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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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2
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Bazzicalupo A. Local adaptation in fungi. FEMS Microbiol Rev 2022; 46:6604384. [PMID: 35675293 DOI: 10.1093/femsre/fuac026] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/24/2022] [Accepted: 05/30/2022] [Indexed: 01/09/2023] Open
Abstract
In this review, I explore the pervasive but underappreciated role of local adaptation in fungi. It has been difficult historically to study local adaptation in fungi because of the limited understanding of fungal species and their traits, but new hope has been offered with technological advances in sequencing. The filamentous nature of fungi invalidates some assumptions made in evolution because of their ability to exist as multinucleate entities with genetically different nuclei sharing the same cytoplasm. Many insights on local adaptation have come from studying fungi, and much of the empirical evidence gathered about local adaptation in the context of host-pathogen interactions comes from studying fungal virulence genes, drug resistance, and environmental adaptation. Together, these insights paint a picture of the variety of processes involved in fungal local adaptation and their connections to the unusual cell biology of Fungi (multinucleate, filamentous habit), but there is much that remains unknown, with major gaps in our knowledge of fungal species, their phenotypes, and the ways by which they adapt to local conditions.
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Affiliation(s)
- Anna Bazzicalupo
- Department of Zoology, University of British Columbia, 4200 - 6270 University Blvd., Vancouver V6T 1Z4, Canada
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Rodrigues ASB, Silva DN, Várzea V, Paulo OS, Batista D. Worldwide Population Structure of the Coffee Rust Fungus Hemileia vastatrix Is Strongly Shaped by Local Adaptation and Breeding History. PHYTOPATHOLOGY 2022; 112:1998-2011. [PMID: 35322716 DOI: 10.1094/phyto-09-21-0376-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: 06/14/2023]
Abstract
The devastating disease coffee leaf rust, caused by Hemileia vastatrix, has been a major constraint to worldwide coffee production. Recently, H. vastatrix populations were shown to be structured into three divergent genetic lineages with marked host specialization (C1, C2, and C3). However, there is yet no overall understanding of the population dynamics and adaptation of the most widespread and epidemiological relevant H. vastatrix group (C3). We used restriction site-associated DNA sequencing to generate 13,804 single nucleotide polymorphisms (SNPs) across a worldwide collection of 99 H. vastatrix isolates. Phylogenetic analyses uncovered a well-supported structuring within C3, with three main subgroups (SGs; SGI, SGII, and SGIII), which seem to reflect the historical distribution, breeding, and exchange of coffee cultivars. SGI shows a ladder-like diversification pattern and occurs across all four continents sampled, SGII is mainly restricted to Africa, and SGIII is observed only in Timor, revealing a higher genetic differentiation. Outlier and association tests globally identified 112 SNPs under putative positive selection, which impacted population structure. In particular, 29 overlapping SNPs per se seemed to have an extremely strong effect on H. vastatrix population divergence. We also found exclusive and fixed alleles associated with the SGs supporting local adaptation. Functional annotation revealed that transposable elements may play a role in host adaptation. Our study provides a higher-resolution perspective on the evolutionary history of H. vastatrix on cultivated coffee, showing its strong ability to adapt and the strength of the selective force imposed by coffee hosts, which should be taken into account when designing strategies for pathogen dissemination control and selective breeding.
