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Nkurikiyimfura O, Waheed A, Fang H, Yuan X, Chen L, Wang YP, Lu G, Zhan J, Yang L. Fitness difference between two synonymous mutations of Phytophthora infestans ATP6 gene. BMC Ecol Evol 2024; 24:36. [PMID: 38494489 PMCID: PMC10946160 DOI: 10.1186/s12862-024-02223-4] [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: 12/27/2023] [Accepted: 03/11/2024] [Indexed: 03/19/2024] Open
Abstract
BACKGROUND Sequence variation produced by mutation provides the ultimate source of natural selection for species adaptation. Unlike nonsynonymous mutation, synonymous mutations are generally considered to be selectively neutral but accumulating evidence suggests they also contribute to species adaptation by regulating the flow of genetic information and the development of functional traits. In this study, we analysed sequence characteristics of ATP6, a housekeeping gene from 139 Phytophthora infestans isolates, and compared the fitness components including metabolic rate, temperature sensitivity, aggressiveness, and fungicide tolerance among synonymous mutations. RESULTS We found that the housekeeping gene exhibited low genetic variation and was represented by two major synonymous mutants at similar frequency (0.496 and 0.468, respectively). The two synonymous mutants were generated by a single nucleotide substitution but differed significantly in fitness as well as temperature-mediated spatial distribution and expression. The synonymous mutant ending in AT was more common in cold regions and was more expressed at lower experimental temperature than the synonymous mutant ending in GC and vice versa. CONCLUSION Our results are consistent with the argument that synonymous mutations can modulate the adaptive evolution of species including pathogens and have important implications for sustainable disease management, especially under climate change.
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Affiliation(s)
- Oswald Nkurikiyimfura
- Institute of Plant Virology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Abdul Waheed
- Institute of Plant Virology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Hanmei Fang
- Institute of Plant Virology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Xiaoxian Yuan
- Institute of Plant Virology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Lixia Chen
- Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, Minjiang University, Fuzhou, 350108, China
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Yan-Ping Wang
- College of Chemistry and Life Sciences, Sichuan Provincial Key Laboratory for Development and Utilization of Characteristic Horticultural Biological Resources, Chengdu Normal University, Chengdu, Sichuan, 611130, China
| | - Guodong Lu
- Department of Plant Pathology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Jiasui Zhan
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, 75007, Sweden.
| | - Lina Yang
- Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, Minjiang University, Fuzhou, 350108, China.
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2
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Badet T, Tralamazza SM, Feurtey A, Croll D. Recent reactivation of a pathogenicity-associated transposable element is associated with major chromosomal rearrangements in a fungal wheat pathogen. Nucleic Acids Res 2024; 52:1226-1242. [PMID: 38142443 PMCID: PMC10853768 DOI: 10.1093/nar/gkad1214] [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: 04/09/2023] [Revised: 11/30/2023] [Accepted: 12/11/2023] [Indexed: 12/26/2023] Open
Abstract
Transposable elements (TEs) are key drivers of genomic variation contributing to recent adaptation in most species. Yet, the evolutionary origins and insertion dynamics within species remain poorly understood. We recapitulate the spread of the pathogenicity-associated Styx element across five species that last diverged ∼11 000 years ago. We show that the element likely originated in the Zymoseptoria fungal pathogen genus and underwent multiple independent reactivation events. Using a global 900-genome panel of the wheat pathogen Zymoseptoria tritici, we assess Styx copy number variation and identify renewed transposition activity in Oceania and South America. We show that the element can mobilize to create additional Styx copies in a four-generation pedigree. Importantly, we find that new copies of the element are not affected by genomic defenses suggesting minimal control against the element. Styx copies are preferentially located in recombination breakpoints and likely triggered multiple types of large chromosomal rearrangements. Taken together, we establish the origin, diversification and reactivation of a highly active TE with likely major consequences for chromosomal integrity and the expression of disease.
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Affiliation(s)
- Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
| | - Sabina Moser Tralamazza
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000 Neuchâtel, Switzerland
| | - 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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3
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Ballot A, Dore J, Rey M, Meiffren G, Langin T, Joly P, Dreux-Zigha A, Taibi A, Prigent-Combaret C. Dimethylpolysulfides production as the major mechanism behind wheat fungal pathogen biocontrol, by Arthrobacter and Microbacterium actinomycetes. Microbiol Spectr 2023; 11:e0529222. [PMID: 37800942 PMCID: PMC10715130 DOI: 10.1128/spectrum.05292-22] [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] [Received: 12/23/2022] [Accepted: 08/07/2023] [Indexed: 10/07/2023] Open
Abstract
IMPORTANCE As the management of wheat fungal diseases becomes increasingly challenging, the use of bacterial agents with biocontrol potential against the two major wheat phytopathogens, Fusarium graminearum and Zymoseptoria tritici, may prove to be an interesting alternative to conventional pest management. Here, we have shown that dimethylpolysulfide volatiles are ubiquitously and predominantly produced by wheat-associated Microbacterium and Arthrobacter actinomycetes, displaying antifungal activity against both pathogens. By limiting pathogen growth and DON virulence factor production, the use of such DMPS-producing strains as soil biocontrol inoculants could limit the supply of pathogen inocula in soil and plant residues, providing an attractive alternative to dimethyldisulfide fumigant, which has many non-targeted toxicities. Notably, this study demonstrates the importance of bacterial volatile organic compound uptake by inhibited F. graminearum, providing new insights for the study of volatiles-mediated toxicity mechanisms within bacteria-fungus signaling crosstalk.
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Affiliation(s)
- Aline Ballot
- Laboratoire Ecologie Microbienne UMR 5557, Université Lyon 1, Villeurbanne, France
| | - Jeanne Dore
- Laboratoire Ecologie Microbienne UMR 5557, Université Lyon 1, Villeurbanne, France
| | - Marjolaine Rey
- Laboratoire Ecologie Microbienne UMR 5557, Université Lyon 1, Villeurbanne, France
| | - Guillaume Meiffren
- Laboratoire Ecologie Microbienne UMR 5557, Université Lyon 1, Villeurbanne, France
| | - Thierry Langin
- Université Clermont Auvergne, INRAE, GDEC, Clermont-Ferrand, France
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4
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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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5
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Glad HM, Tralamazza SM, Croll D. The expression landscape and pangenome of long non-coding RNA in the fungal wheat pathogen Zymoseptoria tritici. Microb Genom 2023; 9. [PMID: 37991492 DOI: 10.1099/mgen.0.001136] [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] [Indexed: 11/23/2023] Open
Abstract
Long non-coding RNAs (lncRNAs) are regulatory molecules interacting in a wide array of biological processes. lncRNAs in fungal pathogens can be responsive to stress and play roles in regulating growth and nutrient acquisition. Recent evidence suggests that lncRNAs may also play roles in virulence, such as regulating pathogenicity-associated enzymes and on-host reproductive cycles. Despite the importance of lncRNAs, only a few model fungi have well-documented inventories of lncRNA. In this study, we apply a recent computational pipeline to predict high-confidence lncRNA candidates in Zymoseptoria tritici, an important global pathogen of wheat impacting global food production. We analyse genomic features of lncRNAs and the most likely associated processes through analyses of expression over a host infection cycle. We find that lncRNAs are frequently expressed during early infection, before the switch to necrotrophic growth. They are mostly located in facultative heterochromatic regions, which are known to contain many genes associated with pathogenicity. Furthermore, we find that lncRNAs are frequently co-expressed with genes that may be involved in responding to host defence signals, such as oxidative stress. Finally, we assess pangenome features of lncRNAs using four additional reference-quality genomes. We find evidence that the repertoire of expressed lncRNAs varies substantially between individuals, even though lncRNA loci tend to be shared at the genomic level. Overall, this study provides a repertoire and putative functions of lncRNAs in Z. tritici enabling future molecular genetics and functional analyses in an important pathogen.
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Affiliation(s)
- Hanna M Glad
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Sabina Moser Tralamazza
- 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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6
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Rad SH, Ebrahimi L, Croll D. Virulence Associations and Global Context of AvrStb6 Genetic Diversity in Iranian Populations of Zymoseptoria tritici. PHYTOPATHOLOGY 2023; 113:1924-1933. [PMID: 37261424 DOI: 10.1094/phyto-09-22-0348-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: 06/02/2023]
Abstract
Managing pathogen damage in wheat production is important for sustaining yields. Fungal plant pathogen genomes encode many small secreted proteins acting as effectors that play key roles in the successful colonization of host tissue and triggering host defenses. AvrStb6 is the first described Zymoseptoria tritici avirulence effector, which triggers Stb6-mediated immunity in the wheat host in a gene-for-gene manner. Evasion of major resistance factors such as Stb6 challenges deployment decisions on wheat cultivars. In this study, we analyzed the evolution of the AvrStb6 effector in Iranian isolates of Z. tritici. In total, 78 isolates were isolated and purified from 30 infected wheat specimens collected from the East Azerbaijan and Ardabil provinces of Iran. The pathogenicity of all isolates was evaluated on the susceptible wheat cultivar 'Tajan'. A subset of 40 isolates were also tested for pathogenicity on the resistant cultivar 'Shafir' carrying Stb6. Genetic diversity at the AvrStb6 locus was analyzed for 14 isolates covering the breadth of the observed disease severity. The AvrStb6 sequence variation was high, with virulent isolates carrying highly diverse AvrStb6 haplotypes. In an analysis including more than 1,000 additional AvrStb6 sequences from a global set of isolates, we found that virulent isolates carried AvrStb6 haplotypes either clustering with known virulent haplotypes on different continents or constituting previously unknown haplotypes. Furthermore, we found that AvrStb6 variants from avirulent isolates clustered with known avirulent genotypes from Europe. Our study highlights the relevance of AvrStb6 for Z. tritici virulence and the exceptional global diversity patterns of this effector.
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Affiliation(s)
- Sepideh Hatami Rad
- Department of Entomology and Plant Pathology, College of Agricultural Technology, University College of Agriculture and Natural Resources, University of Tehran, Tehran 33916-53755, Iran
| | - Leila Ebrahimi
- Department of Entomology and Plant Pathology, College of Agricultural Technology, University College of Agriculture and Natural Resources, University of Tehran, Tehran 33916-53755, Iran
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchatel, CH-2000 Neuchatel, Switzerland
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7
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Ababa G. Biology, taxonomy, genetics, and management of Zymoseptoria tritici: the causal agent of wheat leaf blotch. Mycology 2023; 14:292-315. [PMID: 38187886 PMCID: PMC10769150 DOI: 10.1080/21501203.2023.2241492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/22/2023] [Indexed: 01/09/2024] Open
Abstract
Septoria tritici blotch or Septoria leaf blotch has been used for long time, but leaf blotch is a correct disease name. Moreover, Lb resistant gene is the correct name, but, not Stb gene. It has sexual and asexual parts on the mycelia, known as heterothallic fungi. Its pathogenic diversity ranged from 40% to 93% and has produced a wide variety of AvrLb6 haplotypes. M. graminicola has a plasmogamy and karyogamy sexual process. The pathogen can use macropycnidiospores, micropycnidiospores, and pycnidia vegetative growths for infection and overwintering. Synthetic M3, Kavkaz-K4500, Synthetic 6×, and TE9111 wheat genotypes have horizontal resistance. Avirulence (Avr) genes in Z. tritici and their matching wheat (R) genes indicate gene for gene mechanisms of resistance. Twenty-two R genes (vertical resistance) have been identified. In both horizontal and vertical resistance, different Lb genes have been broken down due to new Z.tritici virulent gene and currently Lb19 resistant gene is being recommended. Mixing of resistant and susceptible cultivars is also the most effective management strategy. Moreover, different cultural practices and biological control have been proposed. Lastly, different fungicides are also available. However, in developing countries cultivar mixture, isolates diversity, biological control, and epidemic studies have been greatly missed.
