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Upadhaya A, Upadhaya SGC, Brueggeman R. Association mapping with a diverse population of Puccinia graminis f. sp. tritici identified avirulence loci interacting with the barley Rpg1 stem rust resistance gene. BMC Genomics 2024; 25:751. [PMID: 39090588 PMCID: PMC11295639 DOI: 10.1186/s12864-024-10670-y] [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: 05/23/2024] [Accepted: 07/26/2024] [Indexed: 08/04/2024] Open
Abstract
BACKGROUND Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is an important disease of barley and wheat. A diverse sexual Pgt population from the Pacific Northwest (PNW) region of the US contains a high proportion of individuals with virulence on the barley stem rust resistance (R) gene, Rpg1. However, the evolutionary mechanisms of this virulence on Rpg1 are mysterious considering that Rpg1 had not been deployed in the region and the gene had remained remarkably durable in the Midwestern US and prairie provinces of Canada. METHODS AND RESULTS To identify AvrRpg1 effectors, genome wide association studies (GWAS) were performed using 113 Pgt isolates collected from the PNW (n = 89 isolates) and Midwest (n = 24 isolates) regions of the US. Disease phenotype data were generated on two barley lines Morex and the Golden Promise transgenic (H228.2c) that carry the Rpg1 gene. Genotype data was generated by whole genome sequencing (WGS) of 96 isolates (PNW = 89 isolates and Midwest = 7 isolates) and RNA sequencing (RNAseq) data from 17 Midwestern isolates. Utilizing ~1.2 million SNPs generated from WGS and phenotype data (n = 96 isolates) on the transgenic line H228.2c, 53 marker trait associations (MTAs) were identified. Utilizing ~140 K common SNPs generated from combined analysis of WGS and RNAseq data, two significant MTAs were identified using the cv Morex phenotyping data. The 55 MTAs defined two distinct avirulence loci, on supercontig 2.30 and supercontig 2.11 of the Pgt reference genome of Pgt isolate CRL 75-36-700-3. The major avirulence locus designated AvrRpg1A was identified with the GWAS using both barley lines and was delimited to a 35 kb interval on supercontig 2.30 containing four candidate genes (PGTG_10878, PGTG_10884, PGTG_10885, and PGTG_10886). The minor avirulence locus designated AvrRpg1B identified with cv Morex contained a single candidate gene (PGTG_05433). AvrRpg1A haplotype analysis provided strong evidence that a dominant avirulence gene underlies the locus. CONCLUSIONS The association analysis identified strong candidate AvrRpg1 genes. Further analysis to validate the AvrRpg1 genes will fill knowledge gaps in our understanding of rust effector biology and the evolution and mechanism/s of Pgt virulence on Rpg1.
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Affiliation(s)
- Arjun Upadhaya
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164-6420, USA
| | - Sudha G C Upadhaya
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164-6420, USA
| | - Robert Brueggeman
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164-6420, USA.
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Upadhaya A, Upadhaya SGC, Brueggeman R. Identification of Candidate Avirulence and Virulence Genes Corresponding to Stem Rust ( Puccinia graminis f. sp. tritici) Resistance Genes in Wheat. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:635-649. [PMID: 38780476 DOI: 10.1094/mpmi-05-24-0056-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: 05/25/2024]
Abstract
Stem rust, caused by the biotrophic fungal pathogen Puccinia graminis f. sp. tritici (Pgt), is an important disease of wheat. However, the majority of Pgt virulence/avirulence loci and underlying genes remain uncharacterized due to the constraints of developing bi-parental populations with this obligate biotroph. Genome-wide association studies (GWAS) using a sexual Pgt population mainly collected from the Pacific Northwestern United States were used to identify candidate virulence/avirulence effector genes corresponding to the six wheat Sr genes: Sr5, Sr21, Sr8a, Sr17, Sr9a, and Sr9d. The Pgt isolates were genotyped using whole-genome shotgun sequencing that identified approximately 1.2 million single nucleotide polymorphisms (SNPs) and were phenotyped at the seedling stage on six Sr gene differential lines. Association mapping analyses identified 17 Pgt loci associated with virulence or avirulence phenotypes on six Pgt resistance genes. Among these loci, 16 interacted with a specific Sr gene, indicating Sr-gene specific interactions. However, one avirulence locus interacted with two separate Sr genes (Sr9a and Sr17), suggesting two distinct Sr genes identifying a single avirulence effector. A total of 24 unique effector gene candidates were identified, and haplotype analysis suggests that within this population, AvrSr5, AvrSr21, AvrSr8a, AvrSr17, and AvrSr9a are dominant avirulence genes, while avrSr9d is a dominant virulence gene. The putative effector genes will be fundamental for future effector gene cloning efforts, allowing for further understanding of rust effector biology and the mechanisms underlying virulence evolution in Pgt with respect to race-specific R-genes. [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)
- Arjun Upadhaya
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, U.S.A
| | - Sudha G C Upadhaya
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, U.S.A
| | - Robert Brueggeman
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, U.S.A
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3
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Tralamazza SM, Gluck-Thaler E, Feurtey A, Croll D. Copy number variation introduced by a massive mobile element facilitates global thermal adaptation in a fungal wheat pathogen. Nat Commun 2024; 15:5728. [PMID: 38977688 PMCID: PMC11231334 DOI: 10.1038/s41467-024-49913-7] [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: 10/17/2023] [Accepted: 06/25/2024] [Indexed: 07/10/2024] Open
Abstract
Copy number variation (CNV) can drive rapid evolution in changing environments. In microbial pathogens, such adaptation is a key factor underpinning epidemics and colonization of new niches. However, the genomic determinants of such adaptation remain poorly understood. Here, we systematically investigate CNVs in a large genome sequencing dataset spanning a worldwide collection of 1104 genomes from the major wheat pathogen Zymoseptoria tritici. We found overall strong purifying selection acting on most CNVs. Genomic defense mechanisms likely accelerated gene loss over episodes of continental colonization. Local adaptation along climatic gradients was likely facilitated by CNVs affecting secondary metabolite production and gene loss in general. One of the strongest loci for climatic adaptation is a highly conserved gene of the NAD-dependent Sirtuin family. The Sirtuin CNV locus localizes to an ~68-kb Starship mobile element unique to the species carrying genes highly expressed during plant infection. The element has likely lost the ability to transpose, demonstrating how the ongoing domestication of cargo-carrying selfish elements can contribute to selectable variation within populations. Our work highlights how standing variation in gene copy numbers at the global scale can be a major factor driving climatic and metabolic adaptation in microbial species.
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Affiliation(s)
- Sabina Moser Tralamazza
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
| | - Emile Gluck-Thaler
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - 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
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland.
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Buttar ZA, Cheng M, Wei P, Zhang Z, Lv C, Zhu C, Ali NF, Kang G, Wang D, Zhang K. Update on the Basic Understanding of Fusarium graminearum Virulence Factors in Common Wheat Research. PLANTS (BASEL, SWITZERLAND) 2024; 13:1159. [PMID: 38674569 PMCID: PMC11053692 DOI: 10.3390/plants13081159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 04/16/2024] [Accepted: 04/19/2024] [Indexed: 04/28/2024]
Abstract
Wheat is one of the most important food crops, both in China and worldwide. Wheat production is facing extreme stresses posed by different diseases, including Fusarium head blight (FHB), which has recently become an increasingly serious concerns. FHB is one of the most significant and destructive diseases affecting wheat crops all over the world. Recent advancements in genomic tools provide a new avenue for the study of virulence factors in relation to the host plants. The current review focuses on recent progress in the study of different strains of Fusarium infection. The presence of genome-wide repeat-induced point (RIP) mutations causes genomic mutations, eventually leading to host plant susceptibility against Fusarium invasion. Furthermore, effector proteins disrupt the host plant resistance mechanism. In this study, we proposed systematic modification of the host genome using modern biological tools to facilitate plant resistance against foreign invasion. We also suggested a number of scientific strategies, such as gene cloning, developing more powerful functional markers, and using haplotype marker-assisted selection, to further improve FHB resistance and associated breeding methods.
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Affiliation(s)
- Zeeshan Ali Buttar
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
| | - Mengquan Cheng
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
| | - Panqin Wei
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
| | - Ziwei Zhang
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
| | - Chunlei Lv
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
| | - Chenjia Zhu
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
| | - Nida Fatima Ali
- Department of Plant Biotechnology, Atta-Ur-Rehman School of Applied Biosciences (ASAB), National University of Science and Technology, Islamabad 44000, Pakistan
| | - Guozhang Kang
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
| | - Daowen Wang
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
| | - Kunpu Zhang
- State Key Laboratory of Wheat and Maize Crop Science, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
- The Shennong Laboratory, Zhengzhou 450002, China
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5
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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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7
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Zaccaron AZ, Stergiopoulos I. Analysis of five near-complete genome assemblies of the tomato pathogen Cladosporium fulvum uncovers additional accessory chromosomes and structural variations induced by transposable elements effecting the loss of avirulence genes. BMC Biol 2024; 22:25. [PMID: 38281938 PMCID: PMC10823647 DOI: 10.1186/s12915-024-01818-z] [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: 11/02/2023] [Accepted: 01/04/2024] [Indexed: 01/30/2024] Open
Abstract
BACKGROUND Fungal plant pathogens have dynamic genomes that allow them to rapidly adapt to adverse conditions and overcome host resistance. One way by which this dynamic genome plasticity is expressed is through effector gene loss, which enables plant pathogens to overcome recognition by cognate resistance genes in the host. However, the exact nature of these loses remains elusive in many fungi. This includes the tomato pathogen Cladosporium fulvum, which is the first fungal plant pathogen from which avirulence (Avr) genes were ever cloned and in which loss of Avr genes is often reported as a means of overcoming recognition by cognate tomato Cf resistance genes. A recent near-complete reference genome assembly of C. fulvum isolate Race 5 revealed a compartmentalized genome architecture and the presence of an accessory chromosome, thereby creating a basis for studying genome plasticity in fungal plant pathogens and its impact on avirulence genes. RESULTS Here, we obtained near-complete genome assemblies of four additional C. fulvum isolates. The genome assemblies had similar sizes (66.96 to 67.78 Mb), number of predicted genes (14,895 to 14,981), and estimated completeness (98.8 to 98.9%). Comparative analysis that included the genome of isolate Race 5 revealed high levels of synteny and colinearity, which extended to the density and distribution of repetitive elements and of repeat-induced point (RIP) mutations across homologous chromosomes. Nonetheless, structural variations, likely mediated by transposable elements and effecting the deletion of the avirulence genes Avr4E, Avr5, and Avr9, were also identified. The isolates further shared a core set of 13 chromosomes, but two accessory chromosomes were identified as well. Accessory chromosomes were significantly smaller in size, and one carried pseudogenized copies of two effector genes. Whole-genome alignments further revealed genomic islands of near-zero nucleotide diversity interspersed with islands of high nucleotide diversity that co-localized with repeat-rich regions. These regions were likely generated by RIP, which generally asymmetrically affected the genome of C. fulvum. CONCLUSIONS Our results reveal new evolutionary aspects of the C. fulvum genome and provide new insights on the importance of genomic structural variations in overcoming host resistance in fungal plant pathogens.
