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Booker WW, Schrider DR. The genetic consequences of range expansion and its influence on diploidization in polyploids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.18.562992. [PMID: 37905020 PMCID: PMC10614938 DOI: 10.1101/2023.10.18.562992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Despite newly formed polyploids being subjected to myriad fitness consequences, the relative prevalence of polyploidy both contemporarily and in ancestral branches of the tree of life suggests alternative advantages that outweigh these consequences. One proposed advantage is that polyploids may more easily colonize novel habitats such as deglaciated areas. However, previous research conducted in diploids suggests that range expansion comes with a fitness cost as deleterious mutations may fix rapidly on the expansion front. Here, we interrogate the potential consequences of expansion in polyploids by conducting spatially explicit forward-in-time simulations to investigate how ploidy and inheritance patterns impact the relative ability of polyploids to expand their range. We show that under realistic dominance models, autopolyploids suffer greater fitness reductions than diploids as a result of range expansion due to the fixation of increased mutational load that is masked in the range core. Alternatively, the disomic inheritance of allopolyploids provides a shield to this fixation resulting in minimal fitness consequences. In light of this advantage provided by disomy, we investigate how range expansion may influence cytogenetic diploidization through the reversion to disomy in autotetraploids. We show that under a wide range of parameters investigated for two models of diploidization, disomy frequently evolves more rapidly on the expansion front than in the range core, and that this dynamic inheritance model has additional effects on fitness. Together our results point to a complex interaction between dominance, ploidy, inheritance, and recombination on fitness as a population spreads across a geographic range.
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Affiliation(s)
- William W. Booker
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514-2916, United States of America
| | - Daniel R. Schrider
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514-2916, United States of America
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Orlovskaya О, Dubovets N, Solovey L, Leonova I. Molecular cytological analysis of alien introgressions in common wheat lines derived from the cross of TRITICUM AESTIVUM with T. kiharae. BMC PLANT BIOLOGY 2020; 20:201. [PMID: 33050882 PMCID: PMC7556913 DOI: 10.1186/s12870-020-02407-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 04/27/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND Triticum kiharae (AtAtGGDD, 2n = 42) is of interest for the improvement of bread wheat as a source of high grain protein and gluten content, as well as resistance to many diseases. The use of T. kiharae for the improvement of T. aestivum L. is complicated by the fact that the homology degree of their genomes is low and this leads to an unbalanced set of chromosomes in the gametes of its first generations and the elimination of some genotypes. The aim of this study was to analyze the nature of alien introgressions and their effect on the cytological stability of hybrids obtained from crossing of bread wheat varieties with T. kiharae. RESULTS Using C-banding, the presence of entire chromosomes of T. kiharae in the karyotypes of hybrid lines (intergenomic substitution 2G/2B), chromosome arms (centric translocation Т2AtS:2AL) and large inserts in the form of terminal translocations involving chromosomes of 1st, 3rd and 5th homoeologous groups of B- and G-genomes were found. Molecular markers revealed short introgression of T. kiharae into the genome of common wheat varieties. The highest introgression frequency was shown for 1A, 1B, 2A, 5B, and 6A chromosomes, while no foreign chromatin was detected in 4A and 4B chromosomes. A high level of cytological stability (a meiotic index of 88.18-93.0%) was noted for the majority of introgression lines. An exception was found for the lines containing the structural reorganization of chromosome 5B, affecting the main genes of chromosome synapsis in terms of their functioning. CONCLUSIONS During the stabilization of hybrid karyotypes, the introgression of genetic material from T. kiharae into the genome of T. aestivum occurs in the form of short fragments detectable only by molecular markers and in the form of whole chromosomes (intergenomic substitution) and their large fragments (centric and terminal translocations). The level of cytological stability achieved in F10 by the majority of introgression lines ensures the formation of functional gametes sufficient for the successful reproduction of the obtained hybrids.
