenic mechanism. Sci Rep 2017; 7:46553. [PMID: 28417959 PMCID: PMC5394536 DOI: 10.1038/srep46553] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/22/2017] [Indexed: 12/17/2022] Open
Abstract
Plasmopara viticola causes downy mildew disease of grapevine which is one of the most devastating diseases of viticulture worldwide. Here we report a 101.3 Mb whole genome sequence of P. viticola isolate 'JL-7-2' obtained by a combination of Illumina and PacBio sequencing technologies. The P. viticola genome contains 17,014 putative protein-coding genes and has ~26% repetitive sequences. A total of 1,301 putative secreted proteins, including 100 putative RXLR effectors and 90 CRN effectors were identified in this genome. In the secretome, 261 potential pathogenicity genes and 95 carbohydrate-active enzymes were predicted. Transcriptional analysis revealed that most of the RXLR effectors, pathogenicity genes and carbohydrate-active enzymes were significantly up-regulated during infection. Comparative genomic analysis revealed that P. viticola evolved independently from the Arabidopsis downy mildew pathogen Hyaloperonospora arabidopsidis. The availability of the P. viticola genome provides a valuable resource not only for comparative genomic analysis and evolutionary studies among oomycetes, but also enhance our knowledge on the mechanism of interactions between this biotrophic pathogen and its host.
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Affiliation(s)
- Ling Yin
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
- Guangxi Crop Genetic Improvement and Biotechnology Laboratory, Guangxi Academy of Agricultural Sciences, Nanning 530007, China
| | - Yunhe An
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
- Beijing Center for Physical and Chemical Analysis, Beijing 100089, China
| | - Junjie Qu
- Guangxi Crop Genetic Improvement and Biotechnology Laboratory, Guangxi Academy of Agricultural Sciences, Nanning 530007, China
| | - Xinlong Li
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yali Zhang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Ian Dry
- CSIRO Agriculture & Food, Wine Innovation West Building, Hartley Grove, Urrbrae, SA 5064, Australia
| | - Huijuan Wu
- Beijing Center for Physical and Chemical Analysis, Beijing 100089, China
| | - Jiang Lu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
- Center for Viticulture and Enology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200024, China
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Amaro TMMM, Thilliez GJA, Motion GB, Huitema E. A Perspective on CRN Proteins in the Genomics Age: Evolution, Classification, Delivery and Function Revisited. FRONTIERS IN PLANT SCIENCE 2017; 8:99. [PMID: 28217133 PMCID: PMC5289972 DOI: 10.3389/fpls.2017.00099] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/17/2017] [Indexed: 05/20/2023]
Abstract
Plant associated microbes rely on secreted virulence factors (effectors) to modulate host immunity and ensure progressive infection. Amongst the secreted protein repertoires defined and studied in pathogens to date, the CRNs (for CRinkling and Necrosis) have emerged as one of only a few highly conserved protein families, spread across several kingdoms. CRN proteins were first identified in plant pathogenic oomycetes where they were found to be modular factors that are secreted and translocated inside host cells by means of a conserved N-terminal domain. Subsequent localization and functional studies have led to the view that CRN C-termini execute their presumed effector function in the host nucleus, targeting processes required for immunity. These findings have led to great interest in this large protein family and driven the identification of additional CRN-like proteins in other organisms. The identification of CRN proteins and subsequent functional studies have markedly increased the number of candidate CRN protein sequences, expanded the range of phenotypes tentatively associated with function and revealed some of their molecular functions toward virulence. The increased number of characterized CRNs also has presented a set of challenges that may impede significant progress in the future. Here, we summarize our current understanding of the CRNs and re-assess some basic assumptions regarding this protein family. We will discuss the latest findings on CRN biology and highlight exciting new hypotheses that have emanated from the field. Finally, we will discuss new approaches to study CRN functions that would lead to a better understanding of CRN effector biology as well as the processes that lead to host susceptibility and immunity.
