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Booker WW, Schrider DR. The genetic consequences of range expansion and its influence on diploidization in polyploids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.18.562992. [PMID: 37905020 PMCID: PMC10614938 DOI: 10.1101/2023.10.18.562992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Despite newly formed polyploids being subjected to myriad fitness consequences, the relative prevalence of polyploidy both contemporarily and in ancestral branches of the tree of life suggests alternative advantages that outweigh these consequences. One proposed advantage is that polyploids may more easily colonize novel habitats such as deglaciated areas. However, previous research conducted in diploids suggests that range expansion comes with a fitness cost as deleterious mutations may fix rapidly on the expansion front. Here, we interrogate the potential consequences of expansion in polyploids by conducting spatially explicit forward-in-time simulations to investigate how ploidy and inheritance patterns impact the relative ability of polyploids to expand their range. We show that under realistic dominance models, autopolyploids suffer greater fitness reductions than diploids as a result of range expansion due to the fixation of increased mutational load that is masked in the range core. Alternatively, the disomic inheritance of allopolyploids provides a shield to this fixation resulting in minimal fitness consequences. In light of this advantage provided by disomy, we investigate how range expansion may influence cytogenetic diploidization through the reversion to disomy in autotetraploids. We show that under a wide range of parameters investigated for two models of diploidization, disomy frequently evolves more rapidly on the expansion front than in the range core, and that this dynamic inheritance model has additional effects on fitness. Together our results point to a complex interaction between dominance, ploidy, inheritance, and recombination on fitness as a population spreads across a geographic range.
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Affiliation(s)
- William W. Booker
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514-2916, United States of America
| | - Daniel R. Schrider
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514-2916, United States of America
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Kalfusová R, Herklotz V, Kumke K, Houben A, Kovařík A, Ritz CM, Lunerová J. Epigenetic histone H3 phosphorylation marks discriminate between univalent- and bivalent-forming chromosomes during canina asymmetrical meiosis. ANNALS OF BOTANY 2024; 133:435-446. [PMID: 38127060 PMCID: PMC11006542 DOI: 10.1093/aob/mcad198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/18/2023] [Indexed: 12/23/2023]
Abstract
BACKGROUND AND AIMS Dogroses (Rosa sect. Caninae) are mostly pentaploid, bearing 2n = 5x = 35 chromosomes in somatic cells. They evolved a unique form of asymmetrical meiosis characterized by two types of chromosomes: (1) chromosomes forming bivalents and distributed in the normal sexual way; and (2) chromosomes occurring as univalents and transferred by a female gamete only. In the mature pollen of pentaploid species, seven bivalent-derived chromosomes are transmitted to offspring, and 21 unpaired univalent chromosomes are eliminated during microsporogenesis. To discriminate between bivalent- and univalent-forming chromosomes, we studied histone H3 phosphorylation patterns regulating meiotic chromosome condensation and segregation. METHODS We analysed histone modification patterns during male canina meiosis in two representative dogrose species, 5x Rosa canina and 5x Rosa rubiginosa, by immunohistochemical and molecular cytogenetics approaches. Immunostaining of meiotic cells included α-tubulin, histone H3 phosphorylation (H3S10p, H3S28p and H3T3p) and methylation (H3K4me3 and H3K27me3) marks. In addition, fluorescent in situ hybridization was carried out with an 18S rDNA probe. KEY RESULTS In the first meiotic division, univalent chromosomes underwent equational division into chromatids, while homologues in bivalents were segregated as regular dyads. In diakinesis, bivalent chromosomes displayed strong H3 phosphorylation signals in proximal regions, spreading to the rest of the chromosome. In contrast, in univalents, the H3 phosphorylation signals were weaker, occurring mostly outside proximal regions largely overlapping with the H3K4me3 signals. Reduced phosphorylation was associated with relative under-condensation of the univalent chromosomes, particularly at early diakinesis. CONCLUSIONS We hypothesize that the absence of pairing and/or recombination in univalent chromosomes negatively affects the histone H3 phosphorylation of their chromatin and perhaps the loading of meiotic-specific cohesins. This apparently destabilizes cohesion of sister chromatids, leading to their premature split in the first meiotic division.
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Affiliation(s)
- Radka Kalfusová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 00 Brno, Czech Republic
| | - Veit Herklotz
- Senckenberg Museum of Natural History, Senckenberg – Member of the Leibniz Association, Am Museum 1, 02826 Görlitz, Germany
| | - Katrin Kumke
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, 06466 Stadt Seeland, Germany
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, 06466 Stadt Seeland, Germany
| | - Aleš Kovařík
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 00 Brno, Czech Republic
| | - Christiane M Ritz
- Senckenberg Museum of Natural History, Senckenberg – Member of the Leibniz Association, Am Museum 1, 02826 Görlitz, Germany
- Chair of Biodiversity of Higher Plants, Technical University Dresden, D-01069, Dresden, Germany
| | - Jana Lunerová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 00 Brno, Czech Republic
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Zavallo D, Cara N, Leone M, Crescente JM, Marfil C, Masuelli R, Asurmendi S. Assessing small RNA profiles in potato diploid hybrid and its resynthesized allopolyploid reveals conserved abundance with distinct genomic distribution. PLANT CELL REPORTS 2024; 43:85. [PMID: 38453711 DOI: 10.1007/s00299-024-03170-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 02/07/2024] [Indexed: 03/09/2024]
Abstract
KEY MESSAGE The shock produced by the allopolyploidization process on a potato interspecific diploid hybrid displays a non-random remobilization of the small RNAs profile on a variety of genomic features. Allopolyploidy, a complex process involving interspecific hybridization and whole genome duplication, significantly impacts plant evolution, leading to the emergence of novel phenotypes. Polyploids often present phenotypic nuances that enhance adaptability, enabling them to compete better and occasionally to colonize new habitats. Whole-genome duplication represents a genomic "shock" that can trigger genetic and epigenetic changes that yield novel expression patterns. In this work, we investigate the polyploidization effect on a diploid interspecific hybrid obtained through the cross between the cultivated potato Solanum tuberosum and the wild potato Solanum kurtzianum, by assessing the small RNAs (sRNAs) profile of the parental diploid hybrid and its derived allopolyploid. Small RNAs are key components of the epigenetic mechanisms involved in silencing by RNA-directed DNA Methylation (RdDM). A sRNA sequencing (sRNA-Seq) analysis was performed to individually profile the 21 to 22 nucleotide (21 to 22-nt) and 24-nt sRNA size classes due to their unique mechanism of biogenesis and mode of function. The composition and distribution of different genomic features and differentially accumulated (DA) sRNAs were evaluated throughout the potato genome. We selected a subset of genes associated with DA sRNAs for messenger RNA (mRNA) expression analysis to assess potential impacts on the transcriptome. Interestingly, we noted that 24-nt DA sRNAs that exclusively mapped to exons were correlated with differentially expressed mRNAs between genotypes, while this behavior was not observed when 24-nt DA sRNAs were mapped to intronic regions. These findings collectively emphasize the nonstochastic nature of sRNA remobilization in response to the genomic shock induced by allopolyploidization.
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Affiliation(s)
- Diego Zavallo
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CICVyA - Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Los Reseros y Nicolás Repetto, 1686, Hurlingham, CP, Argentina
| | - Nicolas Cara
- Instituto de Biología Agrícola de Mendoza (IBAM), Facultad de Ciencias Agrarias (FCA), CONICET-UNCuyo, Almirante Brown 500, M5528AHB, Chacras de Coria, Mendoza, Argentina
| | - Melisa Leone
- Universidad Nacional de Hurlingham, Instituto de Biotecnología, Av. Vergara 2222 (B1688GEZ), Villa Tesei, Buenos Aires, Argentina
| | - Juan Manuel Crescente
- Grupo Biotecnología y Recursos Genéticos, EEA INTA Marcos Juárez, Ruta 12 Km 3, 2580, Marcos Juárez, Argentina
| | - Carlos Marfil
- Estación Experimental Agropecuaria Mendoza, Instituto Nacional de Tecnología Agropecuaria (EEA-Mendoza-INTA), San Martín 3853, Luján de Cuyo, 5534, Mendoza, Argentina
| | - Ricardo Masuelli
- Instituto de Biología Agrícola de Mendoza (IBAM), Facultad de Ciencias Agrarias (FCA), CONICET-UNCuyo, Almirante Brown 500, M5528AHB, Chacras de Coria, Mendoza, Argentina
| | - Sebastián Asurmendi
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CICVyA - Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Los Reseros y Nicolás Repetto, 1686, Hurlingham, CP, Argentina.
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Westermann J, Srikant T, Gonzalo A, Tan HS, Bomblies K. Defective pollen tube tip growth induces neo-polyploid infertility. Science 2024; 383:eadh0755. [PMID: 38422152 DOI: 10.1126/science.adh0755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 01/24/2024] [Indexed: 03/02/2024]
Abstract
Genome duplication (generating polyploids) is an engine of novelty in eukaryotic evolution and a promising crop improvement tool. Yet newly formed polyploids often have low fertility. Here we report that a severe fertility-compromising defect in pollen tube tip growth arises in new polyploids of Arabidopsis arenosa. Pollen tubes of newly polyploid A. arenosa grow slowly, have aberrant anatomy and disrupted physiology, often burst prematurely, and have altered gene expression. These phenotypes recover in evolved polyploids. We also show that gametophytic (pollen tube) genotypes of two tip-growth genes under selection in natural tetraploid A. arenosa are strongly associated with pollen tube performance in the tetraploid. Our work establishes pollen tube tip growth as an important fertility challenge for neo-polyploid plants and provides insights into a naturally evolved multigenic solution.
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Affiliation(s)
- Jens Westermann
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Thanvi Srikant
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Adrián Gonzalo
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Hui San Tan
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Kirsten Bomblies
- Institute of Molecular Plant Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
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Chéron F, Petiot V, Lambing C, White C, Serra H. Incorrect recombination partner associations contribute to meiotic instability of neo-allopolyploid Arabidopsis suecica. THE NEW PHYTOLOGIST 2024; 241:2025-2038. [PMID: 38158491 DOI: 10.1111/nph.19487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024]
Abstract
Combining two or more related homoeologous genomes in a single nucleus, newly formed allopolyploids must rapidly adapt meiosis to restore balanced chromosome segregation, production of euploid gametes and fertility. The poor fertility of such neo-allopolyploids thus strongly selects for the limitation or avoidance of genetic crossover formation between homoeologous chromosomes. In this study, we have reproduced the interspecific hybridization between Arabidopsis thaliana and Arabidopsis arenosa leading to the allotetraploid Arabidopsis suecica and have characterized the first allopolyploid meioses. First-generation neo-allopolyploid siblings vary considerably in fertility, meiotic behavior and levels of homoeologous recombination. We show that centromere dynamics at early meiosis is altered in synthetic neo-allopolyploids compared with evolved A. suecica, with a significant increase in homoeologous centromere interactions at zygotene. At metaphase I, the presence of multivalents involving homoeologous chromosomes confirms that homoeologous recombination occurs in the first-generation synthetic allopolyploid plants and this is associated with a significant reduction in homologous recombination, compared to evolved A. suecica. Together, these data strongly suggest that the fidelity of recombination partner choice, likely during the DNA invasion step, is strongly impaired during the first meiosis of neo-allopolyploids and requires subsequent adaptation.
