151
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Great majority of recombination events in Arabidopsis are gene conversion events. Proc Natl Acad Sci U S A 2012; 109:20992-7. [PMID: 23213238 DOI: 10.1073/pnas.1211827110] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The evolutionary importance of meiosis may not solely be associated with allelic shuffling caused by crossing-over but also have to do with its more immediate effects such as gene conversion. Although estimates of the crossing-over rate are often well resolved, the gene conversion rate is much less clear. In Arabidopsis, for example, next-generation sequencing approaches suggest that the two rates are about the same, which contrasts with indirect measures, these suggesting an excess of gene conversion. Here, we provide analysis of this problem by sequencing 40 F(2) Arabidopsis plants and their parents. Small gene conversion tracts, with biased gene conversion content, represent over 90% (probably nearer 99%) of all recombination events. The rate of alteration of protein sequence caused by gene conversion is over 600 times that caused by mutation. Finally, our analysis reveals recombination hot spots and unexpectedly high recombination rates near centromeres. This may be responsible for the previously unexplained pattern of high genetic diversity near Arabidopsis centromeres.
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152
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Henderson IR. Control of meiotic recombination frequency in plant genomes. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:556-561. [PMID: 23017241 DOI: 10.1016/j.pbi.2012.09.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Revised: 07/18/2012] [Accepted: 09/05/2012] [Indexed: 05/27/2023]
Abstract
Sexual eukaryotes reproduce via the meiotic cell division, where ploidy is halved and homologous chromosomes undergo reciprocal genetic exchange, termed crossover (CO). CO frequency has a profound effect on patterns of genetic variation and species evolution. Relative CO rates vary extensively both within and between plant genomes. Plant genome size varies by over 1000-fold, largely due to differential expansion of repetitive sequences, and increased genome size is associated with reduced CO frequency. Gene versus repeat sequences associate with distinct chromatin modifications, and evidence from plant genomes indicates that this epigenetic information influences CO patterns. This is consistent with data from diverse eukaryotes that demonstrate the importance of chromatin structure for control of meiotic recombination. In this review I will discuss CO frequency patterns in plant genomes and recent advances in understanding recombination distributions.
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Affiliation(s)
- Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom.
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153
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Sun Y, Ambrose JH, Haughey BS, Webster TD, Pierrie SN, Muñoz DF, Wellman EC, Cherian S, Lewis SM, Berchowitz LE, Copenhaver GP. Deep genome-wide measurement of meiotic gene conversion using tetrad analysis in Arabidopsis thaliana. PLoS Genet 2012; 8:e1002968. [PMID: 23055940 PMCID: PMC3464199 DOI: 10.1371/journal.pgen.1002968] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 08/08/2012] [Indexed: 11/18/2022] Open
Abstract
Gene conversion, the non-reciprocal exchange of genetic information, is one of the potential products of meiotic recombination. It can shape genome structure by acting on repetitive DNA elements, influence allele frequencies at the population level, and is known to be implicated in human disease. But gene conversion is hard to detect directly except in organisms, like fungi, that group their gametes following meiosis. We have developed a novel visual assay that enables us to detect gene conversion events directly in the gametes of the flowering plant Arabidopsis thaliana. Using this assay we measured gene conversion events across the genome of more than one million meioses and determined that the genome-wide average frequency is 3.5×10(-4) conversions per locus per meiosis. We also detected significant locus-to-locus variation in conversion frequency but no intra-locus variation. Significantly, we found one locus on the short arm of chromosome 4 that experienced 3-fold to 6-fold more gene conversions than the other loci tested. Finally, we demonstrated that we could modulate conversion frequency by varying experimental conditions.
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Affiliation(s)
- Yujin Sun
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jonathan H. Ambrose
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Brena S. Haughey
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Tyler D. Webster
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sarah N. Pierrie
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Daniela F. Muñoz
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Emily C. Wellman
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Shalom Cherian
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Scott M. Lewis
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Luke E. Berchowitz
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Gregory P. Copenhaver
- Department of Biology and the Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, The University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- * E-mail:
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154
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Higgins JD, Perry RM, Barakate A, Ramsay L, Waugh R, Halpin C, Armstrong SJ, Franklin FCH. Spatiotemporal asymmetry of the meiotic program underlies the predominantly distal distribution of meiotic crossovers in barley. THE PLANT CELL 2012; 24:4096-109. [PMID: 23104831 PMCID: PMC3517238 DOI: 10.1105/tpc.112.102483] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/20/2012] [Accepted: 10/09/2012] [Indexed: 05/18/2023]
Abstract
Meiosis involves reciprocal exchange of genetic information between homologous chromosomes to generate new allelic combinations. In cereals, the distribution of genetic crossovers, cytologically visible as chiasmata, is skewed toward the distal regions of the chromosomes. However, many genes are known to lie within interstitial/proximal regions of low recombination, creating a limitation for breeders. We investigated the factors underlying the pattern of chiasma formation in barley (Hordeum vulgare) and show that chiasma distribution reflects polarization in the spatiotemporal initiation of recombination, chromosome pairing, and synapsis. Consequently, meiotic progression in distal chromosomal regions occurs in coordination with the chromatin cycles that are a conserved feature of the meiotic program. Recombination initiation in interstitial and proximal regions occurs later than distal events, is not coordinated with the cycles, and rarely progresses to form chiasmata. Early recombination initiation is spatially associated with early replicating, euchromatic DNA, which is predominately found in distal regions. We demonstrate that a modest temperature shift is sufficient to alter meiotic progression in relation to the chromosome cycles. The polarization of the meiotic processes is reduced and is accompanied by a shift in chiasma distribution with an increase in interstitial and proximal chiasmata, suggesting a potential route to modify recombination in cereals.
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Affiliation(s)
- James D. Higgins
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Ruth M. Perry
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Abdellah Barakate
- Division of Plant Sciences at James Hutton Institute, University of Dundee, Invergowrie, Dundee DD1 5EH, Scotland
| | - Luke Ramsay
- James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland
| | - Robbie Waugh
- James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland
| | - Claire Halpin
- Division of Plant Sciences at James Hutton Institute, University of Dundee, Invergowrie, Dundee DD1 5EH, Scotland
| | - Susan J. Armstrong
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - F. Chris H. Franklin
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
- Address correspondence to
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155
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Ji J, Tang D, Wang K, Wang M, Che L, Li M, Cheng Z. The role of OsCOM1 in homologous chromosome synapsis and recombination in rice meiosis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 72:18-30. [PMID: 22507309 DOI: 10.1111/j.1365-313x.2012.05025.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
COM1/SAE2 is a highly conserved gene from yeast to higher eukaryotes. Its orthologs, known to cooperate with the MRX complex (Mre11/Rad50/Xrs2), are required for meiotic DNA double-strand break (DSB) ends resection and specific mitotic DSB repair events. Here, the rice (Oryza sativa, 2n = 2x = 24) COM1/SAE2 homolog was identified through positional cloning, termed OsCOM1. Four independent mutants of OsCOM1 were isolated and characterized. In Oscom1 mutants, synaptonemal complex (SC) formation, homologous pairing and recombination were severely inhibited, whereas aberrant non-homologous chromosome entanglements occurred constantly. Several key meiotic proteins, including ZEP1 and OsMER3, were not loaded normally onto chromosomes in Oscom1 mutants, whereas the localization of OsREC8, PAIR2 and PAIR3 seemed to be normal. Moreover, OsCOM1 was loaded normally onto meiotic chromosomes in Osrec8, zep1 and Osmer3 mutants, but could not be properly loaded in Osam1, pair2 and OsSPO11-1(RNAi) plants. These results provide direct evidence for the functions of OsCOM1 in promoting homologous synapsis and recombination in rice meiosis.
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Affiliation(s)
- Jianhui Ji
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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156
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Dong Q, Han F. Phosphorylation of histone H2A is associated with centromere function and maintenance in meiosis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 71:800-9. [PMID: 22519817 DOI: 10.1111/j.1365-313x.2012.05029.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Histone phosphorylation is dynamically regulated during cell division, for example phosphorylation of histone H3 (H3)-Ser10, H3-Thr11 and H3-Ser28. Here we analyzed maize (Zea mays L) for Thr133-phosphorylated histone H2A, which is important for spindle checkpoint control and localization of the centromere cohesion protector Shugoshin in mammals and yeast. Immunostaining results indicate that phosphorylated H2A-Thr133 signals bridged those of the centromeric H3 histone variant CENH3 by using a plant displaying yellow fluorescent protein-CENH3 signals and H2A-Thr133 is phosphorylated in different cell types. During mitosis, H2A-Thr133 phosphorylation becomes strong in metaphase and is specific to centromere regions but drops during later anaphase and telophase. Immunostaining for several maize dicentric chromosomes revealed that the inactive centromeres have lost phosphorylation of H2A-Thr133. During meiosis in maize meiocytes, H2A phosphorylation becomes strong in the early pachytene stage and increases to a maximum at metaphase I. In the maize meiotic mutant afd1 (absence of first division), sister chromatids show equational separation at metaphase I, but there are no changes in H2A-Thr-133 phosphorylation during meiosis compared with the wild type. In sgo1 mutants, sister chromatids segregate randomly during meiosis II, and phosphorylation of H2A-Thr-133 is observed on the centromere regions during meiosis II. The availability of such mutants in maize that lack sister cohesion and Shugoshin indicate that the signals for phosphorylation are not dependent on cohesion but on centromere activity.
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Affiliation(s)
- Qianhua Dong
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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157
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Yelina NE, Choi K, Chelysheva L, Macaulay M, de Snoo B, Wijnker E, Miller N, Drouaud J, Grelon M, Copenhaver GP, Mezard C, Kelly KA, Henderson IR. Epigenetic remodeling of meiotic crossover frequency in Arabidopsis thaliana DNA methyltransferase mutants. PLoS Genet 2012; 8:e1002844. [PMID: 22876192 PMCID: PMC3410864 DOI: 10.1371/journal.pgen.1002844] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 06/07/2012] [Indexed: 12/25/2022] Open
Abstract
Meiosis is a specialized eukaryotic cell division that generates haploid gametes required for sexual reproduction. During meiosis, homologous chromosomes pair and undergo reciprocal genetic exchange, termed crossover (CO). Meiotic CO frequency varies along the physical length of chromosomes and is determined by hierarchical mechanisms, including epigenetic organization, for example methylation of the DNA and histones. Here we investigate the role of DNA methylation in determining patterns of CO frequency along Arabidopsis thaliana chromosomes. In A. thaliana the pericentromeric regions are repetitive, densely DNA methylated, and suppressed for both RNA polymerase-II transcription and CO frequency. DNA hypomethylated methyltransferase1 (met1) mutants show transcriptional reactivation of repetitive sequences in the pericentromeres, which we demonstrate is coupled to extensive remodeling of CO frequency. We observe elevated centromere-proximal COs in met1, coincident with pericentromeric decreases and distal increases. Importantly, total numbers of CO events are similar between wild type and met1, suggesting a role for interference and homeostasis in CO remodeling. To understand recombination distributions at a finer scale we generated CO frequency maps close to the telomere of chromosome 3 in wild type and demonstrate an elevated recombination topology in met1. Using a pollen-typing strategy we have identified an intergenic nucleosome-free CO hotspot 3a, and we demonstrate that it undergoes increased recombination activity in met1. We hypothesize that modulation of 3a activity is caused by CO remodeling driven by elevated centromeric COs. These data demonstrate how regional epigenetic organization can pattern recombination frequency along eukaryotic chromosomes.
