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Campos M, Pérez-Collazos E, Díaz-Pérez A, López-Alvarez D, Oumouloud A, Mur LAJ, Vogel JP, Catalán P. Repeated migration, interbreeding and bottlenecking shaped the phylogeography of the selfing grass Brachypodium stacei. Mol Ecol 2024:e17513. [PMID: 39188107 DOI: 10.1111/mec.17513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 07/24/2024] [Accepted: 08/13/2024] [Indexed: 08/28/2024]
Abstract
Brachypodium stacei is the most ancestral lineage in the genus Brachypodium, a model system for grass functional genomics. B. stacei shows striking and sometimes contradictory biological and evolutionary features, including a high selfing rate yet extensive admixture, an ancient Miocene origin yet with recent evolutionary radiation, and adaptation to different dry climate conditions in its narrow distribution range. Therefore, it constitutes an ideal system to study these life history traits. We studied the phylogeography of 17 native circum-Mediterranean B. stacei populations (39 individuals) using genome-wide RADseq SNP data and complete plastome sequences. Nuclear SNP data revealed the existence of six distinct genetic clusters, low levels of intra-population genetic diversity and high selfing rates, albeit with signatures of admixture. Coalescence-based dating analysis detected a recent split between crown lineages in the Late Quaternary. Plastome sequences showed incongruent evolutionary relationships with those recovered by the nuclear data, suggesting interbreeding and chloroplast capture events between genetically distant populations. Demographic and population dispersal coalescent models identified an ancestral origin of B. stacei in the western-central Mediterranean islands, followed by an early colonization of the Canary Islands and two independent colonization events of the eastern Mediterranean region through long-distance dispersal and bottleneck events as the most likely evolutionary history. Climate niche data identified three arid niches of B. stacei in the southern Mediterranean region. Our findings indicate that the phylogeography of B. stacei populations was shaped by recent radiations, frequent extinctions, long-distance dispersal events, occasional interbreeding, and adaptation to local climates.
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Affiliation(s)
- Miguel Campos
- Departamento de Ciencias Agrarias y del Medio Natural, Escuela Politécnica Superior de Huesca, Universidad de Zaragoza, Huesca, Spain
- Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain
| | - Ernesto Pérez-Collazos
- Departamento de Ciencias Agrarias y del Medio Natural, Escuela Politécnica Superior de Huesca, Universidad de Zaragoza, Huesca, Spain
- Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain
| | - Antonio Díaz-Pérez
- Departamento de Ciencias Agrarias y del Medio Natural, Escuela Politécnica Superior de Huesca, Universidad de Zaragoza, Huesca, Spain
- GESPLAN S.A. C, Las Palmas de Gran Canaria, Spain
- Instituto de Genética, Facultad de Agronomía, Universidad Central de Venezuela, Maracay, Venezuela
| | - Diana López-Alvarez
- Departamento de Ciencias Agrarias y del Medio Natural, Escuela Politécnica Superior de Huesca, Universidad de Zaragoza, Huesca, Spain
- Facultad de Ciencias Agropecuarias, Departamento de Ciencias Biológicas, Universidad Nacional de Colombia, Palmira, Colombia
| | - Ali Oumouloud
- Institute Agronomique et Vétérinaire Hassan II, Agadir, Morocco
| | - Luis A J Mur
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, UK
| | - John P Vogel
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Pilar Catalán
- Departamento de Ciencias Agrarias y del Medio Natural, Escuela Politécnica Superior de Huesca, Universidad de Zaragoza, Huesca, Spain
- Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain
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Minadakis N, Kaderli L, Horvath R, Bourgeois Y, Xu W, Thieme M, Woods DP, Roulin AC. Polygenic architecture of flowering time and its relationship with local environments in the grass Brachypodium distachyon. Genetics 2024; 227:iyae042. [PMID: 38504651 PMCID: PMC11075549 DOI: 10.1093/genetics/iyae042] [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: 01/12/2024] [Revised: 01/12/2024] [Accepted: 03/07/2024] [Indexed: 03/21/2024] Open
Abstract