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Affiliation(s)
- Alex Z Zaccaron
- Department of Plant Pathology, University of California Davis, Davis, CA, 95616-8751, USA
| | - Ioannis Stergiopoulos
- Department of Plant Pathology, University of California Davis, Davis, CA, 95616-8751, USA.
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8
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Oggenfuss U, Badet T, Croll D. A systematic screen for co-option of transposable elements across the fungal kingdom. Mob DNA 2024; 15:2. [PMID: 38245743 PMCID: PMC10799480 DOI: 10.1186/s13100-024-00312-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 01/04/2024] [Indexed: 01/22/2024] Open
Abstract
How novel protein functions are acquired is a central question in molecular biology. Key paths to novelty include gene duplications, recombination or horizontal acquisition. Transposable elements (TEs) are increasingly recognized as a major source of novel domain-encoding sequences. However, the impact of TE coding sequences on the evolution of the proteome remains understudied. Here, we analyzed 1237 genomes spanning the phylogenetic breadth of the fungal kingdom. We scanned proteomes for evidence of co-occurrence of TE-derived domains along with other conventional protein functional domains. We detected more than 13,000 predicted proteins containing potentially TE-derived domain, of which 825 were identified in more than five genomes, indicating that many host-TE fusions may have persisted over long evolutionary time scales. We used the phylogenetic context to identify the origin and retention of individual TE-derived domains. The most common TE-derived domains are helicases derived from Academ, Kolobok or Helitron. We found putative TE co-options at a higher rate in genomes of the Saccharomycotina, providing an unexpected source of protein novelty in these generally TE depleted genomes. We investigated in detail a candidate host-TE fusion with a heterochromatic transcriptional silencing function that may play a role in TE and gene regulation in ascomycetes. The affected gene underwent multiple full or partial losses within the phylum. Overall, our work establishes a kingdom-wide view of putative host-TE fusions and facilitates systematic investigations of candidate fusion proteins.
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Affiliation(s)
- Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
- Department of Microbiology and Immunology, University of Minnesota, Medical School, Minneapolis, Minnesota, United States of America
| | - Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland.
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9
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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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10
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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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11
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Wang Z, Wang YW, Kasuga T, Hassler H, Lopez-Giraldez F, Dong C, Yarden O, Townsend JP. Origins of lineage-specific elements via gene duplication, relocation, and regional rearrangement in Neurospora crassa. Mol Ecol 2023. [PMID: 37843462 DOI: 10.1111/mec.17168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 09/20/2023] [Accepted: 09/27/2023] [Indexed: 10/17/2023]
Abstract
The origin of new genes has long been a central interest of evolutionary biologists. However, their novelty means that they evade reconstruction by the classical tools of evolutionary modelling. This evasion of deep ancestral investigation necessitates intensive study of model species within well-sampled, recently diversified, clades. One such clade is the model genus Neurospora, members of which lack recent gene duplications. Several Neurospora species are comprehensively characterized organisms apt for studying the evolution of lineage-specific genes (LSGs). Using gene synteny, we documented that 78% of Neurospora LSG clusters are located adjacent to the telomeres featuring extensive tracts of non-coding DNA and duplicated genes. Here, we report several instances of LSGs that are likely from regional rearrangements and potentially from gene rebirth. To broadly investigate the functions of LSGs, we assembled transcriptomics data from 68 experimental data points and identified co-regulatory modules using Weighted Gene Correlation Network Analysis, revealing that LSGs are widely but peripherally involved in known regulatory machinery for diverse functions. The ancestral status of the LSG mas-1, a gene with roles in cell-wall integrity and cellular sensitivity to antifungal toxins, was investigated in detail alongside its genomic neighbours, indicating that it arose from an ancient lysophospholipase precursor that is ubiquitous in lineages of the Sordariomycetes. Our discoveries illuminate a "rummage region" in the N. crassa genome that enables the formation of new genes and functions to arise via gene duplication and relocation, followed by fast mutation and recombination facilitated by sequence repeats and unconstrained non-coding sequences.
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Affiliation(s)
- Zheng Wang
- Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut, USA
| | - Yen-Wen Wang
- Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut, USA
| | - Takao Kasuga
- College of Biological Sciences, University of California, Davis, Davis, California, USA
| | - Hayley Hassler
- Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut, USA
| | | | - Caihong Dong
- Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Oded Yarden
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Jeffrey P Townsend
- Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut, USA
- Department of Ecology and Evolutionary Biology, Program in Microbiology, and Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut, USA
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12
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Vande Zande P, Zhou X, Selmecki A. The Dynamic Fungal Genome: Polyploidy, Aneuploidy and Copy Number Variation in Response to Stress. Annu Rev Microbiol 2023; 77:341-361. [PMID: 37307856 PMCID: PMC10599402 DOI: 10.1146/annurev-micro-041320-112443] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Fungal species have dynamic genomes and often exhibit genomic plasticity in response to stress. This genome plasticity often comes with phenotypic consequences that affect fitness and resistance to stress. Fungal pathogens exhibit genome plasticity in both clinical and agricultural settings and often during adaptation to antifungal drugs, posing significant challenges to human health. Therefore, it is important to understand the rates, mechanisms, and impact of large genomic changes. This review addresses the prevalence of polyploidy, aneuploidy, and copy number variation across diverse fungal species, with special attention to prominent fungal pathogens and model species. We also explore the relationship between environmental stress and rates of genomic changes and highlight the mechanisms underlying genotypic and phenotypic changes. A comprehensive understanding of these dynamic fungal genomes is needed to identify novel solutions for the increase in antifungal drug resistance.
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Affiliation(s)
- Pétra Vande Zande
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, Minnesota, USA;
| | - Xin Zhou
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, Minnesota, USA;
| | - Anna Selmecki
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, Minnesota, USA;
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13
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Song Z, Zheng J, Zhao Y, Yin J, Zheng D, Hu H, Liu H, Sun M, Ruan L, Liu F. Population genomics and pathotypic evaluation of the bacterial leaf blight pathogen of rice reveals rapid evolutionary dynamics of a plant pathogen. Front Cell Infect Microbiol 2023; 13:1183416. [PMID: 37305415 PMCID: PMC10250591 DOI: 10.3389/fcimb.2023.1183416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 05/05/2023] [Indexed: 06/13/2023] Open
Abstract
The Xanthomonas oryzae pv. oryzae (Xoo) is a bacterial pathogen causing bacterial blight disease in rice, resulting in significant yield reductions of up to 50% in rice production. Despite its serious threat to food production globally, knowledge of its population structure and virulence evolution is relatively limited. In this study, we employed whole-genome sequencing to explore the diversity and evolution of Xoo in the main rice-growing areas of China over the past 30 years. Using phylogenomic analysis, we revealed six lineages. CX-1 and CX-2 primarily contained Xoo isolates from South China, while CX-3 represented Xoo isolates from North China. Xoo isolates belonging to CX-5 and CX-6 were the most prevalent across all studied areas, persisting as dominant lineages for several decades. Recent sporadic disease outbreaks were primarily caused by Xoo isolates derived from the two major lineages, CX-5 and CX-6, although Xoo isolates from other lineages also contributed to these outbreaks. The lineage and sub-lineage distributions of Xoo isolates were strongly correlated with their geographical origin, which was found to be mainly determined by the planting of the two major rice subspecies, indica and japonica. Moreover, large-scale virulence testing was conducted to evaluate the diversity of pathogenicity for Xoo. We found rapid virulence evolution against rice, and its determinant factors included the genetic background of Xoo, rice resistance genes, and planting environment of rice. This study provides an excellent model for understanding the evolution and dynamics of plant pathogens in the context of their interactions with their hosts, which are shaped by a combination of geographical conditions and farming practices. The findings of this study may have important implications for the development of effective strategies for disease management and crop protection in rice production systems.
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Affiliation(s)
- Zhiwei Song
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Jinshui Zheng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
- Hubei Key Laboratory of Agricultural Bioinformatics, Huazhong Agricultural University, Wuhan, China
| | - Yancun Zhao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Jiakang Yin
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
- Hubei Key Laboratory of Agricultural Bioinformatics, Huazhong Agricultural University, Wuhan, China
| | - Dehong Zheng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
- Hubei Key Laboratory of Agricultural Bioinformatics, Huazhong Agricultural University, Wuhan, China
| | - Huifeng Hu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
- Hubei Key Laboratory of Agricultural Bioinformatics, Huazhong Agricultural University, Wuhan, China
| | - Hongxia Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
- Hubei Key Laboratory of Agricultural Bioinformatics, Huazhong Agricultural University, Wuhan, China
| | - Lifang Ruan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
- Hubei Key Laboratory of Agricultural Bioinformatics, Huazhong Agricultural University, Wuhan, China
| | - Fengquan Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
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14
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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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15
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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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16
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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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17
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Demirjian C, Vailleau F, Berthomé R, Roux F. Genome-wide association studies in plant pathosystems: success or failure? TRENDS IN PLANT SCIENCE 2023; 28:471-485. [PMID: 36522258 DOI: 10.1016/j.tplants.2022.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 10/28/2022] [Accepted: 11/16/2022] [Indexed: 06/17/2023]
Abstract
Harnessing natural genetic variation is an established alternative to artificial genetic variation for investigating the molecular dialog between partners in plant pathosystems. Herein, we review the successes of genome-wide association studies (GWAS) in both plants and pathogens. While GWAS in plants confirmed that the genetic architecture of disease resistance is polygenic, dynamic during the infection kinetics, and dependent on the environment, GWAS shortened the time of identification of quantitative trait loci (QTLs) and revealed both complex epistatic networks and a genetic architecture dependent upon the geographical scale. A similar picture emerges from the few GWAS in pathogens. In addition, the ever-increasing number of functionally validated QTLs has revealed new molecular plant defense mechanisms and pathogenicity determinants. Finally, we propose recommendations to better decode the disease triangle.