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Affiliation(s)
- Nataliya E. Yelina
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Kyuha Choi
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Liudmila Chelysheva
- Institut Jean-Pierre Bourgin, INRA Centre de Versailles-Grignon, Versailles, France
| | | | | | - Erik Wijnker
- Wageningen University, Wageningen, The Netherlands
| | - Nigel Miller
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Jan Drouaud
- Institut Jean-Pierre Bourgin, INRA Centre de Versailles-Grignon, Versailles, France
| | - Mathilde Grelon
- Institut Jean-Pierre Bourgin, INRA Centre de Versailles-Grignon, Versailles, France
| | - Gregory P. Copenhaver
- Department of Biology and The Carolina Center for Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, The University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Christine Mezard
- Institut Jean-Pierre Bourgin, INRA Centre de Versailles-Grignon, Versailles, France
| | - Krystyna A. Kelly
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Ian R. Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
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158
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Phillips D, Nibau C, Wnetrzak J, Jenkins G. High resolution analysis of meiotic chromosome structure and behaviour in barley (Hordeum vulgare L.). PLoS One 2012; 7:e39539. [PMID: 22761818 PMCID: PMC3382580 DOI: 10.1371/journal.pone.0039539] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 05/25/2012] [Indexed: 12/11/2022] Open
Abstract
Reciprocal crossing over and independent assortment of chromosomes during meiosis generate most of the genetic variation in sexually reproducing organisms. In barley, crossovers are confined primarily to distal regions of the chromosomes, which means that a substantial proportion of the genes of this crop rarely, if ever, engage in recombination events. There is potentially much to be gained by redistributing crossovers to more proximal regions, but our ability to achieve this is dependent upon a far better understanding of meiosis in this species. This study explores the meiotic process by describing with unprecedented resolution the early behaviour of chromosomal domains, the progression of synapsis and the structure of the synaptonemal complex (SC). Using a combination of molecular cytogenetics and advanced fluorescence imaging, we show for the first time in this species that non-homologous centromeres are coupled prior to synapsis. We demonstrate that at early meiotic prophase the loading of the SC-associated structural protein ASY1, the cluster of telomeres, and distal synaptic initiation sites occupy the same polarised region of the nucleus. Through the use of advanced 3D image analysis, we show that synapsis is driven predominantly from the telomeres, and that new synaptic initiation sites arise during zygotene. In addition, we identified two different SC configurations through the use of super-resolution 3D structured illumination microscopy (3D-SIM).
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Affiliation(s)
- Dylan Phillips
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom
| | - Candida Nibau
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom
| | - Joanna Wnetrzak
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom
| | - Glyn Jenkins
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom
- * E-mail:
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159
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Qiao H, Offenberg HH, Anderson LK. Altered distribution of MLH1 foci is associated with changes in cohesins and chromosome axis compaction in an asynaptic mutant of tomato. Chromosoma 2012; 121:291-305. [PMID: 22350750 DOI: 10.1007/s00412-012-0363-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 01/03/2012] [Accepted: 01/21/2012] [Indexed: 12/25/2022]
Abstract
In most multicellular eukaryotes, synapsis [synaptonemal complex (SC) formation] between pairs of homologous chromosomes during prophase I of meiosis is closely linked with crossing over. Asynaptic mutants in plants have reduced synapsis and increased univalent frequency, often resulting in genetically unbalanced gametes and reduced fertility. Surprisingly, some asynaptic mutants (like as1 in tomato) have wild-type or increased levels of crossing over. To investigate, we examined SC spreads from as1/as1 microsporocytes using both light and electron microscopic immunolocalization. We observed increased numbers of MLH1 foci (a crossover marker) per unit length of SC in as1 mutants compared to wild-type. These changes are associated with reduced levels of detectable cohesin proteins in the axial and lateral elements (AE/LEs) of SCs, and the AE/LEs of as1 mutants are also significantly longer than those of wild-type or another asynaptic mutant. These results indicate that chromosome axis structure, synapsis, and crossover control are all closely linked in plants.
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Affiliation(s)
- Huanyu Qiao
- Department of Biology and Program in Molecular Plant Biology, Colorado State University, Fort Collins, CO 80523, USA
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160
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Murphy SP, Bass HW. The maize (Zea mays) desynaptic (dy) mutation defines a pathway for meiotic chromosome segregation, linking nuclear morphology, telomere distribution and synapsis. J Cell Sci 2012; 125:3681-90. [PMID: 22553213 DOI: 10.1242/jcs.108290] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Meiosis involves a dramatic reorganization of the genetic material, along with changes in the architecture of the nucleoplasm and cytoplasm. In the opisthokonts, nuclear envelope and meiotic chromosome behavior are coordinated by forces generated in the cytoplasm and transferred to the nucleus by the nuclear-envelope protein linkers SUN and KASH. During meiotic prophase I, the telomere bouquet arrangement has roles in interhomolog recognition, pairing, synapsis, interlock resolution and homologous chromosome recombination. The maize desynaptic (dy) mutant is defective in homologous chromosome synapsis, recombination, telomere-nuclear envelope interactions and chromosome segregation. A detailed three-dimensional cytological analysis of dy revealed telomere misplacement during the bouquet stage, synaptic irregularities, nuclear envelope distortion and chromosome bridges at anaphase I. Using linkage and B-A translocation mapping, we placed dy on the long arm of chromosome 3, genetic bin 3.06. SSR marker analysis narrowed the mapping interval to 9 cM. Candidate genes in this region include a PM3-type SUN domain protein, ZmSUN3. No obvious genetic lesions were found in the ZmSUN3 allele of dy, but a conspicuous splice variant, ZmSUN3-sv1, was observed in mRNA from dy. The variant message is predicted to result in the synthesis of a truncated ZmSUN3 protein lacking two C-terminal transmembrane domains. Other potential candidate genes relevant to the documented phenotypes were also considered. In summary, this study reveals that dy causes disruption of a central meiotic pathway connecting nuclear envelope integrity to telomere localization and synapsis during meiotic prophase.
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Affiliation(s)
- Shaun P Murphy
- Institute of Molecular Biophysics, The Florida State University, Tallahassee, FL 32306-4370, USA
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161
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Kurzbauer MT, Uanschou C, Chen D, Schlögelhofer P. The recombinases DMC1 and RAD51 are functionally and spatially separated during meiosis in Arabidopsis. THE PLANT CELL 2012; 24:2058-70. [PMID: 22589466 PMCID: PMC3442587 DOI: 10.1105/tpc.112.098459] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 04/18/2012] [Accepted: 04/27/2012] [Indexed: 05/18/2023]
Abstract
Meiosis ensures the reduction of the genome before the formation of generative cells and promotes the exchange of genetic information between homologous chromosomes by recombination. Essential for these events are programmed DNA double strand breaks (DSBs) providing single-stranded DNA overhangs after their processing. These overhangs, together with the RADiation sensitive51 (RAD51) and DMC1 Disrupted Meiotic cDNA1 (DMC1) recombinases, mediate the search for homologous sequences. Current models propose that the two ends flanking a meiotic DSB have different fates during DNA repair, but the molecular details remained elusive. Here we present evidence, obtained in the model plant Arabidopsis thaliana, that the two recombinases, RAD51 and DMC1, localize to opposite sides of a meiotic DSB. We further demonstrate that the ATR kinase is involved in regulating DMC1 deposition at meiotic DSB sites, and that its elimination allows DMC1-mediated meiotic DSB repair even in the absence of RAD51. DMC1's ability to promote interhomolog DSB repair is not a property of the protein itself but the consequence of an ASYNAPTIC1 (Hop1)-mediated impediment for intersister repair. Taken together, these results demonstrate that DMC1 functions independently and spatially separated from RAD51 during meiosis and that ATR is an integral part of the regular meiotic program.
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162
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Kogo H, Tsutsumi M, Ohye T, Inagaki H, Abe T, Kurahashi H. HORMAD1-dependent checkpoint/surveillance mechanism eliminates asynaptic oocytes. Genes Cells 2012; 17:439-54. [PMID: 22530760 DOI: 10.1111/j.1365-2443.2012.01600.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Meiotic pachytene checkpoints monitor the failure of homologous recombination and synapsis to ensure faithful chromosome segregation during gamete formation. To date, the molecular basis of the mammalian pachytene checkpoints has remained largely unknown. We here report that mouse HORMAD1 is required for a meiotic prophase checkpoint that eliminates asynaptic oocytes. Hormad1-deficient mice are infertile and show an extensive failure of homologous pairing and synapsis, consistent with the evolutionarily conserved function of meiotic HORMA domain proteins. Unexpectedly, Hormad1-deficient ovaries contain a normal number of oocytes despite asynapsis and consequently produce aneuploid oocytes, indicating a checkpoint failure. By the analysis of Hormad1/Spo11 double mutants, the Hormad1 deficiency was found to abrogate the massive oocyte loss in the Spo11-deficient ovary. The Hormad1 deficiency also causes the eventual loss of pseudo sex body in the Spo11-deficient ovary and testis. These results suggest the involvement of HORMAD1 in the repressive chromatin domain formation that is proposed to be important in the meiotic prophase checkpoints. We also show the extensive phosphorylation of HORMAD1 in the Spo11-deficient testis and ovary, suggesting an involvement of novel DNA damage-independent phosphorylation signaling in the surveillance mechanism. Our present results provide clues to HORMAD1-dependent checkpoint in response to asynapsis in mammalian meiosis.