Synchronizing the timing of reproduction with the environment is crucial in the wild. Among the multiple mechanisms, annual plants evolved to sense their environment, the requirement of cold-mediated vernalization is a major process that prevents individuals from flowering during winter. In many annual plants including crops, both a long and short vernalization requirement can be observed within species, resulting in so-called early-(spring) and late-(winter) flowering genotypes. Here, using the grass model Brachypodium distachyon, we explored the link between flowering-time-related traits (vernalization requirement and flowering time), environmental variation, and diversity at flowering-time genes by combining measurements under greenhouse and outdoor conditions. These experiments confirmed that B. distachyon natural accessions display large differences regarding vernalization requirements and ultimately flowering time. We underline significant, albeit quantitative effects of current environmental conditions on flowering-time-related traits. While disentangling the confounding effects of population structure on flowering-time-related traits remains challenging, population genomics analyses indicate that well-characterized flowering-time genes may contribute significantly to flowering-time variation and display signs of polygenic selection. Flowering-time genes, however, do not colocalize with genome-wide association peaks obtained with outdoor measurements, suggesting that additional genetic factors contribute to flowering-time variation in the wild. Altogether, our study fosters our understanding of the polygenic architecture of flowering time in a natural grass system and opens new avenues of research to investigate the gene-by-environment interaction at play for this trait.
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Affiliation(s)
- Nikolaos Minadakis
- Department of Plant and Microbial Biology, University of Zürich, Zollikerstr. 107, 8008 Zürich, Switzerland
| | - Lars Kaderli
- Department of Plant and Microbial Biology, University of Zürich, Zollikerstr. 107, 8008 Zürich, Switzerland
| | - Robert Horvath
- Department of Plant and Microbial Biology, University of Zürich, Zollikerstr. 107, 8008 Zürich, Switzerland
| | - Yann Bourgeois
- DIADE, University of Montpellier, CIRAD, IRD, 34 000 Montpellier, France
| | - Wenbo Xu
- Department of Plant and Microbial Biology, University of Zürich, Zollikerstr. 107, 8008 Zürich, Switzerland
| | - Michael Thieme
- Department of Plant and Microbial Biology, University of Zürich, Zollikerstr. 107, 8008 Zürich, Switzerland
| | - Daniel P Woods
- Department of Plant Sciences, University of California-Davis, 104 Robbins Hall, Davis, CA 95616, USA
- Howard Hughes Medical Institute, 4000 Jones Bridge Rd, Chevy Chase, MD 20815, USA
| | - Anne C Roulin
- Department of Plant and Microbial Biology, University of Zürich, Zollikerstr. 107, 8008 Zürich, Switzerland
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Horvath R, Minadakis N, Bourgeois Y, Roulin AC. The evolution of transposable elements in Brachypodium distachyon is governed by purifying selection, while neutral and adaptive processes play a minor role. eLife 2024; 12:RP93284. [PMID: 38606833 PMCID: PMC11014726 DOI: 10.7554/elife.93284] [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] [Indexed: 04/13/2024] Open
Abstract
Understanding how plants adapt to changing environments and the potential contribution of transposable elements (TEs) to this process is a key question in evolutionary genomics. While TEs have recently been put forward as active players in the context of adaptation, few studies have thoroughly investigated their precise role in plant evolution. Here, we used the wild Mediterranean grass Brachypodium distachyon as a model species to identify and quantify the forces acting on TEs during the adaptation of this species to various conditions, across its entire geographic range. Using sequencing data from more than 320 natural B. distachyon accessions and a suite of population genomics approaches, we reveal that putatively adaptive TE polymorphisms are rare in wild B. distachyon populations. After accounting for changes in past TE activity, we show that only a small proportion of TE polymorphisms evolved neutrally (<10%), while the vast majority of them are under moderate purifying selection regardless of their distance to genes. TE polymorphisms should not be ignored when conducting evolutionary studies, as they can be linked to adaptation. However, our study clearly shows that while they have a large potential to cause phenotypic variation in B. distachyon, they are not favored during evolution and adaptation over other types of mutations (such as point mutations) in this species.
