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Vaz de Sousa D, Greve M, Oberlander KC. Friends without benefits: Extensive cytotype sympatry and polyploid persistence in an African geophyte. AMERICAN JOURNAL OF BOTANY 2024; 111:e16291. [PMID: 38439133 DOI: 10.1002/ajb2.16291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/08/2023] [Accepted: 12/08/2023] [Indexed: 03/06/2024]
Abstract
PREMISE Polyploidy is a major factor in plant adaptation and speciation. Multiple mechanisms contribute to autopolyploid frequency within populations, but uncertainties remain regarding mechanisms that facilitate polyploid establishment and persistence. Here we aimed to document and predict cytotype distributions of Oxalis obliquifolia Steud. ex A. Rich. across Gauteng, South Africa, and test for evidence of possible mechanisms, including morphological, phenological, and reproductive traits, that may potentially facilitate polyploid persistence. METHODS Over 320 O. obliquifolia plants from 25 sites were cytotyped using flow cytometry, and DNA ploidy was confirmed using meiotic chromosome squashes. Cytotypes were mapped and correlations with abiotic variables assessed using ordinations. To assess morphological and phenological associations with cytotype, we grew multiple cytotypes in a common garden, measured phenotypic traits and compared them using linear models and discriminant analyses. Intercytotype reproductive isolation was assessed using crossing experiments, and AMOVAs based on ITS DNA sequences tested for cytogeographic structure. RESULTS Six cytotypes were identified, and most sites had multiple cytotypes. Abiotic variables were not predictive of cytotype distribution. A clear gigas effect was present. Differences in flower size and phenology suggested pollinator interactions could play a role in polyploid persistence. Intercytotype crosses produced seed at low frequency. DNA data suggested diploids and polyploids were largely reproductively isolated in situ, and polyploidization events were not frequent enough to explain high cytotype sympatry. CONCLUSIONS Diploids and polyploids are behaving as separate species, despite little observable niche differentiation and non-zero potential intercytotype seed set. Tests on biotic interactions and intercytotype F1 fitness may provide insights into diploid and polyploid coexistence.
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Affiliation(s)
- Damian Vaz de Sousa
- Department of Plant and Soil Science, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
- H.G.W.J. Schweickerdt Herbarium, Department of Plant and Soil Science, University of Pretoria, Pretoria, South Africa
| | - Michelle Greve
- Department of Plant and Soil Science, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
| | - Kenneth C Oberlander
- H.G.W.J. Schweickerdt Herbarium, Department of Plant and Soil Science, University of Pretoria, Pretoria, South Africa
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2
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Blonder BW. Why are triploid quaking aspen (Populus tremuloides) common? AMERICAN JOURNAL OF BOTANY 2024; 111:e16325. [PMID: 38704729 DOI: 10.1002/ajb2.16325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 04/06/2024] [Accepted: 04/07/2024] [Indexed: 05/07/2024]
Abstract
PREMISE Quaking aspen is a clonal tree species that has mixed ploidy, often with high relative abundance of both diploids and triploids but no haploids or tetraploids. Triploids typically have low fertility, leaving their occurrence apparently unlikely from an evolutionary perspective, unless they provide a "triploid bridge" to generating higher-fitness tetraploids-which are not observed in this species. This study focused on how triploidy can be maintained in quaking aspen. METHODS A computational model was used to simulate gamete production, sexual reproduction, asexual reproduction, parent survival, and offspring survival in a population. All parameters were assumed to be cytotype-dependent and environment-independent. Sampling methods were used to identify parameter combinations consistent with observed cytotype frequencies. RESULTS Many processes and parameter values were sufficient to yield a moderate frequency of triploids, and very few were necessary. The most plausible route involved higher triploid survival at the parent or offspring stage and limited unreduced gamete production by either diploid or triploid parents. Triploid fertility was helpful but not necessary. CONCLUSIONS The coexistence of diploids and triploids in quaking aspen is statistically likely and promoted by the existence of commonly observed, long-lived triploid clones. However, other mechanisms not captured by the model related to environmental variation could also occur. Further empirical data or more complex but difficult-to-parameterize models are needed to gain further insight.