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Affiliation(s)
- Choghag Demirjian
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France
| | - Fabienne Vailleau
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France
| | - Richard Berthomé
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France
| | - Fabrice Roux
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France.
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18
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Lin YC, Liu HH, Tseng MN, Chang HX. Heritability and gene functions associated with sclerotia formation of Rhizoctonia solani AG-7 using whole genome sequencing and genome-wide association study. Microb Genom 2023; 9:mgen000948. [PMID: 36867092 PMCID: PMC10132059 DOI: 10.1099/mgen.0.000948] [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: 10/14/2022] [Accepted: 12/07/2022] [Indexed: 03/04/2023] Open
Abstract
Sclerotia are specialized fungal structures formed by pigmented and aggregated hyphae, which can survive under unfavourable environmental conditions and serve as the primary inocula for several phytopathogenic fungi including Rhizoctonia solani. Among 154 R. solani anastomosis group 7 (AG-7) isolates collected in fields, the sclerotia-forming capability regarding sclerotia number and sclerotia size varied in the fungal population, but the genetic makeup of these phenotypes remained unclear. As limited studies have focused on the genomics of R. solani AG-7 and the population genetics of sclerotia formation, this study completed the whole genome sequencing and gene prediction of R. solani AG-7 using the Oxford NanoPore and Illumina RNA sequencing. Meanwhile, a high-throughput image-based method was established to quantify the sclerotia-forming capability, and the phenotypic correlation between sclerotia number and sclerotia size was low. A genome-wide association study identified three and five significant SNPs associated with sclerotia number and size in distinct genomic regions, respectively. Of these significant SNPs, two and four showed significant differences in the phenotypic mean separation for sclerotia number and sclerotia size, respectively. Gene ontology enrichment analysis focusing on the linkage disequilibrium blocks of significant SNPs identified more categories related to oxidative stress for sclerotia number, and more categories related to cell development, signalling and metabolism for sclerotia size. These results indicated that different genetic mechanisms may underlie these two phenotypes. Moreover, the heritability of sclerotia number and sclerotia size were estimated for the first time to be 0.92 and 0.31, respectively. This study provides new insights into the heritability and gene functions related to the development of sclerotia number and sclerotia size, which could provide additional knowledge to reduce fungal residues in fields and achieve sustainable disease management.
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Affiliation(s)
- Yu-Cheng Lin
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei City 106319, Taiwan, ROC
| | - Hsien-Hao Liu
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei City 106319, Taiwan, ROC
| | - Min-Nan Tseng
- Kaohsiung District Agricultural Research and Extension Station, Council of Agriculture, Pingtung County 908126, Taiwan, ROC
| | - Hao-Xun Chang
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei City 106319, Taiwan, ROC
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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
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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20
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Chen H, King R, Smith D, Bayon C, Ashfield T, Torriani S, Kanyuka K, Hammond-Kosack K, Bieri S, Rudd J. Combined pangenomics and transcriptomics reveals core and redundant virulence processes in a rapidly evolving fungal plant pathogen. BMC Biol 2023; 21:24. [PMID: 36747219 PMCID: PMC9903594 DOI: 10.1186/s12915-023-01520-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 01/19/2023] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Studying genomic variation in rapidly evolving pathogens potentially enables identification of genes supporting their "core biology", being present, functional and expressed by all strains or "flexible biology", varying between strains. Genes supporting flexible biology may be considered to be "accessory", whilst the "core" gene set is likely to be important for common features of a pathogen species biology, including virulence on all host genotypes. The wheat-pathogenic fungus Zymoseptoria tritici represents one of the most rapidly evolving threats to global food security and was the focus of this study. RESULTS We constructed a pangenome of 18 European field isolates, with 12 also subjected to RNAseq transcription profiling during infection. Combining this data, we predicted a "core" gene set comprising 9807 sequences which were (1) present in all isolates, (2) lacking inactivating polymorphisms and (3) expressed by all isolates. A large accessory genome, consisting of 45% of the total genes, was also defined. We classified genetic and genomic polymorphism at both chromosomal and individual gene scales. Proteins required for essential functions including virulence had lower-than average sequence variability amongst core genes. Both core and accessory genomes encoded many small, secreted candidate effector proteins that likely interact with plant immunity. Viral vector-mediated transient in planta overexpression of 88 candidates failed to identify any which induced leaf necrosis characteristic of disease. However, functional complementation of a non-pathogenic deletion mutant lacking five core genes demonstrated that full virulence was restored by re-introduction of the single gene exhibiting least sequence polymorphism and highest expression. CONCLUSIONS These data support the combined use of pangenomics and transcriptomics for defining genes which represent core, and potentially exploitable, weaknesses in rapidly evolving pathogens.
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Affiliation(s)
- Hongxin Chen
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
- Present address: School of Agriculture, Shenzhen Campus of Sun Yat-sen University, Guangming District, Shenzhen, Guangdong People’s Republic of China
| | - Robert King
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Dan Smith
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Carlos Bayon
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Tom Ashfield
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
- Crop Health and Protection (CHaP), Rothamsted Research, Harpenden, Herts UK
| | - Stefano Torriani
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Kostya Kanyuka
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
- Present address: National Institute for Agricultural Botany (NIAB), 93 Lawrence Weaver Road, Cambridge, UK
| | - Kim Hammond-Kosack
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Stephane Bieri
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Jason Rudd
- Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
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21
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Lofgren LA, Ross BS, Cramer RA, Stajich JE. The pan-genome of Aspergillus fumigatus provides a high-resolution view of its population structure revealing high levels of lineage-specific diversity driven by recombination. PLoS Biol 2022; 20:e3001890. [PMID: 36395320 PMCID: PMC9714929 DOI: 10.1371/journal.pbio.3001890] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 12/01/2022] [Accepted: 10/26/2022] [Indexed: 11/18/2022] Open
Abstract
Aspergillus fumigatus is a deadly agent of human fungal disease where virulence heterogeneity is thought to be at least partially structured by genetic variation between strains. While population genomic analyses based on reference genome alignments offer valuable insights into how gene variants are distributed across populations, these approaches fail to capture intraspecific variation in genes absent from the reference genome. Pan-genomic analyses based on de novo assemblies offer a promising alternative to reference-based genomics with the potential to address the full genetic repertoire of a species. Here, we evaluate 260 genome sequences of A. fumigatus including 62 newly sequenced strains, using a combination of population genomics, phylogenomics, and pan-genomics. Our results offer a high-resolution assessment of population structure and recombination frequency, phylogenetically structured gene presence-absence variation, evidence for metabolic specificity, and the distribution of putative antifungal resistance genes. Although A. fumigatus disperses primarily via asexual conidia, we identified extraordinarily high levels of recombination with the lowest linkage disequilibrium decay value reported for any fungal species to date. We provide evidence for 3 primary populations of A. fumigatus, with recombination occurring only rarely between populations and often within them. These 3 populations are structured by both gene variation and distinct patterns of gene presence-absence with unique suites of accessory genes present exclusively in each clade. Accessory genes displayed functional enrichment for nitrogen and carbohydrate metabolism suggesting that populations may be stratified by environmental niche specialization. Similarly, the distribution of antifungal resistance genes and resistance alleles were often structured by phylogeny. Altogether, the pan-genome of A. fumigatus represents one of the largest fungal pan-genomes reported to date including many genes unrepresented in the Af293 reference genome. These results highlight the inadequacy of relying on a single-reference genome-based approach for evaluating intraspecific variation and the power of combined genomic approaches to elucidate population structure, genetic diversity, and putative ecological drivers of clinically relevant fungi.
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Affiliation(s)
- Lotus A. Lofgren
- Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, California, United States of America
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Brandon S. Ross
- Dartmouth Geisel School of Medicine in the Department of Microbiology and Immunology, Dartmouth, Hanover, New Hampshire, United States of America
| | - Robert A. Cramer
- Dartmouth Geisel School of Medicine in the Department of Microbiology and Immunology, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jason E. Stajich
- Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, California, United States of America
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22
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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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23
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Zhao S, Martin-Vicente A, Colabardini AC, Pereira Silva L, Rinker DC, Fortwendel JR, Goldman GH, Gibbons JG. Genomic and Molecular Identification of Genes Contributing to the Caspofungin Paradoxical Effect in Aspergillus fumigatus. Microbiol Spectr 2022; 10:e0051922. [PMID: 36094204 PMCID: PMC9603777 DOI: 10.1128/spectrum.00519-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 08/17/2022] [Indexed: 11/25/2022] Open
Abstract
Aspergillus fumigatus is a deadly opportunistic fungal pathogen responsible for ~100,000 annual deaths. Azoles are the first line antifungal agent used against A. fumigatus, but azole resistance has rapidly evolved making treatment challenging. Caspofungin is an important second-line therapy against invasive pulmonary aspergillosis, a severe A. fumigatus infection. Caspofungin functions by inhibiting β-1,3-glucan synthesis, a primary and essential component of the fungal cell wall. A phenomenon termed the caspofungin paradoxical effect (CPE) has been observed in several fungal species where at higher concentrations of caspofungin, chitin replaces β-1,3-glucan, morphology returns to normal, and growth rate increases. CPE appears to occur in vivo, and it is therefore clinically important to better understand the genetic contributors to CPE. We applied genomewide association (GWA) analysis and molecular genetics to identify and validate candidate genes involved in CPE. We quantified CPE across 67 clinical isolates and conducted three independent GWA analyses to identify genetic variants associated with CPE. We identified 48 single nucleotide polymorphisms (SNPs) associated with CPE. We used a CRISPR/Cas9 approach to generate gene deletion mutants for seven genes harboring candidate SNPs. Two null mutants, ΔAfu3g13230 and ΔAfu4g07080 (dscP), resulted in reduced basal growth rate and a loss of CPE. We further characterized the dscP phosphatase-null mutant and observed a significant reduction in conidia production and extremely high sensitivity to caspofungin at both low and high concentrations. Collectively, our work reveals the contribution of Afu3g13230 and dscP in CPE and sheds new light on the complex genetic interactions governing this phenotype. IMPORTANCE This is one of the first studies to apply genomewide association (GWA) analysis to identify genes involved in an Aspergillus fumigatus phenotype. A. fumigatus is an opportunistic fungal pathogen that causes hundreds of thousands of infections and ~100,000 deaths each year, and antifungal resistance has rapidly evolved in this species. A phenomenon called the caspofungin paradoxical effect (CPE) occurs in some isolates, where high concentrations of the drug lead to increased growth rate. There is clinical relevance in understanding the genetic basis of this phenotype, since caspofungin concentrations could lead to unintended adverse clinical outcomes in certain cases. Using GWA analysis, we identified several interesting candidate polymorphisms and genes and then generated gene deletion mutants to determine whether these genes were important for CPE. Two of these mutant strains (ΔAfu3g13230 and ΔAfu4g07080/ΔdscP) displayed a loss of the CPE. This study sheds light on the genes involved in clinically important phenotype CPE.