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Affiliation(s)
- Girma Ababa
- Department of Plant Protection (Plant Pathology), Holetta Agricultural Research Center (HARC), Ethiopian Institute of Agricultural Research (EIAR), Holetta, Addis Ababa, Ethiopia
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8
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Ababa G, Kesho A, Tadesse Y, Amare D. Reviews of taxonomy, epidemiology, and management practices of the barley scald ( Rhynchosporium graminicola) disease. Heliyon 2023; 9:e14315. [PMID: 36938428 PMCID: PMC10018571 DOI: 10.1016/j.heliyon.2023.e14315] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/23/2023] [Accepted: 03/01/2023] [Indexed: 03/07/2023] Open
Abstract
Barley scald is very important in temperate and wet regions worldwide and has become one of the most important foliar diseases. Before the development of recent technologies, several scientists had argued that Rhynchosporium secalis is the causal agent of scald disease. However, the causal agent of this disease was revised and recognized as Rhynchosporium commune. Again recently, Rhynchosporium graminicola was suggested to be replaced as the causal agent of R. commune. The disease outbreak is depending on cool and frequent rainfall. Because of scald disease significance, numerous management practices have been advocated. Then, resistance materials, and mixing of resistant and susceptible cultivars have been used as the best management methods. Several studies have demonstrated that some cultivars and landraces of barley are resistant to scald disease during the seedling and adult growth stages. The first cultivar is "Atlas 46″ which was created from the cultivar "Turk". From biological method: Bacillus polymyxa, Paenibacillus polymyxa KaI245, and Bacillus subtilis are very effective in treating this disease. Finally, as a last option, different fungicides have been suggested. Pathogenicity testing, seed treatments, tillage, cultivar mixtures, and biological control are all commonly overlooked in developing countries. Cultural practices such as times of fungicide application, appropriate time of sowing to scape disease, and tillage practices which are adopted for other diseases are greatly missed for scald disease. Then, we are intended to assess the various findings available on barley scald biology, taxonomy, and management.
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9
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Bellah H, Gazeau G, Gélisse S, Amezrou R, Marcel TC, Croll D. A highly multiplexed assay to monitor pathogenicity, fungicide resistance and gene flow in the fungal wheat pathogen Zymoseptoria tritici. PLoS One 2023; 18:e0281181. [PMID: 36745583 PMCID: PMC9901794 DOI: 10.1371/journal.pone.0281181] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 01/17/2023] [Indexed: 02/07/2023] Open
Abstract
Crop pathogens pose severe risks to global food production due to the rapid rise of resistance to pesticides and host resistance breakdowns. Predicting future risks requires monitoring tools to identify changes in the genetic composition of pathogen populations. Here we report the design of a microfluidics-based amplicon sequencing assay to multiplex 798 loci targeting virulence and fungicide resistance genes, and randomly selected genome-wide markers for the fungal pathogen Zymoseptoria tritici. The fungus causes one of the most devastating diseases on wheat showing rapid adaptation to fungicides and host resistance. We optimized the primer design by integrating polymorphism data from 632 genomes of the same species. To test the performance of the assay, we genotyped 192 samples in two replicates. Analysis of the short-read sequence data generated by the assay showed a fairly stable success rate across samples to amplify a large number of loci. The performance was consistent between samples originating from pure genomic DNA as well as material extracted directly from infected wheat leaves. In samples with mixed genotypes, we found that the assay recovers variations in allele frequencies. We also explored the potential of the amplicon assay to recover transposable element insertion polymorphism relevant for fungicide resistance. As a proof-of-concept, we show that the assay recovers the pathogen population structure across French wheat fields. Genomic monitoring of crop pathogens contributes to more sustainable crop protection and yields.
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Affiliation(s)
- Hadjer Bellah
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Gwilherm Gazeau
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
| | - Sandrine Gélisse
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
| | - Reda Amezrou
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
| | - Thierry C. Marcel
- INRAE, UR BIOGER, Université Paris-Saclay, Thiverval-Grignon, France
- * E-mail: (TCM); (DC)
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- * E-mail: (TCM); (DC)
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10
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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: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [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
- grid.418374.d0000 0001 2227 9389Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK ,grid.12981.330000 0001 2360 039XPresent address: School of Agriculture, Shenzhen Campus of Sun Yat-sen University, Guangming District, Shenzhen, Guangdong People’s Republic of China
| | - Robert King
- grid.418374.d0000 0001 2227 9389Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Dan Smith
- grid.418374.d0000 0001 2227 9389Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Carlos Bayon
- grid.418374.d0000 0001 2227 9389Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Tom Ashfield
- grid.418374.d0000 0001 2227 9389Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK ,grid.418374.d0000 0001 2227 9389Crop Health and Protection (CHaP), Rothamsted Research, Harpenden, Herts UK
| | - Stefano Torriani
- grid.420222.40000 0001 0669 0426Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - Kostya Kanyuka
- grid.418374.d0000 0001 2227 9389Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK ,grid.17595.3f0000 0004 0383 6532Present address: National Institute for Agricultural Botany (NIAB), 93 Lawrence Weaver Road, Cambridge, UK
| | - Kim Hammond-Kosack
- grid.418374.d0000 0001 2227 9389Department of Protecting Crops and the Environment, Rothamsted Research, Harpenden, Herts UK
| | - Stephane Bieri
- grid.420222.40000 0001 0669 0426Syngenta 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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11
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Laas M, Adamson K, Barnes I, Janoušek J, Mullett MS, Adamčíková K, Akiba M, Beenken L, Braganca H, Bulgakov TS, Capretti P, Cech T, Cleary M, Enderle R, Ghelardini L, Jankovský L, Markovskaja S, Matsiakh I, Meyer JB, Oskay F, Piškur B, Raitelaitytė K, Sadiković D, Drenkhan R. Diversity, migration routes, and worldwide population genetic structure of Lecanosticta acicola, the causal agent of brown spot needle blight. MOLECULAR PLANT PATHOLOGY 2022; 23:1620-1639. [PMID: 35957598 PMCID: PMC9562577 DOI: 10.1111/mpp.13257] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 05/29/2023]
Abstract
Lecanosticta acicola is a pine needle pathogen causing brown spot needle blight that results in premature needle shedding with considerable damage described in North America, Europe, and Asia. Microsatellite and mating type markers were used to study the population genetics, migration history, and reproduction mode of the pathogen, based on a collection of 650 isolates from 27 countries and 26 hosts across the range of L. acicola. The presence of L. acicola in Georgia was confirmed in this study. Migration analyses indicate there have been several introduction events from North America into Europe. However, some of the source populations still appear to remain unknown. The populations in Croatia and western Asia appear to originate from genetically similar populations in North America. Intercontinental movement of the pathogen was reflected in an identical haplotype occurring on two continents, in North America (Canada) and Europe (Germany). Several shared haplotypes between European populations further suggests more local pathogen movement between countries. Moreover, migration analyses indicate that the populations in northern Europe originate from more established populations in central Europe. Overall, the highest genetic diversity was observed in south-eastern USA. In Europe, the highest diversity was observed in France, where the presence of both known pathogen lineages was recorded. Less than half of the observed populations contained mating types in equal proportions. Although there is evidence of some sexual reproduction taking place, the pathogen spreads predominantly asexually and through anthropogenic activity.
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Affiliation(s)
- Marili Laas
- Institute of Forestry and EngineeringEstonian University of Life SciencesTartuEstonia
| | - Kalev Adamson
- Institute of Forestry and EngineeringEstonian University of Life SciencesTartuEstonia
| | - Irene Barnes
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI)University of PretoriaPretoriaSouth Africa
| | - Josef Janoušek
- Phytophthora Research Centre, Faculty of Forestry and Wood Technology, Department of Forest Protection and Wildlife ManagementMendel University in BrnoBrnoCzech Republic
| | - Martin S. Mullett
- Phytophthora Research Centre, Faculty of Forestry and Wood Technology, Department of Forest Protection and Wildlife ManagementMendel University in BrnoBrnoCzech Republic
| | - Katarína Adamčíková
- Department of Plant Pathology and MycologyInstitute of Forest Ecology, Slovak Academy of SciencesNitraSlovak Republic
| | - Mitsuteru Akiba
- Kyushu Research Center, Forestry and Forest Products Research InstituteKumamotoJapan
| | - Ludwig Beenken
- Swiss Federal Research Institute WSLBirmensdorfSwitzerland
| | - Helena Braganca
- Instituto Nacional de Investigação Agrária e Veterinária IP.OeirasPortugal
- GREEN‐IT Bioresources for Sustainability, ITQB NOVAOeirasPortugal
| | - Timur S. Bulgakov
- Department of Plant ProtectionFederal Research Centre the Subtropical Scientific Centre of the Russian Academy of SciencesKrasnodarRussia
| | - Paolo Capretti
- Department of Agricultural, Food, Environmental and Forest Sciences and TechnologiesUniversity of FlorenceFlorenceItaly
| | - Thomas Cech
- Austrian Research Centre for ForestsDepartment of Forest ProtectionViennaAustria
| | - Michelle Cleary
- Southern Swedish Forest Research CentreSwedish University of Agricultural SciencesAlnarpSweden
| | - Rasmus Enderle
- Institute for Plant Protection in Horticulture and ForestsJulius Kuehn InstituteBraunschweigGermany
| | - Luisa Ghelardini
- Department of Agricultural, Food, Environmental and Forest Sciences and TechnologiesUniversity of FlorenceFlorenceItaly
| | - Libor Jankovský
- Phytophthora Research Centre, Faculty of Forestry and Wood Technology, Department of Forest Protection and Wildlife ManagementMendel University in BrnoBrnoCzech Republic
| | | | - Iryna Matsiakh
- Southern Swedish Forest Research CentreSwedish University of Agricultural SciencesAlnarpSweden
- Institute of Forestry and Park GardeningUkrainian National Forestry UniversityLvivUkraine
- National Forestry Agency of GeorgiaTbilisiGeorgia
| | - Joana B. Meyer
- Forest Protection and Forest Health SectionFederal Office for the Environment FOENBernSwitzerland
| | - Funda Oskay
- Faculty of ForestryÇankırı Karatekin UniversityÇankırıTurkey
| | | | | | - Dušan Sadiković
- Southern Swedish Forest Research CentreSwedish University of Agricultural SciencesAlnarpSweden
- Slovenian Forestry InstituteLjubljanaSlovenia
| | - Rein Drenkhan
- Institute of Forestry and EngineeringEstonian University of Life SciencesTartuEstonia
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12
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Silan E, Ozkilinc H. Phylogenetic divergences in brown rot fungal pathogens of Monilinia species from a worldwide collection: inferences based on the nuclear versus mitochondrial genes. BMC Ecol Evol 2022; 22:119. [PMID: 36271324 PMCID: PMC9585774 DOI: 10.1186/s12862-022-02079-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 10/12/2022] [Indexed: 11/06/2022] Open
Abstract
Background Phylogenetic analyses for plant pathogenic fungi explore many questions on diversities, relationships, origins, and divergences of populations from different sources such as species, host, and geography. This information is highly valuable, especially from a large global sampling, to understand the evolutionary paths of the pathogens worldwide. Monilinia fructicola and M. laxa are two important fungal pathogens of stone fruits that cause the widespread disease commonly known as brown rot. Three nuclear genes (Calmodulin, SDHA, TEF1α) and three mitochondrial genes (Cytochrome_b, NAD2, and NAD5) of the two pathogen species from a worldwide collection including five different countries from four different continents were studied in this work. Results Both Maximum Likelihood and Bayesian approaches were applied to the data sets, and in addition, Maximum Parsimony based approaches were used for the regions having indel polymorphisms. Calmodulin, SDHA, NAD2, and NAD5 regions were found phylogenetically informative and utilized for phylogenetics of Monilinia species for the first time. Each gene region presented a set of haplotypes except Cytochrome_b, which was monomorphic. According to this large collection of two Monilinia species around the world, M. fructicola showed more diversity than M. laxa, a result that should be carefully considered, as M. fructicola is known to be a quarantine pathogen. Moreover, the other two mitochondrial genes (NAD2 and NAD5) did not have any substitution type mutations but presented an intron indel polymorphism indicating the contribution of introns as well as mobile introns to the fungal diversity and evolution. Based on the concatenated gene sets, nuclear DNA carries higher mutations and uncovers more phylogenetic clusters in comparison to the mitochondrial DNA-based data for these fungal species. Conclusions This study provides the most comprehensive knowledge on the phylogenetics of both nuclear and mitochondrial genes of two prominent brown rot pathogens, M. fructicola and M. laxa. Based on the regions used in this study, the nuclear genes resolved phylogenetic branching better than the mitochondrial genes and discovered new phylogenetic lineages for these species. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-022-02079-6.