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Affiliation(s)
- Hiroshi Kogo
- Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan
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163
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Da Ines O, Abe K, Goubely C, Gallego ME, White CI. Differing requirements for RAD51 and DMC1 in meiotic pairing of centromeres and chromosome arms in Arabidopsis thaliana. PLoS Genet 2012; 8:e1002636. [PMID: 22532804 PMCID: PMC3330102 DOI: 10.1371/journal.pgen.1002636] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 02/21/2012] [Indexed: 11/18/2022] Open
Abstract
During meiosis homologous chromosomes pair, recombine, and synapse, thus ensuring accurate chromosome segregation and the halving of ploidy necessary for gametogenesis. The processes permitting a chromosome to pair only with its homologue are not fully understood, but successful pairing of homologous chromosomes is tightly linked to recombination. In Arabidopsis thaliana, meiotic prophase of rad51, xrcc3, and rad51C mutants appears normal up to the zygotene/pachytene stage, after which the genome fragments, leading to sterility. To better understand the relationship between recombination and chromosome pairing, we have analysed meiotic chromosome pairing in these and in dmc1 mutant lines. Our data show a differing requirement for these proteins in pairing of centromeric regions and chromosome arms. No homologous pairing of mid-arm or distal regions was observed in rad51, xrcc3, and rad51C mutants. However, homologous centromeres do pair in these mutants and we show that this does depend upon recombination, principally on DMC1. This centromere pairing extends well beyond the heterochromatic centromere region and, surprisingly, does not require XRCC3 and RAD51C. In addition to clarifying and bringing the roles of centromeres in meiotic synapsis to the fore, this analysis thus separates the roles in meiotic synapsis of DMC1 and RAD51 and the meiotic RAD51 paralogs, XRCC3 and RAD51C, with respect to different chromosome domains. Meiosis is a specialised cell division that acts to halve the chromosome complement, or ploidy, in the production of gametes for sexual reproduction in eukaryotes. To ensure that each gamete has a full complement of the genetic material, homologous chromosomes must pair and then separate in a coordinated manner during meiosis, and this is mediated by recombination in the majority of studied eukaryotes. To better understand the relationship between recombination and meiotic homologue pairing, we have analysed meiotic chromosome pairing in plant mutants lacking key recombination proteins. This work provides new insights into the homologous chromosome pairing mechanisms occurring in meiotic prophase of Arabidopsis thaliana: heterochromatic centromeres and 5S rDNA regions pair early, and their pairing has different requirements for recombination proteins than does that of the chromosome arms. These data raise a number of questions concerning the specificities and roles of recombination at different chromosome and/or chromatin regions in the synapsis of homologous chromosomes at meiosis.
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Affiliation(s)
| | | | | | | | - Charles I. White
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
- * E-mail:
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164
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Knoll A, Higgins JD, Seeliger K, Reha SJ, Dangel NJ, Bauknecht M, Schröpfer S, Franklin FCH, Puchta H. The Fanconi anemia ortholog FANCM ensures ordered homologous recombination in both somatic and meiotic cells in Arabidopsis. THE PLANT CELL 2012; 24:1448-64. [PMID: 22547783 PMCID: PMC3398556 DOI: 10.1105/tpc.112.096644] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/12/2012] [Accepted: 04/17/2012] [Indexed: 05/18/2023]
Abstract
The human hereditary disease Fanconi anemia leads to severe symptoms, including developmental defects and breakdown of the hematopoietic system. It is caused by single mutations in the FANC genes, one of which encodes the DNA translocase FANCM (for Fanconi anemia complementation group M), which is required for the repair of DNA interstrand cross-links to ensure replication progression. We identified a homolog of FANCM in Arabidopsis thaliana that is not directly involved in the repair of DNA lesions but suppresses spontaneous somatic homologous recombination via a RecQ helicase (At-RECQ4A)-independent pathway. In addition, it is required for double-strand break-induced homologous recombination. The fertility of At-fancm mutant plants is compromised. Evidence suggests that during meiosis At-FANCM acts as antirecombinase to suppress ectopic recombination-dependent chromosome interactions, but this activity is antagonized by the ZMM pathway to enable the formation of interference-sensitive crossovers and chromosome synapsis. Surprisingly, mutation of At-FANCM overcomes the sterility phenotype of an At-MutS homolog4 mutant by apparently rescuing a proportion of crossover-designated recombination intermediates via a route that is likely At-MMS and UV sensitive81 dependent. However, this is insufficient to ensure the formation of an obligate crossover. Thus, At-FANCM is not only a safeguard for genome stability in somatic cells but is an important factor in the control of meiotic crossover formation.
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Affiliation(s)
- Alexander Knoll
- Botanical Institute II, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - James D. Higgins
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Katharina Seeliger
- Botanical Institute II, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Sarah J. Reha
- Botanical Institute II, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Natalie J. Dangel
- Botanical Institute II, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Markus Bauknecht
- Botanical Institute II, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Susan Schröpfer
- Botanical Institute II, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | | | - Holger Puchta
- Botanical Institute II, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
- Address correspondence to
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165
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Lu P, Han X, Qi J, Yang J, Wijeratne AJ, Li T, Ma H. Analysis of Arabidopsis genome-wide variations before and after meiosis and meiotic recombination by resequencing Landsberg erecta and all four products of a single meiosis. Genome Res 2012; 22:508-18. [PMID: 22106370 PMCID: PMC3290786 DOI: 10.1101/gr.127522.111] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 11/17/2011] [Indexed: 11/24/2022]
Abstract
Meiotic recombination, including crossovers (COs) and gene conversions (GCs), impacts natural variation and is an important evolutionary force. COs increase genetic diversity by redistributing existing variation, whereas GCs can alter allelic frequency. Here, we sequenced Arabidopsis Landsberg erecta (Ler) and two sets of all four meiotic products from a Columbia (Col)/Ler hybrid to investigate genome-wide variation and meiotic recombination at nucleotide resolution. Comparing Ler and Col sequences uncovered 349,171 Single Nucleotide Polymorphisms (SNPs), 58,085 small and 2315 large insertions/deletions (indels), with highly correlated genome-wide distributions of SNPs, and small indels. A total of 443 genes have at least 10 nonsynonymous substitutions in protein-coding regions, with enrichment for disease-resistance genes. Another 316 genes are affected by large indels, including 130 genes with complete deletion of coding regions in Ler. Using the Arabidopsis qrt1 mutant, two sets of four meiotic products were generated and analyzed by sequencing for meiotic recombination, representing the first tetrad analysis with whole-genome sequencing in a nonfungal species. We detected 18 COs, six of which had an associated GC event, and four GCs without COs (NCOs), and revealed that Arabidopsis GCs are likely fewer and with shorter tracts than those in yeast. Meiotic recombination and chromosome assortment events dramatically redistributed genome variation in meiotic products, contributing to population diversity. In particular, meiosis provides a rapid mechanism to generate copy-number variation (CNV) of sequences that have different chromosomal positions in Col and Ler.
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Affiliation(s)
- Pingli Lu
- Department of Biology and the Huck Institutes of the Life Sciences, the Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Xinwei Han
- Department of Biology and the Huck Institutes of the Life Sciences, the Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Intercollege Graduate Program in Genetics, the Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ji Qi
- State Key Laboratory of Genetic Engineering, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200433, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Jiange Yang
- Department of Biology and the Huck Institutes of the Life Sciences, the Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Asela J. Wijeratne
- Department of Biology and the Huck Institutes of the Life Sciences, the Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Intercollege Graduate Program in Plant Biology, the Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Tao Li
- Institute of Hydrobiology, Chinese Academy of Science, Wuhan 430072, China
| | - Hong Ma
- State Key Laboratory of Genetic Engineering, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200433, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
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166
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Pradillo M, López E, Linacero R, Romero C, Cuñado N, Sánchez-Morán E, Santos JL. Together yes, but not coupled: new insights into the roles of RAD51 and DMC1 in plant meiotic recombination. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 69:921-33. [PMID: 22066484 DOI: 10.1111/j.1365-313x.2011.04845.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The eukaryotic recombinases RAD51 and DMC1 are essential for DNA strand-exchange between homologous chromosomes during meiosis. RAD51 is also expressed during mitosis, and mediates homologous recombination (HR) between sister chromatids. It has been suggested that DMC1 might be involved in the switch from intersister chromatid recombination in somatic cells to interhomolog meiotic recombination. At meiosis, the Arabidopsis Atrad51 null mutant fails to synapse and has extensive chromosome fragmentation. The Atdmc1 null mutant is also asynaptic, but in this case chromosome fragmentation is absent. Thus in plants, AtDMC1 appears to be indispensable for interhomolog homologous recombination, whereas AtRAD51 seems to be more involved in intersister recombination. In this work, we have studied a new AtRAD51 knock-down mutant, Atrad51-2, which expresses only a small quantity of RAD51 protein. Atrad51-2 mutant plants are sterile and hypersensitive to DNA double-strand break induction, but their vegetative development is apparently normal. The meiotic phenotype of the mutant consists of partial synapsis, an elevated frequency of univalents, a low incidence of chromosome fragmentation and multivalent chromosome associations. Surprisingly, non-homologous chromosomes are involved in 51% of bivalents. The depletion of AtDMC1 in the Atrad51-2 background results in the loss of bivalents and in an increase of chromosome fragmentation. Our results suggest that a critical level of AtRAD51 is required to ensure the fidelity of HR during interchromosomal exchanges. Assuming the existence of asymmetrical DNA strand invasion during the initial steps of recombination, we have developed a working model in which the initial step of strand invasion is mediated by AtDMC1, with AtRAD51 required to check the fidelity of this process.
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MESH Headings
- Arabidopsis/drug effects
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Arabidopsis/radiation effects
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Chromosomes, Plant/genetics
- Chromosomes, Plant/metabolism
- Cisplatin/pharmacology
- DNA Breaks, Double-Stranded/radiation effects
- DNA, Plant/genetics
- DNA, Plant/metabolism
- Gamma Rays
- Gene Knockout Techniques
- Genetic Complementation Test
- Homologous Recombination
- Meiosis
- Metaphase
- Models, Genetic
- Phenotype
- Plants, Genetically Modified/drug effects
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- Plants, Genetically Modified/radiation effects
- Rad51 Recombinase/genetics
- Rad51 Recombinase/metabolism
- Rec A Recombinases/genetics
- Rec A Recombinases/metabolism
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Affiliation(s)
- Mónica Pradillo
- Departamento de Genética, Facultad de Biología, Universidad Complutense de Madrid, Madrid 28040, Spain.