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Affiliation(s)
- Tiago M. M. M. Amaro
- Division of Plant Sciences, University of DundeeDundee, UK
- Dundee Effector ConsortiumDundee, UK
| | - Gaëtan J. A. Thilliez
- Division of Plant Sciences, University of DundeeDundee, UK
- Dundee Effector ConsortiumDundee, UK
- Cell and Molecular Sciences, The James Hutton InstituteInvergowrie, UK
| | - Graham B. Motion
- Division of Plant Sciences, University of DundeeDundee, UK
- Dundee Effector ConsortiumDundee, UK
| | - Edgar Huitema
- Division of Plant Sciences, University of DundeeDundee, UK
- Dundee Effector ConsortiumDundee, UK
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Derevnina L, Dagdas YF, De la Concepcion JC, Bialas A, Kellner R, Petre B, Domazakis E, Du J, Wu CH, Lin X, Aguilera-Galvez C, Cruz-Mireles N, Vleeshouwers VGAA, Kamoun S. Nine things to know about elicitins. THE NEW PHYTOLOGIST 2016; 212:888-895. [PMID: 27582271 DOI: 10.1111/nph.14137] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 06/11/2016] [Indexed: 05/27/2023]
Abstract
888 I. 888 II. 889 III. 889 IV. 889 V. 891 VI. 891 VII. 891 VIII. 892 IX. 892 X. 893 XI. 893 893 References 893 SUMMARY: Elicitins are structurally conserved extracellular proteins in Phytophthora and Pythium oomycete pathogen species. They were first described in the late 1980s as abundant proteins in Phytophthora culture filtrates that have the capacity to elicit hypersensitive (HR) cell death and disease resistance in tobacco. Later, they became well-established as having features of microbe-associated molecular patterns (MAMPs) and to elicit defences in a variety of plant species. Research on elicitins culminated in the recent cloning of the elicitin response (ELR) cell surface receptor-like protein, from the wild potato Solanum microdontum, which mediates response to a broad range of elicitins. In this review, we provide an overview on elicitins and the plant responses they elicit. We summarize the state of the art by describing what we consider to be the nine most important features of elicitin biology.
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Affiliation(s)
- Lida Derevnina
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Yasin F Dagdas
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | | | - Aleksandra Bialas
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Ronny Kellner
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Carl-von-Linné weg 10, 50829, Köln, Germany
| | - Benjamin Petre
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Emmanouil Domazakis
- Wageningen UR Plant Breeding, Wageningen University and Research Centre, Droevendaalsesteeg 1, Wageningen, 6708 PB, the Netherlands
| | - Juan Du
- Key Laboratory of Horticultural Plant Biology, College of Life Science and Technology, Ministry of Education National Center for Vegetable Improvement (Central China), Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Chih-Hang Wu
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Xiao Lin
- Wageningen UR Plant Breeding, Wageningen University and Research Centre, Droevendaalsesteeg 1, Wageningen, 6708 PB, the Netherlands
| | - Carolina Aguilera-Galvez
- Wageningen UR Plant Breeding, Wageningen University and Research Centre, Droevendaalsesteeg 1, Wageningen, 6708 PB, the Netherlands
| | | | - Vivianne G A A Vleeshouwers
- Wageningen UR Plant Breeding, Wageningen University and Research Centre, Droevendaalsesteeg 1, Wageningen, 6708 PB, the Netherlands
| | - Sophien Kamoun
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
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Makkonen J, Vesterbacka A, Martin F, Jussila J, Diéguez-Uribeondo J, Kortet R, Kokko H. Mitochondrial genomes and comparative genomics of Aphanomyces astaci and Aphanomyces invadans. Sci Rep 2016; 6:36089. [PMID: 27808238 PMCID: PMC5093560 DOI: 10.1038/srep36089] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/10/2016] [Indexed: 11/11/2022] Open
Abstract
The genus Aphanomyces (Saprolegniales, Oomycetes) includes species with a variety of ecologies from saprotrophs to plant and animal parasites. Two important species in this genus are A. astaci, the cause of crayfish plague and its close relative, A. invadans, which causes the epizootic ulcerative syndrome on fish. In this study, we have assembled and annotated the mitochondrial (mt) genomes of A. astaci and A. invadans from the whole genome shotgun sequence reads (PRJNA187372; PRJNA258292, respectively). The assembly was generated from A. astaci Pc-genotype strain APO3 and A. invadans strain NJM9701. The sizes of the mtDNAs were 49,489 bp and 49,061 bp for A. astaci and A. invadans, respectively. The species shared similar genetic content and organization encoding 35 proteins, two ribosomal RNAs, three putative open reading frames and 33 transfer RNAs of 19 amino acids for peptide synthesis. Both species also had a large inverted repeat region (LIR) of approximately 12 kb, the LIR contained large and small ribosomal RNAs and eight protein coding genes. These annotated mt genomes serve as a valuable genetic backbone for further development of diagnostic methods and phylogenetic and migration studies of the animal parasitic species of Aphanomyces.
