1
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Gutiérrez-Valencia J, Zervakis PI, Postel Z, Fracassetti M, Losvik A, Mehrabi S, Bunikis I, Soler L, Hughes PW, Désamoré A, Laenen B, Abdelaziz M, Pettersson OV, Arroyo J, Slotte T. Genetic Causes and Genomic Consequences of Breakdown of Distyly in Linum trigynum. Mol Biol Evol 2024; 41:msae087. [PMID: 38709782 PMCID: PMC11114476 DOI: 10.1093/molbev/msae087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/22/2024] [Accepted: 04/29/2024] [Indexed: 05/08/2024] Open
Abstract
Distyly is an iconic floral polymorphism governed by a supergene, which promotes efficient pollen transfer and outcrossing through reciprocal differences in the position of sexual organs in flowers, often coupled with heteromorphic self-incompatibility. Distyly has evolved convergently in multiple flowering plant lineages, but has also broken down repeatedly, often resulting in homostylous, self-compatible populations with elevated rates of self-fertilization. Here, we aimed to study the genetic causes and genomic consequences of the shift to homostyly in Linum trigynum, which is closely related to distylous Linum tenue. Building on a high-quality genome assembly, we show that L. trigynum harbors a genomic region homologous to the dominant haplotype of the distyly supergene conferring long stamens and short styles in L. tenue, suggesting that loss of distyly first occurred in a short-styled individual. In contrast to homostylous Primula and Fagopyrum, L. trigynum harbors no fixed loss-of-function mutations in coding sequences of S-linked distyly candidate genes. Instead, floral gene expression analyses and controlled crosses suggest that mutations downregulating the S-linked LtWDR-44 candidate gene for male self-incompatibility and/or anther height could underlie homostyly and self-compatibility in L. trigynum. Population genomic analyses of 224 whole-genome sequences further demonstrate that L. trigynum is highly self-fertilizing, exhibits significantly lower genetic diversity genome-wide, and is experiencing relaxed purifying selection and less frequent positive selection on nonsynonymous mutations relative to L. tenue. Our analyses shed light on the loss of distyly in L. trigynum, and advance our understanding of a common evolutionary transition in flowering plants.
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Affiliation(s)
- Juanita Gutiérrez-Valencia
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Panagiotis-Ioannis Zervakis
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Zoé Postel
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Marco Fracassetti
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Aleksandra Losvik
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Sara Mehrabi
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Ignas Bunikis
- Department of Immunology, Genetics and Pathology, Uppsala Genome Center, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Lucile Soler
- Department of Medical Biochemistry and Microbiology, Uppsala University, National Bioinformatics Infrastructure Sweden (NBIS), Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - P William Hughes
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Aurélie Désamoré
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Benjamin Laenen
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | | | - Olga Vinnere Pettersson
- Department of Immunology, Genetics and Pathology, Uppsala Genome Center, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Juan Arroyo
- Department of Plant Biology and Ecology, University of Seville, Seville, Spain
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
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2
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Runemark A, Moore EC, Larson EL. Hybridization and gene expression: Beyond differentially expressed genes. Mol Ecol 2024:e17303. [PMID: 38411307 DOI: 10.1111/mec.17303] [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: 12/03/2023] [Revised: 02/06/2024] [Accepted: 02/15/2024] [Indexed: 02/28/2024]
Abstract
Gene expression has a key role in reproductive isolation, and studies of hybrid gene expression have identified mechanisms causing hybrid sterility. Here, we review the evidence for altered gene expression following hybridization and outline the mechanisms shown to contribute to altered gene expression in hybrids. Transgressive gene expression, transcending that of both parental species, is pervasive in early generation sterile hybrids, but also frequently observed in viable, fertile hybrids. We highlight studies showing that hybridization can result in transgressive gene expression, also in established hybrid lineages or species. Such extreme patterns of gene expression in stabilized hybrid taxa suggest that altered hybrid gene expression may result in hybridization-derived evolutionary novelty. We also conclude that while patterns of misexpression in hybrids are well documented, the understanding of the mechanisms causing misexpression is lagging. We argue that jointly assessing differences in cell composition and cell-specific changes in gene expression in hybrids, in addition to assessing changes in chromatin and methylation, will significantly advance our understanding of the basis of altered gene expression. Moreover, uncovering to what extent evolution of gene expression results in altered expression for individual genes, or entire networks of genes, will advance our understanding of how selection moulds gene expression. Finally, we argue that jointly studying the dual roles of altered hybrid gene expression, serving both as a mechanism for reproductive isolation and as a substrate for hybrid ecological adaptation, will lead to significant advances in our understanding of the evolution of gene expression.