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167
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Khoo KHP, Able AJ, Able JA. The isolation and characterisation of the wheat molecular ZIPper I homologue, TaZYP1. BMC Res Notes 2012; 5:106. [PMID: 22340255 PMCID: PMC3305362 DOI: 10.1186/1756-0500-5-106] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 02/18/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The synaptonemal complex (SC) is a proteinaceous tripartite structure used to hold homologous chromosomes together during the early stages of meiosis. The yeast ZIP1 and its homologues in other species have previously been characterised as the transverse filament protein of the synaptonemal complex. Proper installation of ZYP1 along chromosomes has been shown to be dependent on the axial element-associated protein, ASY1 in Arabidopsis. RESULTS Here we report the isolation of the wheat (Triticum aestivum) ZYP1 (TaZYP1) and its expression profile (during and post-meiosis) in wild-type, the ph1b deletion mutant as well as in Taasy1 RNAi knock-down mutants. TaZYP1 has a putative DNA-binding S/TPXX motif in its C-terminal region and we provide evidence that TaZYP1 interacts non-preferentially with both single- and double-stranded DNA in vitro. 3-dimensional dual immunofluorescence localisation assays conducted with an antibody raised against TaZYP1 show that TaZYP1 interacts with chromatin during meiosis but does not co-localise to regions of chromatin where TaASY1 is present. The TaZYP1 signal lengthens into regions of chromatin where TaASY1 has been removed in wild-type but this appears delayed in the ph1b mutant. The localisation profile of TaZYP1 in four Taasy1 knock-down mutants is similar to wild-type but TaZYP1 signal intensity appears weaker and more diffused. CONCLUSIONS In contrast to previous studies performed on plant species where ZYP1 signal is sandwiched by ASY1 signal located on both axial elements of the SC, data from the 3-dimensional dual immunofluorescence localisation assays conducted in this study show that TaZYP1 signal only lengthens into regions of chromatin after TaASY1 signal is being unloaded. However, the observation that TaZYP1 loading appears delayed in both the ph1b and Taasy1 mutants suggests that TaASY1 may still be essential for TaZYP1 to play a role in SC formation during meiosis. These data further suggest that the temporal installation of ZYP1 onto pairing homologous chromosomes in wheat is different to that of other plant species and highlights the need to study this synaptonemal complex protein on a species to species basis.
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Affiliation(s)
- Kelvin HP Khoo
- School of Agriculture, Food & Wine, Waite Research Institute, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064
| | - Amanda J Able
- School of Agriculture, Food & Wine, Waite Research Institute, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064
| | - Jason A Able
- School of Agriculture, Food & Wine, Waite Research Institute, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064
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168
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Ferdous M, Higgins JD, Osman K, Lambing C, Roitinger E, Mechtler K, Armstrong SJ, Perry R, Pradillo M, Cuñado N, Franklin FCH. Inter-homolog crossing-over and synapsis in Arabidopsis meiosis are dependent on the chromosome axis protein AtASY3. PLoS Genet 2012; 8:e1002507. [PMID: 22319460 PMCID: PMC3271061 DOI: 10.1371/journal.pgen.1002507] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 12/11/2011] [Indexed: 12/13/2022] Open
Abstract
In this study we have analysed AtASY3, a coiled-coil domain protein that is required for normal meiosis in Arabidopsis. Analysis of an Atasy3-1 mutant reveals that loss of the protein compromises chromosome axis formation and results in reduced numbers of meiotic crossovers (COs). Although the frequency of DNA double-strand breaks (DSBs) appears moderately reduced in Atasy3-1, the main recombination defect is a reduction in the formation of COs. Immunolocalization studies in wild-type meiocytes indicate that the HORMA protein AtASY1, which is related to Hop1 in budding yeast, forms hyper-abundant domains along the chromosomes that are spatially associated with DSBs and early recombination pathway proteins. Loss of AtASY3 disrupts the axial organization of AtASY1. Furthermore we show that the AtASY3 and AtASY1 homologs BoASY3 and BoASY1, from the closely related species Brassica oleracea, are co-immunoprecipitated from meiocyte extracts and that AtASY3 interacts with AtASY1 via residues in its predicted coiled-coil domain. Together our results suggest that AtASY3 is a functional homolog of Red1. Since studies in budding yeast indicate that Red1 and Hop1 play a key role in establishing a bias to favor inter-homolog recombination (IHR), we propose that AtASY3 and AtASY1 may have a similar role in Arabidopsis. Loss of AtASY3 also disrupts synaptonemal complex (SC) formation. In Atasy3-1 the transverse filament protein AtZYP1 forms small patches rather than a continuous SC. The few AtMLH1 foci that remain in Atasy3-1 are found in association with the AtZYP1 patches. This is sufficient to prevent the ectopic recombination observed in the absence of AtZYP1, thus emphasizing that in addition to its structural role the protein is important for CO formation. Homologous recombination (HR) during prophase I of meiosis leads to the formation of physical connections, known as chiasmata, between homologous chromosomes (homologs). Chiasmata are essential for accurate homolog segregation at the first meiotic division. HR is initiated by the formation of DNA double-strand breaks (DSBs). As DNA replication prior to meiosis results in the duplication of each homolog to form two identical sister chromatids, a DSB in one sister chromatid could potentially be repaired using the other as the repair template rather than one of the two non-sister chromatids of the homolog. If this route were predominant, the formation of chiasmata would be disfavored and chromosome segregation would be compromised. However, during meiosis there is a strong bias towards inter-homolog recombination (IHR). In this study we have identified AtASY3, a component of the proteinaceous axes that organize the chromosomes during meiosis in Arabidopsis. We find that AtASY3 interacts with AtASY1, a previously identified axis protein that is essential for crossover formation. We show that loss of AtASY3 disrupts the axis-organization of AtASY1. This results in a substantial reduction in chiasmata, and there is extensive chromosome mis-segregation. We propose that loss of AtASY3 affects the efficiency of the inter-homolog bias.
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Affiliation(s)
- Maheen Ferdous
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - James D. Higgins
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Kim Osman
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Christophe Lambing
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | | | - Karl Mechtler
- Institute of Molecular Pathology (IMP), Vienna, Austria
- Institute of Molecular Biotechnology (IMBA), Vienna, Austria
| | - Susan J. Armstrong
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Ruth Perry
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Mónica Pradillo
- Departamento de Génetica, Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - Nieves Cuñado
- Departamento de Génetica, Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - F. Chris H. Franklin
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
- * E-mail:
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169
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Yelina NE, Choi K, Chelysheva L, Macaulay M, de Snoo B, Wijnker E, Miller N, Drouaud J, Grelon M, Copenhaver GP, Mezard C, Kelly KA, Henderson IR. Epigenetic remodeling of meiotic crossover frequency in Arabidopsis thaliana DNA methyltransferase mutants. PLoS Genet 2012. [PMID: 27472382 DOI: 10.1371/journal.pgen] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023] Open
Abstract
Meiosis is a specialized eukaryotic cell division that generates haploid gametes required for sexual reproduction. During meiosis, homologous chromosomes pair and undergo reciprocal genetic exchange, termed crossover (CO). Meiotic CO frequency varies along the physical length of chromosomes and is determined by hierarchical mechanisms, including epigenetic organization, for example methylation of the DNA and histones. Here we investigate the role of DNA methylation in determining patterns of CO frequency along Arabidopsis thaliana chromosomes. In A. thaliana the pericentromeric regions are repetitive, densely DNA methylated, and suppressed for both RNA polymerase-II transcription and CO frequency. DNA hypomethylated methyltransferase1 (met1) mutants show transcriptional reactivation of repetitive sequences in the pericentromeres, which we demonstrate is coupled to extensive remodeling of CO frequency. We observe elevated centromere-proximal COs in met1, coincident with pericentromeric decreases and distal increases. Importantly, total numbers of CO events are similar between wild type and met1, suggesting a role for interference and homeostasis in CO remodeling. To understand recombination distributions at a finer scale we generated CO frequency maps close to the telomere of chromosome 3 in wild type and demonstrate an elevated recombination topology in met1. Using a pollen-typing strategy we have identified an intergenic nucleosome-free CO hotspot 3a, and we demonstrate that it undergoes increased recombination activity in met1. We hypothesize that modulation of 3a activity is caused by CO remodeling driven by elevated centromeric COs. These data demonstrate how regional epigenetic organization can pattern recombination frequency along eukaryotic chromosomes.
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Affiliation(s)
- Nataliya E Yelina
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
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170
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Seeliger K, Dukowic-Schulze S, Wurz-Wildersinn R, Pacher M, Puchta H. BRCA2 is a mediator of RAD51- and DMC1-facilitated homologous recombination in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2012; 193:364-75. [PMID: 22077663 DOI: 10.1111/j.1469-8137.2011.03947.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
• Mutations in the breast cancer susceptibility gene 2 (BRCA2) are correlated with hereditary breast cancer in humans. Studies have revealed that mammalian BRCA2 plays crucial roles in DNA repair. Therefore, we wished to define the role of the BRCA2 homologs in Arabidopsis in detail. • As Arabidopsis contains two functional BRCA2 homologs, an Atbrca2 double mutant was generated and analyzed with respect to hypersensitivity to genotoxic agents and recombination frequencies. Cytological studies addressing male and female meiosis were also conducted, and immunolocalization was performed in male meiotic prophase I. • The Atbrca2 double mutant showed hypersensitivity to the cross-linking agent mitomycin C and displayed a dramatic reduction in somatic homologous recombination frequency, especially after double-strand break induction. The loss of AtBRCA2 also led to severe defects in male meiosis and development of the female gametophyte and impeded proper localization of the synaptonemal complex protein AtZYP1 and the recombinases AtRAD51 and AtDMC1. • The results demonstrate that AtBRCA2 is important for both somatic and meiotic homologous recombination. We further show that AtBRCA2 is required for proper meiotic synapsis and mediates the recruitment of AtRAD51 and AtDMC1. Our results suggest that BRCA2 controls single-strand invasion steps during homologous recombination in plants.
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Affiliation(s)
- Katharina Seeliger
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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171
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Greer E, Martín AC, Pendle A, Colas I, Jones AM, Moore G, Shaw P. The Ph1 locus suppresses Cdk2-type activity during premeiosis and meiosis in wheat. THE PLANT CELL 2012; 24:152-62. [PMID: 22274628 PMCID: PMC3289575 DOI: 10.1105/tpc.111.094771] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 12/13/2011] [Accepted: 01/09/2012] [Indexed: 05/18/2023]
Abstract
Despite possessing multiple sets of related (homoeologous) chromosomes, hexaploid wheat (Triticum aestivum) restricts pairing to just true homologs at meiosis. Deletion of a single major locus, Pairing homoeologous1 (Ph1), allows pairing of homoeologs. How can the same chromosomes be processed as homologs instead of being treated as nonhomologs? Ph1 was recently defined to a cluster of defective cyclin-dependent kinase (Cdk)-like genes showing some similarity to mammalian Cdk2. We reasoned that the cluster might suppress Cdk2-type activity and therefore affect replication and histone H1 phosphorylation. Our study does indeed reveal such effects, suggesting that Cdk2-type phosphorylation has a major role in determining chromosome specificity during meiosis.