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Affiliation(s)
- Shu Zhao
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, USA
- Department of Food Science, University of Massachusetts, Amherst, Massachusetts, USA
| | - Adela Martin-Vicente
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Ana Cristina Colabardini
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - Lilian Pereira Silva
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - David C. Rinker
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Jarrod R. Fortwendel
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Gustavo Henrique Goldman
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - John G. Gibbons
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, USA
- Department of Food Science, University of Massachusetts, Amherst, Massachusetts, USA
- Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, USA
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24
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Genome-wide association mapping reveals genes underlying population-level metabolome diversity in a fungal crop pathogen. BMC Biol 2022; 20:224. [PMID: 36209159 PMCID: PMC9548119 DOI: 10.1186/s12915-022-01422-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/27/2022] [Indexed: 11/12/2022] Open
Abstract
Background Fungi produce a wide range of specialized metabolites (SMs) involved in biotic interactions. Pathways for the production of SMs are often encoded in clusters of tightly arranged genes identified as biosynthetic gene clusters. Such gene clusters can undergo horizontal gene transfers between species and rapid evolutionary change within species. The acquisition, rearrangement, and deletion of gene clusters can generate significant metabolome diversity. However, the genetic basis underlying variation in SM production remains poorly understood. Results Here, we analyzed the metabolite production of a large population of the fungal pathogen of wheat, Zymoseptoria tritici. The pathogen causes major yield losses and shows variation in gene clusters. We performed untargeted ultra-high performance liquid chromatography-high resolution mass spectrometry to profile the metabolite diversity among 102 isolates of the same species. We found substantial variation in the abundance of the detected metabolites among isolates. Integrating whole-genome sequencing data, we performed metabolite genome-wide association mapping to identify loci underlying variation in metabolite production (i.e., metabolite-GWAS). We found that significantly associated SNPs reside mostly in coding and gene regulatory regions. Associated genes encode mainly transport and catalytic activities. The metabolite-GWAS identified also a polymorphism in the 3′UTR region of a virulence gene related to metabolite production and showing expression variation. Conclusions Taken together, our study provides a significant resource to unravel polymorphism underlying metabolome diversity within a species. Integrating metabolome screens should be feasible for a range of different plant pathogens and help prioritize molecular studies. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01422-z.
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25
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Wang L, Liu Q, Ge S, Liang W, Liao W, Li W, Jiao G, Wei X, Shao G, Xie L, Sheng Z, Hu S, Tang S, Hu P. Genomic footprints related with adaptation and fumonisins production in Fusarium proliferatum. Front Microbiol 2022; 13:1004454. [PMID: 36212817 PMCID: PMC9532532 DOI: 10.3389/fmicb.2022.1004454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 08/26/2022] [Indexed: 11/13/2022] Open
Abstract
Fusarium proliferatum is the principal etiological agent of rice spikelet rot disease (RSRD) in China, causing yield losses and fumonisins contamination in rice. The intraspecific variability and evolution pattern of the pathogen is poorly understood. Here, we performed whole-genome resequencing of 67 F. proliferatum strains collected from major rice-growing regions in China. Population structure indicated that eastern population of F. proliferatum located in Yangtze River with the high genetic diversity and recombinant mode that was predicted as the putative center of origin. Southern population and northeast population were likely been introduced into local populations through gene flow, and genetic differentiation between them might be shaped by rice-driven domestication. A total of 121 distinct genomic loci implicated 85 candidate genes were suggestively associated with variation of fumonisin B1 (FB1) production by genome-wide association study (GWAS). We subsequently tested the function of five candidate genes (gabap, chsD, palA, hxk1, and isw2) mapped in our association study by FB1 quantification of deletion strains, and mutants showed the impact on FB1 production as compared to the wide-type strain. Together, this is the first study to provide insights into the evolution and adaptation in natural populations of F. proliferatum on rice, as well as the complex genetic architecture for fumonisins biosynthesis.
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26
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McDonald BA, Suffert F, Bernasconi A, Mikaberidze A. How large and diverse are field populations of fungal plant pathogens? The case of Zymoseptoria tritici. Evol Appl 2022; 15:1360-1373. [PMID: 36187182 PMCID: PMC9488677 DOI: 10.1111/eva.13434] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/28/2022] [Accepted: 06/06/2022] [Indexed: 12/02/2022] Open
Abstract
Pathogen populations differ in the amount of genetic diversity they contain. Populations carrying higher genetic diversity are thought to have a greater evolutionary potential than populations carrying less diversity. We used published studies to estimate the range of values associated with two critical components of genetic diversity, the number of unique pathogen genotypes and the number of spores produced during an epidemic, for the septoria tritici blotch pathogen Zymoseptoria tritici. We found that wheat fields experiencing typical levels of infection are likely to carry between 3.1 and 14.0 million pathogen genotypes per hectare and produce at least 2.1-9.9 trillion pycnidiospores per hectare. Given the experimentally derived mutation rate of 3 × 10-10 substitutions per site per cell division, we estimate that between 27 and 126 million pathogen spores carrying adaptive mutations to counteract fungicides and resistant cultivars will be produced per hectare during a growing season. This suggests that most of the adaptive mutations that have been observed in Z. tritici populations can emerge through local selection from standing genetic variation that already exists within each field. The consequences of these findings for disease management strategies are discussed.
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Affiliation(s)
- Bruce A. McDonald
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZurichSwitzerland
| | | | - Alessio Bernasconi
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Alexey Mikaberidze
- School of Agriculture, Policy and DevelopmentUniversity of ReadingReadingUK
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27
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Saubin M, Louet C, Bousset L, Fabre F, Frey P, Fudal I, Grognard F, Hamelin F, Mailleret L, Stoeckel S, Touzeau S, Petre B, Halkett F. Improving sustainable crop protection using population genetics concepts. Mol Ecol 2022; 32:2461-2471. [PMID: 35906846 DOI: 10.1111/mec.16634] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 10/16/2022]
Abstract
Growing genetically resistant plants allows pathogen populations to be controlled and reduces the use of pesticides. However, pathogens can quickly overcome such resistance. In this context, how can we achieve sustainable crop protection? This crucial question has remained largely unanswered despite decades of intense debate and research effort. In this study, we used a bibliographic analysis to show that the research field of resistance durability has evolved into three subfields: (i) 'plant breeding' (generating new genetic material), (ii) 'molecular interactions' (exploring the molecular dialogue governing plant-pathogen interactions) and (iii) 'epidemiology and evolution' (explaining and forecasting of pathogen population dynamics resulting from selection pressure(s) exerted by resistant plants). We argue that this triple split of the field impedes integrated research progress and ultimately compromises the sustainable management of genetic resistance. After identifying a gap among the three subfields, we argue that the theoretical framework of population genetics could bridge this gap. Indeed, population genetics formally explains the evolution of all heritable traits, and allows genetic changes to be tracked along with variation in population dynamics. This provides an integrated view of pathogen adaptation, in particular via evolutionary-epidemiological feedbacks. In this Opinion Note, we detail examples illustrating how such a framework can better inform best practices for developing and managing genetically resistant cultivars.
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Affiliation(s)
| | - Clémentine Louet
- Université de Lorraine, INRAE, IAM, Nancy, France.,Université Paris Saclay, INRAE, BIOGER, Thiverval-Grignon, France
| | - Lydia Bousset
- INRAE, Agrocampus Ouest, Université de Rennes, IGEPP, Le Rheu, France
| | - Frédéric Fabre
- INRAE, Bordeaux Sciences Agro, SAVE, F-33882 Villenave d'Ornon, France
| | - Pascal Frey
- Université de Lorraine, INRAE, IAM, Nancy, France
| | - Isabelle Fudal
- Université Paris Saclay, INRAE, BIOGER, Thiverval-Grignon, France
| | - Frédéric Grognard
- Université Côte d'Azur, Inria, INRAE, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France
| | - Frédéric Hamelin
- INRAE, Agrocampus Ouest, Université de Rennes, IGEPP, Le Rheu, France
| | - Ludovic Mailleret
- Université Côte d'Azur, Inria, INRAE, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France.,Université Côte d'Azur, INRAE, CNRS, ISA, Sophia Antipolis, France
| | - Solenn Stoeckel
- INRAE, Agrocampus Ouest, Université de Rennes, IGEPP, Le Rheu, France
| | - Suzanne Touzeau
- Université Côte d'Azur, Inria, INRAE, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France
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28
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Schikora-Tamarit MÀ, Gabaldón T. Using genomics to understand the mechanisms of virulence and drug resistance in fungal pathogens. Biochem Soc Trans 2022; 50:1259-1268. [PMID: 35713390 PMCID: PMC9246328 DOI: 10.1042/bst20211123] [Citation(s) in RCA: 10] [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: 03/17/2022] [Revised: 05/27/2022] [Accepted: 06/06/2022] [Indexed: 02/06/2023]
Abstract
Fungal pathogens pose an increasingly worrying threat to human health, food security and ecosystem diversity. To tackle fungal infections and improve current diagnostic and therapeutic tools it is necessary to understand virulence and antifungal drug resistance mechanisms in diverse species. Recent advances in genomics approaches have provided a suitable framework to understand these phenotypes, which ultimately depend on genetically encoded determinants. In this work, we review how the study of genome sequences has been key to ascertain the bases of virulence and drug resistance traits. We focus on the contribution of comparative genomics, population genomics and directed evolution studies. In addition, we discuss how different types of genomic mutations (small or structural variants) contribute to intraspecific differences in virulence or drug resistance. Finally, we review current challenges in the field and anticipate future directions to solve them. In summary, this work provides a short overview of how genomics can be used to understand virulence and drug resistance in fungal pathogens.
