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Alassimone J, Praz C, Lorrain C, De Francesco A, Carrasco-López C, Faino L, Shen Z, Meile L, Sánchez-Vallet A. The Zymoseptoria tritici Avirulence Factor AvrStb6 Accumulates in Hyphae Close to Stomata and Triggers a Wheat Defense Response Hindering Fungal Penetration. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:432-444. [PMID: 38265007 DOI: 10.1094/mpmi-11-23-0181-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Zymoseptoria tritici, the causal agent of Septoria tritici blotch, is one of Europe's most damaging wheat pathogens, causing significant economic losses. Genetic resistance is a common strategy to control the disease, Stb6 being a resistance gene used for more than 100 years in Europe. This study investigates the molecular mechanisms underlying Stb6-mediated resistance. Utilizing confocal microscopy imaging, we determined that Z. tritici epiphytic hyphae mainly accumulate the corresponding avirulence factor AvrStb6 in close proximity to stomata. Consequently, the progression of AvrStb6-expressing avirulent strains is hampered during penetration. The fungal growth inhibition co-occurs with a transcriptional reprogramming in wheat characterized by an induction of immune responses, genes involved in stomatal regulation, and cell wall-related genes. Overall, we shed light on the gene-for-gene resistance mechanisms in the wheat-Z. tritici pathosystem at the cytological and transcriptomic level, and our results highlight that stomatal penetration is a critical process for pathogenicity and resistance. [Formula: see text] Copyright © 2024 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)
- Julien Alassimone
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Coraline Praz
- Centro de Biotecnología y Genómica de Plantas (CBGP)/Universidad Politécnica de Madrid-Instituto Nacional de Investigación Agraria y Alimentaria/Centro Superior de Investigaciones Científicas (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón (Madrid), Spain
| | - Cécile Lorrain
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Agustina De Francesco
- Centro de Biotecnología y Genómica de Plantas (CBGP)/Universidad Politécnica de Madrid-Instituto Nacional de Investigación Agraria y Alimentaria/Centro Superior de Investigaciones Científicas (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón (Madrid), Spain
| | - Cristian Carrasco-López
- Centro de Biotecnología y Genómica de Plantas (CBGP)/Universidad Politécnica de Madrid-Instituto Nacional de Investigación Agraria y Alimentaria/Centro Superior de Investigaciones Científicas (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón (Madrid), Spain
| | - Luigi Faino
- Environmental Biology, Sapienza University of Rome, Roma, Italy
| | - Ziqi Shen
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Lukas Meile
- Centro de Biotecnología y Genómica de Plantas (CBGP)/Universidad Politécnica de Madrid-Instituto Nacional de Investigación Agraria y Alimentaria/Centro Superior de Investigaciones Científicas (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón (Madrid), Spain
| | - Andrea Sánchez-Vallet
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
- Centro de Biotecnología y Genómica de Plantas (CBGP)/Universidad Politécnica de Madrid-Instituto Nacional de Investigación Agraria y Alimentaria/Centro Superior de Investigaciones Científicas (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón (Madrid), Spain
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Abraham LN, Oggenfuss U, Croll D. Population-level transposable element expression dynamics influence trait evolution in a fungal crop pathogen. mBio 2024; 15:e0284023. [PMID: 38349152 PMCID: PMC10936205 DOI: 10.1128/mbio.02840-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/22/2024] [Indexed: 03/14/2024] Open
Abstract
The rapid adaptive evolution of microbes is driven by strong selection pressure acting on genetic variation. How adaptive genetic variation is generated within species and how such variation influences phenotypic trait expression is often not well understood though. We focused on the recent activity of transposable elements (TEs) using deep population genomics and transcriptomics analyses of a fungal plant pathogen with a highly active content of TEs in the genome. Zymoseptoria tritici causes one of the most damaging diseases on wheat, with recent adaptation to the host and environment being facilitated by TE-associated mutations. We obtained genomic and RNA-sequencing data from 146 isolates collected from a single wheat field. We established a genome-wide map of TE insertion polymorphisms in the population by analyzing recent TE insertions among individuals. We quantified the locus-specific transcription of individual TE copies and found considerable population variation at individual TE loci in the population. About 20% of all TE copies show transcription in the genome suggesting that genomic defenses such as repressive epigenetic marks and repeat-induced polymorphisms are at least partially ineffective at preventing the proliferation of TEs in the genome. A quarter of recent TE insertions are associated with expression variation of neighboring genes providing broad potential to influence trait expression. We indeed found that TE insertions are likely responsible for variation in virulence on the host and potentially diverse components of secondary metabolite production. Our large-scale transcriptomics study emphasizes how TE-derived polymorphisms segregate even in individual microbial populations and can broadly underpin trait variation in pathogens.IMPORTANCEPathogens can rapidly adapt to new hosts, antimicrobials, or changes in the environment. Adaptation arises often from mutations in the genome; however, how such variation is generated remains poorly understood. We investigated the most dynamic regions of the genome of Zymoseptoria tritici, a major fungal pathogen of wheat. We focused on the transcription of transposable elements. A large proportion of the transposable elements not only show signatures of potential activity but are also variable within a single population of the pathogen. We find that this variation in activity is likely influencing many important traits of the pathogen. Hence, our work provides insights into how a microbial species can adapt over the shortest time periods based on the activity of transposable elements.
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Affiliation(s)
- Leen Nanchira Abraham
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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Amezrou R, Ducasse A, Compain J, Lapalu N, Pitarch A, Dupont L, Confais J, Goyeau H, Kema GHJ, Croll D, Amselem J, Sanchez-Vallet A, Marcel TC. Quantitative pathogenicity and host adaptation in a fungal plant pathogen revealed by whole-genome sequencing. Nat Commun 2024; 15:1933. [PMID: 38431601 PMCID: PMC10908820 DOI: 10.1038/s41467-024-46191-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/14/2024] [Indexed: 03/05/2024] Open
Abstract
Knowledge of genetic determinism and evolutionary dynamics mediating host-pathogen interactions is essential to manage fungal plant diseases. Studies on the genetic architecture of fungal pathogenicity often focus on large-effect effector genes triggering strong, qualitative resistance. It is not clear how this translates to predominately quantitative interactions. Here, we use the Zymoseptoria tritici-wheat model to elucidate the genetic architecture of quantitative pathogenicity and mechanisms mediating host adaptation. With a multi-host genome-wide association study, we identify 19 high-confidence candidate genes associated with quantitative pathogenicity. Analysis of genetic diversity reveals that sequence polymorphism is the main evolutionary process mediating differences in quantitative pathogenicity, a process that is likely facilitated by genetic recombination and transposable element dynamics. Finally, we use functional approaches to confirm the role of an effector-like gene and a methyltransferase in phenotypic variation. This study highlights the complex genetic architecture of quantitative pathogenicity, extensive diversifying selection and plausible mechanisms facilitating pathogen adaptation.
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Affiliation(s)
- Reda Amezrou
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France.
| | - Aurélie Ducasse
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Jérôme Compain
- Université Paris-Saclay, INRAE, UR URGI, Versailles, France
| | - Nicolas Lapalu
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
- Université Paris-Saclay, INRAE, UR URGI, Versailles, France
| | - Anais Pitarch
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Laetitia Dupont
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Johann Confais
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | | | - Gert H J Kema
- Plant Research International B.V., Wageningen, The Netherlands
| | - Daniel Croll
- Department of Ecology and Evolution, Université de Neuchâtel, Neuchâtel, Switzerland
| | - Joëlle Amselem
- Université Paris-Saclay, INRAE, UR URGI, Versailles, France
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4
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Wilson S, Dagvadorj B, Tam R, Murphy L, Schulz-Kroenert S, Heng N, Crean E, Greenwood J, Rathjen JP, Schwessinger B. Multiplexed effector screening for recognition by endogenous resistance genes using positive defense reporters in wheat protoplasts. THE NEW PHYTOLOGIST 2024; 241:2621-2636. [PMID: 38282212 DOI: 10.1111/nph.19555] [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: 08/02/2023] [Accepted: 01/05/2024] [Indexed: 01/30/2024]
Abstract
Plant resistance (R) and pathogen avirulence (Avr) gene interactions play a vital role in pathogen resistance. Efficient molecular screening tools for crops lack far behind their model organism counterparts, yet they are essential to rapidly identify agriculturally important molecular interactions that trigger host resistance. Here, we have developed a novel wheat protoplast assay that enables efficient screening of Avr/R interactions at scale. Our assay allows access to the extensive gene pool of phenotypically described R genes because it does not require the overexpression of cloned R genes. It is suitable for multiplexed Avr screening, with interactions tested in pools of up to 50 Avr candidates. We identified Avr/R-induced defense genes to create a promoter-luciferase reporter. Then, we combined this with a dual-color ratiometric reporter system that normalizes read-outs accounting for experimental variability and Avr/R-induced cell death. Moreover, we introduced a self-replicative plasmid reducing the amount of plasmid used in the assay. Our assay increases the throughput of Avr candidate screening, accelerating the study of cellular defense signaling and resistance gene identification in wheat. We anticipate that our assay will significantly accelerate Avr identification for many wheat pathogens, leading to improved genome-guided pathogen surveillance and breeding of disease-resistant crops.
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Affiliation(s)
- Salome Wilson
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Bayantes Dagvadorj
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Rita Tam
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Lydia Murphy
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Sven Schulz-Kroenert
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Nigel Heng
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Emma Crean
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Julian Greenwood
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - John P Rathjen
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Benjamin Schwessinger
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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Chen C, Keunecke H, Bemm F, Gyetvai G, Neu E, Kopisch‐Obuch FJ, McDonald BA, Stapley J. GWAS reveals a rapidly evolving candidate avirulence effector in the Cercospora leaf spot pathogen. MOLECULAR PLANT PATHOLOGY 2024; 25:e13407. [PMID: 38009399 PMCID: PMC10799204 DOI: 10.1111/mpp.13407] [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: 07/31/2023] [Revised: 11/09/2023] [Accepted: 11/09/2023] [Indexed: 11/28/2023]
Abstract
The major resistance gene BvCR4 recently bred into sugar beet hybrids provides a high level of resistance to Cercospora leaf spot caused by the fungal pathogen Cercospora beticola. The occurrence of pathogen strains that overcome BvCR4 was studied using field trials in Switzerland conducted under natural disease pressure. Virulence of a subset of these strains was evaluated in a field trial conducted under elevated artificial disease pressure. We created a new C. beticola reference genome and mapped whole genome sequences of 256 isolates collected in Switzerland and Germany. These were combined with virulence phenotypes to conduct three separate genome-wide association studies (GWAS) to identify candidate avirulence genes. We identified a locus associated with avirulence containing a putative avirulence effector gene named AvrCR4. All virulent isolates either lacked AvrCR4 or had nonsynonymous mutations within the gene. AvrCR4 was present in all 74 isolates from non-BvCR4 hybrids, whereas 33 of 89 isolates from BvCR4 hybrids carried a deletion. We also mapped genomic data from 190 publicly available US isolates to our new reference genome. The AvrCR4 deletion was found in only one of 95 unique isolates from non-BvCR4 hybrids in the United States. AvrCR4 presents a unique example of an avirulence effector in which virulent alleles have only recently emerged. Most likely these were selected out of standing genetic variation after deployment of BvCR4. Identification of AvrCR4 will enable real-time screening of C. beticola populations for the emergence and spread of virulent isolates.
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Affiliation(s)
- Chen Chen
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
| | | | | | | | - Enzo Neu
- KWS SAAT SE & Co. KGaAEinbeckGermany
| | | | - Bruce A. McDonald
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
| | - Jessica Stapley
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
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Abraham LN, Croll D. Genome-wide expression QTL mapping reveals the highly dynamic regulatory landscape of a major wheat pathogen. BMC Biol 2023; 21:263. [PMID: 37981685 PMCID: PMC10658818 DOI: 10.1186/s12915-023-01763-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/07/2023] [Indexed: 11/21/2023] Open
Abstract
BACKGROUND In agricultural ecosystems, outbreaks of diseases are frequent and pose a significant threat to food security. A successful pathogen undergoes a complex and well-timed sequence of regulatory changes to avoid detection by the host immune system; hence, well-tuned gene regulation is essential for survival. However, the extent to which the regulatory polymorphisms in a pathogen population provide an adaptive advantage is poorly understood. RESULTS We used Zymoseptoria tritici, one of the most important pathogens of wheat, to generate a genome-wide map of regulatory polymorphism governing gene expression. We investigated genome-wide transcription levels of 146 strains grown under nutrient starvation and performed expression quantitative trait loci (eQTL) mapping. We identified cis-eQTLs for 65.3% of all genes and the majority of all eQTL loci are within 2kb upstream and downstream of the transcription start site (TSS). We also show that polymorphism in different gene elements contributes disproportionally to gene expression variation. Investigating regulatory polymorphism in gene categories, we found an enrichment of regulatory variants for genes predicted to be important for fungal pathogenesis but with comparatively low effect size, suggesting a separate layer of gene regulation involving epigenetics. We also show that previously reported trait-associated SNPs in pathogen populations are frequently cis-regulatory variants of neighboring genes with implications for the trait architecture. CONCLUSIONS Overall, our study provides extensive evidence that single populations segregate large-scale regulatory variation and are likely to fuel rapid adaptation to resistant hosts and environmental change.