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Affiliation(s)
- Ece Silan
- grid.412364.60000 0001 0680 7807School of Graduate Studies, MSc Program in Biomolecular Sciences, Çanakkale Onsekiz Mart University, Çanakkale, Turkey
| | - Hilal Ozkilinc
- grid.412364.60000 0001 0680 7807School of Graduate Studies, MSc Program in Biomolecular Sciences, Çanakkale Onsekiz Mart University, Çanakkale, Turkey ,grid.412364.60000 0001 0680 7807Dept. of Molecular Biology and Genetics, Faculty of Science, Çanakkale Onsekiz Mart University, Çanakkale, Turkey
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13
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Shen LL, Waheed A, Wang YP, Nkurikiyimfura O, Wang ZH, Yang LN, Zhan J. Mitochondrial Genome Contributes to the Thermal Adaptation of the Oomycete Phytophthora infestans. Front Microbiol 2022; 13:928464. [PMID: 35836411 PMCID: PMC9273971 DOI: 10.3389/fmicb.2022.928464] [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: 04/25/2022] [Accepted: 05/23/2022] [Indexed: 11/13/2022] Open
Abstract
As a vital element of climate change, elevated temperatures resulting from global warming present new challenges to natural and agricultural sustainability, such as ecological disease management. Mitochondria regulate the energy production of cells in responding to environmental fluctuation, but studying their contribution to the thermal adaptation of species is limited. This knowledge is needed to predict future disease epidemiology for ecology conservation and food security. Spatial distributions of the mitochondrial genome (mtDNA) in 405 Phytophthora infestans isolates originating from 15 locations were characterized. The contribution of MtDNA to thermal adaptation was evaluated by comparative analysis of mtDNA frequency and intrinsic growth rate, relative population differentiation in nuclear and mtDNA, and associations of mtDNA distribution with local geography climate conditions. Significant variation in frequency, intrinsic growth rate, and spatial distribution was detected in mtDNA. Population differentiation in mtDNA was significantly higher than that in the nuclear genome, and spatial distribution of mtDNA was strongly associated with local climatic conditions and geographic parameters, particularly air temperature, suggesting natural selection caused by a local temperature is the main driver of the adaptation. Dominant mtDNA grew faster than the less frequent mtDNA. Our results provide useful insights into the evolution of pathogens under global warming. Given its important role in biological functions and adaptation to local air temperature, mtDNA intervention has become an increasing necessity for future disease management. To secure ecological integrity and food production under global warming, a synergistic study on the interactive effect of changing temperature on various components of biological and ecological functions of mitochondria in an evolutionary frame is urgently needed.
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Affiliation(s)
- Lin-Lin Shen
- Institute of Oceanography, Minjiang University, Fuzhou, China
| | - Abdul Waheed
- Institute of Oceanography, Minjiang University, Fuzhou, China
| | - Yan-Ping Wang
- Sichuan Provincial Key Laboratory for Development and Utilization of Characteristic Horticultural Biological Resources, Chengdu Normal University, Chengdu, China
| | - Oswald Nkurikiyimfura
- Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zong-Hua Wang
- Institute of Oceanography, Minjiang University, Fuzhou, China
| | - Li-Na Yang
- Institute of Oceanography, Minjiang University, Fuzhou, China
- *Correspondence: Li-Na Yang
| | - Jiasui Zhan
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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14
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Genetic structure of Sclerotinia sclerotiorum populations from sunflower and cabbage in West Azarbaijan province of Iran. Sci Rep 2022; 12:9263. [PMID: 35662267 PMCID: PMC9166751 DOI: 10.1038/s41598-022-13350-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 05/11/2022] [Indexed: 11/08/2022] Open
Abstract
Sclerotinia sclerotiorum is one of the most destructive fungal pathogens infecting a wide array of plant species worldwide. Management of this pathogen relies on the coordinated use of fungicides and resistant host cultivars with other control measures, but the effectiveness of these methods requires knowledge of the genetic variability and structure of the fungal populations. To provide insight into the genetic diversity and structure of this pathogen in West Azarbaijan province of Iran, a total of 136 isolates were collected from symptomatic sunflower and cabbage plants within fields in three regions and analysed using inter-simple sequence repeat (ISSR) markers and intergenic spacer (IGS) region of the rRNA gene sequences. A total of 83 ISSR multilocus genotypes (MLGs) were identified, some of which were shared among at least two regional or host populations but in a low frequency. High genotypic diversity, low levels of clonal fraction, and random association of ISSR loci in a region indicated a low level of clonal reproduction, and possibly a high level of sexually recombining life cycle for the pathogen in the province. Marker analyses revealed that the pathogen was spatially homogeneous among fields, and thus similar control measures, such as the choice of resistant cultivars and fungicides, may effectively manage S. sclerotiorum within the region. Four IGS haplotypes (IGS1-IGS4) were detected within populations with IGS3 being the most prevalent haplotype. The low IGS haplotype diversity, the absence of spatial structure, and shared MLGs among populations may suggest a single introduction and subsequent dispersal of S. sclerotiorum within West Azarbaijan province.
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15
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Phenotyping Mediterranean Durum Wheat Landraces for Resistance to Zymoseptoria tritici in Tunisia. Genes (Basel) 2022; 13:genes13020355. [PMID: 35205399 PMCID: PMC8872163 DOI: 10.3390/genes13020355] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/21/2022] [Accepted: 02/09/2022] [Indexed: 02/01/2023] Open
Abstract
Durum wheat landraces have huge potential for the identification of genetic factors valuable for improving resistance to biotic stresses. Tunisia is known as a hot spot for Septoria tritici blotch disease (STB), caused by the fungus Zymoseptoria tritici (Z. tritici). In this context, a collection of 3166 Mediterranean durum wheat landraces were evaluated at the seedling and adult stages for STB resistance in the 2016–2017 cropping season under field conditions in Kodia (Tunisia). Unadapted/susceptible accessions were eliminated to reach the final set of 1059 accessions; this was termed the Med-collection, which comprised accessions from 13 countries and was also screened in the 2018–2019 cropping season. The Med-collection showed high frequency of resistance reactions, among which over 50% showed an immune reaction (HR) at both seedling and adult growth stages. Interestingly, 92% of HR and R accessions maintained their resistance levels across the two years, confirming the highly significant correlation found between seedling- and adult-stage reactions. Plant Height was found to have a negative significant effect on adult-stage resistance, suggesting that either this trait can influence disease severity, or that it can be due to environmental/epidemiological factors. Accessions from Italy showed the highest variability, while those from Portugal, Spain and Tunisia showed the highest levels of resistance at both growth stages, suggesting that the latter accessions may harbor novel QTLs effective for STB resistance.
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16
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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. [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] [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
- *Correspondence: Daniel Croll,
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17
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Shen LL, Waheed A, Wang YP, Nkurikiyimfura O, Wang ZH, Yang LN, Zhan J. Multiple Mechanisms Drive the Evolutionary Adaptation of Phytophthora infestans Effector Avr1 to Host Resistance. J Fungi (Basel) 2021; 7:jof7100789. [PMID: 34682211 PMCID: PMC8538934 DOI: 10.3390/jof7100789] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/08/2021] [Accepted: 09/15/2021] [Indexed: 11/16/2022] Open
Abstract
Effectors, a group of small proteins secreted by pathogens, play a central role in antagonistic interactions between plant hosts and pathogens. The evolution of effector genes threatens plant disease management and sustainable food production, but population genetic analyses to understand evolutionary mechanisms of effector genes are limited compared to molecular and functional studies. Here we investigated the evolution of the Avr1 effector gene from 111 Phytophthora infestans isolates collected from six areas covering three potato cropping regions in China using a population genetic approach. High genetic variation of the effector gene resulted from diverse mechanisms including base substitution, pre-termination, intragenic recombination and diversifying selection. Nearly 80% of the 111 sequences had a point mutation in the 512th nucleotide (T512G), which generated a pre-termination stop codon truncating 38 amino acids in the C-terminal, suggesting that the C-terminal may not be essential to ecological and biological functions of P. infestans. A significant correlation between the frequency of Avr1 sequences with the pre-termination and annual mean temperature in the collection sites suggests that thermal heterogeneity might be one of contributors to the diversifying selection, although biological and biochemical mechanisms of the likely thermal adaptation are not known currently. Our results highlight the risk of rapid adaptation of P. infestans and possibly other pathogens as well to host resistance, and the application of eco-evolutionary principles is necessary for sustainable disease management in agricultural ecosystems.
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Affiliation(s)
- Lin-Lin Shen
- Key Lab for Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education, Fuzhou 350002, China; (L.-L.S.); (A.W.); (O.N.)
| | - Abdul Waheed
- Key Lab for Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education, Fuzhou 350002, China; (L.-L.S.); (A.W.); (O.N.)
| | - Yan-Ping Wang
- College of Chemistry and Life Sciences, Sichuan Provincial Key Laboratory for Development and Utilization of Characteristic Horticultural Biological Resources, Chengdu Normal University, Chengdu 611130, China;
| | - Oswald Nkurikiyimfura
- Key Lab for Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education, Fuzhou 350002, China; (L.-L.S.); (A.W.); (O.N.)
| | - Zong-Hua Wang
- Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China;
- Institute of Oceanography, Minjiang University, Fuzhou 350108, China
| | - Li-Na Yang
- Key Lab for Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education, Fuzhou 350002, China; (L.-L.S.); (A.W.); (O.N.)
- Institute of Oceanography, Minjiang University, Fuzhou 350108, China
- Correspondence: (L.-N.Y.); (J.Z.); Tel.: +86-177-2080-5328 (L.-N.Y.); +46-18-673-639 (J.Z.)
| | - Jiasui Zhan
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden
- Correspondence: (L.-N.Y.); (J.Z.); Tel.: +86-177-2080-5328 (L.-N.Y.); +46-18-673-639 (J.Z.)