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Affiliation(s)
- Miquel Àngel Schikora-Tamarit
- Barcelona Supercomputing Centre (BSC-CNS), Plaça Eusebi Güell, 1-3, 08034 Barcelona, Spain
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Toni Gabaldón
- Barcelona Supercomputing Centre (BSC-CNS), Plaça Eusebi Güell, 1-3, 08034 Barcelona, Spain
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
- Centro de Investigación Biomédica En Red de Enfermedades Infecciosas, Barcelona, Spain
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29
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Wyka S, Mondo S, Liu M, Nalam V, Broders K. A large accessory genome and high recombination rates may influence global distribution and broad host range of the fungal plant pathogen Claviceps purpurea. PLoS One 2022; 17:e0263496. [PMID: 35143550 PMCID: PMC8830672 DOI: 10.1371/journal.pone.0263496] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 01/20/2022] [Indexed: 11/18/2022] Open
Abstract
Pangenome analyses are increasingly being utilized to study the evolution of eukaryotic organisms. While pangenomes can provide insight into polymorphic gene content, inferences about the ecological and adaptive potential of such organisms also need to be accompanied by additional supportive genomic analyses. In this study we constructed a pangenome of Claviceps purpurea from 24 genomes and examined the positive selection and recombination landscape of an economically important fungal organism for pharmacology and agricultural research. Together, these analyses revealed that C. purpurea has a relatively large accessory genome (~ 38%), high recombination rates (ρ = 0.044), and transposon mediated gene duplication. However, due to observations of relatively low transposable element (TE) content (8.8%) and a lack of variability in genome sizes, prolific TE expansion may be controlled by frequent recombination. We additionally identified that within the ergoline biosynthetic cluster the lpsA1 and lpsA2 were the result of a recombination event. However, the high recombination rates observed in C. purpurea may be influencing an overall trend of purifying selection across the genome. These results showcase the use of selection and recombination landscapes to identify mechanisms contributing to pangenome structure and primary factors influencing the evolution of an organism.
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Affiliation(s)
- Stephen Wyka
- Department of Agricultural Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Stephen Mondo
- Department of Agricultural Biology, Colorado State University, Fort Collins, Colorado, United States of America
- United States Department of Energy Joint Genome Institute, Berkeley, California, United States of America
| | - Miao Liu
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, Canada
| | - Vamsi Nalam
- Department of Agricultural Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Kirk Broders
- USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Mycotoxin Prevention and Applied Microbiology Research Unit, Peoria, IL, United States of America
- Smithsonian Tropical Research Institute, Apartado Panamá, República de Panamá
- * E-mail:
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30
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Dumartinet T, Ravel S, Roussel V, Perez-Vicente L, Aguayo J, Abadie C, Carlier J. Complex adaptive architecture underlies adaptation to quantitative host resistance in a fungal plant pathogen. Mol Ecol 2021; 31:1160-1179. [PMID: 34845779 DOI: 10.1111/mec.16297] [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: 08/31/2021] [Revised: 11/12/2021] [Accepted: 11/17/2021] [Indexed: 11/26/2022]
Abstract
Plant pathogens often adapt to plant genetic resistance so characterization of the architecture underlying such an adaptation is required to understand the adaptive potential of pathogen populations. Erosion of banana quantitative resistance to a major leaf disease caused by polygenic adaptation of the causal agent, the fungus Pseudocercospora fijiensis, was recently identified in the northern Caribbean region. Genome scan and quantitative genetics approaches were combined to investigate the adaptive architecture underlying this adaptation. Thirty-two genomic regions showing host selection footprints were identified by pool sequencing of isolates collected from seven plantation pairs of two cultivars with different levels of quantitative resistance. Individual sequencing and phenotyping of isolates from one pair revealed significant and variable levels of correlation between haplotypes in 17 of these regions with a quantitative trait of pathogenicity (the diseased leaf area). The multilocus pattern of haplotypes detected in the 17 regions was found to be highly variable across all the population pairs studied. These results suggest complex adaptive architecture underlying plant pathogen adaptation to quantitative resistance with a polygenic basis, redundancy, and a low level of parallel evolution between pathogen populations. Candidate genes involved in quantitative pathogenicity and host adaptation of P. fijiensis were identified in genomic regions by combining annotation analysis with available biological data.
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Affiliation(s)
- Thomas Dumartinet
- CIRAD, UMR PHIM, Montpellier, France.,PHIM, Univ Montpellier, INRAe, CIRAD, Montpellier SupAgro, Montpellier, France
| | - Sébastien Ravel
- CIRAD, UMR PHIM, Montpellier, France.,PHIM, Univ Montpellier, INRAe, CIRAD, Montpellier SupAgro, Montpellier, France
| | - Véronique Roussel
- CIRAD, UMR PHIM, Montpellier, France.,PHIM, Univ Montpellier, INRAe, CIRAD, Montpellier SupAgro, Montpellier, France
| | | | - Jaime Aguayo
- ANSES, Laboratoire de la Santé des Végétaux (LSV), Unité de Mycologie, Malzéville, France
| | - Catherine Abadie
- CIRAD, UMR PHIM, Montpellier, France.,PHIM, Univ Montpellier, INRAe, CIRAD, Montpellier SupAgro, Montpellier, France
| | - Jean Carlier
- CIRAD, UMR PHIM, Montpellier, France.,PHIM, Univ Montpellier, INRAe, CIRAD, Montpellier SupAgro, Montpellier, France
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31
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Louet C, Saubin M, Andrieux A, Persoons A, Gorse M, Pétrowski J, Fabre B, De Mita S, Duplessis S, Frey P, Halkett F. A point mutation and large deletion at the candidate avirulence locus AvrMlp7 in the poplar rust fungus correlate with poplar RMlp7 resistance breakdown. Mol Ecol 2021; 32:2472-2483. [PMID: 34843142 DOI: 10.1111/mec.16294] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 10/21/2021] [Accepted: 11/09/2021] [Indexed: 01/29/2023]
Abstract
The deployment of plant varieties carrying resistance genes (R) exerts strong selection pressure on pathogen populations. Rapidly evolving avirulence genes (Avr) allow pathogens to escape R-mediated plant immunity through a variety of mechanisms, leading to virulence. The poplar rust fungus Melampsora larici-populina is a damaging pathogen of poplars in Europe. It underwent a major adaptive event in 1994, with the breakdown of the poplar RMlp7 resistance gene. Population genomics studies identified a locus in the genome of M. larici-populina that probably corresponds to the candidate avirulence gene AvrMlp7. Here, to further characterize this effector, we used a population genetics approach on a comprehensive set of 281 individuals recovered throughout a 28-year period encompassing the resistance breakdown event. Using two dedicated molecular tools, genotyping at the candidate locus highlighted two different alterations of a predominant allele found mainly before the resistance breakdown: a nonsynonymous mutation and a complete deletion of this locus. This results in six diploid genotypes: three genotypes related to the avirulent phenotype and three related to the virulent phenotype. The temporal survey of the candidate locus revealed that both alterations were found in association during the resistance breakdown event. They pre-existed before the breakdown in a heterozygous state with the predominant allele cited above. Altogether, these results suggest that the association of both alterations at the candidate locus AvrMlp7 drove the poplar rust adaptation to RMlp7-mediated immunity. This study demonstrates for the first time a case of adaptation from standing genetic variation in rust fungi during a qualitative resistance breakdown.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Pascal Frey
- Université de Lorraine, INRAE, IAM, Nancy, France
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32
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Singh NK, Karisto P, Croll D. Population-level deep sequencing reveals the interplay of clonal and sexual reproduction in the fungal wheat pathogen Zymoseptoria tritici. Microb Genom 2021; 7:000678. [PMID: 34617882 PMCID: PMC8627204 DOI: 10.1099/mgen.0.000678] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 08/29/2021] [Indexed: 11/18/2022] Open
Abstract
Pathogens cause significant challenges to global food security. On annual crops, pathogens must re-infect from environmental sources in every growing season. Fungal pathogens have evolved mixed reproductive strategies to cope with the distinct challenges of colonizing growing plants. However, how pathogen diversity evolves during growing seasons remains largely unknown. Here, we performed a deep hierarchical sampling in a single experimental wheat field infected by the major fungal pathogen Zymoseptoria tritici. We analysed whole genome sequences of 177 isolates collected from 12 distinct cultivars replicated in space at three time points of the growing season to maximize capture of genetic diversity. The field population was highly diverse with 37 SNPs per kilobase, a linkage disequilibrium decay within 200-700 bp and a high effective population size. Using experimental infections, we tested a subset of the collected isolates on the dominant cultivar planted in the field. However, we found no significant difference in virulence of isolates collected from the same cultivar compared to isolates collected on other cultivars. About 20 % of the isolate genotypes were grouped into 15 clonal groups. Pairs of clones were disproportionally found at short distances (<5 m), consistent with experimental estimates for per-generation dispersal distances performed in the same field. This confirms predominant leaf-to-leaf transmission during the growing season. Surprisingly, levels of clonality did not increase over time in the field although reproduction is thought to be exclusively asexual during the growing season. Our study shows that the pathogen establishes vast and stable gene pools in single fields. Monitoring short-term evolutionary changes in crop pathogens will inform more durable strategies to contain diseases.
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Affiliation(s)
- Nikhil Kumar Singh
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Petteri Karisto
- Plant Health, Natural Resources Institute Finland (Luke), Jokioinen, Finland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
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33
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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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Spanner R, Taliadoros D, Richards J, Rivera-Varas V, Neubauer J, Natwick M, Hamilton O, Vaghefi N, Pethybridge S, Secor GA, Friesen TL, Stukenbrock EH, Bolton MD. Genome-Wide Association and Selective Sweep Studies Reveal the Complex Genetic Architecture of DMI Fungicide Resistance in Cercospora beticola. Genome Biol Evol 2021; 13:6367780. [PMID: 34499119 DOI: 10.1093/gbe/evab209] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2021] [Indexed: 12/21/2022] Open
Abstract
The rapid and widespread evolution of fungicide resistance remains a challenge for crop disease management. The demethylation inhibitor (DMI) class of fungicides is a widely used chemistry for managing disease, but there has been a gradual decline in efficacy in many crop pathosystems. Reliance on DMI fungicides has increased resistance in populations of the plant pathogenic fungus Cercospora beticola worldwide. To better understand the genetic and evolutionary basis for DMI resistance in C. beticola, a genome-wide association study (GWAS) and selective sweep analysis were conducted for the first time in this species. We performed whole-genome resequencing of 190 C. beticola isolates infecting sugar beet (Beta vulgaris ssp. vulgaris). All isolates were phenotyped for sensitivity to the DMI tetraconazole. Intragenic markers on chromosomes 1, 4, and 9 were significantly associated with DMI fungicide resistance, including a polyketide synthase gene and the gene encoding the DMI target CbCYP51. Haplotype analysis of CbCYP51 identified a synonymous mutation (E170) and nonsynonymous mutations (L144F, I387M, and Y464S) associated with DMI resistance. Genome-wide scans of selection showed that several of the GWAS mutations for fungicide resistance resided in regions that have recently undergone a selective sweep. Using radial plate growth on selected media as a fitness proxy, we did not find a trade-off associated with DMI fungicide resistance. Taken together, we show that population genomic data from a crop pathogen can allow the identification of mutations conferring fungicide resistance and inform about their origins in the pathogen population.