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Affiliation(s)
- Оlga Orlovskaya
- Institute of Genetics and Cytology of the National Academy of Sciences of Belarus, Akademycheskaya Street 27, 220072, Minsk, Belarus.
| | - Nadezhda Dubovets
- Institute of Genetics and Cytology of the National Academy of Sciences of Belarus, Akademycheskaya Street 27, 220072, Minsk, Belarus
| | - Lylia Solovey
- Institute of Genetics and Cytology of the National Academy of Sciences of Belarus, Akademycheskaya Street 27, 220072, Minsk, Belarus
| | - Irina Leonova
- The Federal Research Center "Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences", Prospekt Lavrentyeva 10, Novosibirsk, Russian Federation, 630090.
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Tantray YR, Singhal VK, Kaur M, Gupta RC. Cytomorphological Comparison in Natural Intraspecific Cytotypes (2 x, 4 x) in Brachyactis pubescens from Northwest Himalayas, India. CYTOLOGIA 2018. [DOI: 10.1508/cytologia.83.245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Birchler JA, Han F. Barbara McClintock's Unsolved Chromosomal Mysteries: Parallels to Common Rearrangements and Karyotype Evolution. THE PLANT CELL 2018; 30:771-779. [PMID: 29545470 PMCID: PMC5969279 DOI: 10.1105/tpc.17.00989] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 03/08/2018] [Accepted: 03/15/2018] [Indexed: 05/04/2023]
Abstract
Two obscure studies on chromosomal behavior by Barbara McClintock are revisited in light of subsequent studies and evolutionary genomics of chromosome number reduction. The phenomenon of deficiency recovery in which adjacent genetic markers lost in the zygote reappear in later developmental sectors is discussed in light of de novo centromere formation on chromosomal fragments. Second, McClintock described a small chromosome, which she postulated carried an "X component," that fostered specific types of chromosomal rearrangements mainly involving centromere changes and attachments to the termini of chromosomes. These findings are cast in the context of subsequent studies on centromere misdivision, the tendency of broken fragments to join chromosome ends, and the realization from genomic sequences that nested chromosomal insertion and end-to-end chromosomal fusions are common features of karyotype evolution. Together, these results suggest a synthesis that centromere breaks, inactivation, and de novo formation together with telomeres-acting under some circumstances as double-strand DNA breaks that join with others-is the underlying basis of these chromosomal phenomena.
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Affiliation(s)
- James A Birchler
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
| | - Fangpu Han
- 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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Tennessen JA, Govindarajulu R, Ashman TL, Liston A. Evolutionary origins and dynamics of octoploid strawberry subgenomes revealed by dense targeted capture linkage maps. Genome Biol Evol 2014; 6:3295-313. [PMID: 25477420 PMCID: PMC4986458 DOI: 10.1093/gbe/evu261] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Whole-genome duplications are radical evolutionary events that have driven speciation and adaptation in many taxa. Higher-order polyploids have complex histories often including interspecific hybridization and dynamic genomic changes. This chromosomal reshuffling is poorly understood for most polyploid species, despite their evolutionary and agricultural importance, due to the challenge of distinguishing homologous sequences from each other. Here, we use dense linkage maps generated with targeted sequence capture to improve the diploid strawberry (Fragaria vesca) reference genome and to disentangle the subgenomes of the wild octoploid progenitors of cultivated strawberry, Fragaria virginiana and Fragaria chiloensis. Our novel approach, POLiMAPS (Phylogenetics Of Linkage-Map-Anchored Polyploid Subgenomes), leverages sequence reads to associate informative interhomeolog phylogenetic markers with linkage groups and reference genome positions. In contrast to a widely accepted model, we find that one of the four subgenomes originates with the diploid cytoplasm donor F. vesca, one with the diploid Fragaria iinumae, and two with an unknown ancestor close to F. iinumae. Extensive unidirectional introgression has converted F. iinumae-like subgenomes to be more F. vesca-like, but never the reverse, due either to homoploid hybridization in the F. iinumae-like diploid ancestors or else strong selection spreading F. vesca-like sequence among subgenomes through homeologous exchange. In addition, divergence between homeologous chromosomes has been substantially augmented by interchromosomal rearrangements. Our phylogenetic approach reveals novel aspects of the complicated web of genetic exchanges that occur during polyploid evolution and suggests a path forward for unraveling other agriculturally and ecologically important polyploid genomes.
