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Di Dio C, Serra H, Sourdille P, Higgins JD. ASYNAPSIS 1 ensures crossover fidelity in polyploid wheat by promoting homologous recombination and suppressing non-homologous recombination. FRONTIERS IN PLANT SCIENCE 2023; 14:1188347. [PMID: 37284727 PMCID: PMC10239940 DOI: 10.3389/fpls.2023.1188347] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 04/17/2023] [Indexed: 06/08/2023]
Abstract
During meiosis, the chromosome axes and synaptonemal complex mediate chromosome pairing and homologous recombination to maintain genomic stability and accurate chromosome segregation. In plants, ASYNAPSIS 1 (ASY1) is a key component of the chromosome axis that promotes inter-homolog recombination, synapsis and crossover formation. Here, the function of ASY1 has been cytologically characterized in a series of hypomorphic wheat mutants. In tetraploid wheat, asy1 hypomorphic mutants experience a reduction in chiasmata (crossovers) in a dosage-specific manner, resulting in failure to maintain crossover (CO) assurance. In mutants with only one functional copy of ASY1, distal chiasmata are maintained at the expense of proximal and interstitial chiasmata, indicating that ASY1 is required to promote chiasma formation away from the chromosome ends. Meiotic prophase I progression is delayed in asy1 hypomorphic mutants and is arrested in asy1 null mutants. In both tetraploid and hexaploid wheat, single asy1 mutants exhibit a high degree of ectopic recombination between multiple chromosomes at metaphase I. To explore the nature of the ectopic recombination, Triticum turgidum asy1b-2 was crossed with wheat-wild relative Aegilops variabilis. Homoeologous chiasmata increased 3.75-fold in Ttasy1b-2/Ae. variabilis compared to wild type/Ae. variabilis, indicating that ASY1 suppresses chiasma formation between divergent, but related chromosomes. These data suggest that ASY1 promotes recombination along the chromosome arms of homologous chromosomes whilst suppressing recombination between non-homologous chromosomes. Therefore, asy1 mutants could be utilized to increase recombination between wheat wild relatives and elite varieties for expediting introgression of important agronomic traits.
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Affiliation(s)
- Chiara Di Dio
- Department of Genetics and Genome Biology, Adrian Building, University of Leicester, Leicester, United Kingdom
| | - Heïdi Serra
- Genetics, Diversity and Ecophysiology of Cereals, Unité Mixte de Recherche (UMR) 1095, The Institut National de la Recherche Agronomique (INRAE), Université Clermont Auvergne, Clermont-Ferrand, France
| | - Pierre Sourdille
- Genetics, Diversity and Ecophysiology of Cereals, Unité Mixte de Recherche (UMR) 1095, The Institut National de la Recherche Agronomique (INRAE), Université Clermont Auvergne, Clermont-Ferrand, France
| | - James D. Higgins
- Department of Genetics and Genome Biology, Adrian Building, University of Leicester, Leicester, United Kingdom
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Desjardins SD, Simmonds J, Guterman I, Kanyuka K, Burridge AJ, Tock AJ, Sanchez-Moran E, Franklin FCH, Henderson IR, Edwards KJ, Uauy C, Higgins JD. FANCM promotes class I interfering crossovers and suppresses class II non-interfering crossovers in wheat meiosis. Nat Commun 2022; 13:3644. [PMID: 35752733 PMCID: PMC9233680 DOI: 10.1038/s41467-022-31438-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 06/17/2022] [Indexed: 11/09/2022] Open
Abstract
FANCM suppresses crossovers in plants by unwinding recombination intermediates. In wheat, crossovers are skewed toward the chromosome ends, thus limiting generation of novel allelic combinations. Here, we observe that FANCM maintains the obligate crossover in tetraploid and hexaploid wheat, thus ensuring that every chromosome pair exhibits at least one crossover, by localizing class I crossover protein HEI10 at pachytene. FANCM also suppresses class II crossovers that increased 2.6-fold in fancm msh5 quadruple mutants. These data are consistent with a role for FANCM in second-end capture of class I designated crossover sites, whilst FANCM is also required to promote formation of non-crossovers. In hexaploid wheat, genetic mapping reveals that crossovers increase by 31% in fancm compared to wild type, indicating that fancm could be an effective tool to accelerate breeding. Crossover rate differences in fancm correlate with wild type crossover distributions, suggesting that chromatin may influence the recombination landscape in similar ways in both wild type and fancm. The FANCM helicase functions in limiting crossovers (COs) by unwinding inter-homolog repair intermediates. Here, the authors generate null mutants of fancm in tetraploid and hexaploid wheat and show that FANCM promotes class I interfering COs and suppresses class II noninterfering COs in wheat meiosis.