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Affiliation(s)
- Rebecca Spanner
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA.,Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Demetris Taliadoros
- Environmental Genomics Group, Max Planck Institute for Evolutionary Biology, Plön, Germany.,Christian-Albrechts University of Kiel, Germany
| | - Jonathan Richards
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Viviana Rivera-Varas
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Jonathan Neubauer
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA
| | - Mari Natwick
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA
| | - Olivia Hamilton
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Niloofar Vaghefi
- Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland, Australia
| | - Sarah Pethybridge
- School of Integrative Plant Science, Cornell University, Geneva, New York, USA
| | - Gary A Secor
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Timothy L Friesen
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA.,Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Eva H Stukenbrock
- Botanical Institute, Christian-Albrechts University of Kiel, Kiel, Germany.,Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Melvin D Bolton
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA.,Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
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Zhang J, Shen N, Li C, Xiang X, Liu G, Gui Y, Patev S, Hibbett DS, Barry K, Andreopoulos W, Lipzen A, Riley R, He G, Yan M, Grigoriev IV, Shan Kwan H, Kit Cheung M, Bian Y, Xiao Y. Population genomics provides insights into the genetic basis of adaptive evolution in the mushroom-forming fungus Lentinula edodes. J Adv Res 2021; 38:91-106. [PMID: 35572413 PMCID: PMC9091725 DOI: 10.1016/j.jare.2021.09.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 09/17/2021] [Accepted: 09/19/2021] [Indexed: 02/08/2023] Open
Abstract
We detected three subgroups of L. edodes with robust phenotypic differentiation. The three subgroups were diverged 36,871 generations ago. L. edodes cultivars in China might originate from the vicinity of Northeast China. We dissected the genetic basis of adaptive evolution in L. edodes. Genes related to fruiting body development are involved in adaptive evolution.
Introduction Mushroom-forming fungi comprise diverse species that develop complex multicellular structures. In cultivated species, both ecological adaptation and artificial selection have driven genome evolution. However, little is known about the connections among genotype, phenotype and adaptation in mushroom-forming fungi. Objectives This study aimed to (1) uncover the population structure and demographic history of Lentinula edodes, (2) dissect the genetic basis of adaptive evolution in L. edodes, and (3) determine if genes related to fruiting body development are involved in adaptive evolution. Methods We analyzed genomes and fruiting body-related traits (FBRTs) in 133 L. edodes strains and conducted RNA-seq analysis of fruiting body development in the YS69 strain. Combined methods of genomic scan for divergence, genome-wide association studies (GWAS), and RNA-seq were used to dissect the genetic basis of adaptive evolution. Results We detected three distinct subgroups of L. edodes via single nucleotide polymorphisms, which showed robust phenotypic and temperature response differentiation and correlation with geographical distribution. Demographic history inference suggests that the subgroups diverged 36,871 generations ago. Moreover, L. edodes cultivars in China may have originated from the vicinity of Northeast China. A total of 942 genes were found to be related to genetic divergence by genomic scan, and 719 genes were identified to be candidates underlying FBRTs by GWAS. Integrating results of genomic scan and GWAS, 80 genes were detected to be related to phenotypic differentiation. A total of 364 genes related to fruiting body development were involved in genetic divergence and phenotypic differentiation. Conclusion Adaptation to the local environment, especially temperature, triggered genetic divergence and phenotypic differentiation of L. edodes. A general model for genetic divergence and phenotypic differentiation during adaptive evolution in L. edodes, which involves in signal perception and transduction, transcriptional regulation, and fruiting body morphogenesis, was also integrated here.
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Zhang F, Hu Z, Wu Z, Lu J, Shi Y, Xu J, Wang X, Wang J, Zhang F, Wang M, Shi X, Cui Y, Vera Cruz C, Zhuo D, Hu D, Li M, Wang W, Zhao X, Zheng T, Fu B, Ali J, Zhou Y, Li Z. Reciprocal adaptation of rice and Xanthomonas oryzae pv. oryzae: cross-species 2D GWAS reveals the underlying genetics. THE PLANT CELL 2021; 33:2538-2561. [PMID: 34467412 PMCID: PMC8408478 DOI: 10.1093/plcell/koab146] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 05/15/2021] [Indexed: 05/23/2023]
Abstract
A 1D/2D genome-wide association study strategy was adopted to investigate the genetic systems underlying the reciprocal adaptation of rice (Oryza sativa) and its bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo) using the whole-genome sequencing and large-scale phenotyping data of 701 rice accessions and 23 diverse Xoo strains. Forty-seven Xoo virulence-related genes and 318 rice quantitative resistance genes (QR-genes) mainly located in 41 genomic regions, and genome-wide interactions between the detected virulence-related genes and QR genes were identified, including well-known resistance genes/virulence genes plus many previously uncharacterized ones. The relationship between rice and Xoo was characterized by strong differentiation among Xoo races corresponding to the subspecific differentiation of rice, by strong shifts toward increased resistance/virulence of rice/Xoo populations and by rich genetic diversity at the detected rice QR-genes and Xoo virulence genes, and by genome-wide interactions between many rice QR-genes and Xoo virulence genes in a multiple-to-multiple manner, presumably resulting either from direct protein-protein interactions or from genetic epistasis. The observed complex genetic interaction system between rice and Xoo likely exists in other crop-pathogen systems that would maintain high levels of diversity at their QR-loci/virulence-loci, resulting in dynamic coevolutionary consequences during their reciprocal adaptation.
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Affiliation(s)
- Fan Zhang
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
- College of Agronomy, Anhui Agricultural University, 130 West Chang-Jiang Street, Hefei 230036, China
| | - Zhiqiang Hu
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
| | - Zhichao Wu
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Jialing Lu
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Yingyao Shi
- College of Agronomy, Anhui Agricultural University, 130 West Chang-Jiang Street, Hefei 230036, China
| | - Jianlong Xu
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Xiyin Wang
- School of Life Sciences, North China University of Science and Technology, Tangshan, Hebei 063009, China
| | - Jinpeng Wang
- School of Life Sciences, North China University of Science and Technology, Tangshan, Hebei 063009, China
| | - Fan Zhang
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Mingming Wang
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Xiaorong Shi
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
- College of Agronomy, Anhui Agricultural University, 130 West Chang-Jiang Street, Hefei 230036, China
| | - Yanru Cui
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Casiana Vera Cruz
- International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines
| | - Dalong Zhuo
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
- College of Agronomy, Anhui Agricultural University, 130 West Chang-Jiang Street, Hefei 230036, China
| | - Dandan Hu
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
- College of Agronomy, Anhui Agricultural University, 130 West Chang-Jiang Street, Hefei 230036, China
| | - Min Li
- College of Agronomy, Anhui Agricultural University, 130 West Chang-Jiang Street, Hefei 230036, China
| | - Wensheng Wang
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Xiuqin Zhao
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Tianqing Zheng
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Binying Fu
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Jauhar Ali
- International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines
| | - Yongli Zhou
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
| | - Zhikang Li
- Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Haidian District, Beijing 100081, China
- College of Agronomy, Anhui Agricultural University, 130 West Chang-Jiang Street, Hefei 230036, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
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Harting R, Starke J, Kusch H, Pöggeler S, Maurus I, Schlüter R, Landesfeind M, Bulla I, Nowrousian M, de Jonge R, Stahlhut G, Hoff KJ, Aßhauer KP, Thürmer A, Stanke M, Daniel R, Morgenstern B, Thomma BPHJ, Kronstad JW, Braus‐Stromeyer SA, Braus GH. A 20-kb lineage-specific genomic region tames virulence in pathogenic amphidiploid Verticillium longisporum. MOLECULAR PLANT PATHOLOGY 2021; 22:939-953. [PMID: 33955130 PMCID: PMC8295516 DOI: 10.1111/mpp.13071] [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: 02/19/2021] [Accepted: 03/30/2021] [Indexed: 05/04/2023]
Abstract
Amphidiploid fungal Verticillium longisporum strains Vl43 and Vl32 colonize the plant host Brassica napus but differ in their ability to cause disease symptoms. These strains represent two V. longisporum lineages derived from different hybridization events of haploid parental Verticillium strains. Vl32 and Vl43 carry same-sex mating-type genes derived from both parental lineages. Vl32 and Vl43 similarly colonize and penetrate plant roots, but asymptomatic Vl32 proliferation in planta is lower than virulent Vl43. The highly conserved Vl43 and Vl32 genomes include less than 1% unique genes, and the karyotypes of 15 or 16 chromosomes display changed genetic synteny due to substantial genomic reshuffling. A 20 kb Vl43 lineage-specific (LS) region apparently originating from the Verticillium dahliae-related ancestor is specific for symptomatic Vl43 and encodes seven genes, including two putative transcription factors. Either partial or complete deletion of this LS region in Vl43 did not reduce virulence but led to induction of even more severe disease symptoms in rapeseed. This suggests that the LS insertion in the genome of symptomatic V. longisporum Vl43 mediates virulence-reducing functions, limits damage on the host plant, and therefore tames Vl43 from being even more virulent.