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Affiliation(s)
| | | | | | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University
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Fu SL, Yang MY, Ren ZL, Yan BJ, Tang ZX. Abnormal mitosis induced by wheat-rye 1R monosomic addition lines. Genome 2013; 57:21-8. [PMID: 24564212 DOI: 10.1139/gen-2013-0115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Octoploid triticale were derived from common wheat (Triticum aestivum L. 'Mianyang11') × rye (Secale cereale L. 'Kustro'), and some progeny were obtained by the backcrossing of triticale with 'Mianyang11' followed by self-fertilization. In situ hybridization using rye genomic DNA and repetitive sequences pAs1 and pSc119.2 as probes was used to analyze the mitotic chromosomes of these progeny. Three wheat-rye 1R monosomic addition lines and a wheat line (12FT-1685) containing a 1R and a 1BL.1RS translocation chromosome were identified. Abnormal mitosis was observed in the two lines. During mitosis of a 1R monosomic addition line (3-8-20-1R-2), lagging chromosomes, micronuclei, chromosomal bridges, and the one pole segregation of 1R chromosome were observed. Abnormal mitotic behaviour of chromosomes was also observed in some of the self-progeny plants of lines 12FT-1685 and 3-8-20-1R-2. These progeny contained 1R chromosome or 1R chromosome arm. In addition, 4B chromosomes were absent from one of the progeny of 3-8-20-1R-2. This abnormal mitotic behaviour of chromosomes was not observed in two other 1R monosomic addition lines. These results indicate that a single 1R chromosome added to wheat might cause abnormal mitotic behaviour of both wheat and rye chromosomes and different genetic variations might occurr among the sibling 1R monosomic addition lines.
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Affiliation(s)
- Shu-Lan Fu
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agriculture University, Wenjiang, Chengdu, Sichuan 611130, China
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Förster S, Schumann E, Baumann M, Weber WE, Pillen K. Copy number variation of chromosome 5A and its association with Q gene expression, morphological aberrations, and agronomic performance of winter wheat cultivars. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2013; 126:3049-3063. [PMID: 24078011 DOI: 10.1007/s00122-013-2192-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 09/06/2013] [Indexed: 06/02/2023]
Abstract
KEY MESSAGE Our investigations combine chromosome 5A copy number variation associated with relative 5A Q gene expression and morphological and agronomic data to characterize the occurrence of speltoid plants in winter wheat cultivars. The occurrence of speltoid aberrants in wheat breeding is a serious problem that may result in rejection of a candidate cultivar during licensing. The spear-shaped, hard threshing spike is caused by copy number reduction of the domestication gene Q, located on the long arm of wheat chromosome 5A. As a member of the APETALA2-like transcription factor family, the 5AQ gene is involved in flower development and pleiotropically controls other agronomic traits. In this report, a characterization of instability of chromosome 5A is given and effects due to the loss of the Q gene and other genes are discussed. Based on pyrosequencing, we correctly predicted the 5AQ copy number for 392 of 402 tested offspring plants (97.5 %) originating from single speltoid plants of eleven wheat cultivars. The findings indicate that the resulting speltoid plants were either reduced in chromosome 5A copy number or possessed a partial deletion of the distal end of chromosome arm 5AL. 5AQ specific real-time PCR analysis revealed varying transcription levels among cultivars. During early spike development, the relative transcription of the 5AQ gene was always lower in speltoids than in normal square headed wheat plants, most likely leading to the occurrence of the characteristic speltoid spike phenotype. The parallel analysis of 18 agronomic traits revealed pleiotropic effects governed by genes located on 5A. Our results demonstrate that through pyrosequencing one can identify aneuploidy or deletions within chromosome 5A to select against the occurrence of speltoid plants in wheat seedlings.