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Affiliation(s)
- Benjamin Wong Blonder
- Department of Environmental Science, Policy, and Management, University of California at Berkeley, Berkeley, 94720 USA, CA
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3
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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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Šingliarová B, Hojsgaard D, Müller-Schärer H, Mráz P. The novel expression of clonality following whole-genome multiplication compensates for reduced fertility in natural autopolyploids. Proc Biol Sci 2023; 290:20230389. [PMID: 37357859 PMCID: PMC10291721 DOI: 10.1098/rspb.2023.0389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/06/2023] [Indexed: 06/27/2023] Open
Abstract
Exploring the fitness consequences of whole-genome multiplication (WGM) is essential for understanding the establishment of autopolyploids in diploid parental populations, but suitable model systems are rare. We examined the impact of WGM on reproductive traits in three major cytotypes (2x, 3x, 4x) of Pilosella rhodopea, a species with recurrent formation of neo-autopolyploids in mixed-ploidy populations. We found that diploids had normal female sporogenesis and gametogenesis, high fertility, and produced predominantly euploid seed progeny. By contrast, autopolyploids had highly disturbed developmental programs that resulted in significantly lower seed set and a high frequency of aneuploid progeny. All cytotypes, but particularly triploids, produced gametes of varying ploidy, including unreduced ones, that participated in frequent intercytotype mating. Noteworthy, the reduced investment in sexual reproduction in autopolyploids was compensated by increased production of axillary rosettes and the novel expression of two clonal traits: adventitious rosettes on roots (root-sprouting), and aposporous initial cells in ovules which, however, do not result in functional apomixis. The combination of increased vegetative clonal growth in autopolyploids and frequent intercytotype mating are key mechanisms involved in the formation and maintenance of the largest diploid-autopolyploid primary contact zone ever recorded in angiosperms.
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Affiliation(s)
- Barbora Šingliarová
- Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Diego Hojsgaard
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | | | - Patrik Mráz
- Herbarium Collections and Department of Botany, Charles University, Prague, Czechia
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5
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Li MM, Su QL, Zu JR, Xie L, Wei Q, Guo HR, Chen J, Zeng RZ, Zhang ZS. Triploid cultivars of Cymbidium act as a bridge in the formation of polyploid plants. FRONTIERS IN PLANT SCIENCE 2022; 13:1029915. [PMID: 36684754 PMCID: PMC9853991 DOI: 10.3389/fpls.2022.1029915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 09/23/2022] [Indexed: 06/17/2023]
Abstract
Triploid is considered a reproductive barrier and also a bridge in the formation of polyploids. However, few reports are available in Cymbidium. In this study, diploid 'Xiaofeng', sexual triploid 'Yuchan' and 'Huanghe' of Cymbidium were used to evaluate hybridization compatibility of the triploids. Results showed that the sexual triploids were fertile whether they were used as male or female parents. 'Yuchan' produced male gametes of 1x, 1x~2x, 2x, 2x~3x, and 3x at frequencies of 8.89%, 77.78%, 6.67%, 3.33%, and 3.33%, respectively; while 'Huanghe' produced 3.33% 1x, 80.00% 1x~2x, 8.89% 2x, 5.56% 2x~3x, and 2.22% 3x male gametes. The cross of 'Xiaofeng' with 'Yuchan' produced progenies with a wide range of ploidy levels, including one diploid, 34 2×~3× aneuploids, 12 triploids, and one tetraploid, indicating that male gametes produced by sexual triploid were fertile and could be transmitted and fused with egg cells. On the other hand, 10 progenies obtained from the cross of 'Yuchan' × 'Xiaofeng' were all aneuploids. The cross of 'Yuchan' with 'Huanghe' produced 40 progenies including three 2×~3× aneuploids, nine 3×~4× aneuploids, 21 tetraploids, six 4×~5× aneuploids, and one pentaploid, suggesting that 2x gametes, instead of the unreduced ones played a more important role in the formation of tetraploids. The survival rates of the hybrids were all above 80.00%, with the tetraploids at 96.67%. Cytological analysis revealed that during meiosis of sexual polyploids, two chromosome sets of the 2n gamete were inclined to enter into the same daughter cell, resulting in the production of 2x gametes. Our results indicate that the triploid cymbidiums are not reproductive barrier but serve as a bridge in the formation of polyploid plants.