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Affiliation(s)
- Stuart D Desjardins
- Department of Genetics and Genome Biology, Adrian Building, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - James Simmonds
- Department of Crop Genetics, John Innes Centre, Norwich, NR4 7UH, UK
| | - Inna Guterman
- Department of Genetics and Genome Biology, Adrian Building, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Kostya Kanyuka
- NIAB, 93 Lawrence Weaver Road, Cambridge, CB3 0LE, UK.,Biointeractions and Crop Protection, Rothamsted Research, Harpenden, AL5 2JQ, UK
| | - Amanda J Burridge
- Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Andrew J Tock
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | | | - F Chris H Franklin
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Keith J Edwards
- Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Cristobal Uauy
- Department of Crop Genetics, John Innes Centre, Norwich, NR4 7UH, UK
| | - James D Higgins
- Department of Genetics and Genome Biology, Adrian Building, University of Leicester, University Road, Leicester, LE1 7RH, UK.
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Prusicki MA, Balboni M, Sofroni K, Hamamura Y, Schnittger A. Caught in the Act: Live-Cell Imaging of Plant Meiosis. FRONTIERS IN PLANT SCIENCE 2021; 12:718346. [PMID: 34992616 PMCID: PMC8724559 DOI: 10.3389/fpls.2021.718346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 11/29/2021] [Indexed: 06/14/2023]
Abstract
Live-cell imaging is a powerful method to obtain insights into cellular processes, particularly with respect to their dynamics. This is especially true for meiosis, where chromosomes and other cellular components such as the cytoskeleton follow an elaborate choreography over a relatively short period of time. Making these dynamics visible expands understanding of the regulation of meiosis and its underlying molecular forces. However, the analysis of meiosis by live-cell imaging is challenging; specifically in plants, a temporally resolved understanding of chromosome segregation and recombination events is lacking. Recent advances in live-cell imaging now allow the analysis of meiotic events in plants in real time. These new microscopy methods rely on the generation of reporter lines for meiotic regulators and on the establishment of ex vivo culture and imaging conditions, which stabilize the specimen and keep it alive for several hours or even days. In this review, we combine an overview of the technical aspects of live-cell imaging in plants with a summary of outstanding questions that can now be addressed to promote live-cell imaging in Arabidopsis and other plant species and stimulate ideas on the topics that can be addressed in the context of plant meiotic recombination.
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Affiliation(s)
| | | | | | | | - Arp Schnittger
- Department of Developmental Biology, Institute for Plant Science and Microbiology, University of Hamburg, Hamburg, Germany
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Abstract
Recombination (crossover) drives the release of genetic diversity in plant breeding programs. However, in barley, recombination is skewed toward the telomeric ends of its seven chromosomes, restricting the re-assortment of about 30% of the genes located in the centromeric regions of its large 5.1 Gb genome. A better understanding of meiosis and recombination could provide ways of modulating crossover distribution and frequency in barley as well as in other grasses, including wheat. While most research on recombination has been carried out in the model plant Arabidopsis thaliana, recent studies in barley (Hordeum Vulgare) have provided new insights into the control of crossing over in large genome species. A major achievement in these studies has been the use of cytological procedures to follow meiotic events. This protocol provides detailed practical steps required to perform immunostaining of barley meiocytes (pollen mother cells) for confocal or structured illumination microscopy.
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