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Affiliation(s)
- Anna Runemark
- Department of Biology, Lund University, Lund, Sweden
| | - Emily C Moore
- Department of Biological Sciences, University of Denver, Denver, Colorado, USA
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Erica L Larson
- Department of Biological Sciences, University of Denver, Denver, Colorado, USA
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3
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Identification of Distant Regulatory Elements Using Expression Quantitative Trait Loci Mapping for Heat-Responsive Genes in Oysters. Genes (Basel) 2021; 12:genes12071040. [PMID: 34356056 PMCID: PMC8303352 DOI: 10.3390/genes12071040] [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: 05/30/2021] [Revised: 06/27/2021] [Accepted: 06/28/2021] [Indexed: 11/17/2022] Open
Abstract
Many marine ectotherms, especially those inhabiting highly variable intertidal zones, develop high phenotypic plasticity in response to rapid climate change by modulating gene expression levels. Herein, we examined the regulatory architecture of heat-responsive gene expression plasticity in oysters using expression quantitative trait loci (eQTL) analysis. Using a backcross family of Crassostrea gigas and its sister species Crassostrea angulata under acute stress, 56 distant regulatory regions accounting for 6–26.6% of the gene expression variation were identified for 19 heat-responsive genes. In total, 831 genes and 164 single nucleotide polymorphisms (SNPs) that could potentially regulate expression of the target genes were screened in the eQTL region. The association between three SNPs and the corresponding target genes was verified in an independent family. Specifically, Marker13973 was identified for heat shock protein (HSP) family A member 9 (HspA9). Ribosomal protein L10a (RPL10A) was detected approximately 2 kb downstream of the distant regulatory SNP. Further, Marker14346-48 and Marker14346-85 were in complete linkage disequilibrium and identified for autophagy-related gene 7 (ATG7). Nuclear respiratory factor 1 (NRF1) was detected approximately 3 kb upstream of the two SNPs. These results suggested regulatory relationships between RPL10A and HSPA9 and between NRF1 and ATG7. Our findings indicate that distant regulatory mutations play an important role in the regulation of gene expression plasticity by altering upstream regulatory factors in response to heat stress. The identified eQTLs provide candidate biomarkers for predicting the persistence of oysters under future climate change scenarios.
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4
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Gao Z, Li H, Yang X, Yang P, Chen J, Shi T. Biased allelic expression in tissues of F1 hybrids between tropical and temperate lotus (Nelumbo nuicfera). PLANT MOLECULAR BIOLOGY 2021; 106:207-220. [PMID: 33738679 DOI: 10.1007/s11103-021-01138-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/05/2021] [Indexed: 06/12/2023]
Abstract
The genome-wide allele-specific expression in F1 hybrids from the cross of tropical and temperate lotus unveils how cis-regulatory divergences affect genes in key pathways related to ecotypic divergence. Genetic variation, particularly cis-regulatory variation, plays a crucial role in phenotypic variation and adaptive evolution in plants. Temperate and tropical lotus, the two ecotypes of Nelumbo nucifera, show distinction in the degree of rhizome enlargement, which is associated with winter dormancy. To understand the roles of genome-wide cis-regulatory divergences on adaptive evolution of temperate and tropical lotus (Nelumbo nucifera), here we performed allele-specific expression (ASE) analyses on the tissues including flowers, leaves and rhizome from F1 hybrids of tropical and temperate lotus. For all investigated tissues in F1s, about 36% of genes showed ASE and about 3% of genes showed strong consistent ASE. Most of ASEs were biased towards the tropical parent in all surveyed samples, indicating that the tropical genome might be dominant over the temperate genome in gene expression of tissues from their F1 hybrids. We found that promoter sequences with similar allelic expression are more conserved than genes with significant or conditional ASE, suggesting the cis-regulatory sequence divergence underlie the allelic expression bias. We further uncovered biased genes being related to phenotypic differentiation between two lotus ecotypes, especially metabolic and phytohormone-related pathways in the rhizome. Overall, our study provides a global landscape of cis-regulatory variations between two lotus ecotypes and highlights their roles in rhizome growth variation for the climatic adaptation.
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Affiliation(s)
- Zhiyan Gao
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hui Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xingyu Yang
- Wuhan Institute of Landscape Architecture, Wuhan, 430081, China
| | - Pingfang Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Jinming Chen
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China.
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China.
| | - Tao Shi
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China.
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China.
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5
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Dziasek K, Simon L, Lafon-Placette C, Laenen B, Wärdig C, Santos-González J, Slotte T, Köhler C. Hybrid seed incompatibility in Capsella is connected to chromatin condensation defects in the endosperm. PLoS Genet 2021; 17:e1009370. [PMID: 33571184 PMCID: PMC7904229 DOI: 10.1371/journal.pgen.1009370] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 02/24/2021] [Accepted: 01/15/2021] [Indexed: 11/18/2022] Open
Abstract
Hybridization of closely related plant species is frequently connected to endosperm arrest and seed failure, for reasons that remain to be identified. In this study, we investigated the molecular events accompanying seed failure in hybrids of the closely related species pair Capsella rubella and C. grandiflora. Mapping of QTL for the underlying cause of hybrid incompatibility in Capsella identified three QTL that were close to pericentromeric regions. We investigated whether there are specific changes in heterochromatin associated with interspecific hybridizations and found a strong reduction of chromatin condensation in the endosperm, connected with a strong loss of CHG and CHH methylation and random loss of a single chromosome. Consistent with reduced DNA methylation in the hybrid endosperm, we found a disproportionate deregulation of genes located close to pericentromeric regions, suggesting that reduced DNA methylation allows access of transcription factors to targets located in heterochromatic regions. Since the identified QTL were also associated with pericentromeric regions, we propose that relaxation of heterochromatin in response to interspecies hybridization exposes and activates loci leading to hybrid seed failure.