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Affiliation(s)
- Leen Nanchira Abraham
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland
- Present address: Institute of Plant Sciences, University of Cologne, Cologne, Germany
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland.
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7
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Dutta A, McDonald BA, Croll D. Combined reference-free and multi-reference based GWAS uncover cryptic variation underlying rapid adaptation in a fungal plant pathogen. PLoS Pathog 2023; 19:e1011801. [PMID: 37972199 PMCID: PMC10688896 DOI: 10.1371/journal.ppat.1011801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 11/30/2023] [Accepted: 11/06/2023] [Indexed: 11/19/2023] Open
Abstract
Microbial pathogens often harbor substantial functional diversity driven by structural genetic variation. Rapid adaptation from such standing variation threatens global food security and human health. Genome-wide association studies (GWAS) provide a powerful approach to identify genetic variants underlying recent pathogen adaptation. However, the reliance on single reference genomes and single nucleotide polymorphisms (SNPs) obscures the true extent of adaptive genetic variation. Here, we show quantitatively how a combination of multiple reference genomes and reference-free approaches captures substantially more relevant genetic variation compared to single reference mapping. We performed reference-genome based association mapping across 19 reference-quality genomes covering the diversity of the species. We contrasted the results with a reference-free (i.e., k-mer) approach using raw whole-genome sequencing data in a panel of 145 strains collected across the global distribution range of the fungal wheat pathogen Zymoseptoria tritici. We mapped the genetic architecture of 49 life history traits including virulence, reproduction and growth in multiple stressful environments. The inclusion of additional reference genome SNP datasets provides a nearly linear increase in additional loci mapped through GWAS. Variants detected through the k-mer approach explained a higher proportion of phenotypic variation than a reference genome-based approach and revealed functionally confirmed loci that classic GWAS approaches failed to map. The power of GWAS in microbial pathogens can be significantly enhanced by comprehensively capturing structural genetic variation. Our approach is generalizable to a large number of species and will uncover novel mechanisms driving rapid adaptation of pathogens.
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Affiliation(s)
- Anik Dutta
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Bruce A. McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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8
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Bernasconi A, Lorrain C, Flury P, Alassimone J, McDonald BA, Sánchez-Vallet A. Virulent strains of Zymoseptoria tritici suppress the host immune response and facilitate the success of avirulent strains in mixed infections. PLoS Pathog 2023; 19:e1011767. [PMID: 37972205 PMCID: PMC10721197 DOI: 10.1371/journal.ppat.1011767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 12/14/2023] [Accepted: 10/19/2023] [Indexed: 11/19/2023] Open
Abstract
Plants interact with a plethora of pathogenic microorganisms in nature. Pathogen-plant interaction experiments focus mainly on single-strain infections, typically ignoring the complexity of multi-strain infections even though mixed infections are common and critical for the infection outcome. The wheat pathogen Zymoseptoria tritici forms highly diverse fungal populations in which several pathogen strains often colonize the same leaf. Despite the importance of mixed infections, the mechanisms governing interactions between a mixture of pathogen strains within a plant host remain largely unexplored. Here we demonstrate that avirulent pathogen strains benefit from being in mixed infections with virulent strains. We show that virulent strains suppress the wheat immune response, allowing avirulent strains to colonize the apoplast and to reproduce. Our experiments indicate that virulent strains in mixed infections can suppress the plant immune system, probably facilitating the persistence of avirulent pathogen strains in fields planted with resistant host plants.
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Affiliation(s)
- Alessio Bernasconi
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Cécile Lorrain
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Priska Flury
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Julien Alassimone
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Bruce A. McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Andrea Sánchez-Vallet
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
- Centro de Biotecnología y Genómica de Plantas (CBGP/Universidad Politécnica de Madrid-Instituto Nacional de Investigación Agraria y Alimentaria/Centro Superior de Investigaciones Científicas (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón (Madrid) Spain
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9
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Suarez-Fernandez M, Álvarez-Aragón R, Pastor-Mediavilla A, Maestre-Guillén A, del Olmo I, De Francesco A, Meile L, Sánchez-Vallet A. Sas3-mediated histone acetylation regulates effector gene activation in a fungal plant pathogen. mBio 2023; 14:e0138623. [PMID: 37642412 PMCID: PMC10653901 DOI: 10.1128/mbio.01386-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 07/04/2023] [Indexed: 08/31/2023] Open
Abstract
IMPORTANCE Pathogen infections require the production of effectors that enable host colonization. Effectors have diverse functions and are only expressed at certain stages of the infection cycle. Thus, effector genes are tightly regulated by several mechanisms, including chromatin remodeling. Here, we investigate the role of histone acetylation in effector gene activation in the fungal wheat pathogen Zymoseptoria tritici. We demonstrate that lysine acetyltransferases (KATs) are essential for the spatiotemporal regulation of effector genes. We show that the KAT Sas3 is involved in leaf symptom development and pycnidia formation. Importantly, our results indicate that Sas3 controls histone acetylation of effector loci and is a regulator of effector gene activation during stomatal penetration. Overall, our work demonstrates the key role of histone acetylation in regulating gene expression associated with plant infection.
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Affiliation(s)
- Marta Suarez-Fernandez
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Department of Marine Sciences and Applied Biology, University of Alicante, Alicante, Spain
| | - Rocio Álvarez-Aragón
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Ana Pastor-Mediavilla
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Alejandro Maestre-Guillén
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Ivan del Olmo
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Agustina De Francesco
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Lukas Meile
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Andrea Sánchez-Vallet
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM)—Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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10
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Fones HN, Soanes D, Gurr SJ. Epiphytic proliferation of Zymoseptoria tritici isolates on resistant wheat leaves. Fungal Genet Biol 2023; 168:103822. [PMID: 37343618 DOI: 10.1016/j.fgb.2023.103822] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 06/04/2023] [Accepted: 06/15/2023] [Indexed: 06/23/2023]
Abstract
The wheat pathogen Zymoseptoria tritici is capable of a long period of pre-invasive epiphytic growth. Studies have shown that virulent isolates vary in the extent, duration and growth form of this epiphytic growth, and the fungus has been observed to undergo behaviours such as asexual reproduction by budding and vegetative fusion of hyphae on the leaf surface. This epiphytic colonisation has been investigated very little during interactions in which an isolate of Z. tritici is unable to colonise the apoplast, as occurs during avirulence. However, avirulent isolates have been seen to undergo sexual crosses in the absense of leaf penetration, and it is widely accepted that the main point of distinction between virulent and avirulent isolates occurs at the point of attempted leaf penetration or attempted apoplastic growth, which fails in the avirulent case. In this work, we describe extensive epiphytic growth in three isolates which are unable or have very limited ability to invade the leaf, and show that growth form is as variable as for fully virulent isolates. We demonstrate that during certain interactions, Z. tritici isolates rarely invade the leaf and form pycnidia, but induce necrosis. These isolates are able to achieve higher epiphytic biomass than fully virulent isolates during asymptomatic growth, and may undergo very extensive asexual reproduction on the leaf surface. These findings have implications for open questions such as whether and how Z. tritici obtains nutrients on the leaf surface and the nature of its interaction with wheat defences.
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Affiliation(s)
- H N Fones
- Biosciences, University of Exeter, Exeter, UK
| | - D Soanes
- University of Exeter Medical School, Exeter, UK
| | - S J Gurr
- Biosciences, University of Exeter, Exeter, UK; Department of Biosciences, Utrecht University, Utrecht, the Netherlands.
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11
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Francisco CS, McDonald BA, Palma-Guerrero J. A transcription factor and a phosphatase regulate temperature-dependent morphogenesis in the fungal plant pathogen Zymoseptoria tritici. Fungal Genet Biol 2023; 167:103811. [PMID: 37196910 DOI: 10.1016/j.fgb.2023.103811] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 04/26/2023] [Accepted: 05/10/2023] [Indexed: 05/19/2023]
Abstract
Naturally fluctuating temperatures provide a constant environmental stress that requires adaptation. Some fungal pathogens respond to heat stress by producing new morphotypes that maximize their overall fitness. The fungal wheat pathogen Zymoseptoria tritici responds to heat stress by switching from its yeast-like blastospore form to hyphae or chlamydospores. The regulatory mechanisms underlying this switch are unknown. Here, we demonstrate that a differential heat stress response is ubiquitous in Z. tritici populations around the world. We used QTL mapping to identify a single locus associated with the temperature-dependent morphogenesis and we found two genes, the transcription factor ZtMsr1 and the protein phosphatase ZtYvh1, regulating this mechanism. We find that ZtMsr1 regulates repression of hyphal growth and induces chlamydospore formation whereas ZtYvh1 is required for hyphal growth. We next showed that chlamydospore formation is a response to the intracellular osmotic stress generated by the heat stress. This intracellular stress stimulates the cell wall integrity (CWI) and high-osmolarity glycerol (HOG) MAPK pathways resulting in hyphal growth. If cell wall integrity is compromised, however, ZtMsr1 represses the hyphal development program and may induce the chlamydospore-inducing genes as a stress-response survival strategy. Taken together, these results suggest a novel mechanism through which morphological transitions are orchestrated in Z. tritici - a mechanism that may also be present in other pleomorphic fungi.
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Affiliation(s)
| | - Bruce A McDonald
- Plant Pathology Group, Institute of Integrative Biology, 8092 ETH Zürich, Switzerland
| | - Javier Palma-Guerrero
- Plant Pathology Group, Institute of Integrative Biology, 8092 ETH Zürich, Switzerland.
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12
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Amezrou R, Audéon C, Compain J, Gélisse S, Ducasse A, Saintenac C, Lapalu N, Louet C, Orford S, Croll D, Amselem J, Fillinger S, Marcel TC. A secreted protease-like protein in Zymoseptoria tritici is responsible for avirulence on Stb9 resistance gene in wheat. PLoS Pathog 2023; 19:e1011376. [PMID: 37172036 DOI: 10.1371/journal.ppat.1011376] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 05/24/2023] [Accepted: 04/19/2023] [Indexed: 05/14/2023] Open
Abstract
Zymoseptoria tritici is the fungal pathogen responsible for Septoria tritici blotch on wheat. Disease outcome in this pathosystem is partly determined by isolate-specific resistance, where wheat resistance genes recognize specific fungal factors triggering an immune response. Despite the large number of known wheat resistance genes, fungal molecular determinants involved in such cultivar-specific resistance remain largely unknown. We identified the avirulence factor AvrStb9 using association mapping and functional validation approaches. Pathotyping AvrStb9 transgenic strains on Stb9 cultivars, near isogenic lines and wheat mapping populations, showed that AvrStb9 interacts with Stb9 resistance gene, triggering an immune response. AvrStb9 encodes an unusually large avirulence gene with a predicted secretion signal and a protease domain. It belongs to a S41 protease family conserved across different filamentous fungi in the Ascomycota class and may constitute a core effector. AvrStb9 is also conserved among a global Z. tritici population and carries multiple amino acid substitutions caused by strong positive diversifying selection. These results demonstrate the contribution of an 'atypical' conserved effector protein to fungal avirulence and the role of sequence diversification in the escape of host recognition, adding to our understanding of host-pathogen interactions and the evolutionary processes underlying pathogen adaptation.
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Affiliation(s)
- Reda Amezrou
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Colette Audéon
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Jérôme Compain
- Université Paris-Saclay, INRAE, UR URGI, Versailles, France
| | | | - Aurélie Ducasse
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | | | - Nicolas Lapalu
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
- Université Paris-Saclay, INRAE, UR URGI, Versailles, France
| | | | - Simon Orford
- Crop Genetics, John Innes Centre, Norwich, United Kingdom
| | - Daniel Croll
- University of Neuchâtel, Laboratory of Evolutionary Genetics, Neuchâtel, Switzerland
| | - Joëlle Amselem
- Université Paris-Saclay, INRAE, UR URGI, Versailles, France
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13
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Langlands-Perry C, Pitarch A, Lapalu N, Cuenin M, Bergez C, Noly A, Amezrou R, Gélisse S, Barrachina C, Parrinello H, Suffert F, Valade R, Marcel TC. Quantitative and qualitative plant-pathogen interactions call upon similar pathogenicity genes with a spectrum of effects. FRONTIERS IN PLANT SCIENCE 2023; 14:1128546. [PMID: 37235026 PMCID: PMC10206311 DOI: 10.3389/fpls.2023.1128546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/19/2023] [Indexed: 05/28/2023]
Abstract
Septoria leaf blotch is a foliar wheat disease controlled by a combination of plant genetic resistances and fungicides use. R-gene-based qualitative resistance durability is limited due to gene-for-gene interactions with fungal avirulence (Avr) genes. Quantitative resistance is considered more durable but the mechanisms involved are not well documented. We hypothesize that genes involved in quantitative and qualitative plant-pathogen interactions are similar. A bi-parental population of Zymoseptoria tritici was inoculated on wheat cultivar 'Renan' and a linkage analysis performed to map QTL. Three pathogenicity QTL, Qzt-I05-1, Qzt-I05-6 and Qzt-I07-13, were mapped on chromosomes 1, 6 and 13 in Z. tritici, and a candidate pathogenicity gene on chromosome 6 was selected based on its effector-like characteristics. The candidate gene was cloned by Agrobacterium tumefaciens-mediated transformation, and a pathology test assessed the effect of the mutant strains on 'Renan'. This gene was demonstrated to be involved in quantitative pathogenicity. By cloning a newly annotated quantitative-effect gene in Z. tritici that is effector-like, we demonstrated that genes underlying pathogenicity QTL can be similar to Avr genes. This opens up the previously probed possibility that 'gene-for-gene' underlies not only qualitative but also quantitative plant-pathogen interactions in this pathosystem.