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Affiliation(s)
- Man-Man Li
- Guangdong Province Key Laboratory of Plant Molecular Breeding, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Qing-Lian Su
- Guangzhou Flower Research Center, Guangzhou, China
| | - Jun-Rui Zu
- Guangdong Province Key Laboratory of Plant Molecular Breeding, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Li Xie
- Guangdong Province Key Laboratory of Plant Molecular Breeding, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Qian Wei
- Guangdong Province Key Laboratory of Plant Molecular Breeding, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - He-Rong Guo
- Guangdong Province Key Laboratory of Plant Molecular Breeding, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Jianjun Chen
- Mid-Florida Research and Education Center, Environmental Horticulture Department, Institute of Food and Agricultural Sciences, University of Florida, Apopka, FL, United States
| | - Rui-Zhen Zeng
- Guangdong Province Key Laboratory of Plant Molecular Breeding, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Zhi-Sheng Zhang
- Guangdong Province Key Laboratory of Plant Molecular Breeding, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
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6
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Van Drunen WE, Friedman J. Autopolyploid establishment depends on life-history strategy and the mating outcomes of clonal architecture. Evolution 2022; 76:1953-1970. [PMID: 35861365 DOI: 10.1111/evo.14582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 06/21/2022] [Accepted: 07/11/2022] [Indexed: 01/22/2023]
Abstract
Polyploidy is a significant component in the evolution of many taxa, particularly plant groups. However, new polyploids face substantial fitness disadvantages due to a lack of same-cytotype mates, and the factors promoting or preventing polyploid establishment in natural populations are often unclear. We develop spatially explicit agent-based simulation models to test the hypothesis that a perennial life history and clonal propagation facilitate the early stages of polyploid establishment and persistence. Our models show that polyploids are more likely to establish when they have longer life spans than diploids, especially when self-fertilization rates are high. Polyploids that combine sexual and clonal reproduction can establish across a wide range of life histories, but their success is moderated by clonal strategy. By tracking individuals and mating events, we reveal that clonal architecture has a substantial impact on the spatial structure of the mixed diploid-polyploid population during polyploid establishment: altering patterns of mating within or between cytotypes via geitonogamous self-fertilization, the mechanisms through which polyploid establishment proceeds, and the final composition of the polyploid population. Overall, our findings provide novel insight into the role of clonal structure in modulating the complex relationship between polyploidy, perenniality, and clonality and offer testable predictions for future empirical work.
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Affiliation(s)
- Wendy E Van Drunen
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada.,Biology Department, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Jannice Friedman
- Biology Department, Queen's University, Kingston, ON, K7L 3N6, Canada
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7
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Duchoslav M, Jandová M, Kobrlová L, Šafářová L, Brus J, Vojtěchová K. Intricate Distribution Patterns of Six Cytotypes of Allium oleraceum at a Continental Scale: Niche Expansion and Innovation Followed by Niche Contraction With Increasing Ploidy Level. FRONTIERS IN PLANT SCIENCE 2020; 11:591137. [PMID: 33362819 PMCID: PMC7755979 DOI: 10.3389/fpls.2020.591137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 11/06/2020] [Indexed: 05/23/2023]
Abstract
The establishment and success of polyploids are thought to often be facilitated by ecological niche differentiation from diploids. Unfortunately, most studies compared diploids and polyploids, ignoring variation in ploidy level in polyploids. To fill this gap, we performed a large-scale study of 11,163 samples from 1,283 populations of the polyploid perennial geophyte Allium oleraceum with reported mixed-ploidy populations, revealed distribution ranges of cytotypes, assessed their niches and explored the pattern of niche change with increasing ploidy level. Altogether, six ploidy levels (3x-8x) were identified. The most common were pentaploids (53.6%) followed by hexaploids (22.7%) and tetraploids (21.6%). Higher cytotype diversity was found at lower latitudes than at higher latitudes (>52° N), where only tetraploids and pentaploids occurred. We detected 17.4% of mixed-ploidy populations, usually as a combination of two, rarely of three, cytotypes. The majority of mixed-ploidy populations were found in zones of sympatry of the participating cytotypes, suggesting they have arisen through migration (secondary contact zone). Using coarse-grained variables (climate, soil), we found evidence of both niche expansion and innovation in tetraploids related to triploids, whereas higher ploidy levels showed almost zero niche expansion, but a trend of increased niche unfilling of tetraploids. Niche unfilling in higher ploidy levels was caused by a contraction of niche envelopes toward lower continentality of the climate and resulted in a gradual decrease of niche breadth and a gradual shift in niche optima. Field-recorded data indicated wide habitat breadth of tetraploids and pentaploids, but also a pattern of increasing synanthropy in higher ploidy levels. Wide niche breadth of tetra- and pentaploids might be related to their multiple origins from different environmental conditions, higher "age", and retained sexuality, which likely preserve their adaptive potential. In contrast, other cytotypes with narrower niches are mostly asexual, probably originating from a limited range of contrasting environments. Persistence of local ploidy mixtures could be enabled by the perenniality of A. oleraceum and its prevalence of vegetative reproduction, facilitating the establishment and decreasing exclusion of minority cytotype due to its reproductive costs. Vegetative reproduction might also significantly accelerate colonization of new areas, including recolonization of previously glaciated areas.