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Affiliation(s)
- Ana Sofia B Rodrigues
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Computational Biology and Population Genomics Group (CoBiG2), Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal
| | - Diogo Nuno Silva
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Computational Biology and Population Genomics Group (CoBiG2), Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal
- Centro de Investigação das Ferrugens do Cafeeiro (CIFC)/Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de Lisboa, 1349-017 Lisbon, Portugal
| | - Vitor Várzea
- Centro de Investigação das Ferrugens do Cafeeiro (CIFC)/Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de Lisboa, 1349-017 Lisbon, Portugal
| | - Octávio S Paulo
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Computational Biology and Population Genomics Group (CoBiG2), Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal
| | - Dora Batista
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Computational Biology and Population Genomics Group (CoBiG2), Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal
- Centro de Investigação das Ferrugens do Cafeeiro (CIFC)/Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de Lisboa, 1349-017 Lisbon, Portugal
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Gangwar OP, Kumar S, Bhardwaj SC, Prasad P, Lata C, Adhikari S, Singh GP. Elucidating the Population Structure and Genetic Diversity of Indian Puccinia striiformis f. sp. tritici Pathotypes Based on Microsatellite Markers. PHYTOPATHOLOGY 2022; 112:1444-1453. [PMID: 35050682 DOI: 10.1094/phyto-10-21-0422-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: 06/14/2023]
Abstract
In India, systematic wheat yellow rust survey and pathotype (race) analysis work began in 1930. However, information on population structure and genetic diversity of yellow rust pathogen has not been available. To address this, we conducted studies on population structure and genetic diversity of Puccinia striiformis f. sp. tritici (Pst) pathotypes using 38 simple sequence repeat primer-pairs. Bayesian assignment and discriminant analysis of principal components indicated the presence of two distinct Pst subpopulations (Pop1 and Pop2) along with 37.9% admixed pathotypes. The unweighted pair-group method with arithmetic mean also categorized these pathotypes into two major clusters. Principal coordinates analysis explained 20.06 and 12.50% variance in horizontal and vertical coordinates, respectively. Index of association (IA) and the standardized index of association ([Formula: see text]) values showed that Pst subpopulations reproduced asexually (clonally). In total, 102 alleles were detected, with the expected heterozygosity (Hexp) per locus ranging from 0.13 to 0.73, with a mean of 0.47. The average polymorphic information content value of 0.40 indicated high genetic diversity among pathotypes. Analysis of molecular variance revealed 12% of the total variance between subpopulations, 11% among the pathotypes of each subpopulation, and 77% within pathotypes. A significant moderate level of genetic differentiation (FST = 0.122, P < 0.001) and gene flow (Nm = 1.80) were observed between subpopulations. The Pst virulence phenotypes showed a weak positive correlation (R2 = 0.027, P < 0.02) with molecular genotypes.
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Affiliation(s)
- Om Prakash Gangwar
- Indian Council of Agricultural Research-Indian Institute of Wheat and Barley Research, Shimla, Himachal Pradesh, India
| | - Subodh Kumar
- Indian Council of Agricultural Research-Indian Institute of Wheat and Barley Research, Shimla, Himachal Pradesh, India
| | - Subhash Chander Bhardwaj
- Indian Council of Agricultural Research-Indian Institute of Wheat and Barley Research, Shimla, Himachal Pradesh, India
| | - Pramod Prasad
- Indian Council of Agricultural Research-Indian Institute of Wheat and Barley Research, Shimla, Himachal Pradesh, India
| | - Charu Lata
- Indian Council of Agricultural Research-Indian Institute of Wheat and Barley Research, Shimla, Himachal Pradesh, India
| | - Sneha Adhikari
- Indian Council of Agricultural Research-Indian Institute of Wheat and Barley Research, Shimla, Himachal Pradesh, India
| | - Gyanendra Pratap Singh
- Indian Council of Agricultural Research-Indian Institute of Wheat and Barley Research, Karnal, Haryana, India
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5
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Yuan Z, Druzhinina IS, Gibbons JG, Zhong Z, Van de Peer Y, Rodriguez RJ, Liu Z, Wang X, Wei H, Wu Q, Wang J, Shi G, Cai F, Peng L, Martin FM. Divergence of a genomic island leads to the evolution of melanization in a halophyte root fungus. THE ISME JOURNAL 2021; 15:3468-3479. [PMID: 34108667 PMCID: PMC8629976 DOI: 10.1038/s41396-021-01023-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 05/09/2021] [Accepted: 05/24/2021] [Indexed: 02/05/2023]
Abstract
Understanding how organisms adapt to extreme living conditions is central to evolutionary biology. Dark septate endophytes (DSEs) constitute an important component of the root mycobiome and they are often able to alleviate host abiotic stresses. Here, we investigated the molecular mechanisms underlying the beneficial association between the DSE Laburnicola rhizohalophila and its host, the native halophyte Suaeda salsa, using population genomics. Based on genome-wide Fst (pairwise fixation index) and Vst analyses, which compared the variance in allele frequencies of single-nucleotide polymorphisms (SNPs) and copy number variants (CNVs), respectively, we found a high level of genetic differentiation between two populations. CNV patterns revealed population-specific expansions and contractions. Interestingly, we identified a ~20 kbp genomic island of high divergence with a strong sign of positive selection. This region contains a melanin-biosynthetic polyketide synthase gene cluster linked to six additional genes likely involved in biosynthesis, membrane trafficking, regulation, and localization of melanin. Differences in growth yield and melanin biosynthesis between the two populations grown under 2% NaCl stress suggested that this genomic island contributes to the observed differences in melanin accumulation. Our findings provide a better understanding of the genetic and evolutionary mechanisms underlying the adaptation to saline conditions of the L. rhizohalophila-S. salsa symbiosis.