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Affiliation(s)
- Katarzyna Dziasek
- Department of Plant Biology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala, Sweden
| | - Lauriane Simon
- Department of Plant Biology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala, Sweden
| | - Clément Lafon-Placette
- Department of Plant Biology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala, Sweden
- Present address: Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic
| | - Benjamin Laenen
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Cecilia Wärdig
- Department of Plant Biology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala, Sweden
| | - Juan Santos-González
- Department of Plant Biology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Claudia Köhler
- Department of Plant Biology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala, Sweden
- * E-mail:
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6
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Song MJ, Potter BI, Doyle JJ, Coate JE. Gene Balance Predicts Transcriptional Responses Immediately Following Ploidy Change in Arabidopsis thaliana. THE PLANT CELL 2020; 32:1434-1448. [PMID: 32184347 PMCID: PMC7203931 DOI: 10.1105/tpc.19.00832] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 02/18/2020] [Accepted: 03/14/2020] [Indexed: 05/22/2023]
Abstract
The gene balance hypothesis postulates that there is selection on gene copy number (gene dosage) to preserve the stoichiometric balance among interacting proteins. This presupposes that gene product abundance is governed by gene dosage and that gene dosage responses are consistent for interacting genes in a dosage-balance-sensitive network or complex. Gene dosage responses, however, have rarely been quantified, and the available data suggest that they are highly variable. We sequenced the transcriptomes of two synthetic autopolyploid accessions of Arabidopsis (Arabidopsis thaliana) and their diploid progenitors, as well as one natural tetraploid and its synthetic diploid produced via haploid induction, to estimate transcriptome size and dosage responses immediately following ploidy change. Similar to what has been observed in previous studies, overall transcriptome size does not exhibit a simple doubling in response to genome doubling, and individual gene dosage responses are highly variable in all three accessions, indicating that expression is not strictly coupled with gene dosage. Nonetheless, putatively dosage balance-sensitive gene groups (Gene Ontology terms, metabolic networks, gene families, and predicted interacting proteins) exhibit smaller and more coordinated dosage responses than do putatively dosage-insensitive gene groups, suggesting that constraints on dosage balance operate immediately following whole-genome duplication and that duplicate gene retention patterns are shaped by selection to preserve dosage balance.
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Affiliation(s)
- Michael J Song
- University and Jepson Herbaria and Department of Integrative Biology, University of California, Berkeley, California 94720
| | - Barney I Potter
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
| | - Jeff J Doyle
- School of Integrative Plant Science, Cornell University, Ithaca, New York 14853
| | - Jeremy E Coate
- Department of Biology, Reed College, Portland, Oregon 97202
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7
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Mattila TM, Laenen B, Slotte T. Population Genomics of Transitions to Selfing in Brassicaceae Model Systems. Methods Mol Biol 2020; 2090:269-287. [PMID: 31975171 DOI: 10.1007/978-1-0716-0199-0_11] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Many plants harbor complex mechanisms that promote outcrossing and efficient pollen transfer. These include floral adaptations as well as genetic mechanisms, such as molecular self-incompatibility (SI) systems. The maintenance of such systems over long evolutionary timescales suggests that outcrossing is favorable over a broad range of conditions. Conversely, SI has repeatedly been lost, often in association with transitions to self-fertilization (selfing). This transition is favored when the short-term advantages of selfing outweigh the costs, primarily inbreeding depression. The transition to selfing is expected to have major effects on population genetic variation and adaptive potential, as well as on genome evolution. In the Brassicaceae, many studies on the population genetic, gene regulatory, and genomic effects of selfing have centered on the model plant Arabidopsis thaliana and the crucifer genus Capsella. The accumulation of population genomics datasets have allowed detailed investigation of where, when and how the transition to selfing occurred. Future studies will take advantage of the development of population genetics theory on the impact of selfing, especially regarding positive selection. Furthermore, investigation of systems including recent transitions to selfing, mixed mating populations and/or multiple independent replicates of the same transition will facilitate dissecting the effects of mating system variation from processes driven by demography.
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Affiliation(s)
- Tiina M Mattila
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Benjamin Laenen
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden.
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8
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Bachmann JA, Tedder A, Laenen B, Fracassetti M, Désamoré A, Lafon-Placette C, Steige KA, Callot C, Marande W, Neuffer B, Bergès H, Köhler C, Castric V, Slotte T. Genetic basis and timing of a major mating system shift in Capsella. THE NEW PHYTOLOGIST 2019; 224:505-517. [PMID: 31254395 DOI: 10.1111/nph.16035] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 06/20/2019] [Indexed: 05/23/2023]
Abstract
A crucial step in the transition from outcrossing to self-fertilization is the loss of genetic self-incompatibility (SI). In the Brassicaceae, SI involves the interaction of female and male specificity components, encoded by the genes SRK and SCR at the self-incompatibility locus (S-locus). Theory predicts that S-linked mutations, and especially dominant mutations in SCR, are likely to contribute to loss of SI. However, few studies have investigated the contribution of dominant mutations to loss of SI in wild plant species. Here, we investigate the genetic basis of loss of SI in the self-fertilizing crucifer species Capsella orientalis, by combining genetic mapping, long-read sequencing of complete S-haplotypes, gene expression analyses and controlled crosses. We show that loss of SI in C. orientalis occurred < 2.6 Mya and maps as a dominant trait to the S-locus. We identify a fixed frameshift deletion in the male specificity gene SCR and confirm loss of male SI specificity. We further identify an S-linked small RNA that is predicted to cause dominance of self-compatibility. Our results agree with predictions on the contribution of dominant S-linked mutations to loss of SI, and thus provide new insights into the molecular basis of mating system transitions.