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Affiliation(s)
- Martin Duchoslav
- Plant Biosystematics and Ecology RG, Department of Botany, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Michaela Jandová
- Plant Biosystematics and Ecology RG, Department of Botany, Faculty of Science, Palacký University, Olomouc, Czechia
- Institute of Botany, Czech Academy of Sciences, Pruhonice, Czechia
| | - Lucie Kobrlová
- Plant Biosystematics and Ecology RG, Department of Botany, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Lenka Šafářová
- Plant Biosystematics and Ecology RG, Department of Botany, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Jan Brus
- Department of Geoinformatics, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Kateřina Vojtěchová
- Plant Biosystematics and Ecology RG, Department of Botany, Faculty of Science, Palacký University, Olomouc, Czechia
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8
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Spoelhof JP, Keeffe R, McDaniel SF. Does reproductive assurance explain the incidence of polyploidy in plants and animals? THE NEW PHYTOLOGIST 2020; 227:14-21. [PMID: 31883115 DOI: 10.1111/nph.16396] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 12/17/2019] [Indexed: 06/10/2023]
Affiliation(s)
- Jonathan P Spoelhof
- Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
| | - Rachel Keeffe
- Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
| | - Stuart F McDaniel
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
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9
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Hanušová K, Čertner M, Urfus T, Koutecký P, Košnar J, Rothfels CJ, Jarolímová V, Ptáček J, Ekrt L. Widespread co-occurrence of multiple ploidy levels in fragile ferns (Cystopteris fragilis complex; Cystopteridaceae) probably stems from similar ecology of cytotypes, their efficient dispersal and inter-ploidy hybridization. ANNALS OF BOTANY 2019; 123:845-855. [PMID: 30541055 PMCID: PMC6526313 DOI: 10.1093/aob/mcy219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 11/09/2018] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Polyploidy has played an important role in the evolution of ferns. However, the dearth of data on cytotype diversity, cytotype distribution patterns and ecology in ferns is striking in comparison with angiosperms and prevents an assessment of whether cytotype coexistence and its mechanisms show similar patterns in both plant groups. Here, an attempt to fill this gap was made using the ploidy-variable and widely distributed Cystopteris fragilis complex. METHODS Flow cytometry was used to assess DNA ploidy level and monoploid genome size (Cx value) of 5518 C. fragilis individuals from 449 populations collected over most of the species' global distributional range, supplemented with data from 405 individuals representing other related species from the complex. Ecological preferences of C. fragilis tetraploids and hexaploids were compared using field-recorded parameters and database-extracted climate data. KEY RESULTS Altogether, five different ploidy levels (2x, 4x, 5x, 6x, 8x) were detected and three species exhibited intraspecific ploidy-level variation: C. fragilis, C. alpina and C. diaphana. Two predominant C. fragilis cytotypes, tetraploids and hexaploids, co-occur over most of Europe in a diffuse, mosaic-like pattern. Within this contact zone, 40 % of populations were mixed-ploidy and most also contained pentaploid hybrids. Environmental conditions had only a limited effect on the distribution of cytotypes. Differences were found in the Cx value of tetraploids and hexaploids: between-cytotype divergence was higher in uniform-ploidy than in mixed-ploidy populations. CONCLUSIONS High ploidy-level diversity and widespread cytotype coexistence in the C. fragilis complex match the well-documented patterns in some angiosperms. While ploidy coexistence in C. fragilis is not driven by environmental factors, it could be facilitated by the perennial life-form of the species, its reproductive modes and efficient wind dispersal of spores. Independent origins of hexaploids and/or inter-ploidy gene flow may be expected in mixed-ploidy populations according to Cx value comparisons.
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Affiliation(s)
- Kristýna Hanušová
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
| | - Martin Čertner
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek, Průhonice, Czech Republic
| | - Tomáš Urfus
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
| | - Petr Koutecký
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská, České Budějovice, Czech Republic
| | - Jiří Košnar
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská, České Budějovice, Czech Republic
| | - Carl J Rothfels
- University Herbarium and Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Vlasta Jarolímová
- Institute of Botany, The Czech Academy of Sciences, Zámek, Průhonice, Czech Republic
| | - Jan Ptáček
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
| | - Libor Ekrt
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská, České Budějovice, Czech Republic
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10
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Srisuwan S, Sihachakr D, Martín J, Vallès J, Ressayre A, Brown SC, Siljak-Yakovlev S. Change in nuclear DNA content and pollen size with polyploidisation in the sweet potato (Ipomoea batatas, Convolvulaceae) complex. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:237-247. [PMID: 30468688 DOI: 10.1111/plb.12945] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 11/16/2018] [Indexed: 05/12/2023]
Abstract
Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato (Ipomoea batatas), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa. Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy. 2C DNA content of hexaploid I. batatas ranged between 3.12-3.29 pg; the mean monoploid genome size being 0.539 pg (527 Mbp), similar to the related diploid accessions. In tetraploid species I. trifida and I. tabascana, 2C DNA content was, respectively, 2.07 and 2.03 pg. In the diploid species closely related to sweet potato e.g. I. ×leucantha, I. tiliacea, I. trifida and I. triloba, 2C DNA content was 1.01-1.12 pg. However, two diploid outgroup species, I. setosa and I. purpurea, were clearly different from the other diploid species, with 2C of 1.47-1.49 pg; they also have larger chromosomes. The I. batatas genome presents 60.0% AT bases. DNA content and ploidy level were positively correlated within this complex. In I. batatas and the more closely related species I. trifida, the genome size and ploidy levels were correlated with pollen size. Our results allow us to propose alternative or complementary hypotheses to that currently proposed for the formation of hexaploid Ipomoea batatas.