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Affiliation(s)
- Rebekka Harting
- Department of Molecular Microbiology and GeneticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Jessica Starke
- Department of Molecular Microbiology and GeneticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Harald Kusch
- Department of Molecular Microbiology and GeneticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Stefanie Pöggeler
- Department of Genetics of Eukaryotic MicroorganismsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Isabel Maurus
- Department of Molecular Microbiology and GeneticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Rabea Schlüter
- Imaging Center of the Department of BiologyUniversity of GreifswaldGreifswaldGermany
| | - Manuel Landesfeind
- Department of BioinformaticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Ingo Bulla
- Institute for Mathematics and Computer ScienceUniversity of GreifswaldGreifswaldGermany
| | - Minou Nowrousian
- Department of Molecular and Cellular BotanyRuhr‐Universität BochumBochumGermany
| | - Ronnie de Jonge
- Plant–Microbe Interactions, Department of Biology, Science4LifeUtrecht UniversityUtrechtNetherlands
- Laboratory of PhytopathologyWageningen UniversityWageningenNetherlands
| | - Gertrud Stahlhut
- Department of Genetics of Eukaryotic MicroorganismsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Katharina J. Hoff
- Institute for Mathematics and Computer ScienceUniversity of GreifswaldGreifswaldGermany
- Center for Functional Genomics of MicrobesUniversity of GreifswaldGreifswaldGermany
| | - Kathrin P. Aßhauer
- Department of BioinformaticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Andrea Thürmer
- Department of Genomic and Applied MicrobiologyInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Mario Stanke
- Institute for Mathematics and Computer ScienceUniversity of GreifswaldGreifswaldGermany
- Center for Functional Genomics of MicrobesUniversity of GreifswaldGreifswaldGermany
| | - Rolf Daniel
- Department of Genomic and Applied MicrobiologyInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Burkhard Morgenstern
- Department of BioinformaticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | | | - James W. Kronstad
- Michael Smith Laboratories, Department of Microbiology and ImmunologyUniversity of British ColumbiaVancouverBCCanada
| | - Susanna A. Braus‐Stromeyer
- Department of Molecular Microbiology and GeneticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and GeneticsInstitute of Microbiology and Genetics and Göttingen Center for Molecular BiosciencesUniversity of GöttingenGöttingenGermany
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Pereira D, Oggenfuss U, McDonald BA, Croll D. Population genomics of transposable element activation in the highly repressive genome of an agricultural pathogen. Microb Genom 2021; 7:000540. [PMID: 34424154 PMCID: PMC8549362 DOI: 10.1099/mgen.0.000540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/03/2021] [Indexed: 12/13/2022] Open
Abstract
The activity of transposable elements (TEs) can be an important driver of genetic diversity with TE-mediated mutations having a wide range of fitness consequences. To avoid deleterious effects of TE activity, some fungi have evolved highly sophisticated genomic defences to reduce TE proliferation across the genome. Repeat-induced point mutation (RIP) is a fungal-specific TE defence mechanism efficiently targeting duplicated sequences. The rapid accumulation of RIPs is expected to deactivate TEs over the course of a few generations. The evolutionary dynamics of TEs at the population level in a species with highly repressive genome defences is poorly understood. Here, we analyse 366 whole-genome sequences of Parastagonospora nodorum, a fungal pathogen of wheat with efficient RIP. A global population genomics analysis revealed high levels of genetic diversity and signs of frequent sexual recombination. Contrary to expectations for a species with RIP, we identified recent TE activity in multiple populations. The TE composition and copy numbers showed little divergence among global populations regardless of the demographic history. Miniature inverted-repeat transposable elements (MITEs) and terminal repeat retrotransposons in miniature (TRIMs) were largely underlying recent intra-species TE expansions. We inferred RIP footprints in individual TE families and found that recently active, high-copy TEs have possibly evaded genomic defences. We find no evidence that recent positive selection acted on TE-mediated mutations rather that purifying selection maintained new TE insertions at low insertion frequencies in populations. Our findings highlight the complex evolutionary equilibria established by the joint action of TE activity, selection and genomic repression.
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Affiliation(s)
- Danilo Pereira
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
- Present address: Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, D-24306 Plön, Germany
| | - Ursula Oggenfuss
- 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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39
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Fagundes WC, Haueisen J, Stukenbrock EH. Dissecting the Biology of the Fungal Wheat Pathogen Zymoseptoria tritici: A Laboratory Workflow. ACTA ACUST UNITED AC 2021; 59:e128. [PMID: 33175475 DOI: 10.1002/cpmc.128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The fungus Zymoseptoria tritici is one of the most devastating pathogens of wheat. Aside from its importance as a disease-causing agent, this species has emerged as a powerful model system for evolutionary genetic studies of crop-infecting fungal pathogens. Z. tritici exhibits exceptionally high levels of genetic and phenotypic diversity as well as morphological plasticity, which can make experimental studies and comparability of results obtained in different laboratories, e.g., from infection assays, challenging. Therefore, standardized experimental methods are crucial for research on Z. tritici biology and the interaction of this fungus with its wheat host. Here, we describe a suite of well-tested and optimized protocols ranging from isolation of Z. tritici field specimens to analyses of virulence assays under controlled conditions. Several biological and technical aspects of working with Z. tritici under laboratory conditions are considered and carefully described in each protocol. © 2020 The Authors. Basic Protocol 1: Purification of Z. tritici field isolates from leaf material Basic Protocol 2: Molecular identification of Z. tritici isolates Support Protocol 1: Rapid extraction of Z. tritici genomic DNA Support Protocol 2: Extraction of high-quality Z. tritici genomic DNA Basic Protocol 3: In vitro culture and long-term storage of Z. tritici isolates Basic Protocol 4: Analysis of Z. tritici virulence in wheat Support Protocol 3: Preparation of Z. tritici inoculum.
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Affiliation(s)
- Wagner C Fagundes
- Environmental Genomics Group, Christian-Albrechts University Kiel, Kiel, Germany.,Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Janine Haueisen
- Environmental Genomics Group, Christian-Albrechts University Kiel, Kiel, Germany.,Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Eva H Stukenbrock
- Environmental Genomics Group, Christian-Albrechts University Kiel, Kiel, Germany.,Max Planck Institute for Evolutionary Biology, Plön, Germany
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40
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Torres DE, Thomma BPHJ, Seidl MF. Transposable Elements Contribute to Genome Dynamics and Gene Expression Variation in the Fungal Plant Pathogen Verticillium dahliae. Genome Biol Evol 2021; 13:evab135. [PMID: 34100895 PMCID: PMC8290119 DOI: 10.1093/gbe/evab135] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2021] [Indexed: 12/12/2022] Open
Abstract
Transposable elements (TEs) are a major source of genetic and regulatory variation in their host genome and are consequently thought to play important roles in evolution. Many fungal and oomycete plant pathogens have evolved dynamic and TE-rich genomic regions containing genes that are implicated in host colonization and adaptation. TEs embedded in these regions have typically been thought to accelerate the evolution of these genomic compartments, but little is known about their dynamics in strains that harbor them. Here, we used whole-genome sequencing data of 42 strains of the fungal plant pathogen Verticillium dahliae to systematically identify polymorphic TEs that may be implicated in genomic as well as in gene expression variation. We identified 2,523 TE polymorphisms and characterize a subset of 8% of the TEs as polymorphic elements that are evolutionary younger, less methylated, and more highly expressed when compared with the remaining 92% of the total TE complement. As expected, the polyrmorphic TEs are enriched in the adaptive genomic regions. Besides, we observed an association of polymorphic TEs with pathogenicity-related genes that localize nearby and that display high expression levels. Collectively, our analyses demonstrate that TE dynamics in V. dahliae contributes to genomic variation, correlates with expression of pathogenicity-related genes, and potentially impacts the evolution of adaptive genomic regions.
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Affiliation(s)
- David E Torres
- Theoretical Biology and Bioinformatics Group, Department of Biology, Utrecht University, The Netherlands
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands
| | - Bart P H J Thomma
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands
- Cluster of Excellence on Plant Sciences (CEPLAS), Institute for Plant Sciences, University of Cologne, Germany
| | - Michael F Seidl
- Theoretical Biology and Bioinformatics Group, Department of Biology, Utrecht University, The Netherlands
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Badet T, Fouché S, Hartmann FE, Zala M, Croll D. Machine-learning predicts genomic determinants of meiosis-driven structural variation in a eukaryotic pathogen. Nat Commun 2021; 12:3551. [PMID: 34112792 PMCID: PMC8192914 DOI: 10.1038/s41467-021-23862-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 05/11/2021] [Indexed: 02/05/2023] Open
Abstract
Species harbor extensive structural variation underpinning recent adaptive evolution. However, the causality between genomic features and the induction of new rearrangements is poorly established. Here, we analyze a global set of telomere-to-telomere genome assemblies of a fungal pathogen of wheat to establish a nucleotide-level map of structural variation. We show that the recent emergence of pesticide resistance has been disproportionally driven by rearrangements. We use machine learning to train a model on structural variation events based on 30 chromosomal sequence features. We show that base composition and gene density are the major determinants of structural variation. Retrotransposons explain most inversion, indel and duplication events. We apply our model to Arabidopsis thaliana and show that our approach extends to more complex genomes. Finally, we analyze complete genomes of haploid offspring in a four-generation pedigree. Meiotic crossover locations are enriched for new rearrangements consistent with crossovers being mutational hotspots. The model trained on species-wide structural variation accurately predicts the position of >74% of newly generated variants along the pedigree. The predictive power highlights causality between specific sequence features and the induction of chromosomal rearrangements. Our work demonstrates that training sequence-derived models can accurately identify regions of intrinsic DNA instability in eukaryotic genomes.