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Affiliation(s)
- Emma Greer
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Azahara C. Martín
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Ali Pendle
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Isabelle Colas
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | | | - Graham Moore
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Peter Shaw
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
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172
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Pradillo M, Santos JL. The template choice decision in meiosis: is the sister important? Chromosoma 2011; 120:447-54. [PMID: 21826413 DOI: 10.1007/s00412-011-0336-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 07/23/2011] [Accepted: 07/25/2011] [Indexed: 11/30/2022]
Abstract
Recombination between homologous chromosomes is crucial to ensure their proper segregation during meiosis. This is achieved by regulating the choice of recombination template. In mitotic cells, double-strand break repair with the sister chromatid appears to be preferred, whereas interhomolog recombination is favoured during meiosis. However, in the last year, several studies in yeast have shown the importance of the meiotic recombination between sister chromatids. Although this thinking seems to be new, evidences for sister chromatid exchange during meiosis were obtained more than 50 years ago in non-model organisms. In this mini-review, we comment briefly on the most recent advances in this hot topic and also describe observations which suggest the existence of inter-sister repair during meiotic recombination. For instance, the behaviour of mammalian XY bivalents and that of trivalents in heterozygotes for chromosomal rearrangements are cited as examples. The "rediscovering" of the requirement for the sister template, although it seems to occur at a low frequency, will probably prompt further investigations in organisms other than yeast to understand the complexity of the partner choice during meiosis.
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Affiliation(s)
- Mónica Pradillo
- Departamento de Genética, Universidad Complutense de Madrid, Spain.
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173
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Osman K, Higgins JD, Sanchez-Moran E, Armstrong SJ, Franklin FCH. Pathways to meiotic recombination in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2011; 190:523-44. [PMID: 21366595 DOI: 10.1111/j.1469-8137.2011.03665.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Meiosis is a central feature of sexual reproduction. Studies in plants have made and continue to make an important contribution to fundamental research aimed at the understanding of this complex process. Moreover, homologous recombination during meiosis provides the basis for plant breeders to create new varieties of crops. The increasing global demand for food, combined with the challenges from climate change, will require sustained efforts in crop improvement. An understanding of the factors that control meiotic recombination has the potential to make an important contribution to this challenge by providing the breeder with the means to make fuller use of the genetic variability that is available within crop species. Cytogenetic studies in plants have provided considerable insights into chromosome organization and behaviour during meiosis. More recently, studies, predominantly in Arabidopsis thaliana, are providing important insights into the genes and proteins that are required for crossover formation during plant meiosis. As a result, substantial progress in the understanding of the molecular mechanisms that underpin meiosis in plants has begun to emerge. This article summarizes current progress in the understanding of meiotic recombination and its control in Arabidopsis. We also assess the relationship between meiotic recombination in Arabidopsis and other eukaryotes, highlighting areas of close similarity and apparent differences.
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Affiliation(s)
- Kim Osman
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
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174
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Meiotic homologue alignment and its quality surveillance are controlled by mouse HORMAD1. Nat Cell Biol 2011; 13:599-610. [PMID: 21478856 DOI: 10.1038/ncb2213] [Citation(s) in RCA: 167] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 01/20/2011] [Indexed: 12/14/2022]
Abstract
Meiotic crossover formation between homologous chromosomes (homologues) entails DNA double-strand break (DSB) formation, homology search using DSB ends, and synaptonemal-complex formation coupled with DSB repair. Meiotic progression must be prevented until DSB repair and homologue alignment are completed, to avoid the formation of aneuploid gametes. Here we show that mouse HORMAD1 ensures that sufficient numbers of processed DSBs are available for successful homology search. HORMAD1 is needed for normal synaptonemal-complex formation and for the efficient recruitment of ATR checkpoint kinase activity to unsynapsed chromatin. The latter phenomenon was proposed to be important in meiotic prophase checkpoints in both sexes. Consistent with this hypothesis, HORMAD1 is essential for the elimination of synaptonemal-complex-defective oocytes. Synaptonemal-complex formation results in HORMAD1 depletion from chromosome axes. Thus, we propose that the synaptonemal complex and HORMAD1 are key components of a negative feedback loop that coordinates meiotic progression with homologue alignment: HORMAD1 promotes homologue alignment and synaptonemal-complex formation, and synaptonemal complexes downregulate HORMAD1 function, thereby permitting progression past meiotic prophase checkpoints.
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175
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Edlinger B, Schlögelhofer P. Have a break: determinants of meiotic DNA double strand break (DSB) formation and processing in plants. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:1545-63. [PMID: 21220780 DOI: 10.1093/jxb/erq421] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Meiosis is an essential process for sexually reproducing organisms, leading to the formation of specialized generative cells. This review intends to highlight current knowledge of early events during meiosis derived from various model organisms, including plants. It will particularly focus on cis- and trans-requirements of meiotic DNA double strand break (DSB) formation, a hallmark event during meiosis and a prerequisite for recombination of genetic traits. Proteins involved in DSB formation in different organisms, emphasizing the known factors from plants, will be introduced and their functions outlined. Recent technical advances in DSB detection and meiotic recombination analysis will be reviewed, as these new tools now allow analysis of early meiotic recombination in plants with incredible accuracy. To anticipate future directions in plant meiosis research, unpublished results will be included wherever possible.
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Affiliation(s)
- Bernd Edlinger
- University of Vienna, Max F. Perutz Laboratories, Department of Chromosome Biology, Dr. Bohr-Gasse 1, Vienna, Austria
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176
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Higgins JD, Ferdous M, Osman K, Franklin FCH. The RecQ helicase AtRECQ4A is required to remove inter-chromosomal telomeric connections that arise during meiotic recombination in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 65:492-502. [PMID: 21265901 DOI: 10.1111/j.1365-313x.2010.04438.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
RecQ helicases are a conserved group of proteins with a role in the maintenance of genome integrity. In Saccharomyces cerevisiae (budding yeast), meiotic recombination is increased in the absence of the RecQ helicase Sgs1. Here we investigated the potential meiotic role of the Sgs1 homologue AtRECQ4A and the closely related AtRECQ4B. Both proteins have been shown to function during recombination in somatic cells, but so far their meiotic role has not been investigated. Both AtRECQ4A and AtRECQ4B were expressed in reproductive tissues. Although immunolocalization studies showed that AtRECQ4A associates with recombination intermediates, we found no evidence that its loss or that of AtRECQ4B had a significant effect on meiotic cross-overs, suggesting functional redundancy with other RECQ family members. Nevertheless, pollen viability decreased in Atrecq4A, resulting in a reduction in fertility, although this was not the case in Atrecq4B. Cytological analysis revealed chromatin bridges between the telomeres of non-homologous chromosomes in Atrecq4A at metaphase I, in some instances accompanied by chromosome fragmentation at anaphase I. The bridges required telomeric repeats and were dependent on meiotic recombination. Immunolocalization confirmed the association of AtRECQ4A with the telomeres during prophase I, which we propose enables dissolution of recombination-dependent telomeric associations. Thus, this study has identified a hitherto unknown role for a member of the RECQ helicase family during meiosis that contributes to the maintenance of chromosome integrity. As telomere structure is generally conserved, it seems likely that these associations may arise during meiosis in other species, where they must also be removed.
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Affiliation(s)
- James D Higgins
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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177
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Abstract
The events occurring at the onset of meiosis have not been fully elucidated. In the present study, OsAM1 was identified in rice (Oryza sativa L.) by map-based cloning. OsAM1, a homolog of Arabidopsis SWI1 and maize AM1, encodes a protein with a coiled-coil domain in its central region. In the Osam1 mutant, pollen mother cells are arrested at leptotene, showing that OsAM1 is required for the leptotene-zygotene transition. Immunocytological analysis revealed that OsAM1 exists as foci in early prophase I meiocytes. Very faint OsREC8 foci persisted in the Osam1 mutant, indicating that OsAM1 is not required for the initial meiotic recruitment of OsREC8. In the absence of OsAM1, many other critical meiotic components, including PAIR2, ZEP1 and OsMER3, could not be correctly installed onto chromosomes. In contrast, in pair2, Osmer3 and zep1 mutants, OsAM1 could be loaded normally, suggesting that OsAM1 plays a fundamental role in building the proper chromosome structure at the beginning of meiosis.
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178
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Chen Z, Higgins JD, Hui JTL, Li J, Franklin FCH, Berger F. Retinoblastoma protein is essential for early meiotic events in Arabidopsis. EMBO J 2011; 30:744-55. [PMID: 21217641 DOI: 10.1038/emboj.2010.344] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Accepted: 11/29/2010] [Indexed: 11/09/2022] Open
Abstract
We have analysed the role of RBR (retinoblastoma related), the Arabidopsis homologue of the tumour suppressor Retinoblastoma protein (pRb), during meiosis. We characterise the rbr-2 mutation, which causes a loss of RBR in male meiocytes. The rbr-2 plants exhibit strongly reduced fertility, while vegetative growth is generally unaffected. The reduced fertility is due to a meiotic defect that results in reduced chiasma formation and subsequent errors in chromosome disjunction. Immunolocalisation studies in wild-type meiocytes reveal that RBR is recruited as foci to the chromosomes during early prophase I in a DNA double-strand-break-dependent manner. In the absence of RBR, expression of several meiotic genes is reduced. The localisation of the recombinases AtRAD51 and AtDMC1 is normal. However, localisation of the MutS homologue AtMSH4 is compromised. Additionally, polymerisation of the synaptonemal complex protein AtZYP1 is abnormal. Together, these data indicate that loss of RBR during meiosis results in a reduction of crossover formation and an associated failure in chromosome synapsis. Our results indicate that RBR has an important role in meiosis affecting different aspects of this complex process.
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Affiliation(s)
- Zhong Chen
- Temasek Life Sciences Laboratory, Singapore
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179
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Chen C, Farmer AD, Langley RJ, Mudge J, Crow JA, May GD, Huntley J, Smith AG, Retzel EF. Meiosis-specific gene discovery in plants: RNA-Seq applied to isolated Arabidopsis male meiocytes. BMC PLANT BIOLOGY 2010; 10:280. [PMID: 21167045 PMCID: PMC3018465 DOI: 10.1186/1471-2229-10-280] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 12/17/2010] [Indexed: 05/18/2023]
Abstract
BACKGROUND Meiosis is a critical process in the reproduction and life cycle of flowering plants in which homologous chromosomes pair, synapse, recombine and segregate. Understanding meiosis will not only advance our knowledge of the mechanisms of genetic recombination, but also has substantial applications in crop improvement. Despite the tremendous progress in the past decade in other model organisms (e.g., Saccharomyces cerevisiae and Drosophila melanogaster), the global identification of meiotic genes in flowering plants has remained a challenge due to the lack of efficient methods to collect pure meiocytes for analyzing the temporal and spatial gene expression patterns during meiosis, and for the sensitive identification and quantitation of novel genes. RESULTS A high-throughput approach to identify meiosis-specific genes by combining isolated meiocytes, RNA-Seq, bioinformatic and statistical analysis pipelines was developed. By analyzing the studied genes that have a meiosis function, a pipeline for identifying meiosis-specific genes has been defined. More than 1,000 genes that are specifically or preferentially expressed in meiocytes have been identified as candidate meiosis-specific genes. A group of 55 genes that have mitochondrial genome origins and a significant number of transposable element (TE) genes (1,036) were also found to have up-regulated expression levels in meiocytes. CONCLUSION These findings advance our understanding of meiotic genes, gene expression and regulation, especially the transcript profiles of MGI genes and TE genes, and provide a framework for functional analysis of genes in meiosis.