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Affiliation(s)
- S Srisuwan
- Ecologie, Systématique et Evolution, CNRS AgroParisTech, University of Paris-Sud, Université Paris-Saclay, Orsay, France
| | - D Sihachakr
- Ecologie, Systématique et Evolution, CNRS AgroParisTech, University of Paris-Sud, Université Paris-Saclay, Orsay, France
| | - J Martín
- Laboratori de Botànica (UB) - Unitat associada al CSIC, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - J Vallès
- Laboratori de Botànica (UB) - Unitat associada al CSIC, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - A Ressayre
- GQE- Le Moulon, INRA, University of Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Gif-sur-Yvette, France
| | - S C Brown
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - S Siljak-Yakovlev
- Ecologie, Systématique et Evolution, CNRS AgroParisTech, University of Paris-Sud, Université Paris-Saclay, Orsay, France
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Čertner M, Sudová R, Weiser M, Suda J, Kolář F. Ploidy-altered phenotype interacts with local environment and may enhance polyploid establishment in Knautia serpentinicola (Caprifoliaceae). THE NEW PHYTOLOGIST 2019; 221:1117-1127. [PMID: 30221362 DOI: 10.1111/nph.15426] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/24/2018] [Indexed: 06/08/2023]
Abstract
Whole genome duplication is a key process in plant evolution and has direct phenotypic consequences. However, it remains unclear whether ploidy-related phenotypic changes can significantly alter the fitness of polyploids in nature and thus contribute to establishment of new polyploid mutants in diploid populations. We addressed this question using a unique natural system encompassing a diploid and its sympatric locally established autotetraploid derivative. By setting a common garden experiment with two manipulated environmental factors (presence/absence of serpentine substrate and competition), we tested whether these two locally important factors differently shape the phenotypic response of the two ploidy levels. Tetraploids attained significantly higher values of both above- and below-ground biomass, and root : shoot ratio compared to their diploid progenitors. Tetraploid superiority in vegetative fitness indicators was most prominent when they were cultivated together with a competitor in nutrient-rich nonserpentine substrate. We show that even genetically very closely related diploids and tetraploids can respond differently to key environmental factors. Provided there are sufficient nutrients, tetraploids can be more successful in tolerating interspecific competition than their diploid progenitors. Such superior performance might have provided an adaptive advantage for the newly established tetraploid promoting colonisation of new (micro-)habitats, which was indeed observed at the natural site.