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Affiliation(s)
- Robert Horvath
- Department of Plant and Microbial Biology, University of ZurichZurichSwitzerland
| | - Nikolaos Minadakis
- Department of Plant and Microbial Biology, University of ZurichZurichSwitzerland
| | - Yann Bourgeois
- DIADE, University of Montpellier, CIRAD, IRDMontpellierFrance
- University of PortsmouthPortsmouthUnited Kingdom
| | - Anne C Roulin
- Department of Plant and Microbial Biology, University of ZurichZurichSwitzerland
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Thieme M, Minadakis N, Himber C, Keller B, Xu W, Rutowicz K, Matteoli C, Böhrer M, Rymen B, Laudencia-Chingcuanco D, Vogel JP, Sibout R, Stritt C, Blevins T, Roulin AC. Transposition of HOPPLA in siRNA-deficient plants suggests a limited effect of the environment on retrotransposon mobility in Brachypodium distachyon. PLoS Genet 2024; 20:e1011200. [PMID: 38470914 PMCID: PMC10959353 DOI: 10.1371/journal.pgen.1011200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/22/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
Long terminal repeat retrotransposons (LTR-RTs) are powerful mutagens regarded as a major source of genetic novelty and important drivers of evolution. Yet, the uncontrolled and potentially selfish proliferation of LTR-RTs can lead to deleterious mutations and genome instability, with large fitness costs for their host. While population genomics data suggest that an ongoing LTR-RT mobility is common in many species, the understanding of their dual role in evolution is limited. Here, we harness the genetic diversity of 320 sequenced natural accessions of the Mediterranean grass Brachypodium distachyon to characterize how genetic and environmental factors influence plant LTR-RT dynamics in the wild. When combining a coverage-based approach to estimate global LTR-RT copy number variations with mobilome-sequencing of nine accessions exposed to eight different stresses, we find little evidence for a major role of environmental factors in LTR-RT accumulations in B. distachyon natural accessions. Instead, we show that loss of RNA polymerase IV (Pol IV), which mediates RNA-directed DNA methylation in plants, results in high transcriptional and transpositional activities of RLC_BdisC024 (HOPPLA) LTR-RT family elements, and that these effects are not stress-specific. This work supports findings indicating an ongoing mobility in B. distachyon and reveals that host RNA-directed DNA methylation rather than environmental factors controls their mobility in this wild grass model.