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Affiliation(s)
- Camilla Langlands-Perry
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
- ARVALIS Institut du Végétal, Boigneville, France
| | - Anaïs Pitarch
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Nicolas Lapalu
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Murielle Cuenin
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | | | - Alicia Noly
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Reda Amezrou
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | | | - Célia Barrachina
- MGX-Montpellier GenomiX, Univ. Montpellier, CNRS, INSERM, Montpellier, France
| | - Hugues Parrinello
- MGX-Montpellier GenomiX, Univ. Montpellier, CNRS, INSERM, Montpellier, France
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14
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Meile L, Garrido-Arandia M, Bernasconi Z, Peter J, Schneller A, Bernasconi A, Alassimone J, McDonald BA, Sánchez-Vallet A. Natural variation in Avr3D1 from Zymoseptoria sp. contributes to quantitative gene-for-gene resistance and to host specificity. THE NEW PHYTOLOGIST 2023; 238:1562-1577. [PMID: 36529883 DOI: 10.1111/nph.18690] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Successful host colonization by plant pathogens requires the circumvention of host defense responses, frequently through sequence modifications in secreted pathogen proteins known as avirulence factors (Avrs). Although Avr sequences are often polymorphic, the contribution of these polymorphisms to virulence diversity in natural pathogen populations remains largely unexplored. We used molecular genetic tools to determine how natural sequence polymorphisms of the avirulence factor Avr3D1 in the wheat pathogen Zymoseptoria tritici contributed to adaptive changes in virulence. We showed that there is a continuous distribution in the magnitude of resistance triggered by different Avr3D1 isoforms and demonstrated that natural variation in an Avr gene can lead to a quantitative resistance phenotype. We further showed that homologues of Avr3D1 in two nonpathogenic sister species of Z. tritici are recognized by some wheat cultivars, suggesting that Avr-R gene-for-gene interactions can contribute to nonhost resistance. We suggest that the mechanisms underlying host range, qualitative resistance, and quantitative resistance are not exclusive.
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Affiliation(s)
- Lukas Meile
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223, Pozuelo de Alarcón, Madrid, Spain
| | - María Garrido-Arandia
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), 28040, Madrid, Spain
| | - Zoe Bernasconi
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Jules Peter
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Alissa Schneller
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Alessio Bernasconi
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Julien Alassimone
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Andrea Sánchez-Vallet
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223, Pozuelo de Alarcón, Madrid, Spain
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15
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Rudd JJ. Effector-mediated partial and nonhost disease resistance in wheat. THE NEW PHYTOLOGIST 2023; 238:1340-1342. [PMID: 36999944 DOI: 10.1111/nph.18872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Affiliation(s)
- Jason J Rudd
- Protecting Crops and the Environment, Rothamsted Research, West Common, Harpenden, AL5 2JQ, UK
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16
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Gupta PK, Vasistha NK, Singh S, Joshi AK. Genetics and breeding for resistance against four leaf spot diseases in wheat ( Triticum aestivum L.). FRONTIERS IN PLANT SCIENCE 2023; 14:1023824. [PMID: 37063191 PMCID: PMC10096043 DOI: 10.3389/fpls.2023.1023824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 02/28/2023] [Indexed: 06/19/2023]
Abstract
In wheat, major yield losses are caused by a variety of diseases including rusts, spike diseases, leaf spot and root diseases. The genetics of resistance against all these diseases have been studied in great detail and utilized for breeding resistant cultivars. The resistance against leaf spot diseases caused by each individual necrotroph/hemi-biotroph involves a complex system involving resistance (R) genes, sensitivity (S) genes, small secreted protein (SSP) genes and quantitative resistance loci (QRLs). This review deals with resistance for the following four-leaf spot diseases: (i) Septoria nodorum blotch (SNB) caused by Parastagonospora nodorum; (ii) Tan spot (TS) caused by Pyrenophora tritici-repentis; (iii) Spot blotch (SB) caused by Bipolaris sorokiniana and (iv) Septoria tritici blotch (STB) caused by Zymoseptoria tritici.
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Affiliation(s)
- Pushpendra Kumar Gupta
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
- Murdoch’s Centre for Crop and Food Innovation, Murdoch University, Murdoch, WA, Australia
- Borlaug Institute for South Asia (BISA), National Agricultural Science Complex (NASC), Dev Prakash Shastri (DPS) Marg, New Delhi, India
| | - Neeraj Kumar Vasistha
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
- Department of Genetics-Plant Breeding and Biotechnology, Dr Khem Singh Gill, Akal College of Agriculture, Eternal University, Baru Sahib, Sirmour, India
| | - Sahadev Singh
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
| | - Arun Kumar Joshi
- Borlaug Institute for South Asia (BISA), National Agricultural Science Complex (NASC), Dev Prakash Shastri (DPS) Marg, New Delhi, India
- The International Maize and Wheat Improvement Center (CIMMYT), National Agricultural Science Complex (NASC), Dev Prakash Shastri (DPS) Marg, New Delhi, India
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17
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Feurtey A, Lorrain C, McDonald MC, Milgate A, Solomon PS, Warren R, Puccetti G, Scalliet G, Torriani SFF, Gout L, Marcel TC, Suffert F, Alassimone J, Lipzen A, Yoshinaga Y, Daum C, Barry K, Grigoriev IV, Goodwin SB, Genissel A, Seidl MF, Stukenbrock EH, Lebrun MH, Kema GHJ, McDonald BA, Croll D. A thousand-genome panel retraces the global spread and adaptation of a major fungal crop pathogen. Nat Commun 2023; 14:1059. [PMID: 36828814 PMCID: PMC9958100 DOI: 10.1038/s41467-023-36674-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 02/10/2023] [Indexed: 02/26/2023] Open
Abstract
Human activity impacts the evolutionary trajectories of many species worldwide. Global trade of agricultural goods contributes to the dispersal of pathogens reshaping their genetic makeup and providing opportunities for virulence gains. Understanding how pathogens surmount control strategies and cope with new climates is crucial to predicting the future impact of crop pathogens. Here, we address this by assembling a global thousand-genome panel of Zymoseptoria tritici, a major fungal pathogen of wheat reported in all production areas worldwide. We identify the global invasion routes and ongoing genetic exchange of the pathogen among wheat-growing regions. We find that the global expansion was accompanied by increased activity of transposable elements and weakened genomic defenses. Finally, we find significant standing variation for adaptation to new climates encountered during the global spread. Our work shows how large population genomic panels enable deep insights into the evolutionary trajectory of a major crop pathogen.
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Affiliation(s)
- Alice Feurtey
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
- Plant Pathology, D-USYS, ETH Zurich, CH-8092, Zurich, Switzerland
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Cécile Lorrain
- Plant Pathology, D-USYS, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Megan C McDonald
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Andrew Milgate
- NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Pine Gully Road, Wagga Wagga, NSW, 2650, Australia
| | - Peter S Solomon
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Rachael Warren
- The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand
| | - Guido Puccetti
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
- Syngenta Crop Protection AG, CH-4332, Stein, Switzerland
| | | | | | - Lilian Gout
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | - Thierry C Marcel
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | - Frédéric Suffert
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | | | - Anna Lipzen
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yuko Yoshinaga
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Christopher Daum
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kerrie Barry
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Igor V Grigoriev
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, 9472, USA
| | | | - Anne Genissel
- Université Paris Saclay, INRAE, UR BIOGER, 91120, Palaiseau, France
| | - Michael F Seidl
- Wageningen University and Research, Laboratory of Phytopathology, Wageningen, The Netherlands
- Utrecht University, Theoretical Biology and Bioinformatics, Utrecht, The Netherlands
| | - Eva H Stukenbrock
- Max Planck Institute for Evolutionary Biology, Plön, Germany
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany
| | | | - Gert H J Kema
- Wageningen University and Research, Laboratory of Phytopathology, Wageningen, The Netherlands
| | - Bruce A McDonald
- Plant Pathology, D-USYS, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland.
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18
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Oggenfuss U, Croll D. Recent transposable element bursts are associated with the proximity to genes in a fungal plant pathogen. PLoS Pathog 2023; 19:e1011130. [PMID: 36787337 PMCID: PMC9970103 DOI: 10.1371/journal.ppat.1011130] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 02/27/2023] [Accepted: 01/18/2023] [Indexed: 02/15/2023] Open
Abstract
The activity of transposable elements (TEs) contributes significantly to pathogen genome evolution. TEs often destabilize genome integrity but may also confer adaptive variation in pathogenicity or resistance traits. De-repression of epigenetically silenced TEs often initiates bursts of transposition activity that may be counteracted by purifying selection and genome defenses. However, how these forces interact to determine the expansion routes of TEs within a pathogen species remains largely unknown. Here, we analyzed a set of 19 telomere-to-telomere genomes of the fungal wheat pathogen Zymoseptoria tritici. Phylogenetic reconstruction and ancestral state estimates of individual TE families revealed that TEs have undergone distinct activation and repression periods resulting in highly uneven copy numbers between genomes of the same species. Most TEs are clustered in gene poor niches, indicating strong purifying selection against insertions near coding sequences, or as a consequence of insertion site preferences. TE families with high copy numbers have low sequence divergence and strong signatures of defense mechanisms (i.e., RIP). In contrast, small non-autonomous TEs (i.e., MITEs) are less impacted by defense mechanisms and are often located in close proximity to genes. Individual TE families have experienced multiple distinct burst events that generated many nearly identical copies. We found that a Copia element burst was initiated from recent copies inserted substantially closer to genes compared to older copies. Overall, TE bursts tended to initiate from copies in GC-rich niches that escaped inactivation by genomic defenses. Our work shows how specific genomic environments features provide triggers for TE proliferation in pathogen genomes.
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Affiliation(s)
- Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- * E-mail:
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19
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Bellah H, Gazeau G, Gélisse S, Amezrou R, Marcel TC, Croll D. A highly multiplexed assay to monitor pathogenicity, fungicide resistance and gene flow in the fungal wheat pathogen Zymoseptoria tritici. PLoS One 2023; 18:e0281181. [PMID: 36745583 PMCID: PMC9901794 DOI: 10.1371/journal.pone.0281181] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 01/17/2023] [Indexed: 02/07/2023] Open
Abstract
Crop pathogens pose severe risks to global food production due to the rapid rise of resistance to pesticides and host resistance breakdowns. Predicting future risks requires monitoring tools to identify changes in the genetic composition of pathogen populations. Here we report the design of a microfluidics-based amplicon sequencing assay to multiplex 798 loci targeting virulence and fungicide resistance genes, and randomly selected genome-wide markers for the fungal pathogen Zymoseptoria tritici. The fungus causes one of the most devastating diseases on wheat showing rapid adaptation to fungicides and host resistance. We optimized the primer design by integrating polymorphism data from 632 genomes of the same species. To test the performance of the assay, we genotyped 192 samples in two replicates. Analysis of the short-read sequence data generated by the assay showed a fairly stable success rate across samples to amplify a large number of loci. The performance was consistent between samples originating from pure genomic DNA as well as material extracted directly from infected wheat leaves. In samples with mixed genotypes, we found that the assay recovers variations in allele frequencies. We also explored the potential of the amplicon assay to recover transposable element insertion polymorphism relevant for fungicide resistance. As a proof-of-concept, we show that the assay recovers the pathogen population structure across French wheat fields. Genomic monitoring of crop pathogens contributes to more sustainable crop protection and yields.
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Affiliation(s)
- Hadjer Bellah
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Gwilherm Gazeau
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
| | - Sandrine Gélisse
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
| | - Reda Amezrou
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
| | - Thierry C. Marcel
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
- * E-mail: (TCM); (DC)
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- * E-mail: (TCM); (DC)
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20
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Magnaporthe oryzae pathotype Triticum (MoT) can act as a heterologous expression system for fungal effectors with high transcript abundance in wheat. Sci Rep 2023; 13:108. [PMID: 36596834 PMCID: PMC9810704 DOI: 10.1038/s41598-022-27030-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 12/23/2022] [Indexed: 01/04/2023] Open
Abstract
Plant pathogens deliver effector proteins to reprogramme a host plants circuitry, supporting their own growth and development, whilst thwarting defence responses. A subset of these effectors are termed avirulence factors (Avr) and can be recognised by corresponding host resistance (R) proteins, creating a strong evolutionary pressure on pathogen Avr effectors that favours their modification/deletion to evade the immune response. Hence, identifying Avr effectors and tracking their allele frequencies in a population is critical for understanding the loss of host recognition. However, the current systems available to confirm Avr effector function, particularly for obligate biotrophic fungi, remain limited and challenging. Here, we explored the utility of the genetically tractable wheat blast pathogen Magnaporthe oryzae pathotype Triticum (MoT) as a suitable heterologous expression system in wheat. Using the recently confirmed wheat stem rust pathogen (Puccina graminis f. sp. tritici) avirulence effector AvrSr50 as a proof-of-concept, we found that delivery of AvrSr50 via MoT could elicit a visible Sr50-dependant cell death phenotype. However, activation of Sr50-mediated cell death correlated with a high transgene copy number and transcript abundance in MoT transformants. This illustrates that MoT can act as an effective heterologous delivery system for fungal effectors from distantly related fungal species, but only when enough transgene copies and/or transcript abundance is achieved.