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Affiliation(s)
- Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Simone Fouché
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Fanny E Hartmann
- Ecologie Systématique Evolution, Bâtiment 360, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, Orsay, France
| | - Marcello Zala
- 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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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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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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Möller M, Habig M, Lorrain C, Feurtey A, Haueisen J, Fagundes WC, Alizadeh A, Freitag M, Stukenbrock EH. Recent loss of the Dim2 DNA methyltransferase decreases mutation rate in repeats and changes evolutionary trajectory in a fungal pathogen. PLoS Genet 2021; 17:e1009448. [PMID: 33750960 PMCID: PMC8016269 DOI: 10.1371/journal.pgen.1009448] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 04/01/2021] [Accepted: 02/26/2021] [Indexed: 01/04/2023] Open
Abstract
DNA methylation is found throughout all domains of life, yet the extent and function of DNA methylation differ among eukaryotes. Strains of the plant pathogenic fungus Zymoseptoria tritici appeared to lack cytosine DNA methylation (5mC) because gene amplification followed by Repeat-Induced Point mutation (RIP) resulted in the inactivation of the dim2 DNA methyltransferase gene. 5mC is, however, present in closely related sister species. We demonstrate that inactivation of dim2 occurred recently as some Z. tritici isolates carry a functional dim2 gene. Moreover, we show that dim2 inactivation occurred by a different path than previously hypothesized. We mapped the genome-wide distribution of 5mC in strains with or without functional dim2 alleles. Presence of functional dim2 correlates with high levels of 5mC in transposable elements (TEs), suggesting a role in genome defense. We identified low levels of 5mC in strains carrying non-functional dim2 alleles, suggesting that 5mC is maintained over time, presumably by an active Dnmt5 DNA methyltransferase. Integration of a functional dim2 allele in strains with mutated dim2 restored normal 5mC levels, demonstrating de novo cytosine methylation activity of Dim2. To assess the importance of 5mC for genome evolution, we performed an evolution experiment, comparing genomes of strains with high levels of 5mC to genomes of strains lacking functional dim2. We found that presence of a functional dim2 allele alters nucleotide composition by promoting C to T transitions (C→T) specifically at CpA (CA) sites during mitosis, likely contributing to TE inactivation. Our results show that 5mC density at TEs is a polymorphic trait in Z. tritici populations that can impact genome evolution.
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Affiliation(s)
- Mareike Möller
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Michael Habig
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Cécile Lorrain
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Alice Feurtey
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Janine Haueisen
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Wagner C. Fagundes
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Alireza Alizadeh
- Department of Plant Protection, Faculty of Agriculture, Azarbaijan Shahid Madani University, Tabriz, Iran
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States of America
| | - Eva H. Stukenbrock
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
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45
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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: 10] [Impact Index Per Article: 3.3] [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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46
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Zhao S, Ge W, Watanabe A, Fortwendel JR, Gibbons JG. Genome-Wide Association for Itraconazole Sensitivity in Non-resistant Clinical Isolates of Aspergillus fumigatus. FRONTIERS IN FUNGAL BIOLOGY 2021; 1:617338. [PMID: 37743877 PMCID: PMC10512406 DOI: 10.3389/ffunb.2020.617338] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/15/2020] [Indexed: 09/26/2023]
Abstract
Aspergillus fumigatus is a potentially lethal opportunistic pathogen that infects over ~200,000 people and causes ~100,000 deaths per year globally. Treating A. fumigatus infections is particularly challenging because of the recent emergence of azole-resistance. The majority of studies focusing on the molecular mechanisms underlying azole resistance have examined azole-resistant isolates. However, isolates that are susceptible to azoles also display variation in their sensitivity, presenting a unique opportunity to identify genes contributing to azole sensitivity. Here, we used genome-wide association (GWA) analysis to identify loci involved in azole sensitivity by analyzing the association between 68,853 SNPs and itraconazole (ITCZ) minimum inhibitory concentration (MIC) in 76 clinical isolates of A. fumigatus from Japan. Population structure analysis suggests the presence of four distinct populations, with ITCZ MICs distributed relatively evenly across populations. We independently conducted GWA when treating ITCZ MIC as a quantitative trait and a binary trait, and identified two SNPs with strong associations in both analyses. These SNPs fell within the coding regions of Afu2g02220 and Afu2g02140. We functionally validated Afu2g02220 by knocking it out using a CRISPR/Cas9 approach, because orthologs of this gene are involved in sterol modification and ITCZ targets the ergosterol biosynthesis pathway. Knockout strains displayed no difference in growth compared to the parent strain in minimal media, yet a minor but consistent inhibition of growth in the presence of 0.15 μg/ml ITCZ. Our results suggest that GWA paired with efficient gene deletion is a powerful and unbiased strategy for identifying the genetic basis of complex traits in A. fumigatus.
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Affiliation(s)
- Shu Zhao
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, United States
- Department of Food Science, University of Massachusetts, Amherst, MA, United States
| | - Wenbo Ge
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Akira Watanabe
- Division of Clinical Research, Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Jarrod R. Fortwendel
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, TN, United States
| | - John G. Gibbons
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, United States
- Department of Food Science, University of Massachusetts, Amherst, MA, United States
- Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA, United States
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47
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Vogel G, Gore MA, Smart CD. Genome-Wide Association Study in New York Phytophthora capsici Isolates Reveals Loci Involved in Mating Type and Mefenoxam Sensitivity. PHYTOPATHOLOGY 2021; 111:204-216. [PMID: 32539639 DOI: 10.1094/phyto-04-20-0112-fi] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Phytophthora capsici is a soilborne oomycete plant pathogen that causes severe vegetable crop losses in New York (NY) state and worldwide. This pathogen is difficult to manage, in part due to its production of long-lasting sexual spores and its tendency to quickly evolve fungicide resistance. We single nucleotide polymorphism (SNP) genotyped 252 P. capsici isolates, predominantly from NY, in order to conduct a genome-wide association study for mating type and mefenoxam sensitivity. The population structure and extent of chromosomal copy number variation in this collection of isolates were also characterized. Population structure analyses showed isolates largely clustered by the field site where they were collected, with values of FST between pairs of fields ranging from 0.10 to 0.31. Thirty-three isolates were putative aneuploids, demonstrating evidence for having up to four linkage groups present in more than two copies, and an additional two isolates appeared to be genome-wide triploids. Mating type was mapped to a region on scaffold 4, consistent with previous findings, and mefenoxam sensitivity was associated with several SNP markers at a novel locus on scaffold 62. We identified several candidate genes for mefenoxam sensitivity, including a homolog of yeast ribosome synthesis factor Rrp5, but failed to locate near the scaffold 62 locus any subunits of RNA polymerase I, the hypothesized target site of phenylamide fungicides in oomycetes. This work expands our knowledge of the population biology of P. capsici and provides a foundation for functional validation of candidate genes associated with epidemiologically important phenotypes.
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Affiliation(s)
- Gregory Vogel
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456
| | - Michael A Gore
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
| | - Christine D Smart
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456
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48
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Singh NK, Dutta A, Puccetti G, Croll D. Tackling microbial threats in agriculture with integrative imaging and computational approaches. Comput Struct Biotechnol J 2020; 19:372-383. [PMID: 33489007 PMCID: PMC7787954 DOI: 10.1016/j.csbj.2020.12.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/08/2020] [Accepted: 12/13/2020] [Indexed: 11/29/2022] Open
Abstract
Pathogens and pests are one of the major threats to agricultural productivity worldwide. For decades, targeted resistance breeding was used to create crop cultivars that resist pathogens and environmental stress while retaining yields. The often decade-long process of crossing, selection, and field trials to create a new cultivar is challenged by the rapid rise of pathogens overcoming resistance. Similarly, antimicrobial compounds can rapidly lose efficacy due to resistance evolution. Here, we review three major areas where computational, imaging and experimental approaches are revolutionizing the management of pathogen damage on crops. Recognizing and scoring plant diseases have dramatically improved through high-throughput imaging techniques applicable both under well-controlled greenhouse conditions and directly in the field. However, computer vision of complex disease phenotypes will require significant improvements. In parallel, experimental setups similar to high-throughput drug discovery screens make it possible to screen thousands of pathogen strains for variation in resistance and other relevant phenotypic traits. Confocal microscopy and fluorescence can capture rich phenotypic information across pathogen genotypes. Through genome-wide association mapping approaches, phenotypic data helps to unravel the genetic architecture of stress- and virulence-related traits accelerating resistance breeding. Finally, joint, large-scale screenings of trait variation in crops and pathogens can yield fundamental insights into how pathogens face trade-offs in the adaptation to resistant crop varieties. We discuss how future implementations of such innovative approaches in breeding and pathogen screening can lead to more durable disease control.
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Affiliation(s)
- Nikhil Kumar Singh
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
| | - Anik Dutta
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Guido Puccetti
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
- Syngenta Crop Protection AG, CH-4332 Stein, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
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49
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Harris JM, Balint-Kurti P, Bede JC, Day B, Gold S, Goss EM, Grenville-Briggs LJ, Jones KM, Wang A, Wang Y, Mitra RM, Sohn KH, Alvarez ME. What are the Top 10 Unanswered Questions in Molecular Plant-Microbe Interactions? MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:1354-1365. [PMID: 33106084 DOI: 10.1094/mpmi-08-20-0229-cr] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This article is part of the Top 10 Unanswered Questions in MPMI invited review series.The past few decades have seen major discoveries in the field of molecular plant-microbe interactions. As the result of technological and intellectual advances, we are now able to answer questions at a level of mechanistic detail that we could not have imagined possible 20 years ago. The MPMI Editorial Board felt it was time to take stock and reassess. What big questions remain unanswered? We knew that to identify the fundamental, overarching questions that drive our research, we needed to do this as a community. To reach a diverse audience of people with different backgrounds and perspectives, working in different areas of plant-microbe interactions, we queried the more than 1,400 participants at the 2019 International Congress on Molecular Plant-Microbe Interactions meeting in Glasgow. This group effort resulted in a list of ten, broad-reaching, fundamental questions that influence and inform our research. Here, we introduce these Top 10 unanswered questions, giving context and a brief description of the issues. Each of these questions will be the subject of a detailed review in the coming months. We hope that this process of reflecting on what is known and unknown and identifying the themes that underlie our research will provide a framework to use going forward, giving newcomers a sense of the mystery of the big questions and inspiring new avenues and novel insights.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Jeanne M Harris
- Department of Plant Biology, University of Vermont, Burlington, VT 05405, U.S.A
| | - Peter Balint-Kurti
- USDA-ARS, Plant Science Research Unit, Raleigh NC, and Dept. of Entomology and Plant Pathology, NC State University, Raleigh, NC 27695-7613, U.S.A
| | - Jacqueline C Bede
- Department of Plant Science, McGill University, Ste-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Brad Day
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Scott Gold
- Plant Pathology Department, University of Georgia, USDA-ARS, Athens, GA 30605-2720, U.S.A
| | - Erica M Goss
- Plant Pathology Department and Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, U.S.A
| | - Laura J Grenville-Briggs
- Department of Plant Protection Biology, Swedish University of Agricultural Sciences, SE-230 53 Alnarp, Sweden
| | - Kathryn M Jones
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, U.S.A
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Raka M Mitra
- Biology Department, Carleton College, Northfield, MN 55057, U.S.A
| | - Kee Hoon Sohn
- Department of Life Sciences, Pohang University of Science and Technology and School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Maria Elena Alvarez
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
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50
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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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