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18
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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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19
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Fouché G, Michel T, Lalève A, Wang NX, Young DH, Meunier B, Debieu D, Fillinger S, Walker AS. Directed evolution predicts cytochrome b G37V target site modification as probable adaptive mechanism towards the QiI fungicide fenpicoxamid in Zymoseptoria tritici. Environ Microbiol 2021; 24:1117-1132. [PMID: 34490974 DOI: 10.1111/1462-2920.15760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/03/2021] [Accepted: 09/04/2021] [Indexed: 02/06/2023]
Abstract
Acquired resistance is a threat to antifungal efficacy in medicine and agriculture. The diversity of possible resistance mechanisms and highly adaptive traits of pathogens make it difficult to predict evolutionary outcomes of treatments. We used directed evolution as an approach to assess the resistance risk to the new fungicide fenpicoxamid in the wheat pathogenic fungus Zymoseptoria tritici. Fenpicoxamid inhibits complex III of the respiratory chain at the ubiquinone reduction site (Qi site) of the mitochondrially encoded cytochrome b, a different site than the widely used strobilurins which inhibit the same complex at the ubiquinol oxidation site (Qo site). We identified the G37V change within the cytochrome b Qi site as the most likely resistance mechanism to be selected in Z. tritici. This change triggered high fenpicoxamid resistance and halved the enzymatic activity of cytochrome b, despite no significant penalty for in vitro growth. We identified negative cross-resistance between isolates harbouring G37V or G143A, a Qo site change previously selected by strobilurins. Double mutants were less resistant to both QiIs and quinone outside inhibitors compared to single mutants. This work is a proof of concept that experimental evolution can be used to predict adaptation to fungicides and provides new perspectives for the management of QiIs.
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Affiliation(s)
- Guillaume Fouché
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, Thiverval-Grignon, 78850, France.,Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Thomas Michel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, 91198, France
| | - Anaïs Lalève
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, Thiverval-Grignon, 78850, France
| | - Nick X Wang
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - David H Young
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Brigitte Meunier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, 91198, France
| | - Danièle Debieu
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, Thiverval-Grignon, 78850, France
| | - Sabine Fillinger
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, Thiverval-Grignon, 78850, France
| | - Anne-Sophie Walker
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, Thiverval-Grignon, 78850, France
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20
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Adamson K, Laas M, Blumenstein K, Busskamp J, Langer GJ, Klavina D, Kaur A, Maaten T, Mullett MS, Müller MM, Ondrušková E, Padari A, Pilt E, Riit T, Solheim H, Soonvald L, Tedersoo L, Terhonen E, Drenkhan R. Highly Clonal Structure and Abundance of One Haplotype Characterise the Diplodia sapinea Populations in Europe and Western Asia. J Fungi (Basel) 2021; 7:634. [PMID: 34436173 PMCID: PMC8400067 DOI: 10.3390/jof7080634] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 11/22/2022] Open
Abstract
Diplodia sapinea is a cosmopolitan endophyte and opportunistic pathogen having occurred on several conifer species in Europe for at least 200 years. In Europe, disease outbreaks have increased on several Pinus spp. in the last few decades. In this study, the genetic structure of the European and western Asian D. sapinea population were investigated using 13 microsatellite markers. In total, 425 isolates from 15 countries were analysed. A high clonal fraction and low genetic distance between most subpopulations was found. One single haplotype dominates the European population, being represented by 45.3% of all isolates and found in nearly all investigated countries. Three genetically distinct subpopulations were found: Central/North European, Italian and Georgian. The recently detected subpopulations of D. sapinea in northern Europe (Estonia) share several haplotypes with the German subpopulation. The northern European subpopulations (Latvia, Estonia and Finland) show relatively high genetic diversity compared to those in central Europe suggesting either that the fungus has existed in the North in an asymptomatic/endophytic mode for a long time or that it has spread recently by multiple introductions. Considerable genetic diversity was found even among isolates of a single tree as 16 isolates from a single tree resulted in lower clonal fraction index than most subpopulations in Europe, which might reflect cryptic sexual proliferation. According to currently published allelic patterns, D. sapinea most likely originates from North America or from some unsampled population in Asia or central America. In order to enable the detection of endophytic or latent infections of planting stock by D. sapinea, new species-specific PCR primers (DiSapi-F and Diplo-R) were designed. During the search for Diplodia isolates across the world for species specific primer development, we identified D. africana in California, USA, and in the Canary Islands, which are the first records of this species in North America and in Spain.
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Affiliation(s)
- Kalev Adamson
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Marili Laas
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Kathrin Blumenstein
- Forest Pathology Research Group, Department of Forest Botany and Tree Physiology, Faculty of Forest Sciences and Forest Ecology, Georg-August-University, 37073 Göttingen, Germany; (K.B.); (E.T.)
| | - Johanna Busskamp
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute, 37079 Göttingen, Germany; (J.B.); (G.J.L.)
| | - Gitta J. Langer
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute, 37079 Göttingen, Germany; (J.B.); (G.J.L.)
| | - Darta Klavina
- Latvian State Forest Research Institute Silava, Rigas 111, LV 2169 Salaspils, Latvia;
| | - Anu Kaur
- Tallinn Botanic Garden, Kloostrimetsa Tee 52, 11913 Tallinn, Estonia;
| | - Tiit Maaten
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Martin S. Mullett
- Phytophthora Research Centre, Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic;
| | - Michael M. Müller
- Bioeconomy and Environment, Natural Resources Institute Finland (Luke), P.O. Box 2, 00791 Helsinki, Finland;
| | - Emília Ondrušková
- Department of Plant Pathology and Mycology, Institute of Forest Ecology Slovak Academy of Sciences, 949 01 Nitra, Slovakia;
| | - Allar Padari
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Enn Pilt
- Estonian Environment Agency, Mustamäe Tee 33, 10616 Tallinn, Estonia;
| | - Taavi Riit
- Center of Mycology and Microbiology, Institute of Ecology and Earth Sciences, University of Tartu, 14a Ravila, 50411 Tartu, Estonia; (T.R.); (L.T.)
| | - Halvor Solheim
- Norwegian Institute of Bioeconomy Research, 1431 Ås, Norway;
| | - Liina Soonvald
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia;
| | - Leho Tedersoo
- Center of Mycology and Microbiology, Institute of Ecology and Earth Sciences, University of Tartu, 14a Ravila, 50411 Tartu, Estonia; (T.R.); (L.T.)
| | - Eeva Terhonen
- Forest Pathology Research Group, Department of Forest Botany and Tree Physiology, Faculty of Forest Sciences and Forest Ecology, Georg-August-University, 37073 Göttingen, Germany; (K.B.); (E.T.)
| | - Rein Drenkhan
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
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21
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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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22
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Samils B, Andersson B, Edin E, Elfstrand M, Rönneburg T, Bucur D, Hutton F, Heick TM, Hellin P, Kildea S. Development of a PacBio Long-Read Sequencing Assay for High Throughput Detection of Fungicide Resistance in Zymoseptoria tritici. Front Microbiol 2021; 12:692845. [PMID: 34234765 PMCID: PMC8256687 DOI: 10.3389/fmicb.2021.692845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/26/2021] [Indexed: 11/13/2022] Open
Abstract
Fungicide resistance has become a challenging problem in management of Septoria tritici blotch (STB), caused by Zymoseptoria tritici, the most destructive disease of winter wheat throughout western and northern Europe. To ensure the continued effectiveness of those fungicides currently used, it is essential to monitor the development and spread of such resistance in field populations of the pathogen. Since resistance to the key families of fungicides used for STB control (demethyalation inhibitors or azoles, succinate dehydrogenase inhibitors or SDHIs and Quinone outside Inhibitors or QoIs) is conferred through target-site mutations, the potential exists to monitor resistance through the molecular detection of alterations in the target site genes. As more efficient fungicides were developed and applied, the pathogen has continuously adapted through accumulating multiple target-site alterations. In order to accurately monitor these changes in field populations, it is therefore becoming increasingly important to completely sequence the targeted genes. Here we report the development of a PacBio assay that facilitates the multiplex amplification and long-read sequencing of the target gene(s) for the azole (CYP51), SDHI (Sdh B, C, and D), and QoI (cytochrome b) fungicides. The assay was developed and optimised using three Irish Z. tritici collections established in spring 2017, which capture the range of fungicide resistance present in modern European populations of Z. tritici. The sequences obtained through the PacBio assay were validated using traditional Sanger sequencing and in vitro sensitivity screenings. To further exploit the long-read and high throughput potential of PacBio sequencing, an additional nine housekeeping genes (act, BTUB, cal, cyp, EF1, GAPDH, hsp80-1, PKC, TFC1) were sequenced and used to provide comprehensive Z. tritici strain genotyping.
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Affiliation(s)
- Berit Samils
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Björn Andersson
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Eva Edin
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Malin Elfstrand
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Tilman Rönneburg
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Diana Bucur
- TEAGASC, The Agriculture and Food Development Authority, Carlow, Ireland
| | - Fiona Hutton
- TEAGASC, The Agriculture and Food Development Authority, Carlow, Ireland
| | - Thies M. Heick
- Department of Agroecology, Aarhus University, Aarhus, Denmark
| | - Pierre Hellin
- Plant and Forest Health Unit, Walloon Agricultural Research Center, Gembloux, Belgium
| | - Steven Kildea
- TEAGASC, The Agriculture and Food Development Authority, Carlow, Ireland
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23
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Waheed A, Wang YP, Nkurikiyimfura O, Li WY, Liu ST, Lurwanu Y, Lu GD, Wang ZH, Yang LN, Zhan J. Effector Avr4 in Phytophthora infestans Escapes Host Immunity Mainly Through Early Termination. Front Microbiol 2021; 12:646062. [PMID: 34122360 PMCID: PMC8192973 DOI: 10.3389/fmicb.2021.646062] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 03/19/2021] [Indexed: 11/13/2022] Open
Abstract
Effector genes play critical roles in the antagonistic interactions between plants and pathogens. However, knowledge of mutation mechanisms and evolutionary processes in effector genes and the contribution of climatic factors to the evolution of effector genes are fragmented but important in sustainable management of plant diseases and securing food supply under changing climates. Here, we used a population genetic approach to explore the evolution of the Avr4 gene in Phytophthora infestans, the causal agent of potato blight. We found that the Avr4 gene exhibited a high genetic diversity generated by point mutation and sequence deletion. Frameshifts caused by a single base-pair deletion at the 194th nucleotide position generate two stop codons, truncating almost the entire C-terminal, which is important for effector function and R4 recognition in all sequences. The effector is under natural selection for adaptation supported by comparative analyses of population differentiation (FST ) and isolation-by-distance between Avr4 sequences and simple sequence repeat marker loci. Furthermore, we found that local air temperature was positively associated with pairwise FST in the Avr4 sequences. These results suggest that the evolution of the effector gene is influenced by local air temperature, and the C-terminal truncation is one of the main mutation mechanisms in the P. infestans effector gene to circumvent the immune response of potato plants. The implication of these results to agricultural and natural sustainability in future climate conditions is discussed.