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Affiliation(s)
- Michael Thieme
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Nikolaos Minadakis
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Christophe Himber
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Bettina Keller
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Wenbo Xu
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Kinga Rutowicz
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Calvin Matteoli
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Marcel Böhrer
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Bart Rymen
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Debbie Laudencia-Chingcuanco
- United States Department of Agriculture Agricultural Research Service Western Regional Research Center, Albany, California, United States of America
| | - John P. Vogel
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Richard Sibout
- Institut National de la Recherche Agronomique Unité BIA- 1268 Biopolymères Interactions Assemblages Equipe Paroi Végétale et Polymères Pariétaux (PVPP), Nantes, France
| | - Christoph Stritt
- Swiss Tropical and Public Health Institute (Swiss TPH), Allschwil, Switzerland
| | - Todd Blevins
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Anne C. Roulin
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
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Jaegle B, Pisupati R, Soto-Jiménez LM, Burns R, Rabanal FA, Nordborg M. Extensive sequence duplication in Arabidopsis revealed by pseudo-heterozygosity. Genome Biol 2023; 24:44. [PMID: 36895055 PMCID: PMC9999624 DOI: 10.1186/s13059-023-02875-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/13/2023] [Indexed: 03/11/2023] Open
Abstract
BACKGROUND It is apparent that genomes harbor much structural variation that is largely undetected for technical reasons. Such variation can cause artifacts when short-read sequencing data are mapped to a reference genome. Spurious SNPs may result from mapping of reads to unrecognized duplicated regions. Calling SNP using the raw reads of the 1001 Arabidopsis Genomes Project we identified 3.3 million (44%) heterozygous SNPs. Given that Arabidopsis thaliana (A. thaliana) is highly selfing, and that extensively heterozygous individuals have been removed, we hypothesize that these SNPs reflected cryptic copy number variation. RESULTS The heterozygosity we observe consists of particular SNPs being heterozygous across individuals in a manner that strongly suggests it reflects shared segregating duplications rather than random tracts of residual heterozygosity due to occasional outcrossing. Focusing on such pseudo-heterozygosity in annotated genes, we use genome-wide association to map the position of the duplicates. We identify 2500 putatively duplicated genes and validate them using de novo genome assemblies from six lines. Specific examples included an annotated gene and nearby transposon that transpose together. We also demonstrate that cryptic structural variation produces highly inaccurate estimates of DNA methylation polymorphism. CONCLUSIONS Our study confirms that most heterozygous SNP calls in A. thaliana are artifacts and suggest that great caution is needed when analyzing SNP data from short-read sequencing. The finding that 10% of annotated genes exhibit copy-number variation, and the realization that neither gene- nor transposon-annotation necessarily tells us what is actually mobile in the genome suggests that future analyses based on independently assembled genomes will be very informative.
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Affiliation(s)
- Benjamin Jaegle
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria
| | - Rahul Pisupati
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria
| | | | - Robin Burns
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | | | - Magnus Nordborg
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria.
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Hasterok R, Catalan P, Hazen SP, Roulin AC, Vogel JP, Wang K, Mur LAJ. Brachypodium: 20 years as a grass biology model system; the way forward? TRENDS IN PLANT SCIENCE 2022; 27:1002-1016. [PMID: 35644781 DOI: 10.1016/j.tplants.2022.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 04/13/2022] [Accepted: 04/26/2022] [Indexed: 06/15/2023]
Abstract
It has been 20 years since Brachypodium distachyon was suggested as a model grass species, but ongoing research now encompasses the entire genus. Extensive Brachypodium genome sequencing programmes have provided resources to explore the determinants and drivers of population diversity. This has been accompanied by cytomolecular studies to make Brachypodium a platform to investigate speciation, polyploidisation, perenniality, and various aspects of chromosome and interphase nucleus organisation. The value of Brachypodium as a functional genomic platform has been underscored by the identification of key genes for development, biotic and abiotic stress, and cell wall structure and function. While Brachypodium is relevant to the biofuel industry, its impact goes far beyond that as an intriguing model to study climate change and combinatorial stress.
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Affiliation(s)
- Robert Hasterok
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice 40-032, Poland.
| | - Pilar Catalan
- Department of Agricultural and Environmental Sciences, High Polytechnic School of Huesca, University of Zaragoza, Huesca 22071, Spain; Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza E-50059, Spain
| | - Samuel P Hazen
- Biology Department, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Anne C Roulin
- Department of Plant and Microbial Biology, University of Zürich, Zürich 8008, Switzerland
| | - John P Vogel
- DOE Joint Genome Institute, Berkeley, CA 94720, USA; University California, Berkeley, Berkeley, CA 94720, USA
| | - Kai Wang
- School of Life Sciences, Nantong University, Nantong 226019, Jiangsu, China
| | - Luis A J Mur
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Edward Llwyd Building, Aberystwyth SY23 3DA, UK; College of Agronomy, Shanxi Agricultural University, Taiyuan 030801, Shanxi, China.
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