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21
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Blyth HR, Smith D, King R, Bayon C, Ashfield T, Walpole H, Venter E, Ray RV, Kanyuka K, Rudd JJ. Fungal plant pathogen "mutagenomics" reveals tagged and untagged mutations in Zymoseptoria tritici and identifies SSK2 as key morphogenesis and stress-responsive virulence factor. FRONTIERS IN PLANT SCIENCE 2023; 14:1140824. [PMID: 37206970 PMCID: PMC10190600 DOI: 10.3389/fpls.2023.1140824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 03/29/2023] [Indexed: 05/21/2023]
Abstract
"Mutagenomics" is the combination of random mutagenesis, phenotypic screening, and whole-genome re-sequencing to uncover all tagged and untagged mutations linked with phenotypic changes in an organism. In this study, we performed a mutagenomics screen on the wheat pathogenic fungus Zymoseptoria tritici for altered morphogenetic switching and stress sensitivity phenotypes using Agrobacterium-mediated "random" T-DNA mutagenesis (ATMT). Biological screening identified four mutants which were strongly reduced in virulence on wheat. Whole genome re-sequencing defined the positions of the T-DNA insertion events and revealed several unlinked mutations potentially affecting gene functions. Remarkably, two independent reduced virulence mutant strains, with similarly altered stress sensitivities and aberrant hyphal growth phenotypes, were found to have a distinct loss of function mutations in the ZtSSK2 MAPKKK gene. One mutant strain had a direct T-DNA insertion affecting the predicted protein's N-terminus, while the other possessed an unlinked frameshift mutation towards the C-terminus. We used genetic complementation to restore both strains' wild-type (WT) function (virulence, morphogenesis, and stress response). We demonstrated that ZtSSK2 has a non-redundant function with ZtSTE11 in virulence through the biochemical activation of the stress-activated HOG1 MAPK pathway. Moreover, we present data suggesting that SSK2 has a unique role in activating this pathway in response to specific stresses. Finally, dual RNAseq-based transcriptome profiling of WT and SSK2 mutant strains revealed many HOG1-dependent transcriptional changes in the fungus during early infection and suggested that the host response does not discriminate between WT and mutant strains during this early phase. Together these data define new genes implicated in the virulence of the pathogen and emphasise the importance of a whole genome sequencing step in mutagenomic discovery pipelines.
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Affiliation(s)
- Hannah R. Blyth
- Protecting Crops and the Environment, Rothamsted Research, Harpenden, United Kingdom
| | - Dan Smith
- Protecting Crops and the Environment, Rothamsted Research, Harpenden, United Kingdom
| | - Robert King
- Protecting Crops and the Environment, Rothamsted Research, Harpenden, United Kingdom
| | - Carlos Bayon
- Protecting Crops and the Environment, Rothamsted Research, Harpenden, United Kingdom
| | - Tom Ashfield
- Crop Health and Protection (CHAP), Rothamsted Research, Harpenden, United Kingdom
| | - Hannah Walpole
- Bioimaging Unit, Rothamsted Research, Harpenden, United Kingdom
| | - Eudri Venter
- Bioimaging Unit, Rothamsted Research, Harpenden, United Kingdom
| | - Rumiana V. Ray
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Loughborough, United Kingdom
| | - Kostya Kanyuka
- Protecting Crops and the Environment, Rothamsted Research, Harpenden, United Kingdom
| | - Jason J. Rudd
- Protecting Crops and the Environment, Rothamsted Research, Harpenden, United Kingdom
- *Correspondence: Jason J. Rudd,
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22
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Anderegg J, Kirchgessner N, Kronenberg L, McDonald BA. Automated Quantitative Measurement of Yellow Halos Suggests Activity of Necrotrophic Effectors in Septoria tritici Blotch. PHYTOPATHOLOGY 2022; 112:2560-2573. [PMID: 35793150 DOI: 10.1094/phyto-11-21-0465-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Many necrotrophic plant pathogens utilize host-selective toxins or necrotrophic effectors during the infection process. We hypothesized that the chlorotic yellow halos frequently observed around necrotic lesions caused by the wheat pathogen Zymoseptoria tritici could result from the activity of necrotrophic effectors interacting with the products of toxin sensitivity genes. As an initial step toward testing this hypothesis, we developed an automated image analysis (AIA) workflow that could quantify the degree of yellow halo formation occurring in wheat leaves naturally infected by a highly diverse pathogen population under field conditions. This AIA based on statistical learning was applied to more than 10,000 naturally infected leaves collected from 335 wheat cultivars grown in a replicated field experiment. We estimated a high heritability (h2 = 0.71) for the degree of yellow halo formation, suggesting that this quantitative trait has a significant genetic component. Using genome-wide association mapping, we identified six chromosome segments significantly associated with the yellow halo phenotype. Most of these segments contained candidate genes associated with targets of necrotrophic effectors in other necrotrophic pathogens. Our findings conform with the hypothesis that toxin sensitivity genes could account for a significant fraction of the observed variation in quantitative resistance to Septoria tritici blotch. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Jonas Anderegg
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Norbert Kirchgessner
- Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Lukas Kronenberg
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Bruce A McDonald
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
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23
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Fraser CJ, Whitehall SK. Heterochromatin in the fungal plant pathogen, Zymoseptoria tritici: Control of transposable elements, genome plasticity and virulence. Front Genet 2022; 13:1058741. [DOI: 10.3389/fgene.2022.1058741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/04/2022] [Indexed: 11/22/2022] Open
Abstract
Heterochromatin is a repressive chromatin state that plays key roles in the functional organisation of eukaryotic genomes. In fungal plant pathogens, effector genes that are required for host colonization tend to be associated with heterochromatic regions of the genome that are enriched with transposable elements. It has been proposed that the heterochromatin environment silences effector genes in the absence of host and dynamic chromatin remodelling facilitates their expression during infection. Here we discuss this model in the context of the key wheat pathogen, Zymoseptoria tritici. We cover progress in understanding the deposition and recognition of heterochromatic histone post translational modifications in Z. tritici and the role that heterochromatin plays in control of genome plasticity and virulence.
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24
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Vogel G, Giles G, Robbins KR, Gore MA, Smart CD. Quantitative Genetic Analysis of Interactions in the Pepper- Phytophthora capsici Pathosystem. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:1018-1033. [PMID: 35914305 DOI: 10.1094/mpmi-12-21-0307-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: 06/15/2023]
Abstract
The development of pepper cultivars with durable resistance to the oomycete Phytophthora capsici has been challenging due to differential interactions between the species that allow certain pathogen isolates to cause disease on otherwise resistant host genotypes. Currently, little is known about the pathogen genes involved in these interactions. To investigate the genetic basis of P. capsici virulence on individual pepper genotypes, we inoculated sixteen pepper accessions, representing commercial varieties, sources of resistance, and host differentials, with 117 isolates of P. capsici, for a total of 1,864 host-pathogen combinations. Analysis of disease outcomes revealed a significant effect of inter-species genotype-by-genotype interactions, although these interactions were quantitative rather than qualitative in scale. Isolates were classified into five pathogen subpopulations, as determined by their genotypes at over 60,000 single-nucleotide polymorphisms (SNPs). While absolute virulence levels on certain pepper accessions significantly differed between subpopulations, a multivariate phenotype reflecting relative virulence levels on certain pepper genotypes compared with others showed the strongest association with pathogen subpopulation. A genome-wide association study (GWAS) identified four pathogen loci significantly associated with virulence, two of which colocalized with putative RXLR effector genes and another with a polygalacturonase gene cluster. All four loci appeared to represent broad-spectrum virulence genes, as significant SNPs demonstrated consistent effects regardless of the host genotype tested. Host genotype-specific virulence variants in P. capsici may be difficult to map via GWAS with all but excessively large sample sizes, perhaps controlled by genes of small effect or by multiple allelic variants that have arisen independently. [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)
- Gregory Vogel
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, U.S.A
| | - Garrett Giles
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, U.S.A
| | - Kelly R Robbins
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
| | - Michael A Gore
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
| | - Christine D Smart
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, U.S.A
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25
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Zymoseptoria tritici white-collar complex integrates light, temperature and plant cues to initiate dimorphism and pathogenesis. Nat Commun 2022; 13:5625. [PMID: 36163135 PMCID: PMC9512790 DOI: 10.1038/s41467-022-33183-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 09/07/2022] [Indexed: 11/08/2022] Open
Abstract
Transitioning from spores to hyphae is pivotal to host invasion by the plant pathogenic fungus Zymoseptoria tritici. This dimorphic switch can be initiated by high temperature in vitro (~27 °C); however, such a condition may induce cellular heat stress, questioning its relevance to field infections. Here, we study the regulation of the dimorphic switch by temperature and other factors. Climate data from wheat-growing areas indicate that the pathogen sporadically experiences high temperatures such as 27 °C during summer months. However, using a fluorescent dimorphic switch reporter (FDR1) in four wild-type strains, we show that dimorphic switching already initiates at 15-18 °C, and is enhanced by wheat leaf surface compounds. Transcriptomics reveals 1261 genes that are up- or down-regulated in hyphae of all strains. These pan-strain core dimorphism genes (PCDGs) encode known effectors, dimorphism and transcription factors, and light-responsive proteins (velvet factors, opsins, putative blue light receptors). An FDR1-based genetic screen reveals a crucial role for the white-collar complex (WCC) in dimorphism and virulence, mediated by control of PCDG expression. Thus, WCC integrates light with biotic and abiotic cues to orchestrate Z. tritici infection.
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26
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Bernasconi A, Alassimone J, McDonald BA, Sánchez‐Vallet A. Asexual reproductive potential trumps virulence as a predictor of competitive ability in mixed infections. Environ Microbiol 2022; 24:4369-4381. [PMID: 35437879 PMCID: PMC9790533 DOI: 10.1111/1462-2920.16018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 04/13/2022] [Indexed: 12/30/2022]
Abstract
Natural infections frequently involve several co-infecting pathogen strains. These mixed infections can affect the extent of the infection, the transmission success of the pathogen and the eventual epidemic outcome. To date, few studies have investigated how mixed infections affect transmission between hosts. Zymoseptoria tritici is a highly diverse wheat pathogen in which multiple strains often coexist in the same lesion. Here we demonstrate that the most competitive strains often exclude their competitors during serial passages of mixed infections. The outcome of the competition depended on both the host genotype and the genotypes of the competing pathogen strains. Differences in virulence among the strains were not associated with competitive advantages during transmission, while differences in reproductive potential had a strong effect on strain competitive ability. Overall, our findings suggest that host specialization is determined mainly by the ability to successfully transmit offspring to new hosts during mixed infections.
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Affiliation(s)
- Alessio Bernasconi
- Plant Pathology, Institute of Integrative Biology, ETH ZürichZürichCH‐8092Switzerland
| | - Julien Alassimone
- Plant Pathology, Institute of Integrative Biology, ETH ZürichZürichCH‐8092Switzerland
| | - Bruce A. McDonald
- Plant Pathology, Institute of Integrative Biology, ETH ZürichZürichCH‐8092Switzerland
| | - Andrea Sánchez‐Vallet
- Plant Pathology, Institute of Integrative Biology, ETH ZürichZürichCH‐8092Switzerland
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27
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Cadot S, Gfeller V, Hu L, Singh N, Sánchez‐Vallet A, Glauser G, Croll D, Erb M, van der Heijden MGA, Schlaeppi K. Soil composition and plant genotype determine benzoxazinoid-mediated plant-soil feedbacks in cereals. PLANT, CELL & ENVIRONMENT 2021; 44:3502-3514. [PMID: 34505297 PMCID: PMC9292949 DOI: 10.1111/pce.14184] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/02/2021] [Accepted: 07/19/2021] [Indexed: 06/02/2023]
Abstract
Plant-soil feedbacks refer to effects on plants that are mediated by soil modifications caused by the previous plant generation. Maize conditions the surrounding soil by secretion of root exudates including benzoxazinoids (BXs), a class of bioactive secondary metabolites. Previous work found that a BX-conditioned soil microbiota enhances insect resistance while reducing biomass in the next generation of maize plants. Whether these BX-mediated and microbially driven feedbacks are conserved across different soils and response species is unknown. We found the BX-feedbacks on maize growth and insect resistance conserved between two arable soils, but absent in a more fertile grassland soil, suggesting a soil-type dependence of BX feedbacks. We demonstrated that wheat also responded to BX-feedbacks. While the negative growth response to BX-conditioning was conserved in both cereals, insect resistance showed opposite patterns, with an increase in maize and a decrease in wheat. Wheat pathogen resistance was not affected. Finally and consistent with maize, we found the BX-feedbacks to be cultivar-specific. Taken together, BX-feedbacks affected cereal growth and resistance in a soil and genotype-dependent manner. Cultivar-specificity of BX-feedbacks is a key finding, as it hides the potential to optimize crops that avoid negative plant-soil feedbacks in rotations.
