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Vigneau J, Martinho C, Godfroy O, Zheng M, Haas FB, Borg M, Coelho SM. Interactions between U and V sex chromosomes during the life cycle of Ectocarpus. Development 2024; 151:dev202677. [PMID: 38512707 PMCID: PMC11057875 DOI: 10.1242/dev.202677] [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: 01/04/2024] [Accepted: 03/01/2024] [Indexed: 03/23/2024]
Abstract
In many animals and flowering plants, sex determination occurs in the diploid phase of the life cycle with XX/XY or ZW/ZZ sex chromosomes. However, in early diverging plants and most macroalgae, sex is determined by female (U) or male (V) sex chromosomes in a haploid phase called the gametophyte. Once the U and V chromosomes unite at fertilization to produce a diploid sporophyte, sex determination no longer occurs, raising key questions about the fate of the U and V sex chromosomes in the sporophyte phase. Here, we investigate genetic and molecular interactions of the UV sex chromosomes in both the haploid and diploid phases of the brown alga Ectocarpus. We reveal extensive developmental regulation of sex chromosome genes across its life cycle and implicate the TALE-HD transcription factor OUROBOROS in suppressing sex determination in the diploid phase. Small RNAs may also play a role in the repression of a female sex-linked gene, and transition to the diploid sporophyte coincides with major reconfiguration of histone H3K79me2, suggesting a more intricate role for this histone mark in Ectocarpus development than previously appreciated.
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Affiliation(s)
| | | | - Olivier Godfroy
- Roscoff Biological Station, CNRS-Sorbonne University, Place Georges Teissier, Roscoff 29680, France
| | - Min Zheng
- Max Planck Institute for Biology, 72076 Tübingen, Germany
| | - Fabian B. Haas
- Max Planck Institute for Biology, 72076 Tübingen, Germany
| | - Michael Borg
- Max Planck Institute for Biology, 72076 Tübingen, Germany
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Hoshino M, Cossard G, Haas FB, Kane EI, Kogame K, Jomori T, Wakimoto T, Glemin S, Coelho SM. Parallel loss of sexual reproduction in field populations of a brown alga sheds light on the mechanisms underlying the emergence of asexuality. Nat Ecol Evol 2024; 8:1916-1932. [PMID: 39152327 PMCID: PMC11461277 DOI: 10.1038/s41559-024-02490-w] [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: 02/01/2024] [Accepted: 06/18/2024] [Indexed: 08/19/2024]
Abstract
Sexual reproduction is widespread, but asexual lineages have repeatedly arisen from sexual ancestors across a wide range of eukaryotic taxa. The molecular changes underpinning the switch to asexuality remain elusive, particularly in organisms with haploid sexual systems. Here we explore independent events of loss of sex in the brown alga Scytosiphon, examine the proximate and evolutionary mechanisms involved, and test the importance of sexual conflict on gene expression changes following loss of sex. We find that asexual females ('Amazons') lose ability to produce sex pheromone and, consequently, are incapable of attracting males, whereas they gain rapid parthenogenic development from large, unfertilized eggs. These phenotypic changes are accompanied by convergent changes in gene expression. Decay of female functions, rather than relaxation of sexual antagonism, may be a dominant force at play during the emergence of asexuality in haploid sexual systems. Moreover, we show that haploid purifying selection plays a key role in limiting the accumulation of deleterious alleles in Amazons, and we identify an autosomal locus associated with the Amazon phenotype. The sex chromosome, together with this autosomal locus, may underlie the switch to obligate asexuality in the Amazon populations.
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Affiliation(s)
- Masakazu Hoshino
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
- Research Center for Inland Seas, Kobe University, Rokkodai 1-1, Nadaku, Kobe, Japan
| | - Guillaume Cossard
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Fabian B Haas
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Emma I Kane
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Kazuhiro Kogame
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Takahiro Jomori
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | | | - Sylvain Glemin
- Laboratoire ECOBIO (Ecosystèmes, biodiversité, évolution), UMR 6553, CNRS, Université de Rennes, Rennes, France
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Susana M Coelho
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany.