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Affiliation(s)
- Jenny Makkonen
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Arto Vesterbacka
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Frank Martin
- United States Department of Agriculture, ARS, 1636 E. Alisal St., CA-93905 Salinas, USA
| | - Japo Jussila
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
| | | | - Raine Kortet
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
- Department of Biology, Biological & Geological Sciences, University of Western Ontario, 1151 Richmond St N, London, Ontario N6A 5B7, Canada
| | - Harri Kokko
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
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Ye W, Wang Y, Shen D, Li D, Pu T, Jiang Z, Zhang Z, Zheng X, Tyler BM, Wang Y. Sequencing of the Litchi Downy Blight Pathogen Reveals It Is a Phytophthora Species With Downy Mildew-Like Characteristics. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:573-83. [PMID: 27183038 DOI: 10.1094/mpmi-03-16-0056-r] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
On the basis of its downy mildew-like morphology, the litchi downy blight pathogen was previously named Peronophythora litchii. Recently, however, it was proposed to transfer this pathogen to Phytophthora clade 4. To better characterize this unusual oomycete species and important fruit pathogen, we obtained the genome sequence of Phytophthora litchii and compared it to those from other oomycete species. P. litchii has a small genome with tightly spaced genes. On the basis of a multilocus phylogenetic analysis, the placement of P. litchii in the genus Phytophthora is strongly supported. Effector proteins predicted included 245 RxLR, 30 necrosis-and-ethylene-inducing protein-like, and 14 crinkler proteins. The typical motifs, phylogenies, and activities of these effectors were typical for a Phytophthora species. However, like the genome features of the analyzed downy mildews, P. litchii exhibited a streamlined genome with a relatively small number of genes in both core and species-specific protein families. The low GC content and slight codon preferences of P. litchii sequences were similar to those of the analyzed downy mildews and a subset of Phytophthora species. Taken together, these observations suggest that P. litchii is a Phytophthora pathogen that is in the process of acquiring downy mildew-like genomic and morphological features. Thus P. litchii may provide a novel model for investigating morphological development and genomic adaptation in oomycete pathogens.
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Affiliation(s)
- Wenwu Ye
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yang Wang
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Danyu Shen
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Delong Li
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Tianhuizi Pu
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Zide Jiang
- 3 Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
| | - Zhengguang Zhang
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaobo Zheng
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Brett M Tyler
- 2 Center for Genome Research and Biocomputing, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A.; and
| | - Yuanchao Wang
- 1 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
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Goritschnig S, Steinbrenner AD, Grunwald DJ, Staskawicz BJ. Structurally distinct Arabidopsis thaliana NLR immune receptors recognize tandem WY domains of an oomycete effector. THE NEW PHYTOLOGIST 2016; 210:984-96. [PMID: 26725254 DOI: 10.1111/nph.13823] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/18/2015] [Indexed: 05/27/2023]
Abstract
Nucleotide-binding leucine-rich repeat (NB-LRR, or NLR) receptors mediate pathogen recognition. The Arabidopsis thaliana NLR RPP1 recognizes the tandem WY-domain effector ATR1 from the oomycete Hyaloperonospora arabidopsidis through direct association with C-terminal LRRs. We isolated and characterized homologous NLR genes RPP1-EstA and RPP1-ZdrA from two Arabidopsis ecotypes, Estland (Est-1) and Zdarec (Zdr-1), responsible for recognizing a novel spectrum of ATR1 alleles. RPP1-EstA and -ZdrA encode nearly identical NLRs that are phylogenetically distinct from known immunity-activating RPP1 homologs and possess greatly expanded LRR domains. Site-directed mutagenesis and truncation analysis of ATR1 suggests that these homologs recognize a novel surface of the 2(nd) WY domain of ATR1, partially specified by a C-terminal region of the LRR domain. Synteny comparison with RPP1 loci involved in hybrid incompatibility suggests that these functions evolved independently. Closely related RPP1 homologs have diversified their recognition spectra through LRR expansion and sequence variation, allowing them to detect multiple surfaces of the same pathogen effector. Engineering NLR receptor specificity may require a similar combination of repeat expansion and tailored amino acid variation.