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Affiliation(s)
- Jörg A Bachmann
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Andrew Tedder
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Benjamin Laenen
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Marco Fracassetti
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Aurélie Désamoré
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Clément Lafon-Placette
- Department of Plant Biology, Swedish University of Agricultural Sciences & Linnean Center for Plant Biology, SE-750 07, Uppsala, Sweden
| | - Kim A Steige
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Caroline Callot
- Institut National de la Recherche Agronomique, UPR 1258, Centre National des Ressources Génomiques Végétales, 31326, Castanet-Tolosan, France
| | - William Marande
- Institut National de la Recherche Agronomique, UPR 1258, Centre National des Ressources Génomiques Végétales, 31326, Castanet-Tolosan, France
| | - Barbara Neuffer
- Department of Botany, University of Osnabruck, 49076, Osnabrück, Germany
| | - Hélène Bergès
- Institut National de la Recherche Agronomique, UPR 1258, Centre National des Ressources Génomiques Végétales, 31326, Castanet-Tolosan, France
| | - Claudia Köhler
- Department of Plant Biology, Swedish University of Agricultural Sciences & Linnean Center for Plant Biology, SE-750 07, Uppsala, Sweden
| | - Vincent Castric
- Univ. Lille, CNRS, UMR 8198 - Evo-Eco-Paleo, F-59000, Lille, France
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
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9
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Abstract
Fruit morphological diversity reflects the versatility of these angiosperm-specific structures, which facilitate plant progeny dispersal from their sessile parents. A recent study links regulatory changes in a key genetic network for fruit patterning with the origin of heart-shaped pods in Brassicaceae.
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Affiliation(s)
- Cristina Ferrandiz
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain.
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10
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de Meaux J. Cis-regulatory variation in plant genomes and the impact of natural selection. AMERICAN JOURNAL OF BOTANY 2018; 105:1788-1791. [PMID: 30358892 PMCID: PMC7610988 DOI: 10.1002/ajb2.1180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/09/2018] [Indexed: 05/04/2023]
Abstract
Understanding the molecular mechanisms that allow phenotypic diversification in response to natural or artificial selection is one of the major challenges of modern biology (Barrett and Hoekstra, 2011). The evolution of gene regulation is a prominent pillar for adaptation in sessile organisms like plants because the activity of genes must be tuned to the environment. Today, we can accurately document the genome-wide distribution of cis-regulatory variants. Here, I summarize how current data show that both positive selection and purifying selection contribute to shape cis-regulatory variation. To disentangle their relative impact, I argue that cis-regulatory and amino-acid evolutionary rates should be analyzed jointly.
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Affiliation(s)
- Juliette de Meaux
- Institute of Botany, University of Cologne, Zülpicherstr 47b, 50674 Cologne, Germany
- Author for correspondence ()
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11
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Gould BA, Chen Y, Lowry DB. Gene regulatory divergence between locally adapted ecotypes in their native habitats. Mol Ecol 2018; 27:4174-4188. [PMID: 30168223 DOI: 10.1111/mec.14852] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 08/15/2018] [Accepted: 08/19/2018] [Indexed: 01/04/2023]
Abstract
Local adaptation is a key driver of ecological specialization and the formation of new species. Despite its importance, the evolution of gene regulatory divergence among locally adapted populations is poorly understood, especially how that divergence manifests in nature. Here, we evaluate gene expression divergence and allele-specific gene expression responses for locally adapted coastal perennial and inland annual accessions of the yellow monkeyflower, Mimulus guttatus, in a field reciprocal transplant experiment. Overall, 6765 (73%) of surveyed genes were differentially expressed between coastal and inland habitats, while 7213 (77%) were differentially expressed between the coastal perennial and inland annual accessions. Cis-regulatory variation was pervasive, affecting 79% (5532) of differentially expressed genes. We detected trans effects for 52% (3611) of differentially expressed genes. Expression plasticity of alleles across habitats (G × E interactions) appears to be relatively common (affecting 18% of transcripts) and could minimize fitness trade-offs at loci that contribute to local adaptation. We also found evidence that at least one chromosomal inversion may act as supergene by holding together haplotypes of differentially expressed genes, but this pattern depends on habitat context. Our results highlight multiple key patterns regarding the relationship between gene expression and the evolution of locally adapted populations.
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Affiliation(s)
- Billie A Gould
- Department of Plant Biology, Michigan State University, East Lansing, Michigan.,Myriad Women's Health, South San Francisco, California
| | - Yani Chen
- Department of Plant Biology, Michigan State University, East Lansing, Michigan
| | - David B Lowry
- Department of Plant Biology, Michigan State University, East Lansing, Michigan.,Program in Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, Michigan.,Plant Resilience Institute, Michigan State University, East Lansing, Michigan
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12
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Horvath R, Slotte T. The Role of Small RNA-Based Epigenetic Silencing for Purifying Selection on Transposable Elements in Capsella grandiflora. Genome Biol Evol 2018; 9:2911-2920. [PMID: 29036316 PMCID: PMC5737465 DOI: 10.1093/gbe/evx206] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2017] [Indexed: 12/13/2022] Open
Abstract
To avoid negative effects of transposable element (TE) proliferation, plants epigenetically silence TEs using a number of mechanisms, including RNA-directed DNA methylation. These epigenetic modifications can extend outside the boundaries of TE insertions and lead to silencing of nearby genes, resulting in a trade-off between TE silencing and interference with nearby gene regulation. Therefore, purifying selection is expected to remove silenced TE insertions near genes more efficiently and prevent their accumulation within a population. To explore how effects of TE silencing on gene regulation shapes purifying selection on TEs, we analyzed whole genome sequencing data from 166 individuals of a large population of the outcrossing species Capsella grandiflora. We found that most TEs are rare, and in chromosome arms, silenced TEs are exposed to stronger purifying selection than those that are not silenced by 24-nucleotide small RNAs, especially with increasing proximity to genes. An age-of-allele test of neutrality on a subset of TEs supports our inference of purifying selection on silenced TEs, suggesting that our results are robust to varying transposition rates. Our results provide new insights into the processes affecting the accumulation of TEs in an outcrossing species and support the view that epigenetic silencing of TEs results in a trade-off between preventing TE proliferation and interference with nearby gene regulation. We also suggest that in the centromeric and pericentromeric regions, the negative aspects of epigenetic TE silencing are missing.