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Affiliation(s)
- Sebastian Förster
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Betty-Heimann-Str. 3, 06120, Halle (Saale), Germany,
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Fu S, Yang M, Fei Y, Tan F, Ren Z, Yan B, Zhang H, Tang Z. Alterations and abnormal mitosis of wheat chromosomes induced by wheat-rye monosomic addition lines. PLoS One 2013; 8:e70483. [PMID: 23936213 PMCID: PMC3728071 DOI: 10.1371/journal.pone.0070483] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/19/2013] [Indexed: 11/18/2022] Open
Abstract
Background Wheat-rye addition lines are an old topic. However, the alterations and abnormal mitotic behaviours of wheat chromosomes caused by wheat-rye monosomic addition lines are seldom reported. Methodology/Principal Findings Octoploid triticale was derived from common wheat T. aestivum L. ‘Mianyang11’×rye S. cereale L. ‘Kustro’ and some progeny were obtained by the controlled backcrossing of triticale with ‘Mianyang11’ followed by self-fertilization. Genomic in situ hybridization (GISH) using rye genomic DNA and fluorescence in situ hybridization (FISH) using repetitive sequences pAs1 and pSc119.2 as probes were used to analyze the mitotic chromosomes of these progeny. Strong pSc119.2 FISH signals could be observed at the telomeric regions of 3DS arms in ‘Mianyang11’. However, the pSc119.2 FISH signals were disappeared from the selfed progeny of 4R monosomic addition line and the changed 3D chromosomes could be transmitted to next generation stably. In one of the selfed progeny of 7R monosomic addition line, one 2D chromosome was broken and three 4A chromosomes were observed. In the selfed progeny of 6R monosomic addition line, structural variation and abnormal mitotic behaviour of 3D chromosome were detected. Additionally, 1A and 4B chromosomes were eliminated from some of the progeny of 6R monosomic addition line. Conclusions/Significance These results indicated that single rye chromosome added to wheat might cause alterations and abnormal mitotic behaviours of wheat chromosomes and it is possible that the stress caused by single alien chromosome might be one of the factors that induced karyotype alteration of wheat.
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Affiliation(s)
- Shulan Fu
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
- * E-mail: (SLF); (ZXT)
| | - Manyu Yang
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
| | - Yunyan Fei
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
| | - Feiquan Tan
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
| | - Zhenglong Ren
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
| | - Benju Yan
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
| | - Huaiyu Zhang
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
| | - Zongxiang Tang
- State Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, People’s Republic of China
- * E-mail: (SLF); (ZXT)
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9
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Abstract
The wheat group has evolved through allopolyploidization, namely, through hybridization among species from the plant genera Aegilops and Triticum followed by genome doubling. This speciation process has been associated with ecogeographical expansion and with domestication. In the past few decades, we have searched for explanations for this impressive success. Our studies attempted to probe the bases for the wide genetic variation characterizing these species, which accounts for their great adaptability and colonizing ability. Central to our work was the investigation of how allopolyploidization alters genome structure and expression. We found in wheat that allopolyploidy accelerated genome evolution in two ways: (1) it triggered rapid genome alterations through the instantaneous generation of a variety of cardinal genetic and epigenetic changes (which we termed "revolutionary" changes), and (2) it facilitated sporadic genomic changes throughout the species' evolution (i.e., evolutionary changes), which are not attainable at the diploid level. Our major findings in natural and synthetic allopolyploid wheat indicate that these alterations have led to the cytological and genetic diploidization of the allopolyploids. These genetic and epigenetic changes reflect the dynamic structural and functional plasticity of the allopolyploid wheat genome. The significance of this plasticity for the successful establishment of wheat allopolyploids, in nature and under domestication, is discussed.