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Affiliation(s)
- Floriane Chéron
- Genetics, Reproduction and Development Institute (iGReD), CNRS UMR 6293, Inserm U1103, Université Clermont Auvergne, 63000, Clermont-Ferrand, France
| | - Valentine Petiot
- Genetics, Reproduction and Development Institute (iGReD), CNRS UMR 6293, Inserm U1103, Université Clermont Auvergne, 63000, Clermont-Ferrand, France
| | | | - Charles White
- Genetics, Reproduction and Development Institute (iGReD), CNRS UMR 6293, Inserm U1103, Université Clermont Auvergne, 63000, Clermont-Ferrand, France
| | - Heïdi Serra
- Genetics, Reproduction and Development Institute (iGReD), CNRS UMR 6293, Inserm U1103, Université Clermont Auvergne, 63000, Clermont-Ferrand, France
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Wang B, Liang N, Shen X, Xie Z, Zhang L, Tian B, Yuan Y, Guo J, Zhang X, Wei F, Wei X. Cytological and transcriptomic analyses provide insights into the pollen fertility of synthetic allodiploid Brassica juncea hybrids. PLANT CELL REPORTS 2023; 43:23. [PMID: 38150101 DOI: 10.1007/s00299-023-03089-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 10/10/2023] [Indexed: 12/28/2023]
Abstract
KEY MESSAGE Imbalanced chromosomes and cell cycle arrest, along with down-regulated genes in DNA damage repair and sperm cell differentiation, caused pollen abortion in synthetic allodiploid Brassica juncea hybrids. Interspecific hybridization is considered to be a major pathway for species formation and evolution in angiosperms, but the occurrence of pollen abortion in the hybrids is common, prompting us to recheck male gamete development in allodiploid hybrids after the initial combination of different genomes. Here, we investigated the several key meiotic and mitotic events during pollen development using the newly synthesised allodiploid B. juncea hybrids (AB, 2n = 2× = 18) as a model system. Our results demonstrated the partial synapsis and pairing of non-homologous chromosomes concurrent with chaotic spindle assembly, affected chromosome assortment and distribution during meiosis, which finally caused difference in genetic constitution amongst the final tetrads. The mitotic cell cycle arrest during microspore development resulted in the production of anucleate pollen cells. Transcription analysis showed that sets of key genes regulating cyclin (CYCA1;2 and CYCA2;3), DNA damage repair (DMC1, NBS1 and MMD1), and ubiquitin-proteasome pathway (SINAT4 and UBC) were largely downregulated at the early pollen meiosis stages, and those genes involved in sperm cell differentiation (DUO1, PIRL1, PIRL9 and LBD27) and pollen wall synthesis (PME48, VGDH11 and COBL10) were mostly repressed at the late pollen mitosis stages in the synthetic allodiploid B. juncea hybrids (AB). In conclusion, this study elucidated the related mechanisms affecting pollen fertility during male gametophyte development at the cytological and transcriptomic levels in the synthetic allodiploid B. juncea hybrids.
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Affiliation(s)
- Boyang Wang
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, 450002, China
| | - Niannian Liang
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, 450002, China
| | - Xiaohan Shen
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Zhengqing Xie
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Luyue Zhang
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Baoming Tian
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Yuxiang Yuan
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, 450002, China
| | - Jialin Guo
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Xiaowei Zhang
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, 450002, China
| | - Fang Wei
- Henan International Joint Laboratory of Crop Gene Resource and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China.
| | - Xiaochun Wei
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, 450002, China.
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7
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Lv R, Gou X, Li N, Zhang Z, Wang C, Wang R, Wang B, Yang C, Gong L, Zhang H, Liu B. Chromosome translocation affects multiple phenotypes, causes genome-wide dysregulation of gene expression, and remodels metabolome in hexaploid wheat. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:1564-1582. [PMID: 37265000 DOI: 10.1111/tpj.16338] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/17/2023] [Accepted: 05/30/2023] [Indexed: 06/03/2023]
Abstract
Chromosomal rearrangements (CRs) may occur in newly formed polyploids due to compromised meiotic fidelity. Moreover, CRs can be more readily tolerated in polyploids allowing their longer-term retention and hence potential spreading/fixation within a lineage. The direct functional consequences of CRs in plant polyploids remain unexplored. Here, we identified a heterozygous individual from a synthetic allohexaploid wheat in which the terminal parts of the long-arms of chromosomes 2D (approximately 193 Mb) and 4A (approximately 167 Mb) were reciprocally translocated. Five homogeneous translocation lines including both unbalanced and balanced types were developed by selfing fertilization of the founder mutant (RT [2DL; 4AL]-ter/1, reciprocal translocation). We investigated impacts of these translocations on phenotype, genome-wide gene expression and metabolome. We find that, compared with sibling wild-type, CRs in the form of both unbalanced and balanced translocations induced substantial changes of gene expression primarily via trans-regulation in the nascent allopolyploid wheat. The CRs also manifested clear phenotypic and metabolic consequences. In particular, the genetically balanced, stable reciprocal translocations lines showed immediate enhanced reproductive fitness relative to wild type. Our results underscore the profound impact of CRs on gene expression in nascent allopolyploids with wide-ranging phenotypic and metabolic consequences, suggesting CRs are an important source of genetic variation that can be exploited for crop breeding.
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Affiliation(s)
- Ruili Lv
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Xiaowan Gou
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
- School of Life Sciences, Jiangsu Normal University, Xuzhou, 221116, China
| | - Ning Li
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Zhibin Zhang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Changyi Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Ruisi Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Bin Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Chunwu Yang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Lei Gong
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Huakun Zhang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Bao Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
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8
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Resistance strategies for defense against Albugo candida causing white rust disease. Microbiol Res 2023; 270:127317. [PMID: 36805163 DOI: 10.1016/j.micres.2023.127317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 12/12/2022] [Accepted: 02/01/2023] [Indexed: 02/11/2023]
Abstract
Albugo candida, the causal organism of white rust, is an oomycete obligate pathogen infecting crops of Brassicaceae family occurred on aerial part, including vegetable and oilseed crops at all growth stages. The disease expression is characterized by local infection appearing on the abaxial region developing white or creamy yellow blister (sori) on leaves and systemic infections cause hypertrophy and hyperplasia leading to stag-head of reproductive organ. To overcome this problem, several disease management strategies like fungicide treatments were used in the field and disease-resistant varieties have also been developed using conventional and molecular breeding. Due to high variability among A. candida isolates, there is no single approach available to understand the diverse spectrum of disease symptoms. In absence of resistance sources against pathogen, repetitive cultivation of genetically-similar varieties locally tends to attract oomycete pathogen causing heavy yield losses. In the present review, a deep insight into the underlying role of the non-host resistance (NHR) defence mechanism available in plants, and the strategies to exploit available gene pools from plant species that are non-host to A. candida could serve as novel sources of resistance. This work summaries the current knowledge pertaining to the resistance sources available in non-host germ plasm, the understanding of defence mechanisms and the advance strategies covers molecular, biochemical and nature-based solutions in protecting Brassica crops from white rust disease.
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Scarlett VT, Lovell JT, Shao M, Phillips J, Shu S, Lusinska J, Goodstein DM, Jenkins J, Grimwood J, Barry K, Chalhoub B, Schmutz J, Hasterok R, Catalán P, Vogel JP. Multiple origins, one evolutionary trajectory: gradual evolution characterizes distinct lineages of allotetraploid Brachypodium. Genetics 2022; 223:6758249. [PMID: 36218464 PMCID: PMC9910409 DOI: 10.1093/genetics/iyac146] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/16/2022] [Indexed: 11/13/2022] Open
Abstract
The "genomic shock" hypothesis posits that unusual challenges to genome integrity such as whole genome duplication may induce chaotic genome restructuring. Decades of research on polyploid genomes have revealed that this is often, but not always the case. While some polyploids show major chromosomal rearrangements and derepression of transposable elements in the immediate aftermath of whole genome duplication, others do not. Nonetheless, all polyploids show gradual diploidization over evolutionary time. To evaluate these hypotheses, we produced a chromosome-scale reference genome for the natural allotetraploid grass Brachypodium hybridum, accession "Bhyb26." We compared 2 independently derived accessions of B. hybridum and their deeply diverged diploid progenitor species Brachypodium stacei and Brachypodium distachyon. The 2 B. hybridum lineages provide a natural timecourse in genome evolution because one formed 1.4 million years ago, and the other formed 140 thousand years ago. The genome of the older lineage reveals signs of gradual post-whole genome duplication genome evolution including minor gene loss and genome rearrangement that are missing from the younger lineage. In neither B. hybridum lineage do we find signs of homeologous recombination or pronounced transposable element activation, though we find evidence supporting steady post-whole genome duplication transposable element activity in the older lineage. Gene loss in the older lineage was slightly biased toward 1 subgenome, but genome dominance was not observed at the transcriptomic level. We propose that relaxed selection, rather than an abrupt genomic shock, drives evolutionary novelty in B. hybridum, and that the progenitor species' similarity in transposable element load may account for the subtlety of the observed genome dominance.
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Affiliation(s)
- Virginia T Scarlett
- U.S. Dept. of Energy Joint Genome Institute, Berkeley, CA 94720, USA,Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - John T Lovell
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Mingqin Shao
- U.S. Dept. of Energy Joint Genome Institute, Berkeley, CA 94720, USA
| | - Jeremy Phillips
- U.S. Dept. of Energy Joint Genome Institute, Berkeley, CA 94720, USA
| | - Shengqiang Shu
- U.S. Dept. of Energy Joint Genome Institute, Berkeley, CA 94720, USA
| | | | - David M Goodstein
- U.S. Dept. of Energy Joint Genome Institute, Berkeley, CA 94720, USA
| | - Jerry Jenkins
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Jane Grimwood
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Kerrie Barry
- U.S. Dept. of Energy Joint Genome Institute, Berkeley, CA 94720, USA
| | | | - Jeremy Schmutz
- U.S. Dept. of Energy Joint Genome Institute, Berkeley, CA 94720, USA,Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | | | | | - John P Vogel
- Corresponding author: U.S. Dept. of Energy Joint Genome Institute, 1 Cyclotron Road, Berkeley, CA 94720, USA.
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10
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Lv R, Wang C, Wang R, Wang X, Zhao J, Wang B, Aslam T, Han F, Liu B. Chromosomal instability and phenotypic variation in a specific lineage derived from a synthetic allotetraploid wheat. FRONTIERS IN PLANT SCIENCE 2022; 13:981234. [PMID: 36072314 PMCID: PMC9441941 DOI: 10.3389/fpls.2022.981234] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023]
Abstract
Newly formed plant allopolyploids usually have meiosis defect, resulting in chromosomal instability manifested as variation in chromosome number and/or structure. However, not all nascent allopolyploids are equally unstable. The wheat group (Aegilops/Triticum) contains 13 diploid species with distinct genome types. Many of these species can be artificially hybridized to produce viable but sterile inter-specific/intergeneric F1 hybrids, which can generate fertile synthetic allotetraploid wheats after whole genome doubling. Compared with synthetic allotetraploid wheats that contain genome combinations of AADD and S*S*DD (S* refers to related S genomes of a different species), those containing an S*S*AA genome are significantly more stable. However, robustness of the relative stability of S*S*AA genomes is unknown, nor are the phenotypic and fitness consequences during occurrences of secondary chromosomal instability. Here, we report a specific lineage originated from a single individual plant of a relatively stable synthetic allotetraploid wheat with genomes S l S l AA (S l and A subgenomes were from Ae. longissima and T. urartu, respectively) that showed a high degree of transgenerational chromosomal instability. Both numerical chromosome variation (NCV) and structural chromosome variation (SCV) occurred widely. While substantial differences in frequencies of both NCV and SCV were detected across the different chromosomes, only NCV frequencies were significantly different between the two subgenomes. We found that NCVs and SCVs occurred primarily due to perturbed meiosis, allowing formation of multivalents and univalents as well as homoeologous exchanges. Thus, the combination of NCVs and SCVs affected multiple phenotypic traits, particularly those related to reproductive fitness.