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Affiliation(s)
- Zhilin Yuan
- grid.216566.00000 0001 2104 9346State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China ,grid.216566.00000 0001 2104 9346Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, China
| | - Irina S. Druzhinina
- grid.27871.3b0000 0000 9750 7019Fungal Genomics Laboratory (FungiG), College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
| | - John G. Gibbons
- grid.266683.f0000 0001 2166 5835Department of Food Science, University of Massachusetts, Amherst, MA USA
| | - Zhenhui Zhong
- grid.256111.00000 0004 1760 2876State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China ,grid.19006.3e0000 0000 9632 6718Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA USA
| | - Yves Van de Peer
- grid.5342.00000 0001 2069 7798Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium ,grid.511033.5VIB Center for Plant Systems Biology, Ghent, Belgium ,grid.49697.350000 0001 2107 2298Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield, South Africa
| | - Russell J. Rodriguez
- grid.34477.330000000122986657Adaptive Symbiotic Technologies, University of Washington, Seattle, WA USA
| | - Zhongjian Liu
- grid.256111.00000 0004 1760 2876Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xinyu Wang
- grid.216566.00000 0001 2104 9346Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, China
| | - Huanshen Wei
- grid.216566.00000 0001 2104 9346State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China ,grid.216566.00000 0001 2104 9346Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, China
| | - Qi Wu
- grid.9227.e0000000119573309State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jieyu Wang
- grid.9227.e0000000119573309Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Guohui Shi
- grid.9227.e0000000119573309State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Feng Cai
- grid.27871.3b0000 0000 9750 7019Fungal Genomics Laboratory (FungiG), College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
| | - Long Peng
- grid.216566.00000 0001 2104 9346State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China ,grid.216566.00000 0001 2104 9346Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, China
| | - Francis M. Martin
- grid.66741.320000 0001 1456 856XBeijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing, China ,grid.29172.3f0000 0001 2194 6418Université de Lorraine, INRAE, UMR Interactions Arbres/Micro-Organismes, Centre INRAE Grand Est Nancy, Champenoux, France
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6
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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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7
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Chen JY, Zhang DD, Huang JQ, Li R, Wang D, Song J, Puri KD, Yang L, Kong ZQ, Tong BZ, Li JJ, Huang YS, Simko I, Klosterman SJ, Dai XF, Subbarao KV. Dynamics of Verticillium dahliae race 1 population under managed agricultural ecosystems. BMC Biol 2021; 19:131. [PMID: 34172070 PMCID: PMC8235872 DOI: 10.1186/s12915-021-01061-w] [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: 03/10/2021] [Accepted: 06/01/2021] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Plant pathogens and their hosts undergo adaptive changes in managed agricultural ecosystems, by overcoming host resistance, but the underlying genetic adaptations are difficult to determine in natural settings. Verticillium dahliae is a fungal pathogen that causes Verticillium wilt on many economically important crops including lettuce. We assessed the dynamics of changes in the V. dahliae genome under selection in a long-term field experiment. RESULTS In this study, a field was fumigated before the Verticillium dahliae race 1 strain (VdLs.16) was introduced. A derivative 145-strain population was collected over a 6-year period from this field in which a seggregating population of lettuce derived from Vr1/vr1 parents were evaluated. We de novo sequenced the parental genome of VdLs.16 strain and resequenced the derivative strains to analyze the genetic variations that accumulate over time in the field cropped with lettuce. Population genomics analyses identified 2769 single-nucleotide polymorphisms (SNPs) and 750 insertion/deletions (In-Dels) in the 145 isolates compared with the parental genome. Sequence divergence was identified in the coding sequence regions of 378 genes and in the putative promoter regions of 604 genes. Five-hundred and nine SNPs/In-Dels were identified as fixed. The SNPs and In-Dels were significantly enriched in the transposon-rich, gene-sparse regions, and in those genes with functional roles in signaling and transcriptional regulation. CONCLUSIONS Under the managed ecosystem continuously cropped to lettuce, the local adaptation of V. dahliae evolves at a whole genome scale to accumulate SNPs/In-Dels nonrandomly in hypervariable regions that encode components of signal transduction and transcriptional regulation.