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10
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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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Ma XF, Gustafson JP. Genome evolution of allopolyploids: a process of cytological and genetic diploidization. Cytogenet Genome Res 2005; 109:236-49. [PMID: 15753583 DOI: 10.1159/000082406] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2003] [Accepted: 03/09/2004] [Indexed: 11/19/2022] Open
Abstract
Allopolyploidy is a prominent mode of speciation in higher plants. Due to the coexistence of closely related genomes, a successful allopolyploid must have the ability to invoke and maintain diploid-like behavior, both cytologically and genetically. Recent studies on natural and synthetic allopolyploids have raised many discrepancies. Most species have displayed non-Mendelian behavior in the allopolyploids, but others have not. Some species have demonstrated rapid genome changes following allopolyploid formation, while others have conserved progenitor genomes. Some have displayed directed, non-random genome changes, whereas others have shown random changes. Some of the genomic changes have appeared in the F1 hybrids, which have been attributed to the union of gametes from different progenitors, while other changes have occurred during or after genome doubling. Although these observations provide significant novel insights into the evolution of allopolyploids, the overall mechanisms of the event are still elusive. It appears that both genetic and epigenetic operations are involved in the diploidization process of allopolyploids. Overall, genetic and epigenetic variations are often associated with the activities of repetitive sequences and transposon elements. Specifically, genomic sequence elimination and chromosome rearrangement are probably the major forces guiding cytological diploidization. Gene non-functionalization, sub-functionalization, neo-functionalization, as well as other kinds of epigenetic modifications, are likely the leading factors promoting genetic diploidization.
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Affiliation(s)
- X-F Ma
- Department of Agronomy, University of Missouri-Columbia, MO 65211, USA
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Friebe B, Zhang P, Linc G, Gill BS. Robertsonian translocations in wheat arise by centric misdivision of univalents at anaphase I and rejoining of broken centromeres during interkinesis of meiosis II. Cytogenet Genome Res 2005; 109:293-7. [PMID: 15753589 DOI: 10.1159/000082412] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2003] [Accepted: 01/15/2004] [Indexed: 11/19/2022] Open
Abstract
The mechanism of origin of Robertsonian translocations was investigated in plants monosomic for chromosome 1A of wheat and 1H(t) of Elymus trachycaulus by GISH. Chromosomes 1A and 1H(t) stayed univalent in all metaphase I cells analyzed, suggesting that Robertsonian translocations do not originate from meiotic recombination in centromeric regions with shared DNA sequence homology. At ana-/telophase I, the 1H(t) and 1A univalents underwent either chromosome or chromatid segregation and misdivided in 6-7% of the pollen mother cells. None of the ana-/telophases I analyzed had Robertsonian translocations, which were only observed in 2% of the "half tetrads" at ana-/telophase II. The frequency of Robertsonian translocations observed at ana-/telophase II corresponds well with the number of Robertsonian translocations (1-4%) detected in progenies derived from plants monosomic for group-1 chromosomes of wheat (1A, 1B, and 1D) and 1H(t) of E. trachycaulus. Our data suggest that Robertsonian translocations arise from centric misdivision of univalents at ana-/telophase I, followed by segregation of the derived telocentric chromosomes to the same nucleus, and fusion of the broken ends during the ensuing interkinesis.
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Affiliation(s)
- B Friebe
- Wheat Genetics Resource Center and Department of Plant Pathology, Kansas State University, Manhattan 66506-5502, USA.
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13
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Lyusikov OM, Bel’ko NB, Shchet’ko IS, Gordei IA. Construction of Rye-Wheat Amphidiploids with the Cytoplasm of Rye—Secalotriticum (RRAABB, 2n = 42): Meiosis Characteristics in Rye-Triticale F1 Hybrids (RRABR, 5x = 35). RUSS J GENET+ 2005. [DOI: 10.1007/s11177-005-0153-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ma H. Molecular genetic analyses of microsporogenesis and microgametogenesis in flowering plants. ANNUAL REVIEW OF PLANT BIOLOGY 2005; 56:393-434. [PMID: 15862102 DOI: 10.1146/annurev.arplant.55.031903.141717] [Citation(s) in RCA: 418] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
In flowering plants, male reproductive development requires the formation of the stamen, including the differentiation of anther tissues. Within the anther, male meiosis produces microspores, which further develop into pollen grains, relying on both sporophytic and gametophytic gene functions. The mature pollen is released when the anther dehisces, allowing pollination to occur. Molecular studies have identified a large number of genes that are expressed during stamen and pollen development. Genetic analyses have demonstrated the function of some of these genes in specifying stamen identity, regulating anther cell division and differentiation, controlling male meiosis, supporting pollen development, and promoting anther dehiscence. These genes encode a variety of proteins, including transcriptional regulators, signal transduction proteins, regulators of protein degradation, and enzymes for the biosynthesis of hormones. Although much has been learned in recent decades, much more awaits to be discovered and understood; the future of the study of plant male reproduction remains bright and exciting with the ever-growing tool kits and rapidly expanding information and resources for gene function studies.