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Affiliation(s)
- Martin Čertner
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00, Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43, Průhonice, Czech Republic
| | - Radka Sudová
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43, Průhonice, Czech Republic
| | - Martin Weiser
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00, Prague, Czech Republic
| | - Jan Suda
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00, Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43, Průhonice, Czech Republic
| | - Filip Kolář
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00, Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43, Průhonice, Czech Republic
- Institute of Botany, University of Innsbruck, AT-6020, Innsbruck, Austria
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Baduel P, Bray S, Vallejo-Marin M, Kolář F, Yant L. The “Polyploid Hop”: Shifting Challenges and Opportunities Over the Evolutionary Lifespan of Genome Duplications. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00117] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Hojsgaard D. Transient Activation of Apomixis in Sexual Neotriploids May Retain Genomically Altered States and Enhance Polyploid Establishment. FRONTIERS IN PLANT SCIENCE 2018; 9:230. [PMID: 29535745 PMCID: PMC5834478 DOI: 10.3389/fpls.2018.00230] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 02/09/2018] [Indexed: 05/19/2023]
Abstract
Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step mechanism of cell fusions between ubiquitous (reduced) and rare (unreduced) gametes. The primary fusion event creates an intermediate triploid individual with unbalanced genome sets, a situation of genomic-shock characterized by gene expression dysregulation, high dosage sensitivity, disturbed cell divisions, and physiological and reproductive attributes drastically altered. This near-sterile neotriploid must produce (even) eupolyploids through secondary fusion events to restore genome steadiness, meiotic balance, and fertility required for the demographic establishment of a nascent lineage. Natural conditions locate several difficulties to polyploid establishment, including the production of highly unbalanced and rarely unreduced (euploid) gametes, frequency-dependent disadvantages (minority cytotype exclusion), severe fitness loss, and ecological competition with diploid parents. Persistence and adaptation of neopolyploids depend upon genetic and phenotypic novelty coupled to joint selective forces that preserve shock-induced genomic changes (subgenome homeolog partitioning) and drive meiotic (reproductive) stabilization and ecological diversification. Thus, polyploid establishment through the triploid bridge is a feasible but not ubiquitous process that requires a number of low-probability events and singular circumstances. Yet, frequencies of polyploids suggest that polyploid establishment is a pervasive process. To explain this disparity, and supported in experimental evidence, I propose that situations like hybridization and ploidy-state transitions associated to genomic shock and substantial developmental alterations can transiently activate apomixis as a mechanism to halt genomic instability and cancel factors restraining neopolyploid's sexual fertility, particularly in triploids. Apomixis -as a temporal alternative to sex- skip meiosis and syngamy, and thus can freeze genomic attributes, avoid unbalanced chromosomal segregation and increase the formation of unreduced euploid gametes, elude frequency-dependent reproductive disadvantages by parthenogenetic development of the embryo and permissive development of endosperm during seed formation, and increase the effective population size of the neopolyploid lineage favoring the formation rate of eupolyploids compared to aneuploids. The subsequent action of genome resilience mechanisms that alleviate transcriptomic shock and selection upon gene interactions might restore a stable meiosis and sexual fertility within few generations, as observed in synthetic polyploids. Alternatively, provided that resilience mechanisms fail, the neopolyploid might retain apomixis and hold genomically and transcriptionally altered states for many generations.
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Affiliation(s)
- Diego Hojsgaard
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, Georg August University of Göttingen, Göttingen, Germany
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14
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Hybridization and polyploidy enable genomic plasticity without sex in the most devastating plant-parasitic nematodes. PLoS Genet 2017; 13:e1006777. [PMID: 28594822 PMCID: PMC5465968 DOI: 10.1371/journal.pgen.1006777] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 04/24/2017] [Indexed: 11/19/2022] Open
Abstract
Root-knot nematodes (genus Meloidogyne) exhibit a diversity of reproductive modes ranging from obligatory sexual to fully asexual reproduction. Intriguingly, the most widespread and devastating species to global agriculture are those that reproduce asexually, without meiosis. To disentangle this surprising parasitic success despite the absence of sex and genetic exchanges, we have sequenced and assembled the genomes of three obligatory ameiotic and asexual Meloidogyne. We have compared them to those of relatives able to perform meiosis and sexual reproduction. We show that the genomes of ameiotic asexual Meloidogyne are large, polyploid and made of duplicated regions with a high within-species average nucleotide divergence of ~8%. Phylogenomic analysis of the genes present in these duplicated regions suggests that they originated from multiple hybridization events and are thus homoeologs. We found that up to 22% of homoeologous gene pairs were under positive selection and these genes covered a wide spectrum of predicted functional categories. To biologically assess functional divergence, we compared expression patterns of homoeologous gene pairs across developmental life stages using an RNAseq approach in the most economically important asexually-reproducing nematode. We showed that >60% of homoeologous gene pairs display diverged expression patterns. These results suggest a substantial functional impact of the genome structure. Contrasting with high within-species nuclear genome divergence, mitochondrial genome divergence between the three ameiotic asexuals was very low, signifying that these putative hybrids share a recent common maternal ancestor. Transposable elements (TE) cover a ~1.7 times higher proportion of the genomes of the ameiotic asexual Meloidogyne compared to the sexual relative and might also participate in their plasticity. The intriguing parasitic success of asexually-reproducing Meloidogyne species could be partly explained by their TE-rich composite genomes, resulting from allopolyploidization events, and promoting plasticity and functional divergence between gene copies in the absence of sex and meiosis.