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Affiliation(s)
- Ruili Lv
- School of Life Sciences, Linyi University, Linyi, China
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Changyi Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Ruisi Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Xiaofei Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Jing Zhao
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Bin Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Tariq Aslam
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Fangpu Han
- School of Life Sciences, Linyi University, Linyi, China
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), Beijing, China
| | - Bao Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, China
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11
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Nibau C, Gonzalo A, Evans A, Sweet‐Jones W, Phillips D, Lloyd A. Meiosis in allopolyploid Arabidopsis suecica. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:1110-1122. [PMID: 35759495 PMCID: PMC9545853 DOI: 10.1111/tpj.15879] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/23/2022] [Accepted: 05/25/2022] [Indexed: 06/01/2023]
Abstract
Polyploidy is a major force shaping eukaryote evolution but poses challenges for meiotic chromosome segregation. As a result, first-generation polyploids often suffer from more meiotic errors and lower fertility than established wild polyploid populations. How established polyploids adapt their meiotic behaviour to ensure genome stability and accurate chromosome segregation remains an active research question. We present here a cytological description of meiosis in the model allopolyploid species Arabidopsis suecica (2n = 4x = 26). In large part meiosis in A. suecica is diploid-like, with normal synaptic progression and no evidence of synaptic partner exchanges. Some abnormalities were seen at low frequency, including univalents at metaphase I, anaphase bridges and aneuploidy at metaphase II; however, we saw no evidence of crossover formation occurring between non-homologous chromosomes. The crossover number in A. suecica is similar to the combined number reported from its diploid parents Arabidopsis thaliana (2n = 2x = 10) and Arabidopsis arenosa (2n = 2x = 16), with an average of approximately 1.75 crossovers per chromosome pair. This contrasts with naturally evolved autotetraploid A. arenosa, where accurate chromosome segregation is achieved by restricting crossovers to approximately 1 per chromosome pair. Although an autotetraploid donor is hypothesized to have contributed the A. arenosa subgenome to A. suecica, A. suecica harbours diploid A. arenosa variants of key meiotic genes. These multiple lines of evidence suggest that meiosis in the recently evolved allopolyploid A. suecica is essentially diploid like, with meiotic adaptation following a very different trajectory to that described for autotetraploid A. arenosa.
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Affiliation(s)
- Candida Nibau
- Institute of Biological, Environmental & Rural Sciences (IBERS)Aberystwyth UniversityPenglaisAberystwythCeredigionSY23 3DAUK
| | - Adrián Gonzalo
- John Innes CentreColney LaneNorwichNR4 7UHUK
- Department of Biology, Institute of Molecular Plant BiologySwiss Federal Institute of Technology (ETH) ZürichZürich8092Switzerland
| | - Aled Evans
- Institute of Biological, Environmental & Rural Sciences (IBERS)Aberystwyth UniversityPenglaisAberystwythCeredigionSY23 3DAUK
| | - William Sweet‐Jones
- Institute of Biological, Environmental & Rural Sciences (IBERS)Aberystwyth UniversityPenglaisAberystwythCeredigionSY23 3DAUK
| | - Dylan Phillips
- Institute of Biological, Environmental & Rural Sciences (IBERS)Aberystwyth UniversityPenglaisAberystwythCeredigionSY23 3DAUK
| | - Andrew Lloyd
- Institute of Biological, Environmental & Rural Sciences (IBERS)Aberystwyth UniversityPenglaisAberystwythCeredigionSY23 3DAUK
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12
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Morgan C, Knight E, Bomblies K. The meiotic cohesin subunit REC8 contributes to multigenic adaptive evolution of autopolyploid meiosis in Arabidopsis arenosa. PLoS Genet 2022; 18:e1010304. [PMID: 35830475 PMCID: PMC9312919 DOI: 10.1371/journal.pgen.1010304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/25/2022] [Accepted: 06/22/2022] [Indexed: 11/18/2022] Open
Abstract
Genome duplication, which leads to polyploidy, poses challenges to the meiotic segregation of the now-multiple homologous chromosome copies. Genome scan data showed previously that adaptation to polyploid meiosis in autotetraploid Arabidopsis arenosa is likely multigenic, involving genes encoding interacting proteins. But what does this really mean? Functional follow-up studies to genome scans for multigenic traits remain rare in most systems, and thus many mysteries remain about the "functional architecture" of polygenic adaptations. Do different genes all contribute subtle and additive progression towards a fitness optimum, or are there more complex interactions? We previously showed that derived alleles of genes encoding two interacting meiotic axis proteins (ASY1 and ASY3) have additive functional consequences for meiotic adaptation. Here we study derived versus ancestral alleles of the meiotic cohesin subunit REC8, which has roles in chromatin condensation, recruiting the axes, and other critical functions in meiosis. We use genetic and cytological approaches to assess the functional effects of REC8 diploid versus tetraploid alleles, as well as their interaction with ancestral versus derived alleles of ASY1 and ASY3. We show that homozygotes for derived (tetraploid) REC8 alleles have significantly fewer unpaired univalents, a common problem in neotetraploids. Interactions with ASY1 and ASY3 are complex, with the genes in some cases affecting distinct traits, and additive or even antagonistic effects on others. These findings suggest that the road to meiotic adaptation in A. arenosa was perhaps neither straight nor smooth.
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Affiliation(s)
| | | | - Kirsten Bomblies
- Plant Evolutionary Genetics, Institute of Plant Molecular Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
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13
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Yang F, Pecinka A. Multiple Roles of SMC5/6 Complex during Plant Sexual Reproduction. Int J Mol Sci 2022; 23:ijms23094503. [PMID: 35562893 PMCID: PMC9099584 DOI: 10.3390/ijms23094503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/06/2022] [Accepted: 04/13/2022] [Indexed: 12/01/2022] Open
Abstract
Chromatin-based processes are essential for cellular functions. Structural maintenance of chromosomes (SMCs) are evolutionarily conserved molecular machines that organize chromosomes throughout the cell cycle, mediate chromosome compaction, promote DNA repair, or control sister chromatid attachment. The SMC5/6 complex is known for its pivotal role during the maintenance of genome stability. However, a dozen recent plant studies expanded the repertoire of SMC5/6 complex functions to the entire plant sexual reproductive phase. The SMC5/6 complex is essential in meiosis, where its activity must be precisely regulated to allow for normal meiocyte development. Initially, it is attenuated by the recombinase RAD51 to allow for efficient strand invasion by the meiosis-specific recombinase DMC1. At later stages, it is essential for the normal ratio of interfering and non-interfering crossovers, detoxifying aberrant joint molecules, preventing chromosome fragmentation, and ensuring normal chromosome/sister chromatid segregation. The latter meiotic defects lead to the production of diploid male gametes in Arabidopsis SMC5/6 complex mutants, increased seed abortion, and production of triploid offspring. The SMC5/6 complex is directly involved in controlling normal embryo and endosperm cell divisions, and pioneer studies show that the SMC5/6 complex is also important for seed development and normal plant growth in cereals.
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Affiliation(s)
- Fen Yang
- Centre of the Region Haná for Biotechnological and Agricultural Research (CRH), Institute of Experimental Botany (IEB), Czech Academy of Sciences, 77900 Olomouc, Czech Republic;
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, 77900 Olomouc, Czech Republic
| | - Ales Pecinka
- Centre of the Region Haná for Biotechnological and Agricultural Research (CRH), Institute of Experimental Botany (IEB), Czech Academy of Sciences, 77900 Olomouc, Czech Republic;
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, 77900 Olomouc, Czech Republic
- Correspondence:
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14
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Zhu Q, Jiang Z, He X. Pcp1/pericentrin controls the SPB number in fission yeast meiosis and ploidy homeostasis. J Cell Biol 2022; 221:212751. [PMID: 34747981 PMCID: PMC8579193 DOI: 10.1083/jcb.202104099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 08/31/2021] [Accepted: 10/13/2021] [Indexed: 11/22/2022] Open
Abstract
During sexual reproduction, the zygote must inherit exactly one centrosome (spindle pole body [SPB] in yeasts) from the gametes, which then duplicates and assembles a bipolar spindle that supports the subsequent cell division. Here, we show that in the fission yeast Schizosaccharomyces pombe, the fusion of SPBs from the gametes is blocked in polyploid zygotes. As a result, the polyploid zygotes cannot proliferate mitotically and frequently form supernumerary SPBs during subsequent meiosis, which leads to multipolar nuclear divisions and the generation of extra spores. The blockage of SPB fusion is caused by persistent SPB localization of Pcp1, which, in normal diploid zygotic meiosis, exhibits a dynamic association with the SPB. Artificially induced constitutive localization of Pcp1 on the SPB is sufficient to cause blockage of SPB fusion and formation of extra spores in diploids. Thus, Pcp1-dependent SPB quantity control is crucial for sexual reproduction and ploidy homeostasis in fission yeast.
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Affiliation(s)
- Qian Zhu
- The Ministry of Education Key Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Zhaodi Jiang
- National Institute of Biological Sciences, Beijing, China
| | - Xiangwei He
- The Ministry of Education Key Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, China
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15
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Blasio F, Prieto P, Pradillo M, Naranjo T. Genomic and Meiotic Changes Accompanying Polyploidization. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11010125. [PMID: 35009128 PMCID: PMC8747196 DOI: 10.3390/plants11010125] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/24/2021] [Accepted: 12/29/2021] [Indexed: 05/04/2023]
Abstract
Hybridization and polyploidy have been considered as significant evolutionary forces in adaptation and speciation, especially among plants. Interspecific gene flow generates novel genetic variants adaptable to different environments, but it is also a gene introgression mechanism in crops to increase their agronomical yield. An estimate of 9% of interspecific hybridization has been reported although the frequency varies among taxa. Homoploid hybrid speciation is rare compared to allopolyploidy. Chromosome doubling after hybridization is the result of cellular defects produced mainly during meiosis. Unreduced gametes, which are formed at an average frequency of 2.52% across species, are the result of altered spindle organization or orientation, disturbed kinetochore functioning, abnormal cytokinesis, or loss of any meiotic division. Meiotic changes and their genetic basis, leading to the cytological diploidization of allopolyploids, are just beginning to be understood especially in wheat. However, the nature and mode of action of homoeologous recombination suppressor genes are poorly understood in other allopolyploids. The merger of two independent genomes causes a deep modification of their architecture, gene expression, and molecular interactions leading to the phenotype. We provide an overview of genomic changes and transcriptomic modifications that particularly occur at the early stages of allopolyploid formation.
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Affiliation(s)
- Francesco Blasio
- Departamento de Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid, 28040 Madrid, Spain; (F.B.); (M.P.)
| | - Pilar Prieto
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Alameda del Obispo s/n, Apartado 4048, 14080 Cordova, Spain;
| | - Mónica Pradillo
- Departamento de Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid, 28040 Madrid, Spain; (F.B.); (M.P.)
| | - Tomás Naranjo
- Departamento de Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid, 28040 Madrid, Spain; (F.B.); (M.P.)
- Correspondence:
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16
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Tian S, Ge J, Ai G, Jiang J, Liu Q, Chen X, Liu M, Yang J, Zhang X, Yuan L. A 2.09 Mb fragment translocation on chromosome 6 causes abnormalities during meiosis and leads to less seed watermelon. HORTICULTURE RESEARCH 2021; 8:256. [PMID: 34848689 PMCID: PMC8633341 DOI: 10.1038/s41438-021-00687-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 07/09/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
Seedlessness is a valuable agronomic trait in watermelon (Citrullus lanatus) breeding. Conventional less seed watermelons are mainly triploid, which has many disadvantages due to unbalanced genome content. Less seed watermelon can be achieved at the diploid level when certain reproductive genes are mutated or by chromosome translocation, which leads to defects during meiosis. However, the formation mechanism of diploid less seed watermelons remains largely unknown. Here, we identified a spontaneous mutant line, watermelon line "148", which can set seeds normally when self-pollinated. A total of 148 × JM F1 hybrid plants exhibited seed number reductions to 50.3% and 47.3% of those of the two parental lines, respectively, which are considered to be less seed. Examination of pollen viability and hybridization experiments revealed that F1 hybrids produce semisterile pollen and ovules. Further cytological observations indicated that semisterility was a result of a reciprocal translocation of chromosomes, which exhibited one quadrivalent ring of four chromosomes at prometaphase I during meiosis. RT-qPCR analysis indirectly confirmed that the semisterile phenotype is caused by chromosome translocation rather than disruption of specific meiotic gene expression. F2 population genetic analysis indicated that the "148" watermelon line is a homozygous translocation and that the less seed phenotype of the F1 hybrid is prompted by one chromosome fragment translocation. The translocated fragment was further fine mapped to a 2.09 Mb region on chromosome 6 by whole-genome resequencing and genetic map cloning procedures. Our work revealed that a 2.09 Mb chromosome fragment translocation on chromosome 6, causing meiotic defects at metaphase I during meiosis, leads to diploid less seed watermelon. Our findings provide a new promising method for less seed watermelon breeding at the diploid level, as well as a fragment size reference for breeding less seed watermelon through artificially induced chromosome translocation.