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Affiliation(s)
- Jie-Yin Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Dan-Dan Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | | | - Ran Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Dan Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jian Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Krishna D Puri
- Department of Plant Pathology, University of California, Davis, c/o U.S. Agricultural Research Station, Salinas, CA, USA
| | - Lin Yang
- BGI-Shenzhen, Shenzhen, Guangdong, China
| | - Zhi-Qiang Kong
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | | | - Jun-Jiao Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | | | - Ivan Simko
- United States Department of Agriculture, Agricultural Research Service, Crop Improvement and Protection Research Unit, Salinas, CA, USA
| | - Steven J Klosterman
- United States Department of Agriculture, Agricultural Research Service, Crop Improvement and Protection Research Unit, Salinas, CA, USA.
| | - Xiao-Feng Dai
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Krishna V Subbarao
- Department of Plant Pathology, University of California, Davis, c/o U.S. Agricultural Research Station, Salinas, CA, USA.
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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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Pereira D, McDonald BA, Croll D. The Genetic Architecture of Emerging Fungicide Resistance in Populations of a Global Wheat Pathogen. Genome Biol Evol 2020; 12:2231-2244. [PMID: 32986802 PMCID: PMC7846115 DOI: 10.1093/gbe/evaa203] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2020] [Indexed: 12/22/2022] Open
Abstract
Containing fungal diseases often depends on the application of fungicidal compounds. Fungicides can rapidly lose effectiveness due to the rise of resistant individuals in populations. However, the lack of knowledge about resistance mutations beyond known target genes challenges investigations into pathways to resistance. We used whole-genome sequencing data and association mapping to reveal the multilocus genetic architecture of fungicide resistance in a global panel of 159 isolates of Parastagonospora nodorum, an important fungal pathogen of wheat. We found significant differences in azole resistance among global field populations. The populations evolved distinctive combinations of resistance alleles which can interact when co-occurring in the same genetic background. We identified 34 significantly associated single nucleotide polymorphisms located in close proximity to genes associated with fungicide resistance in other fungi, including a major facilitator superfamily transporter. Using fungal colony growth rates and melanin production at different temperatures as fitness proxies, we found no evidence that resistance was constrained by genetic trade-offs. Our study demonstrates how genome-wide association studies of a global collection of pathogen strains can recapitulate the emergence of fungicide resistance. The distinct complement of resistance mutations found among populations illustrates how the evolutionary trajectory of fungicide adaptation can be complex and challenging to predict.
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Affiliation(s)
- Danilo Pereira
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, 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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Lin M, Ficke A, Cockram J, Lillemo M. Genetic Structure of the Norwegian Parastagonospora nodorum Population. Front Microbiol 2020; 11:1280. [PMID: 32612592 PMCID: PMC7309014 DOI: 10.3389/fmicb.2020.01280] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 05/19/2020] [Indexed: 01/27/2023] Open
Abstract
The necrotrophic fungal pathogen Parastagonospora nodorum causes Septoria nodorum blotch (SNB), which is one of the dominating leaf blotch diseases of wheat in Norway. A total of 165 P. nodorum isolates were collected from three wheat growing regions in Norway from 2015 to 2017. These isolates, as well as nine isolates from other countries, were analyzed for genetic variation using 20 simple sequence repeat (SSR) markers. Genetic analysis of the isolate collection indicated that the P. nodorum pathogen population infecting Norwegian spring and winter wheat underwent regular sexual reproduction and exhibited a high level of genetic diversity, with no genetic subdivisions between sampled locations, years or host cultivars. A high frequency of the presence of necrotrophic effector (NE) gene SnToxA was found in Norwegian P. nodorum isolates compared to other parts of Europe, and we hypothesize that the SnToxA gene is the major virulence factor among the three known P. nodorum NE genes (SnToxA, SnTox1, and SnTox3) in the Norwegian pathogen population. While the importance of SNB has declined in much of Europe, Norway has remained as a P. nodorum hotspot, likely due at least in part to local adaptation of the pathogen population to ToxA sensitive Norwegian spring wheat cultivars.
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Affiliation(s)
- Min Lin
- Department of Plant Sciences, Faculty of Biosciences, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Andrea Ficke
- Division of Biotechnology and Plant Health, Norwegian Institute of Bioeconomy Research (NIBIO), Ås, Norway
| | - James Cockram
- John Bingham Laboratory, NIAB, Cambridge, United Kingdom
| | - Morten Lillemo
- Department of Plant Sciences, Faculty of Biosciences, Norwegian University of Life Sciences (NMBU), Ås, Norway
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