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15
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Galdeano F, Urbani MH, Sartor ME, Honfi AI, Espinoza F, Quarin CL. Relative DNA content in diploid, polyploid, and multiploid species of Paspalum (Poaceae) with relation to reproductive mode and taxonomy. JOURNAL OF PLANT RESEARCH 2016; 129:697-710. [PMID: 26965283 DOI: 10.1007/s10265-016-0813-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/21/2016] [Indexed: 05/20/2023]
Abstract
It is generally accepted that polyploids have downsized basic genomes rather than additive values with respect to their related diploids. Changes in genome size have been reported in correlation with several biological characteristics. About 75 % of around 350 species recognized for Paspalum (Poaceae) are polyploid and most polyploids are apomictic. Multiploid species are common with most of them bearing sexual diploid and apomictic tetraploid or other ploidy levels. DNA content in the embryo and the endosperm was measured by flow cytometry in a seed-by-seed analysis of 47 species including 77 different entities. The relative DNA content of the embryo informed the genome size of the accession while the embryo:endosperm ratio of DNA content revealed its reproductive mode. The genome sizes (2C-value) varied from 0.5 to 6.5 pg and for 29 species were measured for the first time. Flow cytometry provided new information on the reproductive mode for 12 species and one botanical variety and supplied new data for 10 species concerning cytotypes reported for the first time. There was no significant difference between the mean basic genome sizes (1Cx-values) of 32 sexual and 45 apomictic entities. Seventeen entities were diploid and 60 were polyploids with different degrees. There were no clear patterns of changes in 1Cx-values due to polyploidy or reproductive systems, and the existing variations are in concordance with subgeneric taxonomical grouping.
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Affiliation(s)
- Florencia Galdeano
- Instituto de Botánica del Nordeste, CONICET-UNNE, Facultad de Ciencias Agrarias, FCA-UNNE, J.B. Cabral 2131, 3400, Corrientes, Argentina.
| | - M H Urbani
- Instituto de Botánica del Nordeste, CONICET-UNNE, Facultad de Ciencias Agrarias, FCA-UNNE, J.B. Cabral 2131, 3400, Corrientes, Argentina
| | - M E Sartor
- Instituto de Botánica del Nordeste, CONICET-UNNE, Facultad de Ciencias Agrarias, FCA-UNNE, J.B. Cabral 2131, 3400, Corrientes, Argentina
| | - A I Honfi
- Instituto de Biología Subtropical, CONICET-UNaM, Facultad de Ciencias Exactas, Químicas y Naturales, UNaM, Rivadavia 2370, 3300, Posadas, Misiones, Argentina
| | - F Espinoza
- Instituto de Botánica del Nordeste, CONICET-UNNE, Facultad de Ciencias Agrarias, FCA-UNNE, J.B. Cabral 2131, 3400, Corrientes, Argentina
| | - C L Quarin
- Instituto de Botánica del Nordeste, CONICET-UNNE, Facultad de Ciencias Agrarias, FCA-UNNE, J.B. Cabral 2131, 3400, Corrientes, Argentina
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16
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Gross K, Schiestl FP. Are tetraploids more successful? Floral signals, reproductive success and floral isolation in mixed-ploidy populations of a terrestrial orchid. ANNALS OF BOTANY 2015; 115:263-73. [PMID: 25652914 PMCID: PMC4551083 DOI: 10.1093/aob/mcu244] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/07/2014] [Accepted: 10/22/2014] [Indexed: 05/11/2023]
Abstract
BACKGROUND AND AIMS Polyploidization, the doubling of chromosome sets, is common in angiosperms and has a range of evolutionary consequences. Newly formed polyploid lineages are reproductively isolated from their diploid progenitors due to triploid sterility, but also prone to extinction because compatible mating partners are rare. Models have suggested that assortative mating and increased reproductive fitness play a key role in the successful establishment and persistence of polyploids. However, little is known about these factors in natural mixed-ploidy populations. This study investigated floral traits that can affect pollinator attraction and efficiency, as well as reproductive success in diploid and tetraploid Gymnadenia conopsea (Orchidaceae) plants in two natural, mixed-ploidy populations. METHODS Ploidy levels were determined using flow cytometry, and flowering phenology and herbivory were also assessed. Reproductive success was determined by counting fruits and viable seeds of marked plants. Pollinator-mediated floral isolation was measured using experimental arrays, with pollen flow tracked by means of staining pollinia with histological dye. KEY RESULTS Tetraploids had larger floral displays and different floral scent bouquets than diploids, but cytotypes differed only slightly in floral colour. Significant floral isolation was found between the two cytotypes. Flowering phenology of the two cytotypes greatly overlapped, and herbivory did not differ between cytotypes or was lower in tetraploids. In addition, tetraploids had higher reproductive success compared with diploids. CONCLUSIONS The results suggest that floral isolation and increased reproductive success of polyploids may help to explain their successful persistence in mixed-ploidy populations. These factors might even initiate transformation of populations from pure diploid to pure tetraploid.