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Affiliation(s)
- Robert Horvath
- Science for Life Laboratory, Department of Ecology, Environment and Plant Sciences, Stockholm University, Sweden
| | - Tanja Slotte
- Science for Life Laboratory, Department of Ecology, Environment and Plant Sciences, Stockholm University, Sweden
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13
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Cesar ASM, Regitano LCA, Reecy JM, Poleti MD, Oliveira PSN, de Oliveira GB, Moreira GCM, Mudadu MA, Tizioto PC, Koltes JE, Fritz-Waters E, Kramer L, Garrick D, Beiki H, Geistlinger L, Mourão GB, Zerlotini A, Coutinho LL. Identification of putative regulatory regions and transcription factors associated with intramuscular fat content traits. BMC Genomics 2018; 19:499. [PMID: 29945546 PMCID: PMC6020320 DOI: 10.1186/s12864-018-4871-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 06/14/2018] [Indexed: 12/21/2022] Open
Abstract
Background Integration of high throughput DNA genotyping and RNA-sequencing data allows for the identification of genomic regions that control gene expression, known as expression quantitative trait loci (eQTL), on a whole genome scale. Intramuscular fat (IMF) content and carcass composition play important roles in metabolic and physiological processes in mammals because they influence insulin sensitivity and consequently prevalence of metabolic diseases such as obesity and type 2 diabetes. However, limited information is available on the genetic variants and mechanisms associated with IMF deposition in mammals. Thus, our hypothesis was that eQTL analyses could identify putative regulatory regions and transcription factors (TFs) associated with intramuscular fat (IMF) content traits. Results We performed an integrative eQTL study in skeletal muscle to identify putative regulatory regions and factors associated with intramuscular fat content traits. Data obtained from skeletal muscle samples of 192 animals was used for association analysis between 461,466 SNPs and the transcription level of 11,808 genes. This yielded 1268 cis- and 10,334 trans-eQTLs, among which we identified nine hotspot regions that each affected the expression of > 119 genes. These putative regulatory regions overlapped with previously identified QTLs for IMF content. Three of the hotspots respectively harbored the transcription factors USF1, EGR4 and RUNX1T1, which are known to play important roles in lipid metabolism. From co-expression network analysis, we further identified modules significantly correlated with IMF content and associated with relevant processes such as fatty acid metabolism, carbohydrate metabolism and lipid metabolism. Conclusion This study provides novel insights into the link between genotype and IMF content as evident from the expression level. It thereby identifies genomic regions of particular importance and associated regulatory factors. These new findings provide new knowledge about the biological processes associated with genetic variants and mechanisms associated with IMF deposition in mammals. Electronic supplementary material The online version of this article (10.1186/s12864-018-4871-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aline S M Cesar
- Department of Animal Science, University of São Paulo, Piracicaba, SP, 13418-900, Brazil.,Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | | | - James M Reecy
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - Mirele D Poleti
- Department of Animal Science, University of São Paulo, Piracicaba, SP, 13418-900, Brazil
| | | | | | - Gabriel C M Moreira
- Department of Animal Science, University of São Paulo, Piracicaba, SP, 13418-900, Brazil
| | | | - Polyana C Tizioto
- Department of Animal Science, University of São Paulo, Piracicaba, SP, 13418-900, Brazil
| | - James E Koltes
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - Elyn Fritz-Waters
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - Luke Kramer
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - Dorian Garrick
- School of Agriculture, Massey University, Ruakura, Hamilton, New Zealand
| | - Hamid Beiki
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | | | - Gerson B Mourão
- Department of Animal Science, University of São Paulo, Piracicaba, SP, 13418-900, Brazil
| | | | - Luiz L Coutinho
- Department of Animal Science, University of São Paulo, Piracicaba, SP, 13418-900, Brazil.
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14
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Wang M, Uebbing S, Pawitan Y, Scofield DG. RPASE: Individual-based allele-specific expression detection without prior knowledge of haplotype phase. Mol Ecol Resour 2018; 18:1247-1262. [PMID: 29858523 DOI: 10.1111/1755-0998.12909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/09/2018] [Accepted: 05/21/2018] [Indexed: 01/04/2023]
Abstract
Variation in gene expression is believed to make a significant contribution to phenotypic diversity and divergence. The analysis of allele-specific expression (ASE) can reveal important insights into gene expression regulation. We developed a novel method called RPASE (Read-backed Phasing-based ASE detection) to test for genes that show ASE. With mapped RNA-seq data from a single individual and a list of SNPs from the same individual as the only input, RPASE is capable of aggregating information across multiple dependent SNPs and producing individual-based gene-level tests for ASE. RPASE performs well in simulations and comparisons. We applied RPASE to multiple bird species and found a potentially rich landscape of ASE.