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Affiliation(s)
- Selma Cadot
- Division of Agroecology and EnvironmentAgroscopeZurichSwitzerland
- Institute of Plant SciencesUniversity of BernBernSwitzerland
- Department of Environmental SciencesUniversity of BaselBaselSwitzerland
| | | | - Lingfei Hu
- Zhejiang Provincial Key Laboratory of Agricultural Resources and EnvironmentZhejiang UniversityZhejiangChina
| | - Nikhil Singh
- Laboratory of Evolutionary GeneticsUniversity of NeuchâtelNeuchâtelSwitzerland
| | - Andrea Sánchez‐Vallet
- Plant Pathology, Institute of Integrative BiologyETH ZürichZürichSwitzerland
- Centro de Biotecnología y Genómica de Plantas (CBGP)Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Universidad Politécnica de Madrid (UPM)Campus de Montegancedo UPMPozuelo de Alarcón (Madrid)Spain
| | - Gaétan Glauser
- Neuchâtel Platform of Analytical ChemistryUniversity of NeuchâtelNeuchâtelSwitzerland
| | - Daniel Croll
- Laboratory of Evolutionary GeneticsUniversity of NeuchâtelNeuchâtelSwitzerland
| | - Matthias Erb
- Institute of Plant SciencesUniversity of BernBernSwitzerland
| | | | - Klaus Schlaeppi
- Division of Agroecology and EnvironmentAgroscopeZurichSwitzerland
- Institute of Plant SciencesUniversity of BernBernSwitzerland
- Department of Environmental SciencesUniversity of BaselBaselSwitzerland
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28
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Oggenfuss U, Badet T, Wicker T, Hartmann FE, Singh NK, Abraham L, Karisto P, Vonlanthen T, Mundt C, McDonald BA, Croll D. A population-level invasion by transposable elements triggers genome expansion in a fungal pathogen. eLife 2021; 10:e69249. [PMID: 34528512 PMCID: PMC8445621 DOI: 10.7554/elife.69249] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 08/28/2021] [Indexed: 12/16/2022] Open
Abstract
Genome evolution is driven by the activity of transposable elements (TEs). The spread of TEs can have deleterious effects including the destabilization of genome integrity and expansions. However, the precise triggers of genome expansions remain poorly understood because genome size evolution is typically investigated only among deeply divergent lineages. Here, we use a large population genomics dataset of 284 individuals from populations across the globe of Zymoseptoria tritici, a major fungal wheat pathogen. We built a robust map of genome-wide TE insertions and deletions to track a total of 2456 polymorphic loci within the species. We show that purifying selection substantially depressed TE frequencies in most populations, but some rare TEs have recently risen in frequency and likely confer benefits. We found that specific TE families have undergone a substantial genome-wide expansion from the pathogen's center of origin to more recently founded populations. The most dramatic increase in TE insertions occurred between a pair of North American populations collected in the same field at an interval of 25 years. We find that both genome-wide counts of TE insertions and genome size have increased with colonization bottlenecks. Hence, the demographic history likely played a major role in shaping genome evolution within the species. We show that both the activation of specific TEs and relaxed purifying selection underpin this incipient expansion of the genome. Our study establishes a model to recapitulate TE-driven genome evolution over deeper evolutionary timescales.
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Affiliation(s)
- Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Thomas Wicker
- Institute for Plant and Microbial Biology, University of ZurichZurichSwitzerland
| | - Fanny E Hartmann
- Ecologie Systématique Evolution, Bâtiment 360, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-SaclayOrsayFrance
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Nikhil Kumar Singh
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Leen Abraham
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Petteri Karisto
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Tiziana Vonlanthen
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Christopher Mundt
- Department of Botany and Plant Pathology, Oregon State UniversityCorvallisUnited States
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
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29
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Zhong Z, McDonald BA, Palma-Guerrero J. Tolerance to oxidative stress is associated with both oxidative stress response and inherent growth in a fungal wheat pathogen. Genetics 2021; 217:6029569. [PMID: 33724407 DOI: 10.1093/genetics/iyaa022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 11/23/2020] [Indexed: 01/25/2023] Open
Abstract
Reactive oxygen species are toxic byproducts of aerobic respiration that are also important in mediating a diversity of cellular functions. Reactive oxygen species form an important component of plant defenses to inhibit microbial pathogens during pathogen-plant interactions. Tolerance to oxidative stress is likely to make a significant contribution to the viability and pathogenicity of plant pathogens, but the complex network of oxidative stress responses hinders identification of the genes contributing to this trait. Here, we employed a forward genetic approach to investigate the genetic architecture of oxidative stress tolerance in the fungal wheat pathogen Zymoseptoria tritici. We used quantitative trait locus (QTL) mapping of growth and melanization under axenic conditions in two cross-populations to identify genomic regions associated with tolerance to oxidative stress. We found that QTLs associated with growth under oxidative stress as well as inherent growth can affect oxidative stress tolerance, and we identified two uncharacterized genes in a major QTL associated with this trait. Our data suggest that melanization does not affect tolerance to oxidative stress, which differs from what was found for animal pathogens. This study provides a whole-genome perspective on the genetic basis of oxidative stress tolerance in a plant pathogen.
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Affiliation(s)
- Ziming Zhong
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, 8092 Zürich, Switzerland
| | - Bruce A McDonald
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, 8092 Zürich, Switzerland
| | - Javier Palma-Guerrero
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, 8092 Zürich, Switzerland.,Department of Biointeractions and Crop Protection, Rothamsted Research, AL5 2JQ Harpenden, UK
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30
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Friesen TL, Faris JD. Characterization of Effector-Target Interactions in Necrotrophic Pathosystems Reveals Trends and Variation in Host Manipulation. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:77-98. [PMID: 33909478 DOI: 10.1146/annurev-phyto-120320-012807] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Great strides have been made in defining the details of the plant defense response involving biotrophic fungal and bacterial pathogens. The groundwork for the current model was laid by H.H. Flor and others who defined the gene-for-gene hypothesis, which is now known to involve effector-triggered immunity (ETI). PAMP-triggered immunity (PTI) is also a highly effective response to most pathogens because of the recognition of common pathogen molecules by pattern recognition receptors. In this article, we consider the three pathogens that make up the foliar disease complex of wheat, Zymoseptoria tritici, Pyrenophora tritici-repentis, and Parastagonospora nodorum, to review the means by which necrotrophic pathogens circumvent, or outright hijack, the ETI and PTI pathways to cause disease.
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Affiliation(s)
- Timothy L Friesen
- Edward T. Schafer Agricultural Research Center, USDA-ARS, Fargo, North Dakota 58102, USA; ,
| | - Justin D Faris
- Edward T. Schafer Agricultural Research Center, USDA-ARS, Fargo, North Dakota 58102, USA; ,
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31
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Jiquel A, Gervais J, Geistodt‐Kiener A, Delourme R, Gay EJ, Ollivier B, Fudal I, Faure S, Balesdent M, Rouxel T. A gene-for-gene interaction involving a 'late' effector contributes to quantitative resistance to the stem canker disease in Brassica napus. THE NEW PHYTOLOGIST 2021; 231:1510-1524. [PMID: 33621369 PMCID: PMC8360019 DOI: 10.1111/nph.17292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/15/2021] [Indexed: 05/19/2023]
Abstract
The control of stem canker disease of Brassica napus (rapeseed), caused by the fungus Leptosphaeria maculans is based largely on plant genetic resistance: single-gene specific resistance (Rlm genes) or quantitative, polygenic, adult-stage resistance. Our working hypothesis was that quantitative resistance partly obeys the gene-for-gene model, with resistance genes 'recognizing' fungal effectors expressed during late systemic colonization. Five LmSTEE (stem-expressed effector) genes were selected and placed under the control of the AvrLm4-7 promoter, an effector gene highly expressed at the cotyledon stage of infection, for miniaturized cotyledon inoculation test screening of a gene pool of 204 rapeseed genotypes. We identified a rapeseed genotype, 'Yudal', expressing hypersensitive response to LmSTEE98. The LmSTEE98-RlmSTEE98 interaction was further validated by inactivation of the LmSTEE98 gene with a CRISPR-Cas9 approach. Isolates with mutated versions of LmSTEE98 induced more severe stem symptoms than the wild-type isolate in 'Yudal'. This single-gene resistance was mapped in a 0.6 cM interval of the 'Darmor_bzh' × 'Yudal' genetic map. One typical gene-for-gene interaction contributes partly to quantitative resistance when L. maculans colonizes the stems of rapeseed. With numerous other effectors specific to stem colonization, our study provides a new route for resistance gene discovery, elucidation of quantitative resistance mechanisms and selection for durable resistance.
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Affiliation(s)
- Audren Jiquel
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
- Euralis Semences6 Chemin des PanedautesMondonville31700France
| | - Julie Gervais
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
| | - Aude Geistodt‐Kiener
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
- Université Paris‐SaclayRoute de l'Orme aux MerisiersSaint‐Aubin91190France
| | | | - Elise J. Gay
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
- Université Paris‐SaclayRoute de l'Orme aux MerisiersSaint‐Aubin91190France
| | - Bénédicte Ollivier
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
| | - Isabelle Fudal
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
| | | | - Marie‐Hélène Balesdent
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
| | - Thierry Rouxel
- INRAEAgroParisTechUMR BIOGERUniversité Paris‐SaclayAvenue Lucien Brétignières, BP 01Thiverval‐GrignonF‐78850France
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32
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Veneault-Fourrey C, Rep M. Quantitative resistance linked to late effectors. THE NEW PHYTOLOGIST 2021; 231:1301-1303. [PMID: 34107082 DOI: 10.1111/nph.17462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Claire Veneault-Fourrey
- Laboratory of Excellence ARBRE, INRAE, UMR1136 Trees-Microbes Interactions, University of Lorraine, Nancy, F-54000, France
| | - Martijn Rep
- Swammerdam Institute for Life Sciences, Molecular Plant Pathology, University of Amsterdam, Science Park 904, Amsterdam, 1098 XH, the Netherlands
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33
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Wang C, Milgate AW, Solomon PS, McDonald MC. The identification of a transposon affecting the asexual reproduction of the wheat pathogen Zymoseptoria tritici. MOLECULAR PLANT PATHOLOGY 2021; 22:800-816. [PMID: 33949756 PMCID: PMC8232023 DOI: 10.1111/mpp.13064] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 05/13/2023]
Abstract
Zymoseptoria tritici, the causal agent of Septoria tritici blotch, is a fungal wheat pathogen that causes significant global yield losses. Within Z. tritici populations, quantitative differences in virulence among different isolates are commonly observed; however, the genetic components that underpin these differences remain elusive. In this study, intraspecific comparative transcriptomic analysis was used to identify candidate genes that contribute to differences in virulence on the wheat cultivar WW2449. This led to the identification of a multicopy gene that was not expressed in the high-virulence isolate when compared to the medium- and low-virulence isolates. Further investigation suggested this gene resides in a 7.9-kb transposon. Subsequent long-read sequencing of the isolates used in the transcriptomic analysis confirmed that this gene did reside in an active Class II transposon, which is composed of four genes named REP9-1 to -4. Silencing and overexpression of REP9-1 in two distinct genetic backgrounds demonstrated that its expression alone reduces the number of pycnidia produced by Z. tritici during infection. The REP9-1 gene identified within a Class II transposon is the first discovery of a gene in a transposable element that influences the virulence of Z. tritici. This discovery adds further complexity to genetic loci that contribute to quantitative virulence in this important pathogen.