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Affiliation(s)
- Shujuan Tian
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jie Ge
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Gongli Ai
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jiao Jiang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Qiyan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Xiner Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Man Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jianqiang Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Xian Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Li Yuan
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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17
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Morgan C, White MA, Franklin FCH, Zickler D, Kleckner N, Bomblies K. Evolution of crossover interference enables stable autopolyploidy by ensuring pairwise partner connections in Arabidopsis arenosa. Curr Biol 2021; 31:4713-4726.e4. [PMID: 34480856 PMCID: PMC8585506 DOI: 10.1016/j.cub.2021.08.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/23/2021] [Accepted: 08/09/2021] [Indexed: 11/25/2022]
Abstract
Polyploidy is a major driver of evolutionary change. Autopolyploids, which arise by within-species whole-genome duplication, carry multiple nearly identical copies of each chromosome. This presents an existential challenge to sexual reproduction. Meiotic chromosome segregation requires formation of DNA crossovers (COs) between two homologous chromosomes. How can this outcome be achieved when more than two essentially equivalent partners are available? We addressed this question by comparing diploid, neo-autotetraploid, and established autotetraploid Arabidopsis arenosa using new approaches for analysis of meiotic CO patterns in polyploids. We discover that crossover interference, the classical process responsible for patterning of COs in diploid meiosis, is defective in the neo-autotetraploid but robust in the established autotetraploid. The presented findings suggest that, initially, diploid-like interference fails to act effectively on multivalent pairing and accompanying pre-CO recombination interactions and that stable autopolyploid meiosis can emerge by evolution of a “supercharged” interference process, which can now act effectively on such configurations. Thus, the basic interference mechanism responsible for simplifying CO patterns along chromosomes in diploid meiosis has evolved the capability to also simplify CO patterns among chromosomes in autopolyploids, thereby promoting bivalent formation. We further show that evolution of stable autotetraploidy preadapts meiosis to higher ploidy, which in turn has interesting mechanistic and evolutionary implications. In a neo-autotetraploid, aberrant crossover interference confers aberrant meiosis In a stable autotetraploid, regular crossover interference confers regular meiosis Crossover and synaptic patterns point to evolution of “supercharged” interference Accordingly, evolution of stable autotetraploidy preadapts to higher ploidies
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Affiliation(s)
- Chris Morgan
- John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | - Martin A White
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA
| | | | - Denise Zickler
- University Paris-Saclay, Commissariat à l'Energie Atomique at aux Energies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | - Nancy Kleckner
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA.
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18
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Soares NR, Mollinari M, Oliveira GK, Pereira GS, Vieira MLC. Meiosis in Polyploids and Implications for Genetic Mapping: A Review. Genes (Basel) 2021; 12:genes12101517. [PMID: 34680912 PMCID: PMC8535482 DOI: 10.3390/genes12101517] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 02/06/2023] Open
Abstract
Plant cytogenetic studies have provided essential knowledge on chromosome behavior during meiosis, contributing to our understanding of this complex process. In this review, we describe in detail the meiotic process in auto- and allopolyploids from the onset of prophase I through pairing, recombination, and bivalent formation, highlighting recent findings on the genetic control and mode of action of specific proteins that lead to diploid-like meiosis behavior in polyploid species. During the meiosis of newly formed polyploids, related chromosomes (homologous in autopolyploids; homologous and homoeologous in allopolyploids) can combine in complex structures called multivalents. These structures occur when multiple chromosomes simultaneously pair, synapse, and recombine. We discuss the effectiveness of crossover frequency in preventing multivalent formation and favoring regular meiosis. Homoeologous recombination in particular can generate new gene (locus) combinations and phenotypes, but it may destabilize the karyotype and lead to aberrant meiotic behavior, reducing fertility. In crop species, understanding the factors that control pairing and recombination has the potential to provide plant breeders with resources to make fuller use of available chromosome variations in number and structure. We focused on wheat and oilseed rape, since there is an abundance of elucidating studies on this subject, including the molecular characterization of the Ph1 (wheat) and PrBn (oilseed rape) loci, which are known to play a crucial role in regulating meiosis. Finally, we exploited the consequences of chromosome pairing and recombination for genetic map construction in polyploids, highlighting two case studies of complex genomes: (i) modern sugarcane, which has a man-made genome harboring two subgenomes with some recombinant chromosomes; and (ii) hexaploid sweet potato, a naturally occurring polyploid. The recent inclusion of allelic dosage information has improved linkage estimation in polyploids, allowing multilocus genetic maps to be constructed.
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Affiliation(s)
- Nina Reis Soares
- Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba 13400-918, Brazil; (N.R.S.); (G.K.O.); (G.S.P.)
| | - Marcelo Mollinari
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695-7566, USA;
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7555, USA
| | - Gleicy K. Oliveira
- Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba 13400-918, Brazil; (N.R.S.); (G.K.O.); (G.S.P.)
| | - Guilherme S. Pereira
- Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba 13400-918, Brazil; (N.R.S.); (G.K.O.); (G.S.P.)
- Department of Agronomy, Federal University of Viçosa, Viçosa 36570-900, Brazil
| | - Maria Lucia Carneiro Vieira
- Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba 13400-918, Brazil; (N.R.S.); (G.K.O.); (G.S.P.)
- Correspondence:
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19
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Weitz AP, Dukic M, Zeitler L, Bomblies K. Male meiotic recombination rate varies with seasonal temperature fluctuations in wild populations of autotetraploid Arabidopsis arenosa. Mol Ecol 2021; 30:4630-4641. [PMID: 34273213 PMCID: PMC9292783 DOI: 10.1111/mec.16084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 07/08/2021] [Accepted: 07/12/2021] [Indexed: 12/16/2022]
Abstract
Meiosis, the cell division by which eukaryotes produce haploid gametes, is essential for fertility in sexually reproducing species. This process is sensitive to temperature, and can fail outright at temperature extremes. At less extreme values, temperature affects the genome‐wide rate of homologous recombination, which has important implications for evolution and population genetics. Numerous studies in laboratory conditions have shown that recombination rate plasticity is common, perhaps nearly universal, among eukaryotes. These studies have also shown that variation in the length or timing of stresses can strongly affect results, raising the important question whether these findings translate to more variable field conditions. Moreover, lower or higher recombination rate could cause certain kinds of meiotic aberrations, especially in polyploid species—raising the additional question whether temperature fluctuations in field conditions cause problems. Here, we tested whether (1) recombination rate varies across a season in the wild in two natural populations of autotetraploid Arabidopsis arenosa, (2) whether recombination rate correlates with temperature fluctuations in nature, and (3) whether natural temperature fluctuations might cause meiotic aberrations. We found that plants in two genetically distinct populations showed a similar plastic response with recombination rate increases correlated with both high and low temperatures. In addition, increased recombination rate correlated with increased multivalent formation, especially at lower temperature, hinting that polyploids in particular may suffer meiotic problems in conditions they encounter in nature. Our results show that studies of recombination rate plasticity done in laboratory settings inform our understanding of what happens in nature.
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Affiliation(s)
- Andrew P Weitz
- Department of Biology, Institute of Molecular Plant Biology, Swiss Federal Institute of Technology (ETH) Zürich, Zürich, Switzerland.,Department of Environmental Sciences, Western Washington University, Bellingham, Washington, USA
| | - Marinela Dukic
- Department of Biology, Institute of Molecular Plant Biology, Swiss Federal Institute of Technology (ETH) Zürich, Zürich, Switzerland
| | - Leo Zeitler
- Department of Biology, Institute of Molecular Plant Biology, Swiss Federal Institute of Technology (ETH) Zürich, Zürich, Switzerland.,Department of Biology, Ecological Genomics, Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Kirsten Bomblies
- Department of Biology, Institute of Molecular Plant Biology, Swiss Federal Institute of Technology (ETH) Zürich, Zürich, Switzerland
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20
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Ferreira de Carvalho J, Stoeckel S, Eber F, Lodé-Taburel M, Gilet MM, Trotoux G, Morice J, Falentin C, Chèvre AM, Rousseau-Gueutin M. Untangling structural factors driving genome stabilization in nascent Brassica napus allopolyploids. THE NEW PHYTOLOGIST 2021; 230:2072-2084. [PMID: 33638877 DOI: 10.1111/nph.17308] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 02/22/2021] [Indexed: 05/28/2023]
Abstract
Allopolyploids have globally higher fitness than their diploid progenitors; however, by comparison, most resynthesized allopolyploids have poor fertility and highly unstable genome. Elucidating the evolutionary processes promoting genome stabilization and fertility is thus essential to comprehend allopolyploid success. Using the Brassica model, we mimicked the speciation process of a nascent allopolyploid species by resynthesizing allotetraploid Brassica napus and systematically selecting for euploid individuals over eight generations in four independent allopolyploidization events with contrasted genetic backgrounds, cytoplasmic donors, and polyploid formation type. We evaluated the evolution of meiotic behavior and fertility and identified rearrangements in S1 to S9 lineages to explore the positive consequences of euploid selection on B. napus genome stability. Recurrent selection of euploid plants for eight generations drastically reduced the percentage of aneuploid progenies as early as the fourth generation, concomitantly with a decrease in number of newly fixed homoeologous rearrangements. The consequences of homoeologous rearrangements on meiotic behavior and seed number depended strongly on the genetic background and cytoplasm donor. The combined use of both self-fertilization and recurrent euploid selection allowed identification of genomic regions associated with fertility and meiotic behavior, providing complementary evidence to explain B. napus speciation success.
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Affiliation(s)
| | - Solenn Stoeckel
- IGEPP, INRAE, Institut Agro, Université de Rennes, Le Rheu, 35650, France
| | - Frédérique Eber
- IGEPP, INRAE, Institut Agro, Université de Rennes, Le Rheu, 35650, France
| | | | | | - Gwenn Trotoux
- IGEPP, INRAE, Institut Agro, Université de Rennes, Le Rheu, 35650, France
| | - Jérôme Morice
- IGEPP, INRAE, Institut Agro, Université de Rennes, Le Rheu, 35650, France
| | - Cyril Falentin
- IGEPP, INRAE, Institut Agro, Université de Rennes, Le Rheu, 35650, France
| | - Anne-Marie Chèvre
- IGEPP, INRAE, Institut Agro, Université de Rennes, Le Rheu, 35650, France
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Barke BH, Karbstein K, Daubert M, Hörandl E. The relation of meiotic behaviour to hybridity, polyploidy and apomixis in the Ranunculus auricomus complex (Ranunculaceae). BMC PLANT BIOLOGY 2020; 20:523. [PMID: 33203395 PMCID: PMC7672892 DOI: 10.1186/s12870-020-02654-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/20/2020] [Indexed: 05/23/2023]
Abstract
BACKGROUND Hybridization and polyploidization are powerful evolutionary factors that are associated with manifold developmental changes in plants such as irregular progression of meiosis and sporogenesis. The emergence of apomixis, which is asexual reproduction via seeds, is supposed to be connected to these factors and was often regarded as an escape from hybrid sterility. However, the functional trigger of apomixis is still unclear. Recently formed di- and polyploid Ranunculus hybrids, as well as their parental species were analysed for their modes of mega- and microsporogenesis by microscopy. Chromosomal configurations during male meiosis were screened for abnormalities. Meiotic and developmental abnormalities were documented qualitatively and collected quantitatively for statistical evaluations. RESULTS Allopolyploids showed significantly higher frequencies of erroneous microsporogenesis than homoploid hybrid plants. Among diploids, F2 hybrids had significantly more disturbed meiosis than F1 hybrids and parental plants. Chromosomal aberrations included laggard chromosomes, chromatin bridges and disoriented spindle activities. Failure of megasporogenesis appeared to be much more frequent in than of microsporogenesis is correlated to apomixis onset. CONCLUSIONS Results suggest diverging selective pressures on female and male sporogenesis, with only minor effects of hybridity on microsporogenesis, but fatal effects on the course of megasporogenesis. Hence, pollen development continues without major alterations, while selection will favour apomixis as alternative to the female meiotic pathway. Relation of investigated errors of megasporogenesis with the observed occurrence of apospory in Ranunculus hybrids identifies disturbed female meiosis as potential elicitor of apomixis in order to rescue these plants from hybrid sterility. Male meiotic disturbance appears to be stronger in neopolyploids than in homoploid hybrids, while disturbances of megasporogenesis were not ploidy-dependent.