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Affiliation(s)
- Mi Wang
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Severin Uebbing
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Yudi Pawitan
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Douglas G Scofield
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
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15
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Fyon F, Lenormand T. Cis-regulator runaway and divergence in asexuals. Evolution 2018; 72:426-439. [DOI: 10.1111/evo.13424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/06/2017] [Accepted: 12/09/2017] [Indexed: 12/26/2022]
Affiliation(s)
- Frédéric Fyon
- CEFE, CNRS, Univ Montpellier, Univ Paul Valéry Montpellier 3, EPHE, IRD; Montpellier France
| | - Thomas Lenormand
- CEFE, CNRS, Univ Montpellier, Univ Paul Valéry Montpellier 3, EPHE, IRD; Montpellier France
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16
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Wang M, Uebbing S, Ellegren H. Bayesian Inference of Allele-Specific Gene Expression Indicates Abundant Cis-Regulatory Variation in Natural Flycatcher Populations. Genome Biol Evol 2017; 9:1266-1279. [PMID: 28453623 PMCID: PMC5434935 DOI: 10.1093/gbe/evx080] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2017] [Indexed: 12/13/2022] Open
Abstract
Polymorphism in cis-regulatory sequences can lead to different levels of expression for the two alleles of a gene, providing a starting point for the evolution of gene expression. Little is known about the genome-wide abundance of genetic variation in gene regulation in natural populations but analysis of allele-specific expression (ASE) provides a means for investigating such variation. We performed RNA-seq of multiple tissues from population samples of two closely related flycatcher species and developed a Bayesian algorithm that maximizes data usage by borrowing information from the whole data set and combines several SNPs per transcript to detect ASE. Of 2,576 transcripts analyzed in collared flycatcher, ASE was detected in 185 (7.2%) and a similar frequency was seen in the pied flycatcher. Transcripts with statistically significant ASE commonly showed the major allele in >90% of the reads, reflecting that power was highest when expression was heavily biased toward one of the alleles. This would suggest that the observed frequencies of ASE likely are underestimates. The proportion of ASE transcripts varied among tissues, being lowest in testis and highest in muscle. Individuals often showed ASE of particular transcripts in more than one tissue (73.4%), consistent with a genetic basis for regulation of gene expression. The results suggest that genetic variation in regulatory sequences commonly affects gene expression in natural populations and that it provides a seedbed for phenotypic evolution via divergence in gene expression.
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Affiliation(s)
- Mi Wang
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Sweden
| | - Severin Uebbing
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Sweden
| | - Hans Ellegren
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Sweden
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17
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Rhoné B, Mariac C, Couderc M, Berthouly-Salazar C, Ousseini IS, Vigouroux Y. No Excess of Cis-Regulatory Variation Associated with Intraspecific Selection in Wild Pearl Millet (Cenchrus americanus). Genome Biol Evol 2017; 9:388-397. [PMID: 28137746 PMCID: PMC5381623 DOI: 10.1093/gbe/evx004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2017] [Indexed: 12/15/2022] Open
Abstract
Several studies suggest that cis-regulatory mutations are the favorite target of evolutionary changes, one reason being that cis-regulatory mutations might have fewer deleterious pleiotropic effects than protein-coding mutations. A review of the process also suggests that this bias towards adaptive cis-regulatory variation might be less pronounced at the intraspecific level compared with the interspecific level. In this study, we assessed the contribution of cis-regulatory variation to adaptation at the intraspecific level using populations of wild pearl millet (Cenchrus americanus ssp. monodii) sampled along an environmental gradient in Niger. From RNA sequencing of hybrids to assess allele-specific expression, we identified genes with cis-regulatory divergence between two parental accessions collected in contrasted environmental conditions. This revealed that ∼15% of transcribed genes showed cis-regulatory variation. Intersecting the gene set exhibiting cis-regulatory variation with the gene set identified as targets of selection revealed no excess of cis-acting mutations among the selected genes. We additionally found no excess of cis-regulatory variation among genes associated with adaptive traits. As our approach relied on methods identifying mainly genes submitted to strong selection pressure or with high phenotypic effect, the contribution of cis-regulatory changes to soft selection or polygenic adaptive traits remains to be tested. However our results favor the hypothesis that enrichment of adaptive cis-regulatory divergence builds up over time. For short evolutionary time-scales, cis-acting mutations are not predominantly involved in adaptive evolution associated with strong selective signal.
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Affiliation(s)
- Bénédicte Rhoné
- Unité Mixte de Recherche Diversité Adaptation et Développement des Plantes (UMR DIADE), Institut de Recherche pour le Développement, Montpellier, France.,Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, Lyon, France
| | - Cédric Mariac
- Unité Mixte de Recherche Diversité Adaptation et Développement des Plantes (UMR DIADE), Institut de Recherche pour le Développement, Montpellier, France
| | - Marie Couderc
- Unité Mixte de Recherche Diversité Adaptation et Développement des Plantes (UMR DIADE), Institut de Recherche pour le Développement, Montpellier, France
| | - Cécile Berthouly-Salazar
- Unité Mixte de Recherche Diversité Adaptation et Développement des Plantes (UMR DIADE), Institut de Recherche pour le Développement, Montpellier, France.,Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux (LMI LAPSE), Centre de Recherche de Bel Air, Dakar, Sénégal
| | - Issaka Salia Ousseini
- Unité Mixte de Recherche Diversité Adaptation et Développement des Plantes (UMR DIADE), Institut de Recherche pour le Développement, Montpellier, France.,Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux (LMI LAPSE), Centre de Recherche de Bel Air, Dakar, Sénégal.,Biology Department, Unité Mixte de Recherche Diversité Adaptation et Développement des plantes (UMR DIADE), Université Montpellier, France.,Université Abdou Moumouni de Niamey, Niger
| | - Yves Vigouroux
- Unité Mixte de Recherche Diversité Adaptation et Développement des Plantes (UMR DIADE), Institut de Recherche pour le Développement, Montpellier, France.,Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux (LMI LAPSE), Centre de Recherche de Bel Air, Dakar, Sénégal.,Biology Department, Unité Mixte de Recherche Diversité Adaptation et Développement des plantes (UMR DIADE), Université Montpellier, France
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18
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Genomic analysis reveals major determinants of cis-regulatory variation in Capsella grandiflora. Proc Natl Acad Sci U S A 2017; 114:1087-1092. [PMID: 28096395 DOI: 10.1073/pnas.1612561114] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Understanding the causes of cis-regulatory variation is a long-standing aim in evolutionary biology. Although cis-regulatory variation has long been considered important for adaptation, we still have a limited understanding of the selective importance and genomic determinants of standing cis-regulatory variation. To address these questions, we studied the prevalence, genomic determinants, and selective forces shaping cis-regulatory variation in the outcrossing plant Capsella grandiflora We first identified a set of 1,010 genes with common cis-regulatory variation using analyses of allele-specific expression (ASE). Population genomic analyses of whole-genome sequences from 32 individuals showed that genes with common cis-regulatory variation (i) are under weaker purifying selection and (ii) undergo less frequent positive selection than other genes. We further identified genomic determinants of cis-regulatory variation. Gene body methylation (gbM) was a major factor constraining cis-regulatory variation, whereas presence of nearby transposable elements (TEs) and tissue specificity of expression increased the odds of ASE. Our results suggest that most common cis-regulatory variation in C. grandiflora is under weak purifying selection, and that gene-specific functional constraints are more important for the maintenance of cis-regulatory variation than genome-scale variation in the intensity of selection. Our results agree with previous findings that suggest TE silencing affects nearby gene expression, and provide evidence for a link between gbM and cis-regulatory constraint, possibly reflecting greater dosage sensitivity of body-methylated genes. Given the extensive conservation of gbM in flowering plants, this suggests that gbM could be an important predictor of cis-regulatory variation in a wide range of plant species.