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Affiliation(s)
- Abdul Waheed
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yan-Ping Wang
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Oswald Nkurikiyimfura
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Wen-Yang Li
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shi-Ting Liu
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yahuza Lurwanu
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Department of Crop Protection, Bayero University Kano, Kano, Nigeria
| | - Guo-Dong Lu
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zong-Hua Wang
- Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Institute of Oceanography, Minjiang University, Fuzhou, China
| | - Li-Na Yang
- Key Lab for Bio Pesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Institute of Oceanography, Minjiang University, Fuzhou, China
| | - Jiasui Zhan
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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24
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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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25
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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: 16] [Impact Index Per Article: 5.3] [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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26
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Worldwide Genetic Structure Elucidates the Eurasian Origin and Invasion Pathways of Dothistroma septosporum, Causal Agent of Dothistroma Needle Blight. J Fungi (Basel) 2021; 7:jof7020111. [PMID: 33546260 PMCID: PMC7913368 DOI: 10.3390/jof7020111] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/28/2022] Open
Abstract
Dothistroma septosporum, the primary causal agent of Dothistroma needle blight, is one of the most significant foliar pathogens of pine worldwide. Its wide host and environmental ranges have led to its global success as a pathogen and severe economic damage to pine forests in many regions. This comprehensive global population study elucidated the historical migration pathways of the pathogen to reveal the Eurasian origin of the fungus. When over 3800 isolates were examined, three major population clusters were revealed: North America, Western Europe, and Eastern Europe, with distinct subclusters in the highly diverse Eastern European cluster. Modeling of historical scenarios using approximate Bayesian computation revealed the North American cluster was derived from an ancestral population in Eurasia. The Northeastern European subcluster was shown to be ancestral to all other European clusters and subclusters. The Turkish subcluster diverged first, followed by the Central European subcluster, then the Western European cluster, which has subsequently spread to much of the Southern Hemisphere. All clusters and subclusters contained both mating-types of the fungus, indicating the potential for sexual reproduction, although asexual reproduction remained the primary mode of reproduction. The study strongly suggests the native range of D. septosporum to be in Eastern Europe (i.e., the Baltic and Western Russia) and Western Asia.
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27
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Nsibo DL, Barnes I, Omondi DO, Dida MM, Berger DK. Population genetic structure and migration patterns of the maize pathogenic fungus, Cercospora zeina in East and Southern Africa. Fungal Genet Biol 2021; 149:103527. [PMID: 33524555 DOI: 10.1016/j.fgb.2021.103527] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 12/13/2020] [Accepted: 12/20/2020] [Indexed: 11/16/2022]
Abstract
Cercospora zeina is a causal pathogen of gray leaf spot (GLS) disease of maize in Africa. This fungal pathogen exhibits a high genetic diversity in South Africa. However, little is known about the pathogen's population structure in the rest of Africa. In this study, we aimed to assess the diversity and gene flow of the pathogen between major maize producing countries in East and Southern Africa (Kenya, Uganda, Zambia, Zimbabwe, and South Africa). A total of 964 single-spore isolates were made from GLS lesions and confirmed as C.zeina using PCR diagnostics. The other causal agent of GLS, Cercospora zeae-maydis, was absent. Genotyping all the C.zeina isolates with 11 microsatellite markers and a mating-type gene diagnostic revealed (i) high genetic diversity with some population structure between the five African countries, (ii) cryptic sexual recombination, (iii) that South Africa and Kenya were the greatest donors of migrants, and (iv) that Zambia had a distinct population. We noted evidence of human-mediated long-distance dispersal, since four haplotypes from one South African site were also present at five sites in Kenya and Uganda. There was no evidence for a single-entry point of the pathogen into Africa. South Africa was the most probable origin of the populations in Kenya, Uganda, and Zimbabwe. Continuous annual maize production in the tropics (Kenya and Uganda) did not result in greater genetic diversity than a single maize season (Southern Africa). Our results will underpin future management of GLS in Africa through effective monitoring of virulent C.zeina strains.
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Affiliation(s)
- David L Nsibo
- Department of Plant and Soil Sciences, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa
| | - Irene Barnes
- Department of Biochemistry, Genetics and Microbiology, FABI, University of Pretoria, South Africa
| | | | | | - Dave K Berger
- Department of Plant and Soil Sciences, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa.
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28
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Gur L, Reuveni M, Cohen Y, Cadle-Davidson L, Kisselstein B, Ovadia S, Frenkel O. Population structure of Erysiphe necator on domesticated and wild vines in the Middle East raises questions on the origin of the grapevine powdery mildew pathogen. Environ Microbiol 2021; 23:6019-6037. [PMID: 33459475 DOI: 10.1111/1462-2920.15401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 11/28/2022]
Abstract
Plant pathogens usually originate and diversify in geographical regions where hosts and pathogens co-evolve. Erysiphe necator, the causal agent of grape powdery mildew, is a destructive pathogen of grapevines worldwide. Although Eastern US is considered the centre of origin and diversity of E. necator, previous reports on resistant native wild and domesticated Asian grapevines suggest Asia as another possible origin of the pathogen. By using multi-locus sequencing, microsatellites and a novel application of amplicon sequencing (AmpSeq), we show that the population of E. necator in Israel is composed of three genetic groups: Groups A and B that are common worldwide, and a new group IL, which is genetically differentiated from any known group in Europe and Eastern US. Group IL showed distinguished ecological characteristics: it was dominant on wild and traditional vines (95%); its abundance increased along the season; and was more aggressive than A and B isolates on both wild and domesticated vines. The low genetic diversity within group IL suggests that it has invaded Israel from another origin. Therefore, we suggest that the Israeli E. necator population was founded by at least two invasions, of which one could be from a non-East American source, possibly from Asian origin.
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Affiliation(s)
- Lior Gur
- Shamir Research Institute, University of Haifa, Katzrin, Israel.,Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Department of Plant Pathology and Weed Research, Agricultural Research Organization (ARO), The Volcani Center, Rishon Lezion, Israel
| | - Moshe Reuveni
- Shamir Research Institute, University of Haifa, Katzrin, Israel
| | - Yigal Cohen
- Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Lance Cadle-Davidson
- USDA Agricultural Research Service, Geneva, NY, USA.,School of Integrative Plant Sciences, Cornell AgriTech, Geneva, NY, USA
| | - Breanne Kisselstein
- USDA Agricultural Research Service, Geneva, NY, USA.,School of Integrative Plant Sciences, Cornell AgriTech, Geneva, NY, USA
| | | | - Omer Frenkel
- Department of Plant Pathology and Weed Research, Agricultural Research Organization (ARO), The Volcani Center, Rishon Lezion, Israel
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29
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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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30
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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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31
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Naranjo‐Ortiz MA, Gabaldón T. Fungal evolution: cellular, genomic and metabolic complexity. Biol Rev Camb Philos Soc 2020; 95:1198-1232. [PMID: 32301582 PMCID: PMC7539958 DOI: 10.1111/brv.12605] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 12/13/2022]
Abstract
The question of how phenotypic and genomic complexity are inter-related and how they are shaped through evolution is a central question in biology that historically has been approached from the perspective of animals and plants. In recent years, however, fungi have emerged as a promising alternative system to address such questions. Key to their ecological success, fungi present a broad and diverse range of phenotypic traits. Fungal cells can adopt many different shapes, often within a single species, providing them with great adaptive potential. Fungal cellular organizations span from unicellular forms to complex, macroscopic multicellularity, with multiple transitions to higher or lower levels of cellular complexity occurring throughout the evolutionary history of fungi. Similarly, fungal genomes are very diverse in their architecture. Deep changes in genome organization can occur very quickly, and these phenomena are known to mediate rapid adaptations to environmental changes. Finally, the biochemical complexity of fungi is huge, particularly with regard to their secondary metabolites, chemical products that mediate many aspects of fungal biology, including ecological interactions. Herein, we explore how the interplay of these cellular, genomic and metabolic traits mediates the emergence of complex phenotypes, and how this complexity is shaped throughout the evolutionary history of Fungi.
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Affiliation(s)
- Miguel A. Naranjo‐Ortiz
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG)The Barcelona Institute of Science and TechnologyDr. Aiguader 88, Barcelona08003Spain
| | - Toni Gabaldón
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG)The Barcelona Institute of Science and TechnologyDr. Aiguader 88, Barcelona08003Spain
- Department of Experimental Sciences, Universitat Pompeu Fabra (UPF)Dr. Aiguader 88, 08003BarcelonaSpain
- ICREAPg. Lluís Companys 23, 08010BarcelonaSpain
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Badet T, Croll D. The rise and fall of genes: origins and functions of plant pathogen pangenomes. CURRENT OPINION IN PLANT BIOLOGY 2020; 56:65-73. [PMID: 32480355 DOI: 10.1016/j.pbi.2020.04.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/14/2020] [Accepted: 04/18/2020] [Indexed: 06/11/2023]
Abstract
Plant pathogens can rapidly overcome resistance of their hosts by mutating key pathogenicity genes encoding for effectors. Pathogen adaptation is fuelled by extensive genetic variability in populations and different strains may not share the same set of genes. Recently, such an intra-specific variation in gene content became formalized as pangenomes distinguishing core genes (i.e. shared) and accessory genes (i.e. lineage or strain-specific). Across pathogens species, key effectors tend to be part of the rapidly evolving accessory genome. Here, we show how the construction and analysis of pathogen pangenomes provide deep insights into the dynamic host adaptation process. We also discuss how pangenomes should ideally be built and how geography, niche and lifestyle likely determine pangenome sizes.
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Affiliation(s)
- Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Switzerland.
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Fones HN, Bebber DP, Chaloner TM, Kay WT, Steinberg G, Gurr SJ. Threats to global food security from emerging fungal and oomycete crop pathogens. ACTA ACUST UNITED AC 2020; 1:332-342. [PMID: 37128085 DOI: 10.1038/s43016-020-0075-0] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 04/09/2020] [Indexed: 11/09/2022]
Abstract
Emerging fungal and oomycete pathogens infect staple calorie crops and economically important commodity crops, thereby posing a significant risk to global food security. Our current agricultural systems - with emphasis on intensive monoculture practices - and globalized markets drive the emergence and spread of new pathogens and problematic traits, such as fungicide resistance. Climate change further promotes the emergence of pathogens on new crops and in new places. Here we review the factors affecting the introduction and spread of pathogens and current disease control strategies, illustrating these with the historic example of the Irish potato famine and contemporary examples of soybean rust, wheat blast and blotch, banana wilt and cassava root rot. Our Review looks to the future, summarizing what we see as the main challenges and knowledge gaps, and highlighting the direction that research must take to face the challenge of emerging crop pathogens.
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Chaudhari Y, Cairns TC, Sidhu Y, Attah V, Thomas G, Csukai M, Talbot NJ, Studholme DJ, Haynes K. The Zymoseptoria tritici ORFeome: A Functional Genomics Community Resource. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1564-1570. [PMID: 31272284 DOI: 10.1094/mpmi-05-19-0123-a] [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: 06/09/2023]
Abstract
Libraries of protein-encoding sequences can be generated by identification of open reading frames (ORFs) from a genome of choice that are then assembled into collections of plasmids termed ORFeome libraries. These represent powerful resources to facilitate functional genomic characterization of genes and their encoded products. Here, we report the generation of an ORFeome for Zymoseptoria tritici, which causes the most serious disease of wheat in temperate regions of the world. We screened the genome of strain IP0323 for high confidence gene models, identifying 4,075 candidates from 10,933 predicted genes. These were amplified from genomic DNA, were cloned into the Gateway entry vector pDONR207, and were sequenced, providing a total of 3,022 quality-controlled plasmids. The ORFeome includes genes predicted to encode effectors (n = 410) and secondary metabolite biosynthetic proteins (n = 171) in addition to genes residing at dispensable chromosomes (n = 122) or those that are preferentially expressed during plant infection (n = 527). The ORFeome plasmid library is compatible with our previously developed suite of Gateway destination vectors, which have various combinations of promoters, selection markers, and epitope tags. The Z. tritici ORFeome constitutes a powerful resource for functional genomics and offers unparalleled opportunities to understand the biology of Z. tritici.[Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
| | | | | | | | - Graham Thomas
- Biosciences, University of Exeter, Exeter EX4 4QD, U.K
| | - Michael Csukai
- Syngenta, Jealott's Hill International Research Centre, Bracknell, RG42 6EY, U.K
| | - Nicholas J Talbot
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, NR47UH, U.K
| | | | - Ken Haynes
- Biosciences, University of Exeter, Exeter EX4 4QD, U.K
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35
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Ajayi-Oyetunde OO, Everhart SE, Brown PJ, Tenuta AU, Dorrance AE, Bradley CA. Genetic Structure of Rhizoctonia solani AG-2-2IIIB from Soybean in Illinois, Ohio, and Ontario. PHYTOPATHOLOGY 2019; 109:2132-2141. [PMID: 31381483 DOI: 10.1094/phyto-01-19-0015-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Rhizoctonia solani AG-2-2IIIB is an important seedling pathogen of soybean in North America and other soybean-growing regions around the world. There is no information regarding the population genetics of field populations of R. solani associated with soybean seedling disease. More specifically, information regarding genetic diversity, the mode of reproduction, and the evolutionary factors that shape different R. solani populations separated in time and space are lacking. We exploited genotyping by sequencing as a tool to assess the genetic structure of R. solani AG-2-2IIIB populations from Illinois, Ohio, and Ontario and investigate the reproductive mode of this subgroup. Our results revealed differences in genotypic diversity among three populations, with the Ontario population having greatest diversity. An overrepresentation of multilocus genotypes (MLGs) and a rejection of the null hypothesis of random mating in all three populations suggested clonality within each population. However, phylogenetic analysis revealed long terminal multifurcating branches for most members of the Ontario population, suggesting a mixed reproductive mode for this population. Analysis of molecular variance revealed low levels of population differentiation, and sharing of similar MLGs among populations highlights the role of genotype flow as an evolutionary force shaping population structure of this subgroup.