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Affiliation(s)
- Birthe H Barke
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany.
| | - Kevin Karbstein
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany
| | - Mareike Daubert
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany
- Present Address: Carl von Ossietzky University, Institute of Biology and Environmental Sciences, Carl von Ossietzky Straße 9-11, D-26129, Oldenburg, Germany
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany
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Mason AS, Wendel JF. Homoeologous Exchanges, Segmental Allopolyploidy, and Polyploid Genome Evolution. Front Genet 2020; 11:1014. [PMID: 33005183 PMCID: PMC7485112 DOI: 10.3389/fgene.2020.01014] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/10/2020] [Indexed: 01/08/2023] Open
Abstract
Polyploidy is a major force in plant evolution and speciation. In newly formed allopolyploids, pairing between related chromosomes from different subgenomes (homoeologous chromosomes) during meiosis is common. The initial stages of allopolyploid formation are characterized by a spectrum of saltational genomic and regulatory alterations that are responsible for evolutionary novelty. Here we highlight the possible effects and roles of recombination between homoeologous chromosomes during the early stages of allopolyploid stabilization. Homoeologous exchanges (HEs) have been reported in young allopolyploids from across the angiosperms. Although all lineages undergo karyotype change via chromosome rearrangements over time, the early generations after allopolyploid formation are predicted to show an accelerated rate of genomic change. HEs can also cause changes in allele dosage, genome-wide methylation patterns, and downstream phenotypes, and can hence be responsible for speciation and genome stabilization events. Additionally, we propose that fixation of duplication - deletion events resulting from HEs could lead to the production of genomes which appear to be a mix of autopolyploid and allopolyploid segments, sometimes termed "segmental allopolyploids." We discuss the implications of these findings for our understanding of the relationship between genome instability in novel polyploids and genome evolution.
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Affiliation(s)
- Annaliese S. Mason
- Plant Breeding Department, Justus Liebig University Giessen, Giessen, Germany
| | - Jonathan F. Wendel
- Ecology, Evolution, and Organismal Biology Department, Iowa State University, Ames, IA, United States
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Parthenogenesis as a Solution to Hybrid Sterility: The Mechanistic Basis of Meiotic Distortions in Clonal and Sterile Hybrids. Genetics 2020; 215:975-987. [PMID: 32518062 PMCID: PMC7404241 DOI: 10.1534/genetics.119.302988] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 06/03/2020] [Indexed: 11/25/2022] Open
Abstract
Hybrid sterility is a hallmark of speciation, but the underlying molecular mechanisms remain poorly understood. Here, we report that speciation may regularly proceed through a stage at which gene flow is completely interrupted, but hybrid sterility occurs only in male hybrids whereas female hybrids reproduce asexually. We analyzed gametogenic pathways in hybrids between the fish species Cobitis elongatoides and C. taenia, and revealed that male hybrids were sterile owing to extensive asynapsis and crossover reduction among heterospecific chromosomal pairs in their gametes, which was subsequently followed by apoptosis. We found that polyploidization allowed pairing between homologous chromosomes and therefore partially rescued the bivalent formation and crossover rates in triploid hybrid males. However, it was not sufficient to overcome sterility. In contrast, both diploid and triploid hybrid females exhibited premeiotic genome endoreplication, thereby ensuring proper bivalent formation between identical chromosomal copies. This endoreplication ultimately restored female fertility but it simultaneously resulted in the obligate production of clonal gametes, preventing any interspecific gene flow. In conclusion, we demonstrate that the emergence of asexuality can remedy hybrid sterility in a sex-specific manner and contributes to the speciation process.
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Derived alleles of two axis proteins affect meiotic traits in autotetraploid Arabidopsis arenosa. Proc Natl Acad Sci U S A 2020; 117:8980-8988. [PMID: 32273390 PMCID: PMC7183234 DOI: 10.1073/pnas.1919459117] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Genome duplication is an important factor in the evolution of eukaryotic lineages, but it poses challenges for the regular segregation of chromosomes in meiosis and thus fertility. To survive, polyploid lineages must evolve to overcome initial challenges that accompany doubling the chromosome complement. Understanding how evolution can solve the challenge of segregating multiple homologous chromosomes promises fundamental insights into the mechanisms of genome maintenance and could open polyploidy as a crop improvement tool. We previously identified candidate genes for meiotic stabilization of Arabidopsis arenosa, which has natural diploid and tetraploid variants. Here we test the role that derived alleles of two genes under selection in tetraploid A. arenosa might have in meiotic stabilization in tetraploids. Polyploidy, which results from whole genome duplication (WGD), has shaped the long-term evolution of eukaryotic genomes in all kingdoms. Polyploidy is also implicated in adaptation, domestication, and speciation. Yet when WGD newly occurs, the resulting neopolyploids face numerous challenges. A particularly pernicious problem is the segregation of multiple chromosome copies in meiosis. Evolution can overcome this challenge, likely through modification of chromosome pairing and recombination to prevent deleterious multivalent chromosome associations, but the molecular basis of this remains mysterious. We study mechanisms underlying evolutionary stabilization of polyploid meiosis using Arabidopsis arenosa, a relative of A. thaliana with natural diploid and meiotically stable autotetraploid populations. Here we investigate the effects of ancestral (diploid) versus derived (tetraploid) alleles of two genes, ASY1 and ASY3, that were among several meiosis genes under selection in the tetraploid lineage. These genes encode interacting proteins critical for formation of meiotic chromosome axes, long linear multiprotein structures that form along sister chromatids in meiosis and are essential for recombination, chromosome segregation, and fertility. We show that derived alleles of both genes are associated with changes in meiosis, including reduced formation of multichromosome associations, reduced axis length, and a tendency to more rod-shaped bivalents in metaphase I. Thus, we conclude that ASY1 and ASY3 are components of a larger multigenic solution to polyploid meiosis in which individual genes have subtle effects. Our results are relevant for understanding polyploid evolution and more generally for understanding how meiotic traits can evolve when faced with challenges.
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Yang Y, Yan G, Li Z, Yuan J, Wei X, Wei F, Tian B, Xie Z, Shi G, Zhang X, Cao G. Cytological atlas at meiosis reveals insights into pollen fertility in synthetic Brassica allotriploids between allotetraploid B. carinata and diploid B. rapa. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 148:237-245. [PMID: 31981876 DOI: 10.1016/j.plaphy.2020.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/16/2019] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
The formation of allopolyploid crops basically depends on the successful interspecific hybridization and polyploidization, which generally involves in a combination of distinct but related genomes from independent species. But cytological analysis of these initially synthesized allohaploids immediately after genome merging is poorly explored in regards to anther and pollen development to date. In this study, Brassica trigenomic allohaploids (ABC) were produced to investigate the immediate effects of the genome combinations on pollen fertility during anther development via crosses between natural allotetraploid B. carinata (BBCC) and diploid B. rapa (AA). The results showed that in the synthetic Brassica allotriploids (ABC), the anther development was completely disrupted, and the pollen grains were mostly inviable with varied genetic complements. In addition, the meiosis course was aberrantly altered and eccentric chromosomal configurations including multivalent, bridges and lags occurred frequently during metaphase I to anaphase II. Genomic in situ hybridization (GISH) further revealed that B genome of homoeology was frequently apt to interact with A and C genomes, and cytoskeletal organizations was improperly distributed during meiosis in these synthetic Brassica allotriploids. Furthermore, we also confirmed that the expression of typical meiosis-related genes was obviously repressed during anther development in these Brassica allotriploids. Taken together, our results provide a detailed cytology for insights into pollen development in the synthetic allotriploid hybrids, which are conventionally considered as a useful genetic resource for polyploid Brassica breeding.
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Affiliation(s)
- Yan Yang
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China; School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Ge Yan
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Zishuang Li
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Jiachen Yuan
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Xiaochun Wei
- Institute of Horticultural Research, Henan Academy of Agricultural Sciences, Zhengzhou, Henan, 450002, China
| | - Fang Wei
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China; School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China.
| | - Baoming Tian
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Zhengqing Xie
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Gongyao Shi
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China; School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Xiaowei Zhang
- Institute of Horticultural Research, Henan Academy of Agricultural Sciences, Zhengzhou, Henan, 450002, China
| | - Gangqiang Cao
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, Henan, 450001, China.
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Karunarathne P, Feduzka C, Diego H. Ecological setup, ploidy diversity, and reproductive biology of Paspalum modestum, a promising wetland forage grass from South America. Genet Mol Biol 2020; 43:e20190101. [PMID: 32110794 PMCID: PMC7198000 DOI: 10.1590/1678-4685-gmb-2019-0101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 06/23/2019] [Indexed: 12/03/2022] Open
Abstract
With ever-rising demand for food, forage breeding for intensification of cattle
production is also taking a leap. In South America, cattle production systems
are displaced to marginal areas poorly exploited with cultivated pastures yet
with high potential for growing stocking rates. This places the need for using
native genetic resources to breed locally adapted plant genotypes that benefits
from better forage quality, yield, and lesser threat to the local biodiversity.
Paspalum modestum Mez is a grass species that produces
quality forage and grows in marginal areas like estuaries and floodplains,
suitable for introduction in breeding programs. In this study we characterize
the species' reproductive biology and ecological preferences needed beforehand
any improvement. P. modestum plants found in nature are
commonly diploids, rarely triploids, and tetraploids. Chromosome associations
during meiosis in polyploids indicate they are autopolyploids. While diploids
are sexual self-sterile, analyses of embryology, gamete fertility and
experimental crossings show tetraploids are self-compatible facultative
apomicts, highly fertile and have a high proportion of sexuality compared to
other apomictic species. Ecological niche analysis and species distribution
modelling show mean annual temperature and precipitation as main ecological
drivers and a wide geographical area of climatic suitability where P.
modestum can grow and be exploited as a forage grass. Our study
points to P. modestum as a native plant resource appropriate
for breeding waterlogging tolerant ecotypes and genotypes of high biomass
production adapted to low flow areas in the Subtropics of Brazil, Paraguay,
Uruguay and Argentina.