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19
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Hoban S, Kelley JL, Lotterhos KE, Antolin MF, Bradburd G, Lowry DB, Poss ML, Reed LK, Storfer A, Whitlock MC. Finding the Genomic Basis of Local Adaptation: Pitfalls, Practical Solutions, and Future Directions. Am Nat 2016; 188:379-97. [PMID: 27622873 PMCID: PMC5457800 DOI: 10.1086/688018] [Citation(s) in RCA: 439] [Impact Index Per Article: 54.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Uncovering the genetic and evolutionary basis of local adaptation is a major focus of evolutionary biology. The recent development of cost-effective methods for obtaining high-quality genome-scale data makes it possible to identify some of the loci responsible for adaptive differences among populations. Two basic approaches for identifying putatively locally adaptive loci have been developed and are broadly used: one that identifies loci with unusually high genetic differentiation among populations (differentiation outlier methods) and one that searches for correlations between local population allele frequencies and local environments (genetic-environment association methods). Here, we review the promises and challenges of these genome scan methods, including correcting for the confounding influence of a species' demographic history, biases caused by missing aspects of the genome, matching scales of environmental data with population structure, and other statistical considerations. In each case, we make suggestions for best practices for maximizing the accuracy and efficiency of genome scans to detect the underlying genetic basis of local adaptation. With attention to their current limitations, genome scan methods can be an important tool in finding the genetic basis of adaptive evolutionary change.
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Affiliation(s)
- Sean Hoban
- Morton Arboretum, Lisle, Illinois 60532; and National Institute for Mathematical and Biological Synthesis (NIMBioS), Knoxville, Tennessee 37966
| | - Joanna L. Kelley
- School of Biological Sciences, Washington State University, Pullman, Washington 99164
| | - Katie E. Lotterhos
- Department of Marine and Environmental Sciences, Northeastern University Marine Science Center, Nahant, Massachusetts 01908
| | - Michael F. Antolin
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Gideon Bradburd
- Museum of Vertebrate Zoology and Department of Environmental Science, Policy, and Management, University of California, Berkeley, California 94720
| | - David B. Lowry
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Mary L. Poss
- Department of Biology and Veterinary and Biomedical Sciences, Penn State University, University Park, Pennsylvania 16802
| | - Laura K. Reed
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35406
| | - Andrew Storfer
- School of Biological Sciences, Washington State University, Pullman, Washington 99164
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20
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Hatorangan MR, Laenen B, Steige KA, Slotte T, Köhler C. Rapid Evolution of Genomic Imprinting in Two Species of the Brassicaceae. THE PLANT CELL 2016; 28:1815-27. [PMID: 27465027 PMCID: PMC5006707 DOI: 10.1105/tpc.16.00304] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/16/2016] [Accepted: 07/21/2016] [Indexed: 05/21/2023]
Abstract
Genomic imprinting is an epigenetic phenomenon occurring in mammals and flowering plants that causes genes to adopt a parent-of-origin-specific mode of expression. While the imprinting status of genes is well conserved in mammals, clear estimates for the degree of conservation were lacking in plants. We therefore analyzed the genome-wide imprinting status of Capsella rubella, which shared a common recent ancestor with Arabidopsis thaliana ∼10 to 14 million years ago. However, only ∼14% of maternally expressed genes (MEGs) and ∼29% of paternally expressed genes (PEGs) in C. rubella were commonly imprinted in both species, revealing that genomic imprinting is a rapidly evolving phenomenon in plants. Nevertheless, conserved PEGs exhibited signs of selection, suggesting that a subset of imprinted genes play an important functional role and are therefore maintained in plants. Like in Arabidopsis, PEGs in C. rubella are frequently associated with the presence of transposable elements that preferentially belong to helitron and MuDR families. Our data further reveal that MEGs and PEGs differ in their targeting by 24-nucleotide small RNAs and asymmetric DNA methylation, suggesting different mechanisms establishing DNA methylation at MEGs and PEGs.