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Affiliation(s)
- Chen Wang
- Division of Plant SciencesResearch School of BiologyThe Australian National UniversityCanberraACTAustralia
| | - Andrew W. Milgate
- NSW Department of Primary IndustriesWagga Wagga Agricultural InstituteWagga WaggaNSWAustralia
| | - Peter S. Solomon
- Division of Plant SciencesResearch School of BiologyThe Australian National UniversityCanberraACTAustralia
| | - Megan C. McDonald
- Division of Plant SciencesResearch School of BiologyThe Australian National UniversityCanberraACTAustralia
- School of BiosciencesUniversity of BirminghamEdgbastonBirminghamUK
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34
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He X, Azzimonti G, Sánchez-Vidaña MDR, Pereyra SA, Sansaloni C, Hernández-Anguiano AM, Chawade A, Singh PK. Mapping for Adult-Plant Resistance Against Septoria Tritici Blotch in a Common Wheat Line Murga. PHYTOPATHOLOGY 2021; 111:1001-1007. [PMID: 33141648 DOI: 10.1094/phyto-05-20-0172-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Septoria tritici blotch (STB) is a major foliar disease globally that is notorious for quickly developing fungicide resistance, making host resistance an indispensable component in mitigating STB. The International Maize and Wheat Improvement Center (CIMMYT) wheat line Murga is well known for its high, durable, and broad-spectrum resistance against STB infection. This study aimed to investigate the resistance mechanism of Murga to facilitate its utilization in breeding. A recombinant inbred line population was derived from a cross between Murga and STB-susceptible line Huirivis#1, comprising 297 progenies. The population was evaluated for adult-plant STB resistance in Toluca, Mexico (from 2017 to 2019), and in La Estanzuela, Uruguay (from 2016 to 2018). Genotyping was performed with the DArTseq platform. Quantitative trait locus (QTL) mapping indicated a major and stable QTL on chromosome 3DL, explaining a phenotypic variation for STB of 41.2 to 62.5% in Mexico and 27.5 to 40.3% in Uruguay. This QTL was regarded as Stb16 based on the comparison of its physical position, the possible origin from synthetic wheat, and its broad-spectrum resistance. Additional QTLs with minor effects were identified on chromosomes 2B, 2D, 3A, 3B, and 5B. The QTL on 5BS was significant in four of the six environments and must be new. Murga was the resistant donor for all QTLs except for those on 2B and 3A. Being an elite breeding line, Stb16 carrier Murga could be used as a promising STB resistance donor. Rational employment of Stb16 could contribute to STB management yet avoid the rapid emergence of Stb16-virulent isolates.
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Affiliation(s)
- Xinyao He
- International Maize and Wheat Improvement Center (CIMMYT), 06600 Mexico City, Mexico
| | - Gustavo Azzimonti
- Instituto Nacional de Investigación Agropecuaria, La Estanzuela 39173, Colonia, Uruguay
| | - Mariel Del Rosario Sánchez-Vidaña
- International Maize and Wheat Improvement Center (CIMMYT), 06600 Mexico City, Mexico
- Colegio de Postgraduados, Montecillo, 56230 Texcoco, Mexico
| | - Silvia A Pereyra
- Instituto Nacional de Investigación Agropecuaria, La Estanzuela 39173, Colonia, Uruguay
| | - Carolina Sansaloni
- International Maize and Wheat Improvement Center (CIMMYT), 06600 Mexico City, Mexico
| | | | - Aakash Chawade
- Department of Plant Breeding, Swedish University of Agricultural Sciences, 23053 Alnarp, Sweden
| | - Pawan K Singh
- International Maize and Wheat Improvement Center (CIMMYT), 06600 Mexico City, Mexico
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35
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Singh NK, Badet T, Abraham L, Croll D. Rapid sequence evolution driven by transposable elements at a virulence locus in a fungal wheat pathogen. BMC Genomics 2021; 22:393. [PMID: 34044766 PMCID: PMC8157644 DOI: 10.1186/s12864-021-07691-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/07/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Plant pathogens cause substantial crop losses in agriculture production and threaten food security. Plants evolved the ability to recognize virulence factors and pathogens have repeatedly escaped recognition due rapid evolutionary change at pathogen virulence loci (i.e. effector genes). The presence of transposable elements (TEs) in close physical proximity of effector genes can have important consequences for gene regulation and sequence evolution. Species-wide investigations of effector gene loci remain rare hindering our ability to predict pathogen evolvability. RESULTS Here, we performed genome-wide association studies (GWAS) on a highly polymorphic mapping population of 120 isolates of Zymoseptoria tritici, the most damaging pathogen of wheat in Europe. We identified a major locus underlying significant variation in reproductive success of the pathogen and damage caused on the wheat cultivar Claro. The most strongly associated locus is intergenic and flanked by genes encoding a predicted effector and a serine-type endopeptidase. The center of the locus contained a highly dynamic region consisting of multiple families of TEs. Based on a large global collection of assembled genomes, we show that the virulence locus has undergone substantial recent sequence evolution. Large insertion and deletion events generated length variation between the flanking genes by a factor of seven (5-35 kb). The locus showed also strong signatures of genomic defenses against TEs (i.e. RIP) contributing to the rapid diversification of the locus. CONCLUSIONS In conjunction, our work highlights the power of combining GWAS and population-scale genome analyses to investigate major effect loci in pathogens.
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Affiliation(s)
- Nikhil Kumar Singh
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland
| | - Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland
| | - Leen Abraham
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland.
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36
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Laurent B, Moinard M, Spataro C, Chéreau S, Zehraoui E, Blanc R, Lasserre P, Ponts N, Foulongne-Oriol M. QTL mapping in Fusarium graminearum identified an allele of FgVe1 involved in reduced aggressiveness. Fungal Genet Biol 2021; 153:103566. [PMID: 33991664 DOI: 10.1016/j.fgb.2021.103566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 10/21/2022]
Abstract
Fusarium graminearum is one of the most frequent causal agents of the Fusarium Head Blight, a cereal disease spread throughout the world, reducing grain production and quality. F. graminearum isolates are genetically and phenotypically highly diverse. Notably, remarkable variations of aggressiveness between isolates have been observed, which could reflect an adaptive potential of this pathogen. In this study, we aimed to characterize the genetic basis of aggressiveness variation observed in an F1 population (n = 94), for which genome sequences of both parental strains are available. Aggressiveness was assessed by a panel of in planta and in vitro proxies during two phenotyping trials including, among others, disease severity and mycotoxin accumulation in wheat spike. One major and single QTL was mapped for all the traits measured, on chromosome I, that explained up to 90% of the variance for disease severity. The confidence interval at the QTL spanned 1.2 Mb and contained 428 genes on the reference genome. Of these, four candidates were selected based on the postulate that a non-synonymous mutation affecting protein function may be responsible for phenotypic differences. Finally, a new mutation was identified and functionally validated in the gene FgVe1, coding for a velvet protein known to be involved in pathogenicity and secondary metabolism production in several fungi.
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Affiliation(s)
| | | | | | | | - Enric Zehraoui
- INRAE, MycSA, F-33882 Villenave d'Ornon, France; Université de Bordeaux, INRAE, EGFV, F-33882 Villenave d'Ornon, France
| | - Richard Blanc
- INRAE, UCA, UMR 1095 GDEC, F-63100 Clermont-Ferrand, France
| | | | - Nadia Ponts
- INRAE, MycSA, F-33882 Villenave d'Ornon, France
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37
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Dutta A, Hartmann FE, Francisco CS, McDonald BA, Croll D. Mapping the adaptive landscape of a major agricultural pathogen reveals evolutionary constraints across heterogeneous environments. THE ISME JOURNAL 2021; 15:1402-1419. [PMID: 33452474 PMCID: PMC8115182 DOI: 10.1038/s41396-020-00859-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/17/2020] [Accepted: 11/24/2020] [Indexed: 02/06/2023]
Abstract
The adaptive potential of pathogens in novel or heterogeneous environments underpins the risk of disease epidemics. Antagonistic pleiotropy or differential resource allocation among life-history traits can constrain pathogen adaptation. However, we lack understanding of how the genetic architecture of individual traits can generate trade-offs. Here, we report a large-scale study based on 145 global strains of the fungal wheat pathogen Zymoseptoria tritici from four continents. We measured 50 life-history traits, including virulence and reproduction on 12 different wheat hosts and growth responses to several abiotic stressors. To elucidate the genetic basis of adaptation, we used genome-wide association mapping coupled with genetic correlation analyses. We show that most traits are governed by polygenic architectures and are highly heritable suggesting that adaptation proceeds mainly through allele frequency shifts at many loci. We identified negative genetic correlations among traits related to host colonization and survival in stressful environments. Such genetic constraints indicate that pleiotropic effects could limit the pathogen's ability to cause host damage. In contrast, adaptation to abiotic stress factors was likely facilitated by synergistic pleiotropy. Our study illustrates how comprehensive mapping of life-history trait architectures across diverse environments allows to predict evolutionary trajectories of pathogens confronted with environmental perturbations.
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Affiliation(s)
- Anik Dutta
- grid.5801.c0000 0001 2156 2780Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Fanny E. Hartmann
- grid.5801.c0000 0001 2156 2780Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland ,grid.417885.70000 0001 2185 8223Ecologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, 91400 Orsay, France
| | - Carolina Sardinha Francisco
- grid.5801.c0000 0001 2156 2780Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland ,Present Address: Environmental Genomics Group, Botanical Institute, CAU Kiel, Germany
| | - Bruce A. McDonald
- grid.5801.c0000 0001 2156 2780Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Daniel Croll
- grid.10711.360000 0001 2297 7718Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
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38
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Chavarro‐Carrero EA, Vermeulen JP, E. Torres D, Usami T, Schouten HJ, Bai Y, Seidl MF, Thomma BPHJ. Comparative genomics reveals the in planta-secreted Verticillium dahliae Av2 effector protein recognized in tomato plants that carry the V2 resistance locus. Environ Microbiol 2021; 23:1941-1958. [PMID: 33078534 PMCID: PMC8246953 DOI: 10.1111/1462-2920.15288] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/16/2020] [Accepted: 10/18/2020] [Indexed: 12/12/2022]
Abstract
Plant pathogens secrete effector molecules during host invasion to promote colonization. However, some of these effectors become recognized by host receptors to mount a defence response and establish immunity. Recently, a novel resistance was identified in wild tomato, mediated by the single dominant V2 locus, to control strains of the soil-borne vascular wilt fungus Verticillium dahliae that belong to race 2. With comparative genomics of race 2 strains and resistance-breaking race 3 strains, we identified the avirulence effector that activates V2 resistance, termed Av2. We identified 277 kb of race 2-specific sequence comprising only two genes encoding predicted secreted proteins that are expressed during tomato colonization. Subsequent functional analysis based on genetic complementation into race 3 isolates and targeted deletion from the race 1 isolate JR2 and race 2 isolate TO22 confirmed that one of the two candidates encodes the avirulence effector Av2 that is recognized in V2 tomato plants. Two Av2 allelic variants were identified that encode Av2 variants that differ by a single acid. Thus far, a role in virulence could not be demonstrated for either of the two variants.
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Affiliation(s)
| | - Jasper P. Vermeulen
- Laboratory of PhytopathologyWageningen University and ResearchWageningen6708 PBThe Netherlands
- Laboratory of Plant BreedingWageningen University and ResearchWageningen6708 PBThe Netherlands
| | - David E. Torres
- Laboratory of PhytopathologyWageningen University and ResearchWageningen6708 PBThe Netherlands
- Theoretical Biology and Bioinformatics Group, Department of BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Toshiyuki Usami
- Graduate School of HorticultureChiba UniversityMatsudo, Chiba271‐8510Japan
| | - Henk J. Schouten
- Laboratory of Plant BreedingWageningen University and ResearchWageningen6708 PBThe Netherlands
| | - Yuling Bai
- Laboratory of Plant BreedingWageningen University and ResearchWageningen6708 PBThe Netherlands
| | - Michael F. Seidl
- Laboratory of PhytopathologyWageningen University and ResearchWageningen6708 PBThe Netherlands
- Theoretical Biology and Bioinformatics Group, Department of BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Bart P. H. J. Thomma
- Laboratory of PhytopathologyWageningen University and ResearchWageningen6708 PBThe Netherlands
- Cluster of Excellence on Plant Sciences (CEPLAS)University of Cologne, Botanical InstituteCologneGermany
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39
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Barrett LG, Zala M, Mikaberidze A, Alassimone J, Ahmad M, McDonald BA, Sánchez-Vallet A. Mixed infections alter transmission potential in a fungal plant pathogen. Environ Microbiol 2021; 23:2315-2330. [PMID: 33538383 PMCID: PMC8248022 DOI: 10.1111/1462-2920.15417] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 01/12/2021] [Accepted: 01/28/2021] [Indexed: 01/08/2023]
Abstract
Infections by more than one strain of a pathogen predominate under natural conditions. Mixed infections can have significant, though often unpredictable, consequences for overall virulence, pathogen transmission and evolution. However, effects of mixed infection on disease development in plants often remain unclear and the critical factors that determine the outcome of mixed infections remain unknown. The fungus Zymoseptoria tritici forms genetically diverse infections in wheat fields. Here, for a range of pathogen traits, we experimentally decompose the infection process to determine how the outcomes and consequences of mixed infections are mechanistically realized. Different strains of Z. tritici grow in close proximity and compete in the wheat apoplast, resulting in reductions in growth of individual strains and in pathogen reproduction. We observed different outcomes of competition at different stages of the infection. Overall, more virulent strains had higher competitive ability during host colonization, and less virulent strains had higher transmission potential. We showed that within‐host competition can have a major effect on infection dynamics and pathogen population structure in a pathogen and host genotype‐specific manner. Consequently, mixed infections likely have a major effect on the development of septoria tritici blotch epidemics and the evolution of virulence in Z. tritici.