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Godfroy O, Zheng M, Yao H, Henschen A, Peters AF, Scornet D, Colin S, Ronchi P, Hipp K, Nagasato C, Motomura T, Cock JM, Coelho SM. The baseless mutant links protein phosphatase 2A with basal cell identity in the brown alga Ectocarpus. Development 2023; 150:dev201283. [PMID: 36786333 PMCID: PMC10112911 DOI: 10.1242/dev.201283] [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: 09/15/2022] [Accepted: 01/16/2023] [Indexed: 02/15/2023]
Abstract
The first mitotic division of the initial cell is a key event in all multicellular organisms and is associated with the establishment of major developmental axes and cell fates. The brown alga Ectocarpus has a haploid-diploid life cycle that involves the development of two multicellular generations: the sporophyte and the gametophyte. Each generation deploys a distinct developmental programme autonomously from an initial cell, the first cell division of which sets up the future body pattern. Here, we show that mutations in the BASELESS (BAS) gene result in multiple cellular defects during the first cell division and subsequent failure to produce basal structures during both generations. BAS encodes a type B″ regulatory subunit of protein phosphatase 2A (PP2A), and transcriptomic analysis identified potential effector genes that may be involved in determining basal cell fate. The bas mutant phenotype is very similar to that observed in distag (dis) mutants, which lack a functional Tubulin-binding co-factor Cd1 (TBCCd1) protein, indicating that TBCCd1 and PP2A are two essential components of the cellular machinery that regulates the first cell division and mediates basal cell fate determination.
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Affiliation(s)
- Olivier Godfroy
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Min Zheng
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Haiqin Yao
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Agnes Henschen
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | | | - Delphine Scornet
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Sebastien Colin
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Paolo Ronchi
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Katharina Hipp
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Chikako Nagasato
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Japan
| | - Taizo Motomura
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Japan
| | - J. Mark Cock
- Laboratory of Integrative Biology of Marine Models, Sorbonne Université, UPMC University of Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff, France
| | - Susana M. Coelho
- Department of Algal Development and Evolution, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
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Mignerot L, Avia K, Luthringer R, Lipinska AP, Peters AF, Cock JM, Coelho SM. A key role for sex chromosomes in the regulation of parthenogenesis in the brown alga Ectocarpus. PLoS Genet 2019; 15:e1008211. [PMID: 31194744 PMCID: PMC6592573 DOI: 10.1371/journal.pgen.1008211] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 06/25/2019] [Accepted: 05/24/2019] [Indexed: 02/06/2023] Open
Abstract
Although evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of these shifts remain largely elusive. Here, we used classic quantitative trait analysis, combined with genomic and transcriptomic information to dissect the genetic basis of asexual, parthenogenetic reproduction in the brown alga Ectocarpus. We found that parthenogenesis is controlled by the sex locus, together with two additional autosomal loci, highlighting the key role of the sex chromosome as a major regulator of asexual reproduction. We identify several negative effects of parthenogenesis on male fitness, and different fitness effects of parthenogenetic capacity depending on the life cycle generation. Although allele frequencies in natural populations are currently unknown, we discuss the possibility that parthenogenesis may be under both sex-specific selection and generation/ploidally-antagonistic selection, and/or that the action of fluctuating selection on this trait may contribute to the maintenance of polymorphisms in populations. Importantly, our data provide the first empirical illustration, to our knowledge, of a trade-off between the haploid and diploid stages of the life cycle, where distinct parthenogenesis alleles have opposing effects on sexual and asexual reproduction and may help maintain genetic variation. These types of fitness trade-offs have profound evolutionary implications in natural populations and may structure life history evolution in organisms with haploid-diploid life cycles.
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Affiliation(s)
- Laure Mignerot
- Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France
| | - Komlan Avia
- Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France
| | - Remy Luthringer
- Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France
| | - Agnieszka P. Lipinska
- Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France
| | | | - J. Mark Cock
- Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France
| | - Susana M. Coelho
- Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France
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Cock JM, Arun A, Godfroy O, Macaisne N, Strittmatter M, Peters AF, Coelho SM. Genomics of brown algae: current advances and future prospects. Genes Genomics 2012. [DOI: 10.1007/s13258-010-0225-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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