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Affiliation(s)
- Piyal Karunarathne
- University of Goettingen, Albrecht-von-Haller Institute for Plant Sciences, Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Goettingen, Germany.,University of Goettingen, Georg-August University School of Science, Germany
| | - Cristian Feduzka
- Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Instituto de Botánica del Nordeste (IBONE), Corrientes, Argentina
| | - Hojsgaard Diego
- University of Goettingen, Albrecht-von-Haller Institute for Plant Sciences, Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Goettingen, Germany
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Prieto P, Naranjo T. Analytical Methodology of Meiosis in Autopolyploid and Allopolyploid Plants. Methods Mol Biol 2020; 2061:141-168. [PMID: 31583658 DOI: 10.1007/978-1-4939-9818-0_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Meiosis is the cellular process responsible for producing gametes with half the genetic content of the parent cells. Integral parts of the process in most diploid organisms include the recognition, pairing, synapsis, and recombination of homologous chromosomes, which are prerequisites for balanced segregation of half-bivalents during meiosis I. In polyploids, the presence of more than two sets of chromosomes adds to the basic meiotic program of their diploid progenitors the possibility of interactions between more than two chromosomes and the formation of multivalents, which has implications on chromosome segregations and fertility. The mode of how chromosomes behave in meiosis in competitive situations has been the aim of many studies in polyploid species, some of which are considered here. But polyploids are also of interest in the study of meiosis because some of them tolerate the loss of chromosome segments or complete chromosomes as well as the addition of chromosomes from related species. Deletions allow to assess the effect of specific chromosome segments on meiotic behavior. Introgression lines are excellent materials to monitor the behavior of a given chromosome in the genetic background of the recipient species. We focus on this approach here as based on studies carried out in bread wheat, which is commonly used as a model species for meiosis studies. In addition to highlighting the relevance of the use of materials derived from polyploids in the study of meiosis, cytogenetics tools such as fluorescence in situ hybridization and the immunolabeling of proteins interacting with DNA are also emphasized.
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Affiliation(s)
- Pilar Prieto
- Departamento de Mejora Genética, Instituto de Agricultura Sostenible (IAS), Consejo Superior de Investigaciones Científicas (CSIC), Córdoba, Spain
| | - Tomás Naranjo
- Departamento de Genética, Fisiología y Microbiología, Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain.
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28
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Yang Y, Wei F, Braynen J, Wei X, Tian B, Shi G, Cao G, Yuan J, Zhang X. Cytological and proteomic analyses of floral buds reveal an altered atlas of meiosis in autopolyploid Brassica rapa. Cell Biosci 2019; 9:49. [PMID: 31236208 PMCID: PMC6580506 DOI: 10.1186/s13578-019-0313-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/14/2019] [Indexed: 12/21/2022] Open
Abstract
Background Polyploidy is considered as a basic event in plant speciation and evolution in nature, and the cytological and proteomic profilings of floral buds at meiosis (FAM) would definitely contribute to a better understanding of the polyploid-associated effects during plant reproduction cycle. Results Herein, the cytological investigations demonstrated that chromosome behaviors such as univalent and multivalent at prophase I, chaotic alignments at metaphase, aberrant segregation at telophase, were frequently observed during meiosis in autotetraploid Brassica rapa. The proteomic analysis showed a total of 562 differentially expressed proteins (DEPs) were identified in FAM between autotetraploid and diploid B. rapa. Notably, PARP2 and LIG1 related to base excision repair and BARD1 involved in recombination were significantly down-regulated in autotetraploid B. rapa, which indicated DNA repair pathway were more likely affected during meiosis in autotetraploid B. rapa. The functional analysis showed that DEPs assigned to “chromatin structure and dynamics”, “cell cycle control, cell division, chromosome partitioning” and “cytoskeleton” were preferentially up-regulated, which suggested a robust regulation of cell division in autotetraploid B. rapa. In combination with the floral RNA-seq data released, a number of DEPs were found positively correlated with their transcript abundance, but posttranslational modification of proteins might also play a role in regulating meiosis course after polyploidization. Conclusions In general, this study provides a detailed cytology and proteome landscape of FAM between diploid and autotetraploid B. rapa, which definitely affords us a better understanding of uniformity and discrepancy of meiosis at the plant reproductive stage before and after polyploidization. Electronic supplementary material The online version of this article (10.1186/s13578-019-0313-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yan Yang
- 1School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China.,2School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China
| | - Fang Wei
- 1School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China.,2School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China
| | - Janeen Braynen
- 2School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China.,3Institute of Horticultural Research, Henan Academy of Agricultural Sciences, Zhengzhou, 450002 Henan People's Republic of China
| | - Xiaochun Wei
- 3Institute of Horticultural Research, Henan Academy of Agricultural Sciences, Zhengzhou, 450002 Henan People's Republic of China
| | - Baoming Tian
- 1School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China
| | - Gongyao Shi
- 1School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China
| | - Gangqiang Cao
- 1School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China
| | - Jiachen Yuan
- 2School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan People's Republic of China
| | - Xiaowei Zhang
- 3Institute of Horticultural Research, Henan Academy of Agricultural Sciences, Zhengzhou, 450002 Henan People's Republic of China
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Blary A, Jenczewski E. Manipulation of crossover frequency and distribution for plant breeding. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2019; 132:575-592. [PMID: 30483818 PMCID: PMC6439139 DOI: 10.1007/s00122-018-3240-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/13/2018] [Indexed: 05/12/2023]
Abstract
The crossovers (COs) that occur during meiotic recombination lead to genetic diversity upon which natural and artificial selection can act. The potential of tinkering with the mechanisms of meiotic recombination to increase the amount of genetic diversity accessible for breeders has been under the research spotlight for years. A wide variety of approaches have been proposed to increase CO frequency, alter CO distribution and induce COs between non-homologous chromosomal regions. For most of these approaches, translational biology will be crucial for demonstrating how these strategies can be of practical use in plant breeding. In this review, we describe how tinkering with meiotic recombination could benefit plant breeding and give concrete examples of how these strategies could be implemented into breeding programs.
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Affiliation(s)
- A Blary
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - E Jenczewski
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France.
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31
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Abstract
Meiosis halves diploid chromosome numbers to haploid levels that are essential for sexual reproduction in most eukaryotes. Meiotic recombination ensures the formation of bivalents between homologous chromosomes (homologs) and their subsequent proper segregation. It also results in genetic diversity among progeny that influences evolutionary responses to selection. Moreover, crop breeding depends upon the action of meiotic recombination to rearrange elite traits between parental chromosomes. An understanding of the molecular mechanisms that drive meiotic recombination is important for both fundamental research and practical applications. This review emphasizes advances made during the past 5 years, primarily in Arabidopsis and rice, by summarizing newly characterized genes and proteins and examining the regulatory mechanisms that modulate their action.
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Affiliation(s)
- Yingxiang Wang
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200438, China;
| | - Gregory P Copenhaver
- Department of Biology and the Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3280, USA;
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-3280, USA
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32
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Thirugnanasambandam PP, Hoang NV, Henry RJ. The Challenge of Analyzing the Sugarcane Genome. FRONTIERS IN PLANT SCIENCE 2018; 9:616. [PMID: 29868072 PMCID: PMC5961476 DOI: 10.3389/fpls.2018.00616] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/18/2018] [Indexed: 05/04/2023]
Abstract
Reference genome sequences have become key platforms for genetics and breeding of the major crop species. Sugarcane is probably the largest crop produced in the world (in weight of crop harvested) but lacks a reference genome sequence. Sugarcane has one of the most complex genomes in crop plants due to the extreme level of polyploidy. The genome of modern sugarcane hybrids includes sub-genomes from two progenitors Saccharum officinarum and S. spontaneum with some chromosomes resulting from recombination between these sub-genomes. Advancing DNA sequencing technologies and strategies for genome assembly are making the sugarcane genome more tractable. Advances in long read sequencing have allowed the generation of a more complete set of sugarcane gene transcripts. This is supporting transcript profiling in genetic research. The progenitor genomes are being sequenced. A monoploid coverage of the hybrid genome has been obtained by sequencing BAC clones that cover the gene space of the closely related sorghum genome. The complete polyploid genome is now being sequenced and assembled. The emerging genome will allow comparison of related genomes and increase understanding of the functioning of this polyploidy system. Sugarcane breeding for traditional sugar and new energy and biomaterial uses will be enhanced by the availability of these genomic resources.
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Affiliation(s)
- Prathima P. Thirugnanasambandam
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, Australia
- ICAR - Sugarcane Breeding Institute, Coimbatore, India
- *Correspondence: Prathima P. Thirugnanasambandam,
| | - Nam V. Hoang
- College of Agriculture and Forestry, Hue University, Hue, Vietnam
| | - Robert J. Henry
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, Australia
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Lenormand T, Engelstädter J, Johnston SE, Wijnker E, Haag CR. Evolutionary mysteries in meiosis. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2016.0001. [PMID: 27619705 DOI: 10.1098/rstb.2016.0001] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2016] [Indexed: 01/25/2023] Open
Abstract
Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often 'weird' features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Thomas Lenormand
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Erik Wijnker
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Christoph R Haag
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
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Lamo JM, Rao SR. Meiotic behaviour and its implication on species inter-relationship in the genus Curcuma (Linnaeus, 1753) (Zingiberaceae). COMPARATIVE CYTOGENETICS 2017; 11:691-702. [PMID: 29114361 PMCID: PMC5672274 DOI: 10.3897/compcytogen.v11i4.14726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/04/2017] [Indexed: 06/07/2023]
Abstract
In this paper, detailed meiotic analysis was investigated in seven species of Curcuma (Linnaeus, 1753) which can contribute significantly to our understanding about species inter-relationship, speciation and evolution. The species were divided into two groups viz., Group I having 2n = 42 (C. comosa Roxburgh, 1810, C. haritha Mangaly & M.Sabu, 1993, C. mangga Valeton & Zijp, 1917, and C. motana Roxburgh, 1800) and Group II with 2n = 63 (C. caesia Roxburgh, 1810, C. longa Linnaeus, 1753 and C. sylvatica Valeton, 1918). Both groups display varying degree of chromosome associations. Group I species showed the prevalence of bivalents, however occasional quadrivalents besides univalents were also encountered. About 48% of the PMCs analyzed in C. mangga showed 21 bivalents (II) meiotic configurations, 32% in C. comosa and 16% in C. haritha. Group II species as expected showed the presence of trivalents besides bivalents, univalents and quadrivalents. About 32% of the PMCs analyzed at MI in C. sylvatica showed 21 trivalents (III) meiotic configurations, 24% in C. longa and 8% in C. caesia. Overall, low frequency of multivalent associations as compared to bivalents indicates that Curcuma is an allopolyploid complex. Moreover, x = 21 is too high a basic number, therefore, we suggest that the genus Curcuma has evolved by hybridization of species with different chromosome numbers of 2n = 24 and 18, resulting in a dibasic amphidiploid species.
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Affiliation(s)
- Judith Mary Lamo
- Plant Biotechnology Laboratory, North-Eastern Hill University, Shillong-793022, Meghalaya, India
| | - Satyawada Rama Rao
- Plant Biotechnology Laboratory, North-Eastern Hill University, Shillong-793022, Meghalaya, India
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Alix K, Gérard PR, Schwarzacher T, Heslop-Harrison JS(P. Polyploidy and interspecific hybridization: partners for adaptation, speciation and evolution in plants. ANNALS OF BOTANY 2017; 120:183-194. [PMID: 28854567 PMCID: PMC5737848 DOI: 10.1093/aob/mcx079] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 05/31/2017] [Indexed: 05/15/2023]
Abstract
BACKGROUND Polyploidy or whole-genome duplication is now recognized as being present in almost all lineages of higher plants, with multiple rounds of polyploidy occurring in most extant species. The ancient evolutionary events have been identified through genome sequence analysis, while recent hybridization events are found in about half of the world's crops and wild species. Building from this new paradigm for understanding plant evolution, the papers in this Special Issue address questions about polyploidy in ecology, adaptation, reproduction and speciation of wild and cultivated plants from diverse ecosystems. Other papers, including this review, consider genomic aspects of polyploidy. APPROACHES Discovery of the evolutionary consequences of new, evolutionarily recent and ancient polyploidy requires a range of approaches. Large-scale studies of both single species and whole ecosystems, with hundreds to tens of thousands of individuals, sometimes involving 'garden' or transplant experiments, are important for studying adaptation. Molecular studies of genomes are needed to measure diversity in genotypes, showing ancestors, the nature and number of polyploidy and backcross events that have occurred, and allowing analysis of gene expression and transposable element activation. Speciation events and the impact of reticulate evolution require comprehensive phylogenetic analyses and can be assisted by resynthesis of hybrids. In this Special Issue, we include studies ranging in scope from experimental and genomic, through ecological to more theoretical. CONCLUSIONS The success of polyploidy, displacing the diploid ancestors of almost all plants, is well illustrated by the huge angiosperm diversity that is assumed to originate from recurrent polyploidization events. Strikingly, polyploidization often occurred prior to or simultaneously with major evolutionary transitions and adaptive radiation of species, supporting the concept that polyploidy plays a predominant role in bursts of adaptive speciation. Polyploidy results in immediate genetic redundancy and represents, with the emergence of new gene functions, an important source of novelty. Along with recombination, gene mutation, transposon activity and chromosomal rearrangement, polyploidy and whole-genome duplication act as drivers of evolution and divergence in plant behaviour and gene function, enabling diversification, speciation and hence plant evolution.