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Affiliation(s)
- Sandra Goritschnig
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - Adam D Steinbrenner
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - Derrick J Grunwald
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - Brian J Staskawicz
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
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40
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Bollmann SR, Fang Y, Press CM, Tyler BM, Grünwald NJ. Diverse Evolutionary Trajectories for Small RNA Biogenesis Genes in the Oomycete Genus Phytophthora. FRONTIERS IN PLANT SCIENCE 2016; 7:284. [PMID: 27014308 PMCID: PMC4791657 DOI: 10.3389/fpls.2016.00284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 02/22/2016] [Indexed: 05/10/2023]
Abstract
Gene regulation by small RNA pathways is ubiquitous among eukaryotes, but little is known about small RNA pathways in the Stramenopile kingdom. Phytophthora, a genus of filamentous oomycetes, contains many devastating plant pathogens, causing multibillion-dollar damage to crops, ornamental plants, and natural environments. The genomes of several oomycetes including Phytophthora species such as the soybean pathogen P. sojae, have been sequenced, allowing evolutionary analysis of small RNA-processing enzymes. This study examined the evolutionary origins of the oomycete small RNA-related genes Dicer-like (DCL), and RNA-dependent RNA polymerase (RDR) through broad phylogenetic analyses of the key domains. Two Dicer gene homologs, DCL1 and DCL2, and one RDR homolog were cloned and analyzed from P. sojae. Gene expression analysis revealed only minor changes in transcript levels among different life stages. Oomycete DCL1 homologs clustered with animal and plant Dicer homologs in evolutionary trees, whereas oomycete DCL2 homologs clustered basally to the tree along with Drosha homologs. Phylogenetic analysis of the RDR homologs confirmed a previous study that suggested the last common eukaryote ancestor possessed three RDR homologs, which were selectively retained or lost in later lineages. Our analysis clarifies the position of some Unikont and Chromalveolate RDR lineages within the tree, including oomycete homologs. Finally, we analyzed alterations in the domain structure of oomycete Dicer and RDR homologs, specifically focusing on the proposed domain transfer of the DEAD-box helicase domain from Dicer to RDR. Implications of the oomycete domain structure are discussed, and possible roles of the two oomycete Dicer homologs are proposed.
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Affiliation(s)
- Stephanie R. Bollmann
- Horticultural Crop Research Unit, USDA-Agricultural Research ServiceCorvallis, OR, USA
| | - Yufeng Fang
- Department of Botany and Plant Pathology and Center for Genome Biology and Biocomputing, Oregon State UniversityCorvallis, OR, USA
- Interdisciplinary Ph.D. Program in Genetics, Bioinformatics and Computational Biology, Virginia TechBlacksburg, VA, USA
| | - Caroline M. Press
- Horticultural Crop Research Unit, USDA-Agricultural Research ServiceCorvallis, OR, USA
| | - Brett M. Tyler
- Department of Botany and Plant Pathology and Center for Genome Biology and Biocomputing, Oregon State UniversityCorvallis, OR, USA
| | - Niklaus J. Grünwald
- Horticultural Crop Research Unit, USDA-Agricultural Research ServiceCorvallis, OR, USA
- Department of Botany and Plant Pathology and Center for Genome Biology and Biocomputing, Oregon State UniversityCorvallis, OR, USA
- *Correspondence: Niklaus J. Grünwald
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