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Affiliation(s)
- Hong Ma
- Department of Biology and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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15
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Sutton T, Whitford R, Baumann U, Dong C, Able JA, Langridge P. The Ph2 pairing homoeologous locus of wheat (Triticum aestivum): identification of candidate meiotic genes using a comparative genetics approach. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 36:443-56. [PMID: 14617076 DOI: 10.1046/j.1365-313x.2003.01891.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Colinearity in gene content and order between rice and closely related grass species has emerged as a powerful tool for gene identification. Using a comparative genetics approach, we have identified the rice genomic region syntenous to the region deleted in the wheat chromosome pairing mutant ph2a, with a view to identifying genes at the Ph2 locus that control meiotic processes. Utilising markers known to reside within the region deleted in ph2a, and data from wheat, barley and rice genetic maps, markers delimiting the region deleted on wheat chromosome 3DS in the ph2a mutant were used to locate the syntenous region on the short arm of rice chromosome 1. A contig of rice genomic sequence was identified from publicly available sequence information and used in blast searches to identify wheat expressed sequence tags (ESTs) exhibiting significant similarity. Southern analysis using a subset of identified wheat ESTs confirmed a syntenous relationship between the rice and wheat genomic regions and defined precisely the extent of the deleted segment in the ph2a mutant. A 6.58-Mb rice contig generated from 60 overlapping rice chromosome 1 P1 artificial chromosome (PAC) clones spanning the syntenous rice region has enabled identification of 218 wheat ESTs putatively located in the region deleted in ph2a. What seems to be a terminal deletion on chromosome 3DS is estimated to be 80 Mb in length. Putative candidate genes that may contribute to the altered meiotic phenotype of ph2a are discussed.
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Affiliation(s)
- Tim Sutton
- Molecular Plant Breeding Cooperative Research Centre, School of Agriculture and Wine, The University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia.
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16
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Affiliation(s)
- Justin Ramsey
- Department of Botany, University of Washington, Box 355325, Seattle, Washington 98195-5325;
- Present address: Department of Botany, University of Guelph, Guelph, Ontario N1G 2W1, Canada;
- Department of Plant Biology and Kellogg Biological Station, Michigan State University, East Lansing, Michigan 48824-1312;
| | - Douglas W. Schemske
- Department of Botany, University of Washington, Box 355325, Seattle, Washington 98195-5325;
- Present address: Department of Botany, University of Guelph, Guelph, Ontario N1G 2W1, Canada;
- Department of Plant Biology and Kellogg Biological Station, Michigan State University, East Lansing, Michigan 48824-1312;
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Qi L, Friebe B, Gill BS. Meiotic metaphase I pairing behavior of a 5BL recombinant isochromosome in wheat. Chromosome Res 2001; 8:671-6. [PMID: 11196130 DOI: 10.1023/a:1026785119376] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A recombinant isochromosome i5BLrec of wheat was developed with one arm and the proximal 36% of the other arm of Chinese Spring (CS) origin and the distal 64% of the recombined arm of Triticum turgiduM subsp. dicoccoides origin. The i5BLrec provides an unusual opportunity to analyze the role of the centromere or arm heterozygosity in chromosome prealignment and synapsis during meiosis. In monosomic condition, the i5BLrec formed a ring univalent in 86.8% of the pollen mother cells (PMCs) at meiotic metaphase I. In the disomic condition, the two i5BLrec preferentially paired as a normal bivalent in 74.8% of the PMCs, which differed significantly (p <0.01) from the normal bivalent pairing of 51% observed in diisosomic 5BL chromosomes of the CS (Di5BL(CS)) control plants. In plants with one i5BLrec and a normal 5B(CS), the long arm of 5B(CS) paired with the homologous arm of i5BLrec in 54.4% of the PMCs, and 40.4% of the PMCs had a 5B(CS) univalent and a i5BLrec ring univalent. The implications of the i5BLrec pairing data on the mechanism of Ph1 gene action are discussed.