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Affiliation(s)
- Changbin Chen
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, MN 55108, USA
| | - Andrew D Farmer
- National Center for Genome Resources, 2935 Rodeo Park Drive E., Santa Fe, NM 87505, USA
| | - Raymond J Langley
- National Center for Genome Resources, 2935 Rodeo Park Drive E., Santa Fe, NM 87505, USA
- Immunology, Lovelace Respiratory Research Institute, 2425 Ridgecrest Drive SE, Albuquerque, NM 87108, USA
| | - Joann Mudge
- National Center for Genome Resources, 2935 Rodeo Park Drive E., Santa Fe, NM 87505, USA
| | - John A Crow
- National Center for Genome Resources, 2935 Rodeo Park Drive E., Santa Fe, NM 87505, USA
| | - Gregory D May
- National Center for Genome Resources, 2935 Rodeo Park Drive E., Santa Fe, NM 87505, USA
| | - James Huntley
- National Center for Genome Resources, 2935 Rodeo Park Drive E., Santa Fe, NM 87505, USA
- Illumina Inc., Hayward, California 94545, USA
| | - Alan G Smith
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, MN 55108, USA
| | - Ernest F Retzel
- National Center for Genome Resources, 2935 Rodeo Park Drive E., Santa Fe, NM 87505, USA
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180
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Kim KP, Weiner BM, Zhang L, Jordan A, Dekker J, Kleckner N. Sister cohesion and structural axis components mediate homolog bias of meiotic recombination. Cell 2010; 143:924-37. [PMID: 21145459 PMCID: PMC3033573 DOI: 10.1016/j.cell.2010.11.015] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 10/19/2010] [Accepted: 10/21/2010] [Indexed: 11/19/2022]
Abstract
Meiotic double-strand break (DSB)-initiated recombination must occur between homologous maternal and paternal chromosomes ("homolog bias"), even though sister chromatids are present. Through physical recombination analyses, we show that sister cohesion, normally mediated by meiotic cohesin Rec8, promotes "sister bias"; that meiosis-specific axis components Red1/Mek1kinase counteract this effect, thereby satisfying an essential precondition for homolog bias; and that other components, probably recombinosome-related, directly ensure homolog partner selection. Later, Rec8 acts positively to ensure maintenance of bias. These complexities mirror opposing dictates for global sister cohesion versus local separation and differentiation of sisters at recombination sites. Our findings support DSB formation within axis-tethered recombinosomes containing both sisters and ensuing programmed sequential release of "first" and "second" DSB ends. First-end release would create a homology-searching "tentacle." Rec8 and Red1/Mek1 also independently license recombinational progression and abundantly localize to different domains. These domains could comprise complementary environments that integrate inputs from DSB repair and mitotic chromosome morphogenesis into the complete meiotic program.
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Affiliation(s)
- Keun P. Kim
- Department of Molecular and Cellular Biology Harvard University, 7 Divinity Avenue Cambridge, MA 02138 USA
| | - Beth M. Weiner
- Department of Molecular and Cellular Biology Harvard University, 7 Divinity Avenue Cambridge, MA 02138 USA
| | - Liangran Zhang
- Department of Molecular and Cellular Biology Harvard University, 7 Divinity Avenue Cambridge, MA 02138 USA
| | - Amy Jordan
- Department of Molecular and Cellular Biology Harvard University, 7 Divinity Avenue Cambridge, MA 02138 USA
| | - Job Dekker
- Department of Molecular and Cellular Biology Harvard University, 7 Divinity Avenue Cambridge, MA 02138 USA
- Program in Gene Function and Expression and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester MA 01655 USA
| | - Nancy Kleckner
- Department of Molecular and Cellular Biology Harvard University, 7 Divinity Avenue Cambridge, MA 02138 USA
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181
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Wang K, Wang M, Tang D, Shen Y, Qin B, Li M, Cheng Z. PAIR3, an axis-associated protein, is essential for the recruitment of recombination elements onto meiotic chromosomes in rice. Mol Biol Cell 2010; 22:12-9. [PMID: 21119003 PMCID: PMC3016970 DOI: 10.1091/mbc.e10-08-0667] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PAIR3, an axis-associated protein, is essential for bouquet formation, initial homologous pairing and normal recombination, and SC assembly in rice. During meiosis, the paired homologous chromosomes are tightly held together by the synaptonemal complex (SC). This complex consists of two parallel axial/lateral elements (AEs/LEs) and one central element. Here, we observed that PAIR3 localized to the chromosome core during prophase I and associated with both unsynapsed AEs and synapsed LEs. Analyses of the severe pair3 mutant demonstrated that PAIR3 was essential for bouquet formation, homologous pairing and normal recombination, and SC assembly. In addition, we showed that although PAIR3 was not required for the initial recruitment of PAIR2, it was required for the proper association of PAIR2 with chromosomes. Dual immunostaining revealed that PAIR3 highly colocalized with REC8. Moreover, studies using a rec8 mutant indicated that PAIR3 localized to chromosomes in a REC8-dependent manner.
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Affiliation(s)
- Kejian Wang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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182
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Yu H, Wang M, Tang D, Wang K, Chen F, Gong Z, Gu M, Cheng Z. OsSPO11-1 is essential for both homologous chromosome pairing and crossover formation in rice. Chromosoma 2010; 119:625-36. [DOI: 10.1007/s00412-010-0284-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 06/20/2010] [Accepted: 06/24/2010] [Indexed: 12/01/2022]
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183
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Harrison CJ, Alvey E, Henderson IR. Meiosis in flowering plants and other green organisms. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:2863-75. [PMID: 20576791 DOI: 10.1093/jxb/erq191] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Sexual eukaryotes generate gametes using a specialized cell division called meiosis that serves both to halve the number of chromosomes and to reshuffle genetic variation present in the parent. The nature and mechanism of the meiotic cell division in plants and its effect on genetic variation are reviewed here. As flowers are the site of meiosis and fertilization in angiosperms, meiotic control will be considered within this developmental context. Finally, we review what is known about the control of meiosis in green algae and non-flowering land plants and discuss evolutionary transitions relating to meiosis that have occurred in the lineages giving rise to the angiosperms.
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Affiliation(s)
- C Jill Harrison
- Department of Plant Sciences, University of Cambridge, Cambridge, UK.
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184
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Perrella G, Consiglio MF, Aiese-Cigliano R, Cremona G, Sanchez-Moran E, Barra L, Errico A, Bressan RA, Franklin FCH, Conicella C. Histone hyperacetylation affects meiotic recombination and chromosome segregation in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:796-806. [PMID: 20230492 DOI: 10.1111/j.1365-313x.2010.04191.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In this study, the meiotic role of MEIOTIC CONTROL OF CROSSOVERS1 (MCC1), a GCN5-related histone N-acetyltransferase, is described in Arabidopsis. Analysis of the over-expression mutant obtained by enhancer activation tagging revealed that acetylation of histone H3 increased in male prophase I. MCC1 appeared to be required in meiosis for normal chiasma number and distribution and for chromosome segregation. Overall, elevated MCC1 did not affect crossover number per cell, but has a differential effect on individual chromosomes elevating COs for chromosome 4, in which there is also a shift in chiasma distribution, and reducing COs for chromosome 1 and 2. For the latter there is a loss of the obligate CO/chiasma in 8% of the male meiocytes. The meiotic defects led to abortion in about half of the male and female gametes in the mutant. In wild type, the treatment with trichostatin A, an inhibitor of histone deacetylases, phenocopies MCC1 over-expression in meiosis. Our results provide evidence that histone hyperacetylation has a significant impact on the plant meiosis.
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Affiliation(s)
- Giorgio Perrella
- CNR-IGV, Research Institute of Plant Genetics, Research Division, Portici, Via Università 133, 80055 Portici, Italy
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185
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PHS1 regulates meiotic recombination and homologous chromosome pairing by controlling the transport of RAD50 to the nucleus. Proc Natl Acad Sci U S A 2009; 106:20121-6. [PMID: 19918061 DOI: 10.1073/pnas.0906273106] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recombination and pairing of homologous chromosomes are critical for bivalent formation in meiotic prophase. In many organisms, including yeast, mammals, and plants, pairing and recombination are intimately interconnected. The POOR HOMOLOGOUS SYNAPSIS1 (PHS1) gene acts in coordination of chromosome pairing and early recombination steps in plants, ensuring pairing fidelity and proper repair of meiotic DNA double-strand-breaks. In phs1 mutants, chromosomes exhibit early recombination defects and frequently associate with non-homologous partners, instead of pairing with their proper homologs. Here, we show that the product of the PHS1 gene is a cytoplasmic protein that functions by controlling transport of RAD50 from cytoplasm to the nucleus. RAD50 is a component of the MRN protein complex that processes meiotic double-strand-breaks to produce single-stranded DNA ends, which act in the homology search and recombination. We demonstrate that PHS1 plays the same role in homologous pairing in both Arabidopsis and maize, whose genomes differ dramatically in size and repetitive element content. This suggests that PHS1 affects pairing of the gene-rich fraction of the genome rather than preventing pairing between repetitive DNA elements. We propose that PHS1 is part of a system that regulates the progression of meiotic prophase by controlling entry of meiotic proteins into the nucleus. We also document that in phs1 mutants in Arabidopsis, centromeres interact before pairing commences along chromosome arms. Centromere coupling was previously observed in yeast and polyploid wheat while our data suggest that it may be a more common feature of meiosis.