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Affiliation(s)
| | - Sydney E Everhart
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, U.S.A
| | - Patrick J Brown
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Albert U Tenuta
- Ontario Ministry of Agriculture, Food and Rural Affairs, Ridgetown, Ontario N0P2C0, Canada
| | - Anne E Dorrance
- Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691, OH, U.S.A
| | - Carl A Bradley
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
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36
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Laas M, Adamson K, Drenkhan R. A look into the genetic diversity of Lecanosticta acicola in northern Europe. Fungal Biol 2019; 123:773-782. [PMID: 31542194 DOI: 10.1016/j.funbio.2019.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/28/2019] [Accepted: 06/26/2019] [Indexed: 10/26/2022]
Abstract
For northern Europe Lecanosticta acicola is an emerging pine needle pathogen. This study gives a first look into the population genetics of the pathogen in Estonia, the first population documented in that region. The main aim of this study was to investigate the genetic diversity and population structure of the pathogen in this new region for the fungus. For this purpose, 104 isolates from 2010 to 2017 were analysed with 11 microsatellite and mating type markers. The stand where the pathogen's jump from an exotic host to the native Scots pine was recorded was also involved in this analysis. The analysis revealed low genetic diversity and a high number of clones that indicated L. acicola is an invasive species in northern Europe. Results suggest that several separate introductions have taken place and anthropogenic activity has apparently affected the spread of the pathogen. Clonal reproduction is dominating and although sexual reproduction is possible, it probably takes place infrequently.
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Affiliation(s)
- Marili Laas
- Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Fr. R. Kreutzwaldi 5, 51006, Tartu, Estonia.
| | - Kalev Adamson
- Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Fr. R. Kreutzwaldi 5, 51006, Tartu, Estonia
| | - Rein Drenkhan
- Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Fr. R. Kreutzwaldi 5, 51006, Tartu, Estonia
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Hassine M, Siah A, Hellin P, Cadalen T, Halama P, Hilbert JL, Hamada W, Baraket M, Yahyaoui A, Legrève A, Duvivier M. Sexual reproduction of Zymoseptoria tritici on durum wheat in Tunisia revealed by presence of airborne inoculum, fruiting bodies and high levels of genetic diversity. Fungal Biol 2019; 123:763-772. [PMID: 31542193 DOI: 10.1016/j.funbio.2019.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 04/05/2019] [Accepted: 06/19/2019] [Indexed: 10/26/2022]
Abstract
Septoria tritici blotch (STB) caused by the heterothallic ascomycete Zymoseptoria tritici is currently one of the most devastating diseases of wheat worldwide. The extent of sexual reproduction of this pathogen is well documented on bread wheat, but not on durum wheat. The objective of the present study was to quantify the occurrence of Z. tritici sexual reproduction on durum wheat in the Tunisian environment. The assessment was undertaken using a triple approach combining fruiting body assessment, ascospore trapping and population genetic analyses. The results highlighted the formation of pseudothecia on leaves and stubble from the autumn until the end of the growing season. Likewise, qPCR monitoring highlighted a constant release of Z. tritici airborne inoculum during the wheat-growing season, with a peak of production at the end of the season. Genetic investigations using microsatellites revealed high levels of gene and genotypic diversities, an equal distribution of mating types, and a lack of genetic clustering within and between growing seasons. Taken together, these findings indicate that Z. tritici undergoes sexual reproduction on durum wheat in Tunisia at least to the same extent than on bread wheat in Western Europe, and that the dry and warm climate does not affect the mating process of the fungus. Frequent occurrence of sexual reproduction is a valuable knowledge to take into account in STB control strategies on durum wheat.
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Affiliation(s)
- M Hassine
- University of Carthage, National Agronomic Institute of Tunisia, LR14AGR01, Laboratory of Genetics and Cereal Breeding, National Agronomic Institute of Tunisia, Avenue Charles Nicolle 43, 1082 Tunis, Tunisia.
| | - A Siah
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - P Hellin
- Applied Microbiology, Earth and Life Institute, Université Catholique de Louvain, Croix du Sud 2 Box L7.05.03, 1348 Louvain-la-Neuve, Belgium; Plant Protection and Ecotoxicology Unit, Walloon Agricultural Research Center, Rue du Bordia 11, 5030 Gembloux, Belgium.
| | - T Cadalen
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - P Halama
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - J-L Hilbert
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - W Hamada
- University of Carthage, National Agronomic Institute of Tunisia, LR14AGR01, Laboratory of Genetics and Cereal Breeding, National Agronomic Institute of Tunisia, Avenue Charles Nicolle 43, 1082 Tunis, Tunisia.
| | - M Baraket
- National Research Institute of Rural Engineering, Water and Forestry, Rue Hédi EL Karray El Menzah IV 1004 2080 Ariana, Tunisia.
| | - A Yahyaoui
- International Maize and Wheat Improvement Center, Carretera México-Veracruz Km. 45, El Batán, 56237 Texcoco, México.
| | - A Legrève
- Applied Microbiology, Earth and Life Institute, Université Catholique de Louvain, Croix du Sud 2 Box L7.05.03, 1348 Louvain-la-Neuve, Belgium.
| | - M Duvivier
- Plant Protection and Ecotoxicology Unit, Walloon Agricultural Research Center, Rue du Bordia 11, 5030 Gembloux, Belgium.
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38
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Kashyap PL, Kumar S, Tripathi R, Kumar RS, Jasrotia P, Singh DP, Singh GP. Phylogeography and Population Structure Analysis Reveal Diversity by Gene Flow and Mutation in Ustilago segetum (Pers.) Roussel tritici Causing Loose Smut of Wheat. Front Microbiol 2019; 10:1072. [PMID: 31156587 PMCID: PMC6529584 DOI: 10.3389/fmicb.2019.01072] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 04/29/2019] [Indexed: 02/02/2023] Open
Abstract
Ustilago segetum (Pers.) Roussel tritici (UST) causes loose smut of wheat account for considerable grain yield losses globally. For effective management, knowledge of its genetic variability and population structure is a prerequisite. In this study, UST isolates sampled from four different wheat growing zones of India were analyzed using the second largest subunit of the RNA polymerase II (RPB2) and a set of sixteen neutral simple sequence repeats (SSRs) markers. Among the 112 UST isolates genotyped, 98 haplotypes were identified. All the isolates were categorized into two groups (K = 2), each consisting of isolates from different sampling sites, on the basis of unweighted paired-grouping method with arithmetic averages (UPGMA) and the Bayesian analysis of population structure. The positive and significant index of association (IA = 1.169) and standardized index of association (rBarD = 0.075) indicate population is of non-random mating type. Analysis of molecular variance showed that the highest variance component is among isolates (91%), with significantly low genetic differentiation variation among regions (8%) (Fst = 0.012). Recombination (Rm = 0) was not detected. The results showed that UST isolates have a clonal genetic structure with limited genetic differentiation and human arbitrated gene flow and mutations are the prime evolutionary processes determining its genetic structure. These findings will be helpful in devising management strategy especially for selection and breeding of resistant wheat cultivars.
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Affiliation(s)
- Prem Lal Kashyap
- ICAR-Indian Institute of Wheat and Barley Research (IIWBR), Karnal, India
| | - Sudheer Kumar
- ICAR-Indian Institute of Wheat and Barley Research (IIWBR), Karnal, India
| | - Rahul Tripathi
- ICAR-Indian Institute of Wheat and Barley Research (IIWBR), Karnal, India
| | - Ravi Shekhar Kumar
- ICAR-Indian Institute of Wheat and Barley Research (IIWBR), Karnal, India
| | - Poonam Jasrotia
- ICAR-Indian Institute of Wheat and Barley Research (IIWBR), Karnal, India
| | - Devendra Pal Singh
- ICAR-Indian Institute of Wheat and Barley Research (IIWBR), Karnal, India
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39
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Nsibo DL, Barnes I, Kunene NT, Berger DK. Influence of farming practices on the population genetics of the maize pathogen Cercospora zeina in South Africa. Fungal Genet Biol 2019; 125:36-44. [DOI: 10.1016/j.fgb.2019.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 12/11/2018] [Accepted: 01/11/2019] [Indexed: 12/14/2022]
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40
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Sikdar P, Mazzola M, Xiao CL. Genetic and Pathogenic Characterization of Phacidiopycnis washingtonensis from Apple and Pacific Madrone from the Western United States. PHYTOPATHOLOGY 2019; 109:469-479. [PMID: 30156500 DOI: 10.1094/phyto-10-17-0358-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Phacidiopycnis washingtonensis is the cause of speck rot of apple and leaf blight of Pacific madrone in Washington State. In total, 314 isolates were collected from apple production areas in eastern Washington and Pacific madrone in western Washington. Using eight microsatellite markers designed in this study, 58 unique multilocus haplotypes were identified. Only one of the haplotypes was shared between the apple and Pacific madrone populations. Analysis of molecular variance showed no genetic differentiation between the apple and Pacific madrone populations. Genetic variation was present within each subpopulation of apple from different geographic locations. The apple population possessed higher genotypic diversity than the Pacific madrone population, suggesting that isolates from apple may represent an older population and could have been introduced into the native habitat of Pacific madrone. P. washingtonensis likely reproduces asexually because populations examined in this study were not in linkage equilibrium. In pathogenicity tests, representative isolates from apple and Pacific madrone all incited leaf blight on Pacific madrone and speck rot on apple fruit regardless of their host of origin. Overall, our findings indicate that the P. washingtonensis population in Washington State is largely asexual, with high genotypic flow and that apple, crabapple, and Pacific madrone could serve as sources of P. washingtonensis inoculum for these hosts.