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Affiliation(s)
- L Qi
- Department of Plant Pathology, Kansas State University, Manhattan 66506-5502, USA
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18
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Abstract
Allopolyploid plants are hybrids that contain two copies of the genome from each parent. Whereas wild and cultivated allopolyploids are well adapted, man-made allopolyploids are typically unstable, displaying homeotic transformation and lethality as well as chromosomal rearrangements and changes in the number and distribution of repeated DNA sequences within heterochromatin. Large increases in the length of some chromosomes has been documented in allopolyploid hybrids and could be caused by the activation of dormant retrotransposons, as shown to be the case in marsupial hybrids. Synthetic (man-made) allotetraploids of Arabidopsis exhibit rapid changes in gene regulation, including gene silencing. These regulatory abnormalities could derive from ploidy changes and/or incompatible interactions between parental genomes, although comparison of auto- and allopolyploids suggests that intergenomic incompatibilities play the major role. Models to explain intergenomic incompatibilities incorporate both genetic and epigenetic mechanisms. In one model, the activation of heterochromatic transposons (McClintock's genomic shock) may lead to widespread perturbation of gene expression, perhaps by a silencing interaction between activated transposons and euchromatic genes. Qualitatively similar responses, of lesser intensity, may occur in intraspecific hybrids. Therefore, insight into genome function gained from the study of allopolyploidy may be applicable to hybrids of any type and may even elucidate positive interactions, such as those responsible for hybrid vigor.
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Affiliation(s)
- L Comai
- Department of Botany, University of Washington, Seattle 98195-5325, USA.
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Abstract
Meiotic chromosomes have been studied for many years, in part because of the fundamental life processes they represent, but also because meiosis involves the formation of homolog pairs, a feature which greatly facilitates the study of chromosome behavior. The complex events involved in homolog juxtaposition necessitate prolongation of prophase, thus permitting resolution of events that are temporally compressed in the mitotic cycle. Furthermore, once homologs are paired, the chromosomes are connected by a specific structure: the synaptonemal complex. Finally, interaction of homologs includes recombination at the DNA level, which is intimately linked to structural features of the chromosomes. In consequence, recombination-related events report on diverse aspects of chromosome morphogenesis, notably relationships between sisters, development of axial structure, and variations in chromatin status. The current article reviews recent information on these topics in an historical context. This juxtaposition has suggested new relationships between structure and function. Additional issues were addressed in a previous chapter (551).
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Affiliation(s)
- D Zickler
- Institut de Génétique et Microbiologie, Université Paris-Sud, Orsay, France.
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20
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Abstract
Polyploidy is a prominent process in plants and has been significant in the evolutionary history of vertebrates and other eukaryotes. In plants, interdisciplinary approaches combining phylogenetic and molecular genetic perspectives have enhanced our awareness of the myriad genetic interactions made possible by polyploidy. Here, processes and mechanisms of gene and genome evolution in polyploids are reviewed. Genes duplicated by polyploidy may retain their original or similar function, undergo diversification in protein function or regulation, or one copy may become silenced through mutational or epigenetic means. Duplicated genes also may interact through inter-locus recombination, gene conversion, or concerted evolution. Recent experiments have illuminated important processes in polyploids that operate above the organizational level of duplicated genes. These include inter-genomic chromosomal exchanges, saltational, non-Mendelian genomic evolution in nascent polyploids, inter-genomic invasion, and cytonuclear stabilization. Notwithstanding many recent insights, much remains to be learned about many aspects of polyploid evolution, including: the role of transposable elements in structural and regulatory gene evolution; processes and significance of epigenetic silencing; underlying controls of chromosome pairing; mechanisms and functional significance of rapid genome changes; cytonuclear accommodation; and coordination of regulatory factors contributed by two, sometimes divergent progenitor genomes. Continued application of molecular genetic approaches to questions of polyploid genome evolution holds promise for producing lasting insight into processes by which novel genotypes are generated and ultimately into how polyploidy facilitates evolution and adaptation.