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186
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Wojtasz L, Daniel K, Roig I, Bolcun-Filas E, Xu H, Boonsanay V, Eckmann CR, Cooke HJ, Jasin M, Keeney S, McKay MJ, Toth A. Mouse HORMAD1 and HORMAD2, two conserved meiotic chromosomal proteins, are depleted from synapsed chromosome axes with the help of TRIP13 AAA-ATPase. PLoS Genet 2009; 5:e1000702. [PMID: 19851446 PMCID: PMC2758600 DOI: 10.1371/journal.pgen.1000702] [Citation(s) in RCA: 302] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 09/25/2009] [Indexed: 11/18/2022] Open
Abstract
Meiotic crossovers are produced when programmed double-strand breaks (DSBs) are repaired by recombination from homologous chromosomes (homologues). In a wide variety of organisms, meiotic HORMA-domain proteins are required to direct DSB repair towards homologues. This inter-homologue bias is required for efficient homology search, homologue alignment, and crossover formation. HORMA-domain proteins are also implicated in other processes related to crossover formation, including DSB formation, inhibition of promiscuous formation of the synaptonemal complex (SC), and the meiotic prophase checkpoint that monitors both DSB processing and SCs. We examined the behavior of two previously uncharacterized meiosis-specific mouse HORMA-domain proteins—HORMAD1 and HORMAD2—in wild-type mice and in mutants defective in DSB processing or SC formation. HORMADs are preferentially associated with unsynapsed chromosome axes throughout meiotic prophase. We observe a strong negative correlation between SC formation and presence of HORMADs on axes, and a positive correlation between the presumptive sites of high checkpoint-kinase ATR activity and hyper-accumulation of HORMADs on axes. HORMADs are not depleted from chromosomes in mutants that lack SCs. In contrast, DSB formation and DSB repair are not absolutely required for depletion of HORMADs from synapsed axes. A simple interpretation of these findings is that SC formation directly or indirectly promotes depletion of HORMADs from chromosome axes. We also find that TRIP13 protein is required for reciprocal distribution of HORMADs and the SYCP1/SC-component along chromosome axes. Similarities in mouse and budding yeast meiosis suggest that TRIP13/Pch2 proteins have a conserved role in establishing mutually exclusive HORMAD-rich and synapsed chromatin domains in both mouse and yeast. Taken together, our observations raise the possibility that involvement of meiotic HORMA-domain proteins in the regulation of homologue interactions is conserved in mammals. Generation of haploid gametes in most organisms requires that homologues become connected via crossovers during meiosis. Efficient formation of crossovers depends on HORMA-domain proteins in diverse taxa. These proteins ensure that programmed meiotic DSBs are preferentially repaired from homologues, rather than from sister chromatids. This inter-homologue bias is crucial for homology search and crossovers formation. HORMA-domain proteins have been also implicated in DSB formation, in suppression of synaptonemal complex formation between non-homologous chromosomes, and in the meiotic prophase checkpoint that monitors DSB repair. Despite the importance of HORMA-domain proteins in various organisms, a role for these proteins in mammalian meiosis hasn't been reported. We examined the behaviour of meiotic mouse HORMA-domain proteins—HORMAD1 and HORMAD2—in wild-type and meiotic mutants. HORMAD1/2 preferentially accumulate on unsynapsed chromosome axes. Our data suggest that HORMAD1/2 depletion from chromosomes is a response to synaptonemal complex formation and it that is a conserved process supported by TRIP13/Pch2 AAA-ATPase. Assuming that HORMA-domain functions are conserved in mammals, we speculate that depletion of HORMADs from axes might contribute to the down-regulation of inter-homologue bias and the prophase checkpoint once homology search is completed and synaptonemal complexes form between aligned homologues.
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Affiliation(s)
- Lukasz Wojtasz
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Katrin Daniel
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Ignasi Roig
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | | | - Huiling Xu
- Divisions of Radiation Oncology and Research, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Verawan Boonsanay
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | | | - Howard J. Cooke
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
- Howard Hughes Medical Institute, New York, New York, United States of America
| | - Michael J. McKay
- Department of Radiation Oncology, Australian National University and the Canberra Hospital, Canberra, Australian Capital Territory, Australia
| | - Attila Toth
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
- * E-mail:
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187
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De Muyt A, Pereira L, Vezon D, Chelysheva L, Gendrot G, Chambon A, Lainé-Choinard S, Pelletier G, Mercier R, Nogué F, Grelon M. A high throughput genetic screen identifies new early meiotic recombination functions in Arabidopsis thaliana. PLoS Genet 2009; 5:e1000654. [PMID: 19763177 PMCID: PMC2735182 DOI: 10.1371/journal.pgen.1000654] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 08/19/2009] [Indexed: 11/18/2022] Open
Abstract
Meiotic recombination is initiated by the formation of numerous DNA double-strand breaks (DSBs) catalysed by the widely conserved Spo11 protein. In Saccharomyces cerevisiae, Spo11 requires nine other proteins for meiotic DSB formation; however, unlike Spo11, few of these are conserved across kingdoms. In order to investigate this recombination step in higher eukaryotes, we took advantage of a high-throughput meiotic mutant screen carried out in the model plant Arabidopsis thaliana. A collection of 55,000 mutant lines was screened, and spo11-like mutations, characterised by a drastic decrease in chiasma formation at metaphase I associated with an absence of synapsis at prophase, were selected. This screen led to the identification of two populations of mutants classified according to their recombination defects: mutants that repair meiotic DSBs using the sister chromatid such as Atdmc1 or mutants that are unable to make DSBs like Atspo11-1. We found that in Arabidopsis thaliana at least four proteins are necessary for driving meiotic DSB repair via the homologous chromosomes. These include the previously characterised DMC1 and the Hop1-related ASY1 proteins, but also the meiotic specific cyclin SDS as well as the Hop2 Arabidopsis homologue AHP2. Analysing the mutants defective in DSB formation, we identified the previously characterised AtSPO11-1, AtSPO11-2, and AtPRD1 as well as two new genes, AtPRD2 and AtPRD3. Our data thus increase the number of proteins necessary for DSB formation in Arabidopsis thaliana to five. Unlike SPO11 and (to a minor extent) PRD1, these two new proteins are poorly conserved among species, suggesting that the DSB formation mechanism, but not its regulation, is conserved among eukaryotes.
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Affiliation(s)
- Arnaud De Muyt
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Lucie Pereira
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Daniel Vezon
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Liudmila Chelysheva
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Ghislaine Gendrot
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Aurélie Chambon
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Sandrine Lainé-Choinard
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Georges Pelletier
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Raphaël Mercier
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Fabien Nogué
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
| | - Mathilde Grelon
- INRA de Versailles, Institut Jean-Pierre Bourgin, Station de Génétique et d'Amélioration des Plantes UR-254, Versailles, France
- * E-mail:
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188
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Able JA, Crismani W, Boden SA. Understanding meiosis and the implications for crop improvement. FUNCTIONAL PLANT BIOLOGY : FPB 2009; 36:575-588. [PMID: 32688671 DOI: 10.1071/fp09068] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Accepted: 05/01/2009] [Indexed: 06/11/2023]
Abstract
Over the past 50 years, the understanding of meiosis has aged like a fine bottle of wine: the complexity is developing but the wine itself is still young. While emphasis in the plant kingdom has been placed on the model diploids Arabidopsis (Arabidopsis thaliana L.) and rice (Orzya sativa L.), our research has mainly focussed on the polyploid, bread wheat (Triticum aestivum L.). Bread wheat is an important food source for nearly two-thirds of the world's population. While creating new varieties can be achieved using existing or advanced breeding lines, we would also like to introduce beneficial traits from wild related species. However, expanding the use of non-adapted and wild germplasm in cereal breeding programs will depend on the ability to manipulate the cellular process of meiosis. Three important and tightly-regulated events that occur during early meiosis are chromosome pairing, synapsis and recombination. Which key genes control these events in meiosis (and how they do so) remains to be completely answered, particularly in crops such as wheat. Although the majority of published findings are from model organisms including yeast (Saccharomyces cerevisiae) and the nematode Caenorhabditis elegans, information from the plant kingdom has continued to grow in the past decade at a steady rate. It is with this new knowledge that we ask how meiosis will contribute to the future of cereal breeding. Indeed, how has it already shaped cereal breeding as we know it today?
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Affiliation(s)
- Jason A Able
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia
| | - Wayne Crismani
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia
| | - Scott A Boden
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia 5064, Australia
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189
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Wang K, Tang D, Wang M, Lu J, Yu H, Liu J, Qian B, Gong Z, Wang X, Chen J, Gu M, Cheng Z. MER3 is required for normal meiotic crossover formation, but not for presynaptic alignment in rice. J Cell Sci 2009; 122:2055-63. [DOI: 10.1242/jcs.049080] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
MER3, a ZMM protein, is required for the formation of crossovers in Saccharomyces cerevisiae and Arabidopsis. Here, MER3, the first identified ZMM gene in a monocot, is characterized by map-based cloning in rice (Oryza sativa). The null mutation of MER3 results in complete sterility without any vegetative defects. Cytological analyses show that chiasma frequency is reduced dramatically in mer3 mutants and the remaining chiasmata distribute randomly among different pollen mother cells, implying possible coexistence of two kinds of crossover in rice. Immunocytological analyses reveal that MER3 only exists as foci in prophase I meiocytes. In addition, MER3 does not colocalize with PAIR2 at the beginning of prophase I, but locates on one end of PAIR2 fragments at later stages, whereas MER3 foci merely locate on one end of REC8 fragments when signals start to be seen in early prophase I. The normal loading of PAIR2 and REC8 in mer3 implies that their loading is independent of MER3. On the contrary, the absence of MER3 signal in pair2 mutants indicates that PAIR2 is essential for the loading and further function of MER3.
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Affiliation(s)
- Kejian Wang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ding Tang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Mo Wang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jufei Lu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Hengxiu Yu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Jiafan Liu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Baoxiang Qian
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhiyun Gong
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Xin Wang
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Jianmin Chen
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Minghong Gu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Zhukuan Cheng
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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190
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Viera A, Santos JL, Rufas JS. Relationship between incomplete synapsis and chiasma localization. Chromosoma 2009; 118:377-89. [PMID: 19238420 DOI: 10.1007/s00412-009-0204-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 01/27/2009] [Accepted: 01/27/2009] [Indexed: 12/29/2022]
Abstract
One of the subjects within the meiotic field that has been actively investigated in the recent years is the temporal and functional relationships between meiotic recombination, cohesin loading and synaptonemal complex (SC) assembly. Although the study of meiotic mutants has shed some light, many questions remain to be answered. Here, we have studied this topic in the orthopteran Paratettix meridionalis, a species with telocentric chromosomes, which shows two unusual cytological features: pairing and synapsis of homologues during prophase I are restricted to the non-centromeric distal regions and extremely distal chiasma localization in metaphase I bivalents. In order to determine whether there is a relationship between both phenomena, we have used: (1) a spreading technique for following the ultrastructure of SC assembly and (2) immunofluorescence for SMC3 and SMC1alpha cohesin subunits, which mark the development of the axial element (a SC component); the histone gamma-H2AX, which mostly labels the sites of double-strand breaks; and the recombinase RAD51. Spermatocytes showed conspicuous polarization of both the maturation of cohesin axes and the initiation of meiotic recombination events. Consequently, it is proposed that maturation of cohesin axes, which begins in very distal regions, could drive the latter loading of recombinases to such regions. This restricted distribution of recombination events along homologues would finally be responsible for the incomplete pairing and synapsis observed in all autosomes of the complement and hence for chiasma localization.