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Affiliation(s)
- Luke G Barrett
- CSIRO Agriculture and Food, GPO BOX 1700, Canberra, ACT, 2601, Australia
| | - Marcello Zala
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Alexey Mikaberidze
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Julien Alassimone
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Muhammad Ahmad
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Andrea Sánchez-Vallet
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland.,Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Pozuelo de Alarcón, Madrid, Spain
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40
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Karki SJ, Reilly A, Zhou B, Mascarello M, Burke J, Doohan F, Douchkov D, Schweizer P, Feechan A. A small secreted protein from Zymoseptoria tritici interacts with a wheat E3 ubiquitin ligase to promote disease. JOURNAL OF EXPERIMENTAL BOTANY 2021. [PMID: 33095257 DOI: 10.5061/dryad.9w0vt4bcx] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Septoria tritici blotch (STB), caused by the ascomycete fungus Zymoseptoria tritici, is a major threat to wheat production worldwide. The Z. tritici genome encodes many small secreted proteins (ZtSSPs) that are likely to play a key role in the successful colonization of host tissues. However, few of these ZtSSPs have been functionally characterized for their role during infection. In this study, we identified and characterized a small, conserved cysteine-rich secreted effector from Z. tritici which has homologues in other plant pathogens in the Dothideomycetes. ZtSSP2 was expressed throughout Z. tritici infection in wheat, with the highest levels observed early during infection. A yeast two-hybrid assay revealed an interaction between ZtSSP2 and wheat E3 ubiquitin ligase (TaE3UBQ) in yeast, and this was further confirmed in planta using bimolecular fluorescence complementation and co-immunoprecipitation. Down-regulation of this wheat E3 ligase using virus-induced gene silencing increased the susceptibility of wheat to STB. Together, these results suggest that TaE3UBQ is likely to play a role in plant immunity to defend against Z. tritici.
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Affiliation(s)
- Sujit Jung Karki
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Aisling Reilly
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Binbin Zhou
- School of Biology and Environmental Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Maurizio Mascarello
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
- Ecology, Evolution and Biodiversity Conservation, Charles Deberiotstraat 8 32, 3000 Leuven, Belgium
| | - James Burke
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona Doohan
- School of Biology and Environmental Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Dimitar Douchkov
- Institute of Plant Genetics and Crop Plant Research (IPK), Cytogenetics, Gatersleben, Germany
| | - Patrick Schweizer
- Institute of Plant Genetics and Crop Plant Research (IPK), Cytogenetics, Gatersleben, Germany
| | - Angela Feechan
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
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41
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Karki SJ, Reilly A, Zhou B, Mascarello M, Burke J, Doohan F, Douchkov D, Schweizer P, Feechan A. A small secreted protein from Zymoseptoria tritici interacts with a wheat E3 ubiquitin ligase to promote disease. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:733-746. [PMID: 33095257 PMCID: PMC7853600 DOI: 10.1093/jxb/eraa489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 10/15/2020] [Indexed: 05/05/2023]
Abstract
Septoria tritici blotch (STB), caused by the ascomycete fungus Zymoseptoria tritici, is a major threat to wheat production worldwide. The Z. tritici genome encodes many small secreted proteins (ZtSSPs) that are likely to play a key role in the successful colonization of host tissues. However, few of these ZtSSPs have been functionally characterized for their role during infection. In this study, we identified and characterized a small, conserved cysteine-rich secreted effector from Z. tritici which has homologues in other plant pathogens in the Dothideomycetes. ZtSSP2 was expressed throughout Z. tritici infection in wheat, with the highest levels observed early during infection. A yeast two-hybrid assay revealed an interaction between ZtSSP2 and wheat E3 ubiquitin ligase (TaE3UBQ) in yeast, and this was further confirmed in planta using bimolecular fluorescence complementation and co-immunoprecipitation. Down-regulation of this wheat E3 ligase using virus-induced gene silencing increased the susceptibility of wheat to STB. Together, these results suggest that TaE3UBQ is likely to play a role in plant immunity to defend against Z. tritici.
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Affiliation(s)
- Sujit Jung Karki
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Aisling Reilly
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Binbin Zhou
- School of Biology and Environmental Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Maurizio Mascarello
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
- Ecology, Evolution and Biodiversity Conservation, Charles Deberiotstraat 8 32, 3000 Leuven, Belgium
| | - James Burke
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona Doohan
- School of Biology and Environmental Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Dimitar Douchkov
- Institute of Plant Genetics and Crop Plant Research (IPK), Cytogenetics, Gatersleben, Germany
| | - Patrick Schweizer
- Institute of Plant Genetics and Crop Plant Research (IPK), Cytogenetics, Gatersleben, Germany
| | - Angela Feechan
- School of Agriculture & Food Science and UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
- Correspondence:
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42
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Dutta A, Croll D, McDonald BA, Barrett LG. Maintenance of variation in virulence and reproduction in populations of an agricultural plant pathogen. Evol Appl 2021; 14:335-347. [PMID: 33664780 PMCID: PMC7896723 DOI: 10.1111/eva.13117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/04/2020] [Accepted: 08/13/2020] [Indexed: 11/27/2022] Open
Abstract
Genetic diversity within pathogen populations is critically important for predicting pathogen evolution, disease outcomes and prevalence. However, we lack a good understanding of the processes maintaining genetic variation and constraints on pathogen life-history evolution. Here, we analysed interactions between 12 wheat host genotypes and 145 strains of Zymoseptoria tritici from five global populations to investigate the evolution and maintenance of variation in pathogen virulence and reproduction. We found a strong positive correlation between virulence (amount of leaf necrosis) and reproduction (pycnidia density within lesions), with substantial variation in both traits maintained within populations. On average, highly virulent isolates exhibited higher reproduction, which might increase transmission potential in agricultural fields planted to homogeneous hosts at a high density. We further showed that pathogen strains with a narrow host range (i.e. specialists) for reproduction were on average less virulent, and those with a broader host range (i.e. generalists) were on average less fecund on a given specific host. These costs associated with adaptation to different host genotypes might constrain the emergence of generalists by disrupting the directional evolution of virulence and fecundity. We conclude that selection favouring pathogen strains that are virulent across diverse hosts, coupled with selection that maximizes fecundity on specific hosts, may explain the maintenance of these pathogenicity traits within and among populations.
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Affiliation(s)
- Anik Dutta
- Plant PathologyInstitute of Integrative BiologyETH ZurichZurichSwitzerland
| | - Daniel Croll
- Laboratory of Evolutionary GeneticsInstitute of BiologyUniversity of NeuchâtelNeuchâtelSwitzerland
| | - Bruce A. McDonald
- Plant PathologyInstitute of Integrative BiologyETH ZurichZurichSwitzerland
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43
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Saintenac C, Cambon F, Aouini L, Verstappen E, Ghaffary SMT, Poucet T, Marande W, Berges H, Xu S, Jaouannet M, Favery B, Alassimone J, Sánchez-Vallet A, Faris J, Kema G, Robert O, Langin T. A wheat cysteine-rich receptor-like kinase confers broad-spectrum resistance against Septoria tritici blotch. Nat Commun 2021; 12:433. [PMID: 33469010 PMCID: PMC7815785 DOI: 10.1038/s41467-020-20685-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 12/02/2020] [Indexed: 01/29/2023] Open
Abstract
The poverty of disease resistance gene reservoirs limits the breeding of crops for durable resistance against evolutionary dynamic pathogens. Zymoseptoria tritici which causes Septoria tritici blotch (STB), represents one of the most genetically diverse and devastating wheat pathogens worldwide. No fully virulent Z. tritici isolates against synthetic wheats carrying the major resistant gene Stb16q have been identified. Here, we use comparative genomics, mutagenesis and complementation to identify Stb16q, which confers broad-spectrum resistance against Z. tritici. The Stb16q gene encodes a plasma membrane cysteine-rich receptor-like kinase that was recently introduced into cultivated wheat and which considerably slows penetration and intercellular growth of the pathogen.
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Affiliation(s)
- Cyrille Saintenac
- grid.503180.f0000 0004 0613 5360Université Clermont Auvergne, INRAE, GDEC, 63000 Clermont-Ferrand, France
| | - Florence Cambon
- grid.503180.f0000 0004 0613 5360Université Clermont Auvergne, INRAE, GDEC, 63000 Clermont-Ferrand, France
| | - Lamia Aouini
- grid.4818.50000 0001 0791 5666Wageningen University and Research (Wageningen Plant Research, Biointeractions and Plant Health), PO Box 16, 6700AA Wageningen, The Netherlands ,grid.169077.e0000 0004 1937 2197Present Address: Department of Agronomy, Purdue University, West Lafayette, IN 47907 USA
| | - Els Verstappen
- grid.4818.50000 0001 0791 5666Wageningen University and Research (Wageningen Plant Research, Biointeractions and Plant Health), PO Box 16, 6700AA Wageningen, The Netherlands
| | - Seyed Mahmoud Tabib Ghaffary
- grid.4818.50000 0001 0791 5666Wageningen University and Research (Wageningen Plant Research, Biointeractions and Plant Health), PO Box 16, 6700AA Wageningen, The Netherlands ,Present Address: Seed and Plant Improvement Research Department, Safiabad Agricultural and Natural Resources Research and Education Center, AREEO, Dezful, Iran
| | - Théo Poucet
- grid.503180.f0000 0004 0613 5360Université Clermont Auvergne, INRAE, GDEC, 63000 Clermont-Ferrand, France ,grid.11480.3c0000000121671098Present Address: Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo. 644, 48080 Bilbao, Spain ,grid.412041.20000 0001 2106 639XPresent Address: Université de Bordeaux, 146 rue Leo-Saignat, Bordeaux, Cedex 33076 France
| | - William Marande
- grid.507621.7CNRGV (Centre National des Ressources Génomiques Végétales), INRAE, UPR 1258 Castanet-Tolosan, France
| | - Hélène Berges
- grid.507621.7CNRGV (Centre National des Ressources Génomiques Végétales), INRAE, UPR 1258 Castanet-Tolosan, France ,grid.508749.7Present Address: Inari Agriculture, One Kendall Square Building 600/700, Cambridge, MA 02139 USA
| | - Steven Xu
- grid.463419.d0000 0001 0946 3608United States Department of Agriculture-Agricultural Research Service, Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, Fargo, ND 58102 USA
| | - Maëlle Jaouannet
- grid.4444.00000 0001 2112 9282INRAE, Université Côte d’Azur, CNRS, ISA, 06903 Sophia Antipolis, France
| | - Bruno Favery
- grid.4444.00000 0001 2112 9282INRAE, Université Côte d’Azur, CNRS, ISA, 06903 Sophia Antipolis, France
| | - Julien Alassimone
- grid.5801.c0000 0001 2156 2780Plant Pathology, Institute of Integrative Biology, ETH Zürich, 8092 Zürich, Switzerland
| | - Andrea Sánchez-Vallet
- grid.5801.c0000 0001 2156 2780Plant Pathology, Institute of Integrative Biology, ETH Zürich, 8092 Zürich, Switzerland ,grid.5690.a0000 0001 2151 2978Present Address: Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA). Campus de Montegancedo-UPM, 28223-Pozuelo de Alarcón Madrid, Spain
| | - Justin Faris
- grid.463419.d0000 0001 0946 3608United States Department of Agriculture-Agricultural Research Service, Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, Fargo, ND 58102 USA
| | - Gert Kema
- grid.4818.50000 0001 0791 5666Wageningen University and Research (Wageningen Plant Research, Biointeractions and Plant Health), PO Box 16, 6700AA Wageningen, The Netherlands ,grid.4818.50000 0001 0791 5666Present Address: Wageningen University (Laboratory of Phytopathology), 6700AA Wageningen, The Netherlands
| | - Oliver Robert
- Florimond-Desprez, 3 rue Florimond-Desprez, BP 41, 59242 Cappelle-en-Pevele, France
| | - Thierry Langin
- grid.503180.f0000 0004 0613 5360Université Clermont Auvergne, INRAE, GDEC, 63000 Clermont-Ferrand, France
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44
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Hartmann FE, Vonlanthen T, Singh NK, McDonald MC, Milgate A, Croll D. The complex genomic basis of rapid convergent adaptation to pesticides across continents in a fungal plant pathogen. Mol Ecol 2020; 30:5390-5405. [PMID: 33211369 DOI: 10.1111/mec.15737] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/30/2020] [Accepted: 11/12/2020] [Indexed: 12/12/2022]
Abstract
Convergent evolution leads to identical phenotypic traits in different species or populations. Convergence can be driven by standing variation allowing selection to favour identical alleles in parallel or the same mutations can arise independently. However, the molecular basis of such convergent adaptation remains often poorly resolved. Pesticide resistance in agricultural ecosystems is a hallmark of convergence in phenotypic traits. Here, we analyse the major fungal pathogen Zymoseptoria tritici causing serious losses on wheat and with fungicide resistance emergence across several continents. We sampled three population pairs each from a different continent spanning periods early and late in the application of fungicides. To identify causal loci for resistance, we combined knowledge from molecular genetics work and performed genome-wide association studies (GWAS) on a global set of isolates. We discovered yet unknown factors in azole resistance including a gene encoding membrane associated functions. We found strong support for the "hotspot" model of resistance evolution with convergent changes in a small set of loci but additional loci showed more population-specific allele frequency changes. Genome-wide scans of selection showed that half of all known resistance loci were overlapping a selective sweep region. Hence, the application of fungicides was one of the major selective agents acting on the pathogen over the past decades. Furthermore, loci identified through GWAS showed the highest overlap with selective sweep regions underlining the importance to map phenotypic trait variation in evolving populations. Our population genomic analyses highlighted that both de novo mutations and gene flow contributed to convergent pesticide adaptation.