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Affiliation(s)
- Karine Alix
- GQE – Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
- For correspondence. E-mail
| | - Pierre R. Gérard
- GQE – Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Trude Schwarzacher
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
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Doyle JJ, Sherman-Broyles S. Double trouble: taxonomy and definitions of polyploidy. THE NEW PHYTOLOGIST 2017; 213:487-493. [PMID: 28000935 DOI: 10.1111/nph.14276] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- Jeff J Doyle
- Section of Plant Breeding & Genetics, School of Integrated Plant Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Sue Sherman-Broyles
- Section of Plant Breeding & Genetics, School of Integrated Plant Sciences, Cornell University, Ithaca, NY, 14853, USA
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Mason AS, Snowdon RJ. Oilseed rape: learning about ancient and recent polyploid evolution from a recent crop species. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:883-892. [PMID: 27063780 DOI: 10.1111/plb.12462] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 04/06/2016] [Indexed: 05/18/2023]
Abstract
Oilseed rape (Brassica napus) is one of our youngest crop species, arising several times under cultivation in the last few thousand years and completely unknown in the wild. Oilseed rape originated from hybridisation events between progenitor diploid species B. rapa and B. oleracea, both important vegetable species. The diploid progenitors are also ancient polyploids, with remnants of two previous polyploidisation events evident in the triplicated genome structure. This history of polyploid evolution and human agricultural selection makes B. napus an excellent model with which to investigate processes of genomic evolution and selection in polyploid crops. The ease of de novo interspecific hybridisation, responsiveness to tissue culture, and the close relationship of oilseed rape to the model plant Arabidopsis thaliana, coupled with the recent availability of reference genome sequences and suites of molecular cytogenetic and high-throughput genotyping tools, allow detailed dissection of genetic, genomic and phenotypic interactions in this crop. In this review we discuss the past and present uses of B. napus as a model for polyploid speciation and evolution in crop species, along with current and developing analysis tools and resources. We further outline unanswered questions that may now be tractable to investigation.
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Affiliation(s)
- A S Mason
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Giessen, Germany.
| | - R J Snowdon
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Giessen, Germany
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Doležálková M, Sember A, Marec F, Ráb P, Plötner J, Choleva L. Is premeiotic genome elimination an exclusive mechanism for hemiclonal reproduction in hybrid males of the genus Pelophylax? BMC Genet 2016; 17:100. [PMID: 27368375 PMCID: PMC4930623 DOI: 10.1186/s12863-016-0408-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 06/24/2016] [Indexed: 11/10/2022] Open
Abstract
Background The ability to eliminate a parental genome from a eukaryotic germ cell is a phenomenon observed mostly in hybrid organisms displaying an alternative propagation to sexual reproduction. For most taxa, the underlying cellular pathways and timing of the elimination process is only poorly understood. In the water frog hybrid Pelophylax esculentus (parental taxa are P. ridibundus and P. lessonae) the only described mechanism assumes that one parental genome is excluded from the germline during metamorphosis and prior to meiosis, while only second genome enters meiosis after endoreduplication. Our study of hybrids from a P. ridibundus—P. esculentus-male populations known for its production of more types of gametes shows that hybridogenetic mechanism of genome elimination is not uniform. Results Using comparative genomic hybridization (CGH) on mitotic and meiotic cell stages, we identified at least two pathways of meiotic mechanisms. One type of Pelophylax esculentus males provides supporting evidence of a premeiotic elimination of one parental genome. In several other males we record the presence of both parental genomes in the late phases of meiotic prophase I (diplotene) and metaphase I. Conclusion Some P. esculentus males have no genome elimination from the germ line prior to meiosis. Considering previous cytological and experimental evidence for a formation of both ridibundus and lessonae sperm within a single P. esculentus individual, we propose a hypothesis that genome elimination from the germline can either be postponed to the meiotic stages or absent altogether in these hybrids. Electronic supplementary material The online version of this article (doi:10.1186/s12863-016-0408-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marie Doležálková
- Laboratory of Fish Genetics, Department of Vertebrate Evolutionary Biology and Genetics, Institute of Animal Physiology and Genetics CAS v.v.i, Liběchov, 277 21, Czech Republic. .,Department of Zoology, Faculty of Science, Charles University in Prague, Praha 2, 128 43, Czech Republic.
| | - Alexandr Sember
- Laboratory of Fish Genetics, Department of Vertebrate Evolutionary Biology and Genetics, Institute of Animal Physiology and Genetics CAS v.v.i, Liběchov, 277 21, Czech Republic.,Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Viničná 5, Prague 2, 128 44, Czech Republic
| | - František Marec
- Laboratory of Molecular Cytogenetics, Institute of Entomology, Biology Centre CAS, České Budějovice, 370 05, Czech Republic
| | - Petr Ráb
- Laboratory of Fish Genetics, Department of Vertebrate Evolutionary Biology and Genetics, Institute of Animal Physiology and Genetics CAS v.v.i, Liběchov, 277 21, Czech Republic
| | - Jörg Plötner
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, Berlin, 10115, Germany
| | - Lukáš Choleva
- Laboratory of Fish Genetics, Department of Vertebrate Evolutionary Biology and Genetics, Institute of Animal Physiology and Genetics CAS v.v.i, Liběchov, 277 21, Czech Republic.,Department of Biology and Ecology, Faculty of Science, University of Ostrava, Chittussiho 10, Ostrava, 710 00, Czech Republic
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Walbot V, Egger RL. Pre-Meiotic Anther Development: Cell Fate Specification and Differentiation. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:365-95. [PMID: 26735065 DOI: 10.1146/annurev-arplant-043015-111804] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Research into anther ontogeny has been an active and developing field, transitioning from a strictly lineage-based view of cellular differentiation events to a more complex understanding of cell fate specification. Here we describe the modern interpretation of pre-meiotic anther development, from the earliest cell specifications within the anther lobes through SPL/NZZ-, MSP1-, and MEL1-dependent pathways as well as the initial setup of the abaxial and adaxial axes and outgrowth of the anther lobes. We then continue with a look at the known information regarding further differentiation of the somatic layers of the anther (the epidermis, endothecium, middle layer, and tapetum), with an emphasis on male-sterile mutants identified as defective in somatic cell specification. We also describe the differences in developmental stages among species and use this information to discuss molecular studies that have analyzed transcriptome, proteome, and small-RNA information in the anther.
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Affiliation(s)
- Virginia Walbot
- Department of Biology, Stanford University, Stanford, California 94305-5020; ,
| | - Rachel L Egger
- Department of Biology, Stanford University, Stanford, California 94305-5020; ,
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Lloyd A, Bomblies K. Meiosis in autopolyploid and allopolyploid Arabidopsis. CURRENT OPINION IN PLANT BIOLOGY 2016; 30:116-22. [PMID: 26950252 DOI: 10.1016/j.pbi.2016.02.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/05/2016] [Accepted: 02/08/2016] [Indexed: 05/20/2023]
Abstract
All newly formed polyploids face a challenge in meiotic chromosome segregation due to the presence of an additional set of chromosomes. Nevertheless, naturally occurring auto and allopolyploids are common and generally show high fertility, showing that evolution can find solutions. Exactly how meiosis is adapted in these cases, however, remains a mystery. The rise of Arabidopsis as a model genus for polyploid and meiosis research has seen several new studies begin to shed light on this long standing question.
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Affiliation(s)
- Andrew Lloyd
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA; Institut Jean-Pierre Bourgin (IJPB), INRA, AgroParisTech, CNRS, Université Paris-Saclay, RD10, 78026 Versailles Cedex, France.
| | - Kirsten Bomblies
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA; John Innes Centre, Department of Cell & Developmental Biology, Norwich, UK
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Melamed-Bessudo C, Shilo S, Levy AA. Meiotic recombination and genome evolution in plants. CURRENT OPINION IN PLANT BIOLOGY 2016; 30:82-7. [PMID: 26939088 DOI: 10.1016/j.pbi.2016.02.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 02/07/2016] [Accepted: 02/08/2016] [Indexed: 05/22/2023]
Abstract
Homologous recombination affects genome evolution through crossover, gene conversion and point mutations. Whole genome sequencing together with a detailed epigenome analysis have shed new light on our understanding of how meiotic recombination shapes plant genes and genome structure. Crossover events are associated with DNA sequence motifs, together with an open chromatin signature (hypomethylated CpGs, low nucleosome occupancy or specific histone modifications). The crossover landscape may differ between male and female meiocytes and between species. At the gene level, crossovers occur preferentially in promoter regions in Arabidopsis. In recent years, there is rising support suggesting that biased mismatch repair during meiotic recombination may increase GC content genome-wide and may be responsible for the GC content gradient found in many plant genes.
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Affiliation(s)
- Cathy Melamed-Bessudo
- Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Shay Shilo
- Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Avraham A Levy
- Plant and Environmental Sciences Department, The Weizmann Institute of Science, Rehovot 76100, Israel.
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Bomblies K, Jones G, Franklin C, Zickler D, Kleckner N. The challenge of evolving stable polyploidy: could an increase in "crossover interference distance" play a central role? Chromosoma 2016; 125:287-300. [PMID: 26753761 PMCID: PMC4830878 DOI: 10.1007/s00412-015-0571-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 12/20/2015] [Accepted: 12/28/2015] [Indexed: 11/24/2022]
Abstract
Whole genome duplication is a prominent feature of many highly evolved organisms, especially plants. When duplications occur within species, they yield genomes comprising multiple identical or very similar copies of each chromosome (“autopolyploids”). Such genomes face special challenges during meiosis, the specialized cellular program that underlies gamete formation for sexual reproduction. Comparisons between newly formed (neo)-autotetraploids and fully evolved autotetraploids suggest that these challenges are solved by specific restrictions on the positions of crossover recombination events and, thus, the positions of chiasmata, which govern the segregation of homologs at the first meiotic division. We propose that a critical feature in the evolution of these more effective chiasma patterns is an increase in the effective distance of meiotic crossover interference, which plays a central role in crossover positioning. We discuss the findings in several organisms, including the recent identification of relevant genes in Arabidopsis arenosa, that support this hypothesis.