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Affiliation(s)
- Alberto Viera
- Departamento de Biología, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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191
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Loidl J, Mochizuki K. Tetrahymena meiotic nuclear reorganization is induced by a checkpoint kinase-dependent response to DNA damage. Mol Biol Cell 2009; 20:2428-37. [PMID: 19297526 PMCID: PMC2675622 DOI: 10.1091/mbc.e08-10-1058] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 01/27/2009] [Accepted: 03/05/2009] [Indexed: 11/11/2022] Open
Abstract
In the ciliate Tetrahymena, meiotic micronuclei (MICs) undergo extreme elongation, and meiotic pairing and recombination take place within these elongated nuclei (the "crescents"). We have previously shown that elongation does not occur in the absence of Spo11p-induced DNA double-strand breaks (DSBs). Here we show that elongation is restored in spo11Delta mutants by various DNA-damaging agents including ones that may not cause DSBs to a notable extent. MIC elongation following Spo11p-induced DSBs or artificially induced DNA lesions is probably a DNA-damage response mediated by a phosphokinase signal transduction pathway, since it is suppressed by the ATM/ATR kinase inhibitors caffeine and wortmannin and by knocking out Tetrahymena's ATR orthologue. MIC elongation occurs concomitantly with the movement of centromeres away from the telomeric pole of the MIC. This DNA damage-dependent reorganization of the MIC helps to arrange homologous chromosomes alongside each other but is not sufficient for exact pairing. Thus, Spo11p contributes to bivalent formation in two ways: by creating a favorable spatial disposition of homologues and by stabilizing pairing by crossovers. The polarized chromosome orientation inside the crescent resembles the conserved meiotic bouquet, and crescent and bouquet also share the putative function of aiding meiotic pairing. However, they are regulated differently because in Tetrahymena, DSBs are required for entering rather than exiting this stage.
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Affiliation(s)
- Josef Loidl
- Department of Chromosome Biology and Max F. Perutz Laboratories, Center for Molecular Biology, University of Vienna, A-1030 Vienna, Austria.
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192
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Boden SA, Langridge P, Spangenberg G, Able JA. TaASY1 promotes homologous chromosome interactions and is affected by deletion of Ph1. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:487-97. [PMID: 18826431 DOI: 10.1111/j.1365-313x.2008.03701.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
During meiosis, chromosomes are sorted into homologous pairs as a preface to their intimate association via recombination and synapsis. However, little is known about the mechanism used to distinguish homologous chromosomes from other chromosomes present in the nucleus. Studies in wheat (Triticum aestivum) have shown that the Pairing homoeologous 1 (Ph1) locus is required to suppress interactions between genetically similar homoeologous chromosomes. Here we show that absence of Ph1 causes increased transcription of Asynapsis 1 (ASY1), a gene that encodes an axial-element-associated protein that is essential for synapsis and cross-over formation in Arabidopsis and rice. Localisation of ASY1 during meiosis is also affected by deletion of Ph1. In addition, transgenic wheat mutants with decreased activity of TaASY1 display reduced synapsis during prophase I and exhibit pairing between homoeologous chromosomes at metaphase I. These results suggest that ASY1 is required to promote interactions between homologous chromosomes in bread wheat, and that Ph1 has a gene regulatory role, which is consistent with its suggested genetic identity as a Cdk-like gene. Broader implications of this research suggest that we could use the Taasy1 mutants to assess their efficacy in alien chromatin introgression studies, as seen with the ph1b mutant.
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Affiliation(s)
- Scott A Boden
- Molecular Plant Breeding Cooperative Research Centre, School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, South Australia, 5064, Australia
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193
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Bovill WD, Deveshwar P, Kapoor S, Able JA. Whole genome approaches to identify early meiotic gene candidates in cereals. Funct Integr Genomics 2008; 9:219-29. [PMID: 18836753 DOI: 10.1007/s10142-008-0097-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 09/16/2008] [Accepted: 09/16/2008] [Indexed: 11/25/2022]
Abstract
Early events during meiotic prophase I underpin not only viability but the variation of a species from generation to generation. Understanding and manipulating processes such as chromosome pairing and recombination are integral for improving plant breeding. This study uses comparative genetics, quantitative trait locus (QTL) analysis and a transcriptomics-based approach to identify genes that might have a role in genome-wide recombination control. Comparative genetics and the analysis of the yeast and Arabidopsis sequenced genomes has allowed the identification of early meiotic candidates that are conserved in wheat, rice and barley. Secondly, scoring recombination frequency as a phenotype for QTL analysis across wheat, rice and barley mapping populations has enabled us to identify genomic regions and candidate genes that could be involved in genome-wide recombination. Transcriptome data for candidate genes indicate that they are expressed in meiotic tissues. Candidates identified included a non-annotated expressed protein, a DNA topoisomerase 2-like candidate, RecG, RuvB and RAD54 homologues.
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Affiliation(s)
- William D Bovill
- School of Agriculture, Food & Wine, The University of Adelaide, Waite Campus, Glen Osmond, SA, Australia
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194
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Mochizuki K, Novatchkova M, Loidl J. DNA double-strand breaks, but not crossovers, are required for the reorganization of meiotic nuclei in Tetrahymena. J Cell Sci 2008; 121:2148-58. [PMID: 18522989 PMCID: PMC3184542 DOI: 10.1242/jcs.031799] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
During meiosis, the micronuclei of the ciliated protist Tetrahymena thermophila elongate dramatically. Within these elongated nuclei, chromosomes are arranged in a bouquet-like fashion and homologous pairing and recombination takes place. We studied meiotic chromosome behavior in Tetrahymena in the absence of two genes, SPO11 and a homolog of HOP2 (HOP2A), which have conserved roles in the formation of meiotic DNA double-strand breaks (DSBs) and their repair, respectively. Single-knockout mutants for each gene display only a moderate reduction in chromosome pairing, but show a complete failure to form chiasmata and exhibit chromosome missegregation. The lack of SPO11 prevents the elongation of meiotic nuclei, but it is restored by the artificial induction of DSBs. In the hop2ADelta mutant, the transient appearance of gamma-H2A.X and Rad51p signals indicates the formation and efficient repair of DSBs; but this repair does not occur by interhomolog crossing over. In the absence of HOP2A, the nuclei are elongated, meaning that DSBs but not their conversion to crossovers are required for the development of this meiosis-specific morphology. In addition, by in silico homology searches, we compiled a list of likely Tetrahymena meiotic proteins as the basis for further studies of the unusual synaptonemal complex-less meiosis in this phylogenetically remote model organism.
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Affiliation(s)
- Kazufumi Mochizuki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), A-1030 Vienna, Austria
| | - Maria Novatchkova
- Research Institute of Molecular Pathology (IMP), A-1030 Vienna, Austria
| | - Josef Loidl
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Dr Bohr Gasse 1, A-1030 Vienna, Austria
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195
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Higgins JD, Vignard J, Mercier R, Pugh AG, Franklin FCH, Jones GH. AtMSH5 partners AtMSH4 in the class I meiotic crossover pathway in Arabidopsis thaliana, but is not required for synapsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:28-39. [PMID: 18318687 DOI: 10.1111/j.1365-313x.2008.03470.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
MSH5, a meiosis-specific member of the MutS-homologue family of genes, is required for normal levels of recombination in budding yeast, mouse and Caenorhabditis elegans. In this paper we report the identification and characterization of the Arabidopsis homologue of MSH5 (AtMSH5). Transcripts of AtMSH5 are specific to reproductive tissues, and immunofluorescence studies indicate that expression of the protein is abundant during prophase I of meiosis. In a T-DNA tagged insertional mutant (Atmsh5-1), recombination is reduced to about 13% of wild-type levels. The residual chiasmata are randomly distributed between cells and chromosomes. These data provide further evidence for at least two pathways of meiotic recombination in Arabidopsis and indicate that AtMSH5 protein is required for the formation of class I interference-sensitive crossovers. Localization of AtMSH5 to meiotic chromosomes occurs at leptotene and is dependent on DNA double-strand break formation and strand exchange. Localization of AtMSH5 to the chromatin at mid-prophase I is dependent on expression of AtMSH4. At late zygotene/early pachytene a proportion of AtMSH5 foci co-localize with AtMLH1 which marks crossover-designated sites. Chromosome synapsis appears to proceed normally, without significant delay, in Atmsh5-1 but the pachytene stage is extended by several hours, indicative of the operation of a surveillance system that monitors the progression of prophase I.
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Affiliation(s)
- James D Higgins
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
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196
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Sanchez-Moran E, Osman K, Higgins J, Pradillo M, Cuñado N, Jones G, Franklin F. ASY1 coordinates early events in the plant meiotic recombination pathway. Cytogenet Genome Res 2008; 120:302-12. [DOI: 10.1159/000121079] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2007] [Indexed: 11/19/2022] Open
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197
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Copenhaver GP, Hooykaas PJJ. Plant DNA repair and recombination on the French Mediterranean. Workshop on plant DNA repair & recombination. EMBO Rep 2007; 8:1115-9. [PMID: 18007653 DOI: 10.1038/sj.embor.7401123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Accepted: 10/22/2007] [Indexed: 11/09/2022] Open
Affiliation(s)
- Gregory P Copenhaver
- Department of Biology and the Carolina Center for Genome Science, CB 3280, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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198
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A novel plant gene essential for meiosis is related to the human CtIP and the yeast COM1/SAE2 gene. EMBO J 2007; 26:5061-70. [PMID: 18007598 DOI: 10.1038/sj.emboj.7601913] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Accepted: 10/17/2007] [Indexed: 12/21/2022] Open
Abstract
Obligatory homologous recombination (HR) is required for chiasma formation and chromosome segregation in meiosis I. Meiotic HR is initiated by DNA double-strand breaks (DSBs), generated by Spo11, a homologue of the archaebacterial topoisomerase subunit Top6A. In Saccharomyces cerevisiae, Rad50, Mre11 and Com1/Sae2 are essential to process an intermediate of the cleavage reaction consisting of Spo11 covalently linked to the 5' termini of DNA. While Rad50 and Mre11 also confer genome stability to vegetative cells and are well conserved in evolution, Com1/Sae2 was believed to be fungal-specific. Here, we identify COM1/SAE2 homologues in all eukaryotic kingdoms. Arabidopsis thaliana Com1/Sae2 mutants are sterile, accumulate AtSPO11-1 during meiotic prophase and fail to form AtRAd51 foci despite the presence of unrepaired DSBs. Furthermore, DNA fragmentation in AtCom1 is suppressed by eliminating AtSPO11-1. In addition, AtCOM1 is specifically required for mitomycin C resistance. Interestingly, we identified CtIP, an essential protein interacting with the DNA repair machinery, as the mammalian homologue of Com1/Sae2, with important implications for the molecular role of CtIP.
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