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Affiliation(s)
- Karin Gross
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
| | - Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
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17
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McAllister C, Blaine R, Kron P, Bennett B, Garrett H, Kidson J, Matzenbacher B, Glotzbach A, Miller AJ. Environmental correlates of cytotype distribution in Andropogon gerardii (Poaceae). AMERICAN JOURNAL OF BOTANY 2015; 102:92-102. [PMID: 25587152 DOI: 10.3732/ajb.1400296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
UNLABELLED • PREMISE OF THE STUDY Information about geographic distribution of cytotypes can provide insight into the origin and maintenance of autopolyploid complexes and builds a foundation for understanding cytotype differentiation and the dynamics of mixed-ploidy populations. Here, we investigate environmental correlates of the geographic distributions of 6x and 9x individuals in the ecologically dominant grass Andropogon gerardii to examine the role of climate in shaping patterns of cytotype distribution in this species.• METHODS Flow cytometry was used to estimate ploidy level in 352 individuals from 32 populations across North America. Ecological differentiation of cytotypes was tested by relating BIOCLIM variables to cytotype distribution using principal components analysis and partial linear regression.• KEY RESULTS Broad geographic sampling confirmed two primary cytotypes-6x (hexaploid) and 9x (enneaploid)-and revealed that 9x plants are more common than previously thought. Enneaploids occur frequently in the southern portions of the range, with hexaploids dominating in northern regions. Mixed-ploidy populations were common (46.9%). Principal components analysis and partial linear regression indicated that reduced summer precipitation and increased variation in diurnal and seasonal temperature range were significant predictors of the frequency of 9x plants in a population.• CONCLUSIONS Results indicate that (1) geographic distribution of 6x and 9x individuals is nonrandom; (2) environmental variables are associated with cytotype distribution in A. gerardii; and (3) nearly half of populations surveyed include both 6x and 9x individuals. The persistence of mixed-ploidy populations may reflect a combination of recurrent polyploid formation and the prevalence of clonal reproduction.
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Affiliation(s)
- Christine McAllister
- Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA Saint Louis University, Department of Biology, 3507 Macelwane Hall, St. Louis, Missouri 63103 USA
| | - Russell Blaine
- Southern Illinois University, Edwardsville, 1 Hairpin Drive, Edwardsville, Illinois 62025 USA
| | - Paul Kron
- University of Guelph, Department of Integrative Biology, 50 Stone Road East, Guelph, Ontario, Canada, NIG 2W1
| | - Brent Bennett
- Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA
| | - Heidi Garrett
- Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA
| | - Jennifer Kidson
- Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA
| | - Blanda Matzenbacher
- Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA
| | - Anna Glotzbach
- Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA
| | - Allison J Miller
- Saint Louis University, Department of Biology, 3507 Macelwane Hall, St. Louis, Missouri 63103 USA
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Moghe GD, Shiu SH. The causes and molecular consequences of polyploidy in flowering plants. Ann N Y Acad Sci 2014; 1320:16-34. [PMID: 24903334 DOI: 10.1111/nyas.12466] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Polyploidy is an important force shaping plant genomes. All flowering plants are descendants of an ancestral polyploid species, and up to 70% of extant vascular plant species are believed to be recent polyploids. Over the past century, a significant body of knowledge has accumulated regarding the prevalence and ecology of polyploid plants. In this review, we summarize our current understanding of the causes and molecular consequences of polyploidization in angiosperms. We also provide a discussion on the relationships between polyploidy and adaptation and suggest areas where further research may provide a better understanding of polyploidy.
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Fialová M, Duchoslav M. Response to competition of bulbous geophyte Allium oleraceum differing in ploidy level. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16:186-196. [PMID: 23731026 DOI: 10.1111/plb.12042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 03/21/2013] [Indexed: 06/02/2023]
Abstract
Experimental studies that explore the possible causes of ploidy distributions and niche differentiation are rare. Increased competitive ability may be advantageous for survival in dense vegetation and may strongly affect local and regional abundances of cytotypes and potentially contribute to invasion success. We compared survival, growth and reproduction of plants originating from bulbils of three cytotypes (2n = 4x, 5x, 6x) of Allium oleraceum growing with and without a competitor (Arrhenatherum elatius). There was a strong negative effect of competition but no effect of ploidy or ploidy × competition on survivorship, height and total dry mass of A. oleraceum, i.e. no support for different competitive abilities of the ploidy levels. However, slightly different responses of populations to competition treatments within all cytotypes suggest differentiation within cytotypes. Under competition, plant survivorship was low, surviving plants were small, had low dry mass and produced neither sexual nor asexual propagules. Without competition, plant survivorship was high, and cytotypes differed in three traits after 2 year's growth: dry mass of flowers, number of