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Affiliation(s)
- Kirsten Bomblies
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney, Norwich, NR4 7UH, UK
| | - Gareth Jones
- The Red House, St. David's Street, Presteigne, Powys (Wales), LD8 2BP, UK
| | - Chris Franklin
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Denise Zickler
- Institut de Génétique et Microbiologie, I2BC, Université Paris-Sud, Orsay, France
| | - Nancy Kleckner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
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Borowska-Zuchowska N, Kwasniewski M, Hasterok R. Cytomolecular Analysis of Ribosomal DNA Evolution in a Natural Allotetraploid Brachypodium hybridum and Its Putative Ancestors-Dissecting Complex Repetitive Structure of Intergenic Spacers. FRONTIERS IN PLANT SCIENCE 2016; 7:1499. [PMID: 27790225 PMCID: PMC5064635 DOI: 10.3389/fpls.2016.01499] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/20/2016] [Indexed: 05/22/2023]
Abstract
Nucleolar dominance is an epigenetic phenomenon associated with nuclear 35S rRNA genes and consists in selective suppression of gene loci inherited from one of the progenitors in the allopolyploid. Our understanding of the exact mechanisms that determine this process is still fragmentary, especially in case of the grass species. This study aimed to shed some light on the molecular basis of this genome-specific inactivation of 35S rDNA loci in an allotetraploid Brachypodium hybridum (2n = 30), which arose from the interspecific hybridization between two diploid ancestors that were very similar to modern B. distachyon (2n = 10) and B. stacei (2n = 20). Using fluorescence in situ hybridization with 25S rDNA and chromosome-specific BAC clones as probes we revealed that the nucleolar dominance is present not only in meristematic root-tip cells but also in differentiated cell fraction of B. hybridum. Additionally, the intergenic spacers (IGSs) from both of the putative ancestors and the allotetraploid were sequenced and analyzed. The presumptive transcription initiation sites, spacer promoters and repeated elements were identified within the IGSs. Two different length variants, 2.3 and 3.5 kb, of IGSs were identified in B. distachyon and B. stacei, respectively, however only the IGS that had originated from B. distachyon-like ancestor was present in the allotetraploid. The amplification pattern of B. hybridum IGSs suggests that some genetic changes occurred in inactive B. stacei-like rDNA loci during the evolution of the allotetraploid. We hypothesize that their preferential silencing is an effect of structural changes in the sequence rather than just the result of the sole inactivation at the epigenetic level.
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Affiliation(s)
- Natalia Borowska-Zuchowska
- Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in KatowiceKatowice, Poland
- *Correspondence: Natalia Borowska-Zuchowska
| | - Miroslaw Kwasniewski
- Department of Genetics, Faculty of Biology and Environmental Protection, University of Silesia in KatowiceKatowice, Poland
| | - Robert Hasterok
- Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in KatowiceKatowice, Poland
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del Pozo JC, Ramirez-Parra E. Whole genome duplications in plants: an overview from Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6991-7003. [PMID: 26417017 DOI: 10.1093/jxb/erv432] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Polyploidy is a common event in plants that involves the acquisition of more than two complete sets of chromosomes. Allopolyploidy originates from interspecies hybrids while autopolyploidy originates from intraspecies whole genome duplication (WGD) events. In spite of inconveniences derived from chromosomic rearrangement during polyploidization, natural plant polyploids species often exhibit improved growth vigour and adaptation to adverse environments, conferring evolutionary advantages. These advantages have also been incorporated into crop breeding programmes. Many tetraploid crops show increased stress tolerance, although the molecular mechanisms underlying these different adaptation abilities are poorly known. Understanding the physiological, cellular, and molecular mechanisms coupled to WGD, in both allo- and autopolyploidy, is a major challenge. Over the last few years, several studies, many of them in Arabidopsis, are shedding light on the basis of genetic, genomic, and epigenomic changes linked to WGD. In this review we summarize and discuss the latest advances made in Arabidopsis polyploidy, but also in other agronomic plant species.
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Affiliation(s)
- Juan Carlos del Pozo
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Universidad Politécnica de Madrid, Campus de Montegancedo, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Elena Ramirez-Parra
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Universidad Politécnica de Madrid, Campus de Montegancedo, 28223 Pozuelo de Alarcón, Madrid, Spain
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Bomblies K, Higgins JD, Yant L. Meiosis evolves: adaptation to external and internal environments. THE NEW PHYTOLOGIST 2015; 208:306-23. [PMID: 26075313 DOI: 10.1111/nph.13499] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 05/03/2015] [Indexed: 05/23/2023]
Abstract
306 I. 306 II. 307 III. 312 IV. 317 V. 318 319 References 319 SUMMARY: Meiosis is essential for the fertility of most eukaryotes and its structures and progression are conserved across kingdoms. Yet many of its core proteins show evidence of rapid or adaptive evolution. What drives the evolution of meiosis proteins? How can constrained meiotic processes be modified in response to challenges without compromising their essential functions? In surveying the literature, we found evidence of two especially potent challenges to meiotic chromosome segregation that probably necessitate adaptive evolutionary responses: whole-genome duplication and abiotic environment, especially temperature. Evolutionary solutions to both kinds of challenge are likely to involve modification of homologous recombination and synapsis, probably via adjustments of core structural components important in meiosis I. Synthesizing these findings with broader patterns of meiosis gene evolution suggests that the structural components of meiosis coevolve as adaptive modules that may change in primary sequence and function while maintaining three-dimensional structures and protein interactions. The often sharp divergence of these genes among species probably reflects periodic modification of entire multiprotein complexes driven by genomic or environmental changes. We suggest that the pressures that cause meiosis to evolve to maintain fertility may cause pleiotropic alterations of global crossover rates. We highlight several important areas for future research.
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Affiliation(s)
- Kirsten Bomblies
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - James D Higgins
- Department of Biology, University of Leicester, Leicester, LE1 7RH, UK
| | - Levi Yant
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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Ronceret A, Vielle-Calzada JP. Meiosis, unreduced gametes, and parthenogenesis: implications for engineering clonal seed formation in crops. PLANT REPRODUCTION 2015; 28:91-102. [PMID: 25796397 DOI: 10.1007/s00497-015-0262-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/09/2015] [Indexed: 05/18/2023]
Abstract
Meiosis and unreduced gametes. Sexual flowering plants produce meiotically derived cells that give rise to the male and female haploid gametophytic phase. In the ovule, usually a single precursor (the megaspore mother cell) undergoes meiosis to form four haploid megaspores; however, numerous mutants result in the formation of unreduced gametes, sometimes showing female specificity, a phenomenon reminiscent of the initiation of gametophytic apomixis. Here, we review the developmental events that occur during female meiosis and megasporogenesis at the light of current possibilities to engineer unreduced gamete formation. We also provide an overview of the current understanding of mechanisms leading to parthenogenesis and discuss some of the conceptual implications for attempting the induction of clonal seed production in cultivated plants.
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Affiliation(s)
- Arnaud Ronceret
- Group of Reproductive Development and Apomixis, UGA Laboratorio Nacional de Genómica para la Biodiversidad, CINVESTAV Irapuato, Km 9.6 Libramiento Norte Carretera Irapuato-León, CP 36821, Irapuato, Guanajuato, Mexico
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Betto-Colliard C, Sermier R, Litvinchuk S, Perrin N, Stöck M. Origin and genome evolution of polyploid green toads in Central Asia: evidence from microsatellite markers. Heredity (Edinb) 2015; 114:300-8. [PMID: 25370211 PMCID: PMC4815583 DOI: 10.1038/hdy.2014.100] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 09/10/2014] [Accepted: 09/22/2014] [Indexed: 02/08/2023] Open
Abstract
Polyploidization, which is expected to trigger major genomic reorganizations, occurs much less commonly in animals than in plants, possibly because of constraints imposed by sex-determination systems. We investigated the origins and consequences of allopolyploidization in Palearctic green toads (Bufo viridis subgroup) from Central Asia, with three ploidy levels and different modes of genome transmission (sexual versus clonal), to (i) establish a topology for the reticulate phylogeny in a species-rich radiation involving several closely related lineages and (ii) explore processes of genomic reorganization that may follow polyploidization. Sibship analyses based on 30 cross-amplifying microsatellite markers substantiated the maternal origins and revealed the paternal origins and relationships of subgenomes in allopolyploids. Analyses of the synteny of linkage groups identified three markers affected by translocation events, which occurred only within the paternally inherited subgenomes of allopolyploid toads and exclusively affected the linkage group that determines sex in several diploid species of the green toad radiation. Recombination rates did not differ between diploid and polyploid toad species, and were overall much reduced in males, independent of linkage group and ploidy levels. Clonally transmitted subgenomes in allotriploid toads provided support for strong genetic drift, presumably resulting from recombination arrest. The Palearctic green toad radiation seems to offer unique opportunities to investigate the consequences of polyploidization and clonal transmission on the dynamics of genomes in vertebrates.
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Affiliation(s)
- C Betto-Colliard
- Department of Ecology and Evolution, Biophore Building University of Lausanne, Lausanne, Switzerland
| | - R Sermier
- Department of Ecology and Evolution, Biophore Building University of Lausanne, Lausanne, Switzerland
| | - S Litvinchuk
- Institute of Cytology, Russian Academy of Sciences, St Petersburg, Russia
| | - N Perrin
- Department of Ecology and Evolution, Biophore Building University of Lausanne, Lausanne, Switzerland
| | - M Stöck
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
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Mercier R, Mézard C, Jenczewski E, Macaisne N, Grelon M. The molecular biology of meiosis in plants. ANNUAL REVIEW OF PLANT BIOLOGY 2015; 66:297-327. [PMID: 25494464 DOI: 10.1146/annurev-arplant-050213-035923] [Citation(s) in RCA: 327] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Meiosis is the cell division that reshuffles genetic information between generations. Recently, much progress has been made in understanding this process; in particular, the identification and functional analysis of more than 80 plant genes involved in meiosis have dramatically deepened our knowledge of this peculiar cell division. In this review, we provide an overview of advancements in the understanding of all aspects of plant meiosis, including recombination, chromosome synapsis, cell cycle control, chromosome distribution, and the challenge of polyploidy.
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Affiliation(s)
- Raphaël Mercier
- INRA, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, F-78026 Versailles, France; , , , ,
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Silenced rRNA genes are activated and substitute for partially eliminated active homeologs in the recently formed allotetraploid, Tragopogon mirus (Asteraceae). Heredity (Edinb) 2014; 114:356-65. [PMID: 25537492 DOI: 10.1038/hdy.2014.111] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 11/04/2014] [Accepted: 11/05/2014] [Indexed: 11/08/2022] Open
Abstract
To study the relationship between uniparental rDNA (encoding 18S, 5.8S and 26S ribosomal RNA) silencing (nucleolar dominance) and rRNA gene dosage, we studied a recently emerged (within the last 80 years) allotetraploid Tragopogon mirus (2n=24), formed from the diploid progenitors T. dubius (2n=12, D-genome donor) and T. porrifolius (2n=12, P-genome donor). Here, we used molecular, cytogenetic and genomic approaches to analyse rRNA gene activity in two sibling T. mirus plants (33A and 33B) with widely different rRNA gene dosages. Plant 33B had ~400 rRNA genes at the D-genome locus, which is typical for T. mirus, accounting for ~25% of total rDNA. We observed characteristic expression dominance of T. dubius-origin genes in all organs. Its sister plant 33A harboured a homozygous macrodeletion that reduced the number of T. dubius-origin genes to about 70 copies (~4% of total rDNA). It showed biparental rDNA expression in root, flower and callus, but not in leaf where D-genome rDNA dominance was maintained. There was upregulation of minor rDNA variants in some tissues. The RNA polymerase I promoters of reactivated T. porrifolius-origin rRNA genes showed reduced DNA methylation, mainly at symmetrical CG and CHG nucleotide motifs. We hypothesise that active, decondensed rDNA units are most likely to be deleted via recombination. The silenced homeologs could be used as a 'first reserve' to ameliorate mutational damage and contribute to evolutionary success of polyploids. Deletion and reactivation cycles may lead to bidirectional homogenisation of rRNA arrays in the long term.
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Abstract
Polyploidy can result in both evolutionary dead-ends and successful evolutionary transitions. A pair of recent papers indicates that adapting meiosis is a necessary step on the way to becoming a successful polyploid.
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Affiliation(s)
- Eric Jenczewski
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France.
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