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Affiliation(s)
- P Sikdar
- First author: Department of Plant Pathology, Washington State University, Pullman 99164; second author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Tree Fruit Research Laboratory, 1104 N. Western Ave., Wenatchee, WA 98801; and third author: USDA-ARS, San Joaquin Valley Agricultural Sciences Center, 9611 S. Riverbend Ave, Parlier, CA 93648
| | - M Mazzola
- First author: Department of Plant Pathology, Washington State University, Pullman 99164; second author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Tree Fruit Research Laboratory, 1104 N. Western Ave., Wenatchee, WA 98801; and third author: USDA-ARS, San Joaquin Valley Agricultural Sciences Center, 9611 S. Riverbend Ave, Parlier, CA 93648
| | - C L Xiao
- First author: Department of Plant Pathology, Washington State University, Pullman 99164; second author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Tree Fruit Research Laboratory, 1104 N. Western Ave., Wenatchee, WA 98801; and third author: USDA-ARS, San Joaquin Valley Agricultural Sciences Center, 9611 S. Riverbend Ave, Parlier, CA 93648
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41
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Haueisen J, Möller M, Eschenbrenner CJ, Grandaubert J, Seybold H, Adamiak H, Stukenbrock EH. Highly flexible infection programs in a specialized wheat pathogen. Ecol Evol 2019; 9:275-294. [PMID: 30680113 PMCID: PMC6342133 DOI: 10.1002/ece3.4724] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/04/2018] [Accepted: 10/05/2018] [Indexed: 12/21/2022] Open
Abstract
Many filamentous plant pathogens exhibit high levels of genomic variability, yet the impact of this variation on host-pathogen interactions is largely unknown. We have addressed host specialization in the wheat pathogen Zymoseptoria tritici. Our study builds on comparative analyses of infection and gene expression phenotypes of three isolates and reveals the extent to which genomic variation translates into phenotypic variation. The isolates exhibit genetic and genomic variation but are similarly virulent. By combining confocal microscopy, disease monitoring, staining of ROS, and comparative transcriptome analyses, we conducted a detailed comparison of the infection processes of these isolates in a susceptible wheat cultivar. We characterized four core infection stages: establishment, biotrophic growth, lifestyle transition, and necrotrophic growth and asexual reproduction that are shared by the three isolates. However, we demonstrate differentiated temporal and spatial infection development and significant differences in the expression profiles of the three isolates during the infection stages. More than 20% of the genes were differentially expressed and these genes were located significantly closer to transposable elements, suggesting an impact of epigenetic regulation. Further, differentially expressed genes were enriched in effector candidates suggesting that isolate-specific strategies for manipulating host defenses are present in Z. tritici. We demonstrate that individuals of a host-specialized pathogen have highly differentiated infection programs characterized by flexible infection development and functional redundancy. This illustrates how high genetic diversity in pathogen populations results in highly differentiated infection phenotypes, which fact needs to be acknowledged to understand host-pathogen interactions and pathogen evolution.
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Affiliation(s)
- Janine Haueisen
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyPlönGermany
- Environmental Genomics GroupChristian‐Albrechts University KielKielGermany
| | - Mareike Möller
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyPlönGermany
- Environmental Genomics GroupChristian‐Albrechts University KielKielGermany
| | - Christoph J. Eschenbrenner
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyPlönGermany
- Environmental Genomics GroupChristian‐Albrechts University KielKielGermany
| | - Jonathan Grandaubert
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyPlönGermany
- Fungal Biology and PathogenicityInstitute PasteurParisFrance
| | - Heike Seybold
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyPlönGermany
- Environmental Genomics GroupChristian‐Albrechts University KielKielGermany
| | - Holger Adamiak
- Environmental Genomics GroupChristian‐Albrechts University KielKielGermany
| | - Eva H. Stukenbrock
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyPlönGermany
- Environmental Genomics GroupChristian‐Albrechts University KielKielGermany
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42
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Yates S, Mikaberidze A, Krattinger SG, Abrouk M, Hund A, Yu K, Studer B, Fouche S, Meile L, Pereira D, Karisto P, McDonald BA. Precision Phenotyping Reveals Novel Loci for Quantitative Resistance to Septoria Tritici Blotch. PLANT PHENOMICS (WASHINGTON, D.C.) 2019; 2019:3285904. [PMID: 33313526 PMCID: PMC7706307 DOI: 10.34133/2019/3285904] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 09/02/2019] [Indexed: 05/19/2023]
Abstract
Accurate, high-throughput phenotyping for quantitative traits is a limiting factor for progress in plant breeding. We developed an automated image analysis to measure quantitative resistance to septoria tritici blotch (STB), a globally important wheat disease, enabling identification of small chromosome intervals containing plausible candidate genes for STB resistance. 335 winter wheat cultivars were included in a replicated field experiment that experienced natural epidemic development by a highly diverse but fungicide-resistant pathogen population. More than 5.4 million automatically generated phenotypes were associated with 13,648 SNP markers to perform the GWAS. We identified 26 chromosome intervals explaining 1.9-10.6% of the variance associated with four independent resistance traits. Sixteen of the intervals overlapped with known STB resistance intervals, suggesting that our phenotyping approach can identify simultaneously (i.e., in a single experiment) many previously defined STB resistance intervals. Seventeen of the intervals were less than 5 Mbp in size and encoded only 173 genes, including many genes associated with disease resistance. Five intervals contained four or fewer genes, providing high priority targets for functional validation. Ten chromosome intervals were not previously associated with STB resistance, perhaps representing resistance to pathogen strains that had not been tested in earlier experiments. The SNP markers associated with these chromosome intervals can be used to recombine different forms of quantitative STB resistance that are likely to be more durable than pyramids of major resistance genes. Our experiment illustrates how high-throughput automated phenotyping can accelerate breeding for quantitative disease resistance.
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Affiliation(s)
- Steven Yates
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Alexey Mikaberidze
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Simon G. Krattinger
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Michael Abrouk
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Andreas Hund
- Crop Science, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Kang Yu
- Crop Science, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Bruno Studer
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Simone Fouche
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Lukas Meile
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Danilo Pereira
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Petteri Karisto
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Bruce A. McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
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Yang N, Ma G, Chen K, Wu X. The Population Genetics of Alternaria tenuissima in Four Regions of China as Determined by Microsatellite Markers Obtained by Transcriptome Sequencing. Front Microbiol 2018; 9:2904. [PMID: 30559728 PMCID: PMC6287023 DOI: 10.3389/fmicb.2018.02904] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 11/13/2018] [Indexed: 12/02/2022] Open
Abstract
A total of 32,284 unigenes were obtained from the transcriptome of Alternaria tenuissima, a pathogenic fungus causing foliar disease in tomato, using next-generation sequencing (NGS) technology. In total, 24,670 unigenes were annotated using five databases, including NCBI non-redundant protein, Swiss-Prot, euKaryotic Orthologous Groups, Kyoto Encyclopedia of Genes and Genomes, and the Gene Ontology. A total of 1,140 simple sequence repeats were also identified for use as molecular markers. Sixteen of the simple sequence repeat loci were selected to study the population structure of A. tenuissima. A population genetic analysis of 191 A. tenuissima isolates, sampled from four geographic regions in China, indicated that A. tenuissima had a high level of genetic diversity, and that the selected simple sequence repeat markers could reliably capture the genetic variation. The null hypothesis of random mating was rejected for all four geographic regions in China. Isolation by distance was observed for the entire data set, but not within clusters, which is indicative of barriers to gene flow among geographic regions. The analyses of Bayesian and principal coordinates, however, did not separate four geographic regions into four separate genetic clusters. The different levels of historical migration rates suggest that isolation by distance did not represent a major biological obstacle to the spread of A. tenuissima. The potential epidemic spread of A. tenuissima in China may occur through the transport of plant products or other factors. The presented results provide a basis for a comprehensive understanding of the population genetics of A. tenuissima in China.
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Affiliation(s)
| | | | | | - Xuehong Wu
- College of Plant Protection, Department of Plant Pathology, China Agricultural University, Beijing, China
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44
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Frézal L, Jacqua G, Neema C. Adaptation of a Fungal Pathogen to Host Quantitative Resistance. FRONTIERS IN PLANT SCIENCE 2018; 9:1554. [PMID: 30429860 PMCID: PMC6220312 DOI: 10.3389/fpls.2018.01554] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 10/03/2018] [Indexed: 05/29/2023]
Abstract
Impact of host quantitative resistance on pathogen evolution is still poorly documented. In our study, we characterized the adaptation of the pathogenic fungus Colletotrichum gloeosporioides, to the quantitative resistance of its host, the water yam (Dioscorea alata). Genetic and pathogenic diversities of C. gloeosporioides populations were specified at the field scale. We used nuclear markers to describe fungal population structuring within and between six fields of three cultivars differently susceptible to the fungus. Strain aggressiveness was then quantified in the laboratory through cross-inoculation tests. The high level of genetic diversity and significant linkage disequilibrium revealed a significant influence of clonal reproduction in the C. gloeosporioides evolution. The recorded fungal migration between fields was weak (evidence for a dispersion mode via tubers rather than splashing dispersal), which provides the first molecular evidence for limited C. gloeosporioides migration via yam tuber exchanges. C. gloeosporioides's populations are adapted to their host resistance. The aggressiveness of the fungal clones seems to have evolved toward an accumulation of components specific to each host cultivar. Despite the remaining marks of adaptation to the former widely cultivated host, adaptation to current cultivars was clearly depicted.
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Affiliation(s)
- Lise Frézal
- INRA-URPV, Guadeloupe, France
- CNRS – ENS – INSERM, Institut de Biologie de l’Ecole Normale Supérieure, Paris, France
| | | | - Claire Neema
- UMR BGPI, Montpellier SupAgro, Campus International de Baillarguet, Montpellier, France
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Möller M, Habig M, Freitag M, Stukenbrock EH. Extraordinary Genome Instability and Widespread Chromosome Rearrangements During Vegetative Growth. Genetics 2018; 210:517-529. [PMID: 30072376 PMCID: PMC6216587 DOI: 10.1534/genetics.118.301050] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 07/18/2018] [Indexed: 12/27/2022] Open
Abstract
The haploid genome of the pathogenic fungus Zymoseptoria tritici is contained on "core" and "accessory" chromosomes. While 13 core chromosomes are found in all strains, as many as eight accessory chromosomes show presence/absence variation and rearrangements among field isolates. The factors influencing these presence/absence polymorphisms are so far unknown. We investigated chromosome stability using experimental evolution, karyotyping, and genome sequencing. We report extremely high and variable rates of accessory chromosome loss during mitotic propagation in vitro and in planta Spontaneous chromosome loss was observed in 2 to >50% of cells during 4 weeks of incubation. Similar rates of chromosome loss in the closely related Zymoseptoria ardabiliae suggest that this extreme chromosome dynamic is a conserved phenomenon in the genus. Elevating the incubation temperature greatly increases instability of accessory and even core chromosomes, causing severe rearrangements involving telomere fusion and chromosome breakage. Chromosome losses do not affect the fitness of Zymoseptoria tritici in vitro, but some lead to increased virulence, suggesting an adaptive role of this extraordinary chromosome instability.
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Affiliation(s)
- Mareike Möller
- Environmental Genomics, Christian-Albrechts University, D-24118 Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, D-24306 Plön, Germany
| | - Michael Habig
- Environmental Genomics, Christian-Albrechts University, D-24118 Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, D-24306 Plön, Germany
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331-7305
| | - Eva H Stukenbrock
- Environmental Genomics, Christian-Albrechts University, D-24118 Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, D-24306 Plön, Germany
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Yang L, Ouyang H, Fang Z, Zhu W, Wu E, Luo G, Shang L, Zhan J. Evidence for intragenic recombination and selective sweep in an effector gene of Phytophthora infestans. Evol Appl 2018; 11:1342-1353. [PMID: 30151044 PMCID: PMC6099815 DOI: 10.1111/eva.12629] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 03/06/2018] [Indexed: 01/07/2023] Open
Abstract
Effectors, a group of small proteins secreted by pathogens, play a critical role in the antagonistic interaction between plant hosts and pathogens through their dual functions in regulating host immune systems and pathogen infection capability. In this study, evolution in effector genes was investigated through population genetic analysis of Avr3a sequences generated from 96 Phytophthora infestans isolates collected from six locations representing a range of thermal variation and cropping systems in China. We found high genetic variation in the Avr3a gene resulting from diverse mechanisms extending beyond point mutations, frameshift, and defeated start and stop codons to intragenic recombination. A total of 51 nucleotide haplotypes encoding 38 amino acid isoforms were detected in the 96 full sequences with nucleotide diversity in the pathogen populations ranging from 0.007 to 0.023 (mean = 0.017). Although haplotype and nucleotide diversity were high, the effector gene was dominated by only three haplotypes. Evidence for a selective sweep was provided by (i) the population genetic differentiation (GST) of haplotypes being lower than the population differentiation (FST) of SSR marker loci; and (ii) negative values of Tajima's D and Fu's FS. Annual mean temperature in the collection sites was negatively correlated with the frequency of the virulent form (Avr3aEM), indicating Avr3a may be regulated by temperature. These results suggest that elevated air temperature due to global warming may hamper the development of pathogenicity traits in P. infestans and further study under confined thermal regimes may be required to confirm the hypothesis.
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Affiliation(s)
- Lina Yang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsFujian Agriculture and Forestry UniversityFuzhouChina
- Fujian Key Lab of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - Hai‐Bing Ouyang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsFujian Agriculture and Forestry UniversityFuzhouChina
- Fujian Key Lab of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - Zhi‐Guo Fang
- Fujian Key Lab of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
- Xiangyang Academy of Agricultural SciencesXiangyangChina
| | - Wen Zhu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsFujian Agriculture and Forestry UniversityFuzhouChina
- Fujian Key Lab of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - E‐Jiao Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsFujian Agriculture and Forestry UniversityFuzhouChina
- Fujian Key Lab of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - Gui‐Huo Luo
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsFujian Agriculture and Forestry UniversityFuzhouChina
- Fujian Key Lab of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - Li‐Ping Shang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsFujian Agriculture and Forestry UniversityFuzhouChina
| | - Jiasui Zhan
- Key Lab for Biopesticide and Chemical BiologyMinistry of EducationFujian Agriculture and Forestry UniversityFuzhouChina
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Siah A, Bomble M, Tisserant B, Cadalen T, Holvoet M, Hilbert JL, Halama P, Reignault P. Genetic Structure of Zymoseptoria tritici in Northern France at Region, Field, Plant, and Leaf Layer Scales. PHYTOPATHOLOGY 2018; 108:1114-1123. [PMID: 29658841 DOI: 10.1094/phyto-09-17-0322-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Population genetic structure of the worldwide-distributed wheat pathogen Zymoseptoria tritici has been extensively studied at large geographical scales, but to a much less extent at small or local spatial scales. A total of 627 single-conidial fungal isolates were sampled from several locations in northern France (Hauts-de-France Region) to assess fungal genetic structure at region, field, plant, and leaf layer scales, using highly polymorphic microsatellite markers and mating type idiomorphs. Important and overall similar levels of both gene and genotype diversities (gene diversity values of ≥0.44 and haplotype frequencies of ≥94%) were found at all the examined scales. Such rates of diversity are likely due to an active sexual recombination in the investigated areas, as revealed by equal proportions of the two mating types scored in all sampled populations. Interestingly, a rare occurrence of clones among lesions from a same leaf, as well as among leaves from different plant leaf layers (e.g., upper versus lower leaves), was highlighted, indicating that ascospores contribute much more than expected to Z. tritici epidemics, compared with pycnidiospores. Population structure and analyses of molecular variance revealed significant genetic differentiation at the regional scale (GST = 0.23) and, as expected, not at the other more local scales (GST ≤ 0.01). Further analyses using Bayesian and unweighted neighbor-joining statistical methods detected six genetic clusters within the regional population, overall distributed according to the locations from which the isolates were sampled. Neither clear directional relative migration linked to the geographical distribution of the locations, nor isolation by distance, were observed. Separate evolutionary trajectories caused by selection and adaptations to habitat heterogeneity could be the main forces shaping such structuration. This study provides new insights into the epidemiology and the genetic structure of Z. tritici at small local and, for the first time, at single plant and leaf layer scales. Such findings would be helpful in implementing effective control strategies.
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Affiliation(s)
- Ali Siah
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
| | - Myriam Bomble
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
| | - Benoit Tisserant
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
| | - Thierry Cadalen
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
| | - Maxime Holvoet
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
| | - Jean-Louis Hilbert
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
| | - Patrice Halama
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
| | - Philippe Reignault
- First, second, fourth, fifth, sixth, and seventh authors: Institut Charles Viollette (ICV-EA 7394), ISA, Université de Lille, SFR Condorcet FR CNRS 3417, 48 bd Vauban, BP 41290, F-59014 Lille Cedex, France; and third and eighth authors: Univ. Littoral Côte d'Opale, Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV-EA 4492), SFR Condorcet FR CNRS 3417, CS 80699, F-62228, Calais Cedex, France
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Krishnan P, Meile L, Plissonneau C, Ma X, Hartmann FE, Croll D, McDonald BA, Sánchez-Vallet A. Transposable element insertions shape gene regulation and melanin production in a fungal pathogen of wheat. BMC Biol 2018; 16:78. [PMID: 30012138 PMCID: PMC6047131 DOI: 10.1186/s12915-018-0543-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 06/20/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Fungal plant pathogens pose major threats to crop yield and sustainable food production if they are highly adapted to their host and the local environment. Variation in gene expression contributes to phenotypic diversity within fungal species and affects adaptation. However, very few cases of adaptive regulatory changes have been reported in fungi and the underlying mechanisms remain largely unexplored. Fungal pathogen genomes are highly plastic and harbor numerous insertions of transposable elements, which can potentially contribute to gene expression regulation. In this work, we elucidated how transposable elements contribute to variation in melanin accumulation, a quantitative trait in fungi that affects survival under stressful conditions. RESULTS We demonstrated that differential transcriptional regulation of the gene encoding the transcription factor Zmr1, which controls expression of the genes in the melanin biosynthetic gene cluster, is responsible for variation in melanin accumulation in the fungal plant pathogen Zymoseptoria tritici. We show that differences in melanin levels between two strains of Z. tritici are due to two levels of transcriptional regulation: (1) variation in the promoter sequence of Zmr1 and (2) an insertion of transposable elements upstream of the Zmr1 promoter. Remarkably, independent insertions of transposable elements upstream of Zmr1 occurred in 9% of Z. tritici strains from around the world and negatively regulated Zmr1 expression, contributing to variation in melanin accumulation. CONCLUSIONS Our studies identified two levels of transcriptional control that regulate the synthesis of melanin. We propose that these regulatory mechanisms evolved to balance the fitness costs associated with melanin production against its positive contribution to survival in stressful environments.
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Affiliation(s)
- Parvathy Krishnan
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Lukas Meile
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Clémence Plissonneau
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland.,UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, Thiverval-Grignon, France
| | - Xin Ma
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Fanny E Hartmann
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland.,Ecologie Systématique Evolution, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris Saclay, Orsay, France
| | - Daniel Croll
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland.,Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
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Karisto P, Hund A, Yu K, Anderegg J, Walter A, Mascher F, McDonald BA, Mikaberidze A. Ranking Quantitative Resistance to Septoria tritici Blotch in Elite Wheat Cultivars Using Automated Image Analysis. PHYTOPATHOLOGY 2018; 108:568-581. [PMID: 29210601 DOI: 10.1094/phyto-04-17-0163-r] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Quantitative resistance is likely to be more durable than major gene resistance for controlling Septoria tritici blotch (STB) on wheat. Earlier studies hypothesized that resistance affecting the degree of host damage, as measured by the percentage of leaf area covered by STB lesions, is distinct from resistance that affects pathogen reproduction, as measured by the density of pycnidia produced within lesions. We tested this hypothesis using a collection of 335 elite European winter wheat cultivars that was naturally infected by a diverse population of Zymoseptoria tritici in a replicated field experiment. We used automated image analysis of 21,420 scanned wheat leaves to obtain quantitative measures of conditional STB intensity that were precise, objective, and reproducible. These measures allowed us to explicitly separate resistance affecting host damage from resistance affecting pathogen reproduction, enabling us to confirm that these resistance traits are largely independent. The cultivar rankings based on host damage were different from the rankings based on pathogen reproduction, indicating that the two forms of resistance should be considered separately in breeding programs aiming to increase STB resistance. We hypothesize that these different forms of resistance are under separate genetic control, enabling them to be recombined to form new cultivars that are highly resistant to STB. We found a significant correlation between rankings based on automated image analysis and rankings based on traditional visual scoring, suggesting that image analysis can complement conventional measurements of STB resistance, based largely on host damage, while enabling a much more precise measure of pathogen reproduction. We showed that measures of pathogen reproduction early in the growing season were the best predictors of host damage late in the growing season, illustrating the importance of breeding for resistance that reduces pathogen reproduction in order to minimize yield losses caused by STB. These data can already be used by breeding programs to choose wheat cultivars that are broadly resistant to naturally diverse Z. tritici populations according to the different classes of resistance.
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Affiliation(s)
- Petteri Karisto
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
| | - Andreas Hund
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
| | - Kang Yu
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
| | - Jonas Anderegg
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
| | - Achim Walter
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
| | - Fabio Mascher
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
| | - Bruce A McDonald
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
| | - Alexey Mikaberidze
- First, seventh, and eighth authors: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; second, third, fourth, and fifth authors: Crop Science Group, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland; and sixth author: Crop Breeding and Genetic Resources, Department of Plant Breeding, Agroscope, Nyon, Switzerland
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Ma X, Keller B, McDonald BA, Palma-Guerrero J, Wicker T. Comparative Transcriptomics Reveals How Wheat Responds to Infection by Zymoseptoria tritici. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:420-431. [PMID: 29090630 DOI: 10.1094/mpmi-10-17-0245-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The fungus Zymoseptoria tritici causes septoria tritici blotch (STB) on wheat, an important disease globally and the most damaging wheat disease in Europe. Despite the global significance of STB, the molecular basis of wheat defense against Z. tritici is poorly understood. Here, we use a comparative transcriptomic study to investigate how wheat responds to infection by four distinct strains of Z. tritici. We examined the response of wheat across the entire infection cycle, identifying both shared responses to the four strains and strain-specific responses. We found that the early asymptomatic phase is characterized by strong upregulation of genes encoding receptor-like kinases and pathogenesis-related proteins, indicating the onset of a defense response. We also identified genes that were differentially expressed among the four fungal strains, including genes related to defense. Genes involved in senescence were induced during both the asymptomatic phase and at late stages of infection, suggesting manipulation of senescence processes by both the plant and the pathogen. Our findings illustrate the need, when identifying important genes affecting disease resistance in plants, to include multiple pathogen strains.
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Affiliation(s)
- Xin Ma
- 1 Plant Pathology, Institute of Integrative Biology, ETH Zurich, 8092 Zurich, Switzerland; and
- 2 Department of Plant and Microbial Biology, University of Zurich, Zurich 8008, Switzerland
| | - Beat Keller
- 2 Department of Plant and Microbial Biology, University of Zurich, Zurich 8008, Switzerland
| | - Bruce A McDonald
- 1 Plant Pathology, Institute of Integrative Biology, ETH Zurich, 8092 Zurich, Switzerland; and
| | - Javier Palma-Guerrero
- 1 Plant Pathology, Institute of Integrative Biology, ETH Zurich, 8092 Zurich, Switzerland; and
| | - Thomas Wicker
- 2 Department of Plant and Microbial Biology, University of Zurich, Zurich 8008, Switzerland
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