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Affiliation(s)
- J F Wendel
- Department of Botany, Iowa State University, Ames 50011, USA.
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21
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Abstract
Polyploidy is a prominent process in plants and has been significant in the evolutionary history of vertebrates and other eukaryotes. In plants, interdisciplinary approaches combining phylogenetic and molecular genetic perspectives have enhanced our awareness of the myriad genetic interactions made possible by polyploidy. Here, processes and mechanisms of gene and genome evolution in polyploids are reviewed. Genes duplicated by polyploidy may retain their original or similar function, undergo diversification in protein function or regulation, or one copy may become silenced through mutational or epigenetic means. Duplicated genes also may interact through inter-locus recombination, gene conversion, or concerted evolution. Recent experiments have illuminated important processes in polyploids that operate above the organizational level of duplicated genes. These include inter-genomic chromosomal exchanges, saltational, non-Mendelian genomic evolution in nascent polyploids, inter-genomic invasion, and cytonuclear stabilization. Notwithstanding many recent insights, much remains to be learned about many aspects of polyploid evolution, including: the role of transposable elements in structural and regulatory gene evolution; processes and significance of epigenetic silencing; underlying controls of chromosome pairing; mechanisms and functional significance of rapid genome changes; cytonuclear accommodation; and coordination of regulatory factors contributed by two, sometimes divergent progenitor genomes. Continued application of molecular genetic approaches to questions of polyploid genome evolution holds promise for producing lasting insight into processes by which novel genotypes are generated and ultimately into how polyploidy facilitates evolution and adaptation.
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Affiliation(s)
- J F Wendel
- Department of Botany, Iowa State University, Ames 50011, USA.
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Vega JM, Feldman M. Effect of the pairing gene Ph1 and premeiotic colchicine treatment on intra- and interchromosome pairing of isochromosomes in common wheat. Genetics 1998; 150:1199-208. [PMID: 9799271 PMCID: PMC1460406 DOI: 10.1093/genetics/150.3.1199] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The analysis of the pattern of isochromosome pairing allows one to distinguish factors affecting presynaptic alignment of homologous chromosomes from those affecting synapsis and crossing-over. Because the two homologous arms in an isochromosome are invariably associated by a common centromere, the suppression of pairing between these arms (intrachromosome pairing) would indicate that synaptic or postsynaptic events were impaired. In contrast, the suppression of pairing between an isochromosome and its homologous chromosome (interchromosome pairing), without affecting intrachromosome pairing, would suggest that homologous presynaptic alignment was impaired. We used such an isochromosome system to determine which of the processes associated with chromosome pairing was affected by the Ph1 gene of common wheat-the main gene that restricts pairing to homologues. Ph1 reduced the frequency of interchromosome pairing without affecting intrachromosome pairing. In contrast, intrachromosome pairing was strongly reduced in the absence of the synaptic gene Syn-B1. Premeiotic colchicine treatment, which drastically decreased pairing of conventional chromosomes, reduced interchromosome but not intrachromosome pairing. The results support the hypothesis that premeiotic alignment is a necessary stage for the regularity of meiotic pairing and that Ph1 relaxes this alignment. We suggest that Ph1 acts on premeiotic alignment of homologues and homeologues as a means of ensuring diploid-like meiotic behavior in polyploid wheat.
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Affiliation(s)
- J M Vega
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
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