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Affiliation(s)
- Marcelinus R Hatorangan
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 750 07 Uppsala, Sweden
| | - Benjamin Laenen
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, 114 18 Stockholm, Sweden
| | - Kim A Steige
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, 114 18 Stockholm, Sweden Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, 75236 Uppsala, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, 114 18 Stockholm, Sweden
| | - Claudia Köhler
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 750 07 Uppsala, Sweden
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21
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Arunkumar R, Maddison TI, Barrett SCH, Wright SI. Recent mating-system evolution in Eichhornia is accompanied by cis-regulatory divergence. THE NEW PHYTOLOGIST 2016; 211:697-707. [PMID: 26990568 DOI: 10.1111/nph.13918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 01/30/2016] [Indexed: 06/05/2023]
Abstract
The evolution of predominant self-fertilization from cross-fertilization in plants is accompanied by diverse changes to morphology, ecology and genetics, some of which likely result from regulatory changes in gene expression. We examined changes in gene expression during early stages in the transition to selfing in populations of animal-pollinated Eichhornia paniculata with contrasting mating patterns. We crossed plants from outcrossing and selfing populations and tested for the presence of allele-specific expression (ASE) in floral buds and leaf tissue of F1 offspring, indicative of cis-regulatory changes. We identified 1365 genes exhibiting ASE in floral buds and leaf tissue. These genes preferentially expressed alleles from outcrossing parents. Moreover, we found evidence that genes exhibiting ASE had a greater nonsynonymous diversity compared to synonymous diversity in the selfing parents. Our results suggest that the transition from outcrossing to high rates of self-fertilization may have the potential to shape the cis-regulatory genomic landscape of angiosperm species, but that the changes in ASE may be moderate, particularly during the early stages of this transition.
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Affiliation(s)
- Ramesh Arunkumar
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Teresa I Maddison
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Stephen I Wright
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
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22
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He F, Arce AL, Schmitz G, Koornneef M, Novikova P, Beyer A, de Meaux J. The Footprint of Polygenic Adaptation on Stress-ResponsiveCis-Regulatory Divergence in theArabidopsis Genus. Mol Biol Evol 2016; 33:2088-101. [DOI: 10.1093/molbev/msw096] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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23
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Steige KA, Slotte T. Genomic legacies of the progenitors and the evolutionary consequences of allopolyploidy. CURRENT OPINION IN PLANT BIOLOGY 2016; 30:88-93. [PMID: 26943938 DOI: 10.1016/j.pbi.2016.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/13/2016] [Accepted: 02/15/2016] [Indexed: 06/05/2023]
Abstract
The formation of an allopolyploid species involves the merger of genomes with separate evolutionary histories and thereby different genomic legacies. Contrary to expectations from theory, genes from one are often lost preferentially in allopolyploids - there is biased fractionation. Here, we provide an overview of two ways in which the genomic legacies of the progenitors may impact the fate of duplicated genes in allopolyploids. Specifically, we discuss the role of homeolog expression biases in setting the stage for biased fractionation, and the evidence for transposable element silencing as a possible mechanism for homeolog expression biases. Finally, we highlight how differences between the progenitors with respect to accumulation of deleterious variation may affect trajectories of duplicate gene evolution in allopolyploids.
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Affiliation(s)
- Kim A Steige
- Department of Ecology and Genetics, Uppsala University, Sweden; Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden.
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24
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Fyon F, Cailleau A, Lenormand T. Enhancer Runaway and the Evolution of Diploid Gene Expression. PLoS Genet 2015; 11:e1005665. [PMID: 26561855 PMCID: PMC4642963 DOI: 10.1371/journal.pgen.1005665] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 10/22/2015] [Indexed: 11/18/2022] Open
Abstract
Evidence is mounting that the evolution of gene expression plays a major role in adaptation and speciation. Understanding the evolution of gene regulatory regions is indeed an essential step in linking genotypes and phenotypes and in understanding the molecular mechanisms underlying evolutionary change. The common view is that expression traits (protein folding, expression timing, tissue localization and concentration) are under natural selection at the individual level. Here, we use a theoretical approach to show that, in addition, in diploid organisms, enhancer strength (i.e., the ability of enhancers to activate transcription) may increase in a runaway process due to competition for expression between homologous enhancer alleles. These alleles may be viewed as self-promoting genetic elements, as they spread without conferring a benefit at the individual level. They gain a selective advantage by getting associated to better genetic backgrounds: deleterious mutations are more efficiently purged when linked to stronger enhancers. This process, which has been entirely overlooked so far, may help understand the observed overrepresentation of cis-acting regulatory changes in between-species phenotypic differences, and sheds a new light on investigating the contribution of gene expression evolution to adaptation. With the advent of new sequencing technologies, the evolution of gene expression regulation is becoming a subject of intensive research. In this paper, we report an entirely new phenomenon acting on the evolution of gene regulatory sequences. We show that in a small genomic region around genes there is a selection pressure to increase expression, such that stronger enhancers are favored. This leads to an open-ended escalation of enhancer strength. This outcome is not a particular case and we expect it to occur for all genes in nearly all eukaryotic diploid organisms. We also show that this escalation is not stopped by stabilizing selection on expression profiles. Indeed, regulators may coevolve to maintain optimal phenotypes despite the enhancer strength escalation. This widespread phenomenon can significantly shift our understanding of gene regulatory regions and opens a wide array of possible tests.
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Affiliation(s)
- Frédéric Fyon
- UMR 5175 CEFE, CNRS, Université Montpellier, Université P. Valéry, EPHE, Montpellier, France
- * E-mail:
| | - Aurélie Cailleau
- UMR 5175 CEFE, CNRS, Université Montpellier, Université P. Valéry, EPHE, Montpellier, France
| | - Thomas Lenormand
- UMR 5175 CEFE, CNRS, Université Montpellier, Université P. Valéry, EPHE, Montpellier, France
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