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Affiliation(s)
- Fanny E Hartmann
- Ecologie Systematique Evolution, Batiment 360, Université Paris-Saclay, AgroParisTech, CNRS, Orsay, France.,Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Tiziana Vonlanthen
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.,Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Nikhil Kumar Singh
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Megan C McDonald
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT, Australia.,School of Biosciences, University of Birmingham, Birmingham, UK
| | - Andrew Milgate
- NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW, Australia
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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Chromatin Dynamics Contribute to the Spatiotemporal Expression Pattern of Virulence Genes in a Fungal Plant Pathogen. mBio 2020; 11:mBio.02343-20. [PMID: 33024042 PMCID: PMC7542367 DOI: 10.1128/mbio.02343-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Fungal plant pathogens possess a large repertoire of genes encoding putative effectors, which are crucial for infection. Many of these genes are expressed at low levels in the absence of the host but are strongly induced at specific stages of the infection. The mechanisms underlying this transcriptional reprogramming remain largely unknown. We investigated the role of the genomic environment and associated chromatin modifications of effector genes in controlling their expression pattern in the fungal wheat pathogen Zymoseptoria tritici. Depending on their genomic location, effector genes are epigenetically repressed in the absence of the host and during the initial stages of infection. Derepression of effector genes occurs mainly during and after penetration of plant leaves and is associated with changes in histone modifications. Our work demonstrates the role of chromatin in shaping the expression of virulence components and, thereby, the interaction between fungal pathogens and their plant hosts. Dynamic changes in transcription profiles are key for the success of pathogens in colonizing their hosts. In many pathogens, genes associated with virulence, such as effector genes, are located in regions of the genome that are rich in transposable elements and heterochromatin. The contribution of chromatin modifications to gene expression in pathogens remains largely unknown. Using a combination of a reporter gene-based approach and chromatin immunoprecipitation, we show that the heterochromatic environment of effector genes in the fungal plant pathogen Zymoseptoria tritici is a key regulator of their specific spatiotemporal expression patterns. Enrichment in trimethylated lysine 27 of histone H3 dictates the repression of effector genes in the absence of the host. Chromatin decondensation during host colonization, featuring a reduction in this repressive modification, indicates a major role for epigenetics in effector gene induction. Our results illustrate that chromatin modifications triggered during host colonization determine the specific expression profile of effector genes at the cellular level and, hence, provide new insights into the regulation of virulence in fungal plant pathogens.
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Hill EH, Solomon PS. Extracellular vesicles from the apoplastic fungal wheat pathogen Zymoseptoria tritici. Fungal Biol Biotechnol 2020; 7:13. [PMID: 32968488 PMCID: PMC7501697 DOI: 10.1186/s40694-020-00103-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/11/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The fungal pathogen Zymoseptoria tritici is a significant constraint to wheat production in temperate cropping regions around the world. Despite its agronomic impacts, the mechanisms allowing the pathogen to asymptomatically invade and grow in the apoplast of wheat leaves before causing extensive host cell death remain elusive. Given recent evidence of extracellular vesicles (EVs)-secreted, membrane-bound nanoparticles containing molecular cargo-being implicated in extracellular communication between plants and fungal pathogen, we have initiated an in vitro investigation of EVs from this apoplastic fungal wheat pathogen. We aimed to isolate EVs from Z. tritici broth cultures and examine their protein composition in relation to the soluble protein in the culture filtrate and to existing fungal EV proteomes. RESULTS Zymoseptoria tritici EVs were isolated from broth culture filtrates using differential ultracentrifugation (DUC) and examined with transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Z. tritici EVs were observed as a heterogeneous population of particles, with most between 50 and 250 nm. These particles were found in abundance in the culture filtrates of viable Z. tritici cultures, but not heat-killed cultures incubated for an equivalent time and of comparable biomass. Bottom-up proteomic analysis using LC-MS/MS, followed by stringent filtering revealed 240 Z. tritici EV proteins. These proteins were distinct from soluble proteins identified in Z. tritici culture filtrates, but were similar to proteins identified in EVs from other fungi, based on sequence similarity analyses. Notably, a putative marker protein recently identified in Candida albicans EVs was also consistently detected in Z. tritici EVs. CONCLUSION We have shown EVs can be isolated from the devastating fungal wheat pathogen Z. tritici and are similar to protein composition to previously characterised fungal EVs. EVs from human pathogenic fungi are implicated in virulence, but the role of EVs in the interaction of phytopathogenic fungi and their hosts is unknown. These in vitro analyses provide a basis for expanding investigations of Z. tritici EVs in planta, to examine their involvement in the infection process of this apoplastic wheat pathogen and more broadly, advance understanding of noncanonical secretion in filamentous plant pathogens.
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Affiliation(s)
- Erin H. Hill
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, 2601 Australia
| | - Peter S. Solomon
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, 2601 Australia
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Jallet AJ, Le Rouzic A, Genissel A. Evolution and Plasticity of the Transcriptome Under Temperature Fluctuations in the Fungal Plant Pathogen Zymoseptoria tritici. Front Microbiol 2020; 11:573829. [PMID: 33042084 PMCID: PMC7517895 DOI: 10.3389/fmicb.2020.573829] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/17/2020] [Indexed: 11/28/2022] Open
Abstract
Most species live in a variable environment in nature. Yet understanding the evolutionary processes underlying molecular adaptation to fluctuations remains a challenge. In this study we investigate the transcriptome of the fungal wheat pathogen Zymoseptoria tritici after experimental evolution under stable or fluctuating temperature, by comparing ancestral and evolved populations simultaneously. We found that temperature regimes could have a large and pervasive effect on the transcriptome evolution, with as much as 38% of the genes being differentially expressed between selection regimes. Although evolved lineages showed different changes of gene expression based on ancestral genotypes, we identified a set of genes responding specifically to fluctuation. We found that transcriptome evolution in fluctuating conditions was repeatable between parallel lineages initiated from the same genotype for about 60% of the differentially expressed genes. Further, we detected several hotspots of significantly differentially expressed genes in the genome, in regions known to be enriched in repetitive elements, including accessory chromosomes. Our findings also evidenced gene expression evolution toward a gain of robustness (loss of phenotypic plasticity) associated with the fluctuating regime, suggesting robustness is adaptive in changing environment. This work provides valuable insight into the role of transcriptional rewiring for rapid adaptation to abiotic changes in filamentous plant pathogens.
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Affiliation(s)
- Arthur J. Jallet
- UMR BIOGER, Université Paris Saclay – INRAE – AgroParisTech, Thiverval-Grignon, France
| | - Arnaud Le Rouzic
- UMR Évolution, Génomes, Comportement et Écologie, Université Paris-Saclay – CNRS – IRD, Gif-sur-Yvette, France
| | - Anne Genissel
- UMR BIOGER, Université Paris Saclay – INRAE – AgroParisTech, Thiverval-Grignon, France
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48
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Francisco CS, Zwyssig MM, Palma-Guerrero J. The role of vegetative cell fusions in the development and asexual reproduction of the wheat fungal pathogen Zymoseptoria tritici. BMC Biol 2020; 18:99. [PMID: 32782023 PMCID: PMC7477884 DOI: 10.1186/s12915-020-00838-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 07/27/2020] [Indexed: 12/23/2022] Open
Abstract
Background The ability of fungal cells to undergo cell-to-cell communication and anastomosis, the process of vegetative hyphal fusion, allows them to maximize their overall fitness. Previous studies in a number of fungal species have identified the requirement of several signaling pathways for anastomosis, including the so far best characterized soft (So) gene, and the MAPK pathway components MAK-1 and MAK-2 of Neurospora crassa. Despite the observations of hyphal fusions’ involvement in pathogenicity and host adhesion, the connection between cell fusion and fungal lifestyles is still unclear. Here, we address the role of anastomosis in fungal development and asexual reproduction in Zymoseptoria tritici, the most important fungal pathogen of wheat in Europe. Results We show that Z. tritici undergoes self-fusion between distinct cellular structures, and its mechanism is dependent on the initial cell density. Contrary to other fungi, cell fusion in Z. tritici only resulted in cytoplasmic mixing but not in multinucleated cell formation. The deletion of the So orthologous ZtSof1 disrupted cell-to-cell communication affecting both hyphal and germling fusion. We show that Z. tritici mutants for MAPK-encoding ZtSlt2 (orthologous to MAK-1) and ZtFus3 (orthologous to MAK-2) genes also failed to undergo anastomosis, demonstrating the functional conservation of this signaling mechanism across species. Additionally, the ΔZtSof1 mutant was severely impaired in melanization, suggesting that the So gene function is related to melanization. Finally, we demonstrated that anastomosis is dispensable for pathogenicity, but essential for the pycnidium development, and its absence abolishes the asexual reproduction of Z. tritici. Conclusions We demonstrate the role for ZtSof1, ZtSlt2, and ZtFus3 in cell fusions of Z. tritici. Cell fusions are essential for different aspects of the Z. tritici biology, and the ZtSof1 gene is a potential target to control septoria tritici blotch (STB) disease.
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Affiliation(s)
| | - Maria Manuela Zwyssig
- Plant Pathology Group, Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland
| | - Javier Palma-Guerrero
- Plant Pathology Group, Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland. .,New Address: Department of Biointeractions and Crop Protection, Rothamsted Research, Harpenden, UK.
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Fourie A, de Jonge R, van der Nest MA, Duong TA, Wingfield MJ, Wingfield BD, Barnes I. Genome comparisons suggest an association between Ceratocystis host adaptations and effector clusters in unique transposable element families. Fungal Genet Biol 2020; 143:103433. [PMID: 32652232 DOI: 10.1016/j.fgb.2020.103433] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 06/18/2020] [Accepted: 06/30/2020] [Indexed: 01/04/2023]
Abstract
Ceratocystis fimbriata is a host specific fungal pathogen of sweet potato (Ipomoea batatas). The closely related species, C. manginecans, is an important pathogen of trees (e.g. Acacia mangium and Mangifera indica) but has never been isolated from tuber crops. The genetic factors that determine the host range and host specificity of these species have not been determined. The aim of this study was to compare the genomes of C. fimbriata and C. manginecans in order to identify species-specific genetic differences that could be associated with host specificity. This included whole-genome alignments as well as comparisons of gene content and transposable elements (TEs). The genomes of the two species were found to be very similar, sharing similar catalogues of CAZymes, peptidases and lipases. However, the genomes of the two species also varied, harbouring species-specific genes (e.g. small secreted effectors, nutrient processing proteins and stress response proteins). A portion of the TEs identified (17%) had a unique distribution in each species. Transposable elements appeared to have played a prominent role in the divergence of the two species because they were strongly associated with chromosomal translocations and inversions as well as with unique genomic regions containing species-specific genes. Two large effector clusters, with unique TEs in each species, were identified. These effectors displayed non-synonymous mutations and deletions, conserved within a species, and could serve as mutational hot-spots for the development of host specificity in the two species.
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Affiliation(s)
- Arista Fourie
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa
| | - Ronnie de Jonge
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht 3584 CH, the Netherlands
| | - Magriet A van der Nest
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa; Biotechnology Platform, Agricultural Research Council, Private Bag X05, Onderstepoort 0110, 0002, South Africa
| | - Tuan A Duong
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa
| | - Michael J Wingfield
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa
| | - Brenda D Wingfield
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa
| | - Irene Barnes
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa.
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50
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Badet T, Oggenfuss U, Abraham L, McDonald BA, Croll D. A 19-isolate reference-quality global pangenome for the fungal wheat pathogen Zymoseptoria tritici. BMC Biol 2020; 18:12. [PMID: 32046716 PMCID: PMC7014611 DOI: 10.1186/s12915-020-0744-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/27/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The gene content of a species largely governs its ecological interactions and adaptive potential. A species is therefore defined by both core genes shared between all individuals and accessory genes segregating presence-absence variation. There is growing evidence that eukaryotes, similar to bacteria, show intra-specific variability in gene content. However, it remains largely unknown how functionally relevant such a pangenome structure is for eukaryotes and what mechanisms underlie the emergence of highly polymorphic genome structures. RESULTS Here, we establish a reference-quality pangenome of a fungal pathogen of wheat based on 19 complete genomes from isolates sampled across six continents. Zymoseptoria tritici causes substantial worldwide losses to wheat production due to rapidly evolved tolerance to fungicides and evasion of host resistance. We performed transcriptome-assisted annotations of each genome to construct a global pangenome. Major chromosomal rearrangements are segregating within the species and underlie extensive gene presence-absence variation. Conserved orthogroups account for only ~ 60% of the species pangenome. Investigating gene functions, we find that the accessory genome is enriched for pathogenesis-related functions and encodes genes involved in metabolite production, host tissue degradation and manipulation of the immune system. De novo transposon annotation of the 19 complete genomes shows that the highly diverse chromosomal structure is tightly associated with transposable element content. Furthermore, transposable element expansions likely underlie recent genome expansions within the species. CONCLUSIONS Taken together, our work establishes a highly complex eukaryotic pangenome providing an unprecedented toolbox to study how pangenome structure impacts crop-pathogen interactions.
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Affiliation(s)
- Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Leen Abraham
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
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