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Penselin D, Münsterkötter M, Kirsten S, Felder M, Taudien S, Platzer M, Ashelford K, Paskiewicz KH, Harrison RJ, Hughes DJ, Wolf T, Shelest E, Graap J, Hoffmann J, Wenzel C, Wöltje N, King KM, Fitt BDL, Güldener U, Avrova A, Knogge W. Comparative genomics to explore phylogenetic relationship, cryptic sexual potential and host specificity of Rhynchosporium species on grasses. BMC Genomics 2016; 17:953. [PMID: 27875982 PMCID: PMC5118889 DOI: 10.1186/s12864-016-3299-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 11/15/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The Rhynchosporium species complex consists of hemibiotrophic fungal pathogens specialized to different sweet grass species including the cereal crops barley and rye. A sexual stage has not been described, but several lines of evidence suggest the occurrence of sexual reproduction. Therefore, a comparative genomics approach was carried out to disclose the evolutionary relationship of the species and to identify genes demonstrating the potential for a sexual cycle. Furthermore, due to the evolutionary very young age of the five species currently known, this genus appears to be well-suited to address the question at the molecular level of how pathogenic fungi adapt to their hosts. RESULTS The genomes of the different Rhynchosporium species were sequenced, assembled and annotated using ab initio gene predictors trained on several fungal genomes as well as on Rhynchosporium expressed sequence tags. Structures of the rDNA regions and genome-wide single nucleotide polymorphisms provided a hypothesis for intra-genus evolution. Homology screening detected core meiotic genes along with most genes crucial for sexual recombination in ascomycete fungi. In addition, a large number of cell wall-degrading enzymes that is characteristic for hemibiotrophic and necrotrophic fungi infecting monocotyledonous hosts were found. Furthermore, the Rhynchosporium genomes carry a repertoire of genes coding for polyketide synthases and non-ribosomal peptide synthetases. Several of these genes are missing from the genome of the closest sequenced relative, the poplar pathogen Marssonina brunnea, and are possibly involved in adaptation to the grass hosts. Most importantly, six species-specific genes coding for protein effectors were identified in R. commune. Their deletion yielded mutants that grew more vigorously in planta than the wild type. CONCLUSION Both cryptic sexuality and secondary metabolites may have contributed to host adaptation. Most importantly, however, the growth-retarding activity of the species-specific effectors suggests that host adaptation of R. commune aims at extending the biotrophic stage at the expense of the necrotrophic stage of pathogenesis. Like other apoplastic fungi Rhynchosporium colonizes the intercellular matrix of host leaves relatively slowly without causing symptoms, reminiscent of the development of endophytic fungi. Rhynchosporium may therefore become an object for studying the mutualism-parasitism transition.
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Affiliation(s)
- Daniel Penselin
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany
| | - Martin Münsterkötter
- Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Susanne Kirsten
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany
| | - Marius Felder
- Genomic Analysis, Leibniz Institute on Aging, Fritz Lipmann Institute, Jena, Germany
| | - Stefan Taudien
- Genomic Analysis, Leibniz Institute on Aging, Fritz Lipmann Institute, Jena, Germany
| | - Matthias Platzer
- Genomic Analysis, Leibniz Institute on Aging, Fritz Lipmann Institute, Jena, Germany
| | - Kevin Ashelford
- Institute of Medical Genetics, Cardiff University, Cardiff, UK
| | | | | | - David J. Hughes
- Applied Bioinformatics, Rothamsted Research, Harpenden, Hertfordshire UK
| | - Thomas Wolf
- Systems Biology and Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Ekaterina Shelest
- Systems Biology and Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Jenny Graap
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany
| | - Jan Hoffmann
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany
| | - Claudia Wenzel
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany ,Present address: Food Quality and Nutrition, Agroscope, Bern, Switzerland
| | - Nadine Wöltje
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany
| | - Kevin M. King
- Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire UK
| | - Bruce D. L. Fitt
- Biological and Environmental Sciences, University of Hertfordshire, Hatfield, Hertfordshire UK
| | - Ulrich Güldener
- Department of Genome-Oriented Bioinformatics, Technische Universität München, Wissenschaftszentrum Weihenstephan, Freising, Germany
| | - Anna Avrova
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, Scotland
| | - Wolfgang Knogge
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany
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Hawkins NJ, Cools HJ, Sierotzki H, Shaw MW, Knogge W, Kelly SL, Kelly DE, Fraaije BA. Paralog re-emergence: a novel, historically contingent mechanism in the evolution of antimicrobial resistance. Mol Biol Evol 2014; 31:1793-802. [PMID: 24732957 PMCID: PMC4069618 DOI: 10.1093/molbev/msu134] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Evolution of resistance to drugs and pesticides poses a serious threat to human health and agricultural production. CYP51 encodes the target site of azole fungicides, widely used clinically and in agriculture. Azole resistance can evolve due to point mutations or overexpression of CYP51, and previous studies have shown that fungicide-resistant alleles have arisen by de novo mutation. Paralogs CYP51A and CYP51B are found in filamentous ascomycetes, but CYP51A has been lost from multiple lineages. Here, we show that in the barley pathogen Rhynchosporium commune, re-emergence of CYP51A constitutes a novel mechanism for the evolution of resistance to azoles. Pyrosequencing analysis of historical barley leaf samples from a unique long-term experiment from 1892 to 2008 indicates that the majority of the R. commune population lacked CYP51A until 1985, after which the frequency of CYP51A rapidly increased. Functional analysis demonstrates that CYP51A retains the same substrate as CYP51B, but with different transcriptional regulation. Phylogenetic analyses show that the origin of CYP51A far predates azole use, and newly sequenced Rhynchosporium genomes show CYP51A persisting in the R. commune lineage rather than being regained by horizontal gene transfer; therefore, CYP51A re-emergence provides an example of adaptation to novel compounds by selection from standing genetic variation.
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Affiliation(s)
- Nichola J Hawkins
- Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
| | - Hans J Cools
- Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
| | - Helge Sierotzki
- Research Biology, Syngenta Crop Protection, Basel, Switzerland
| | - Michael W Shaw
- School of Agriculture, Policy and Development, University of Reading, Whiteknights, Reading, United Kingdom
| | - Wolfgang Knogge
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Steven L Kelly
- Institute of Life Science and College of Medicine, Swansea University, Swansea, United Kingdom
| | - Diane E Kelly
- Institute of Life Science and College of Medicine, Swansea University, Swansea, United Kingdom
| | - Bart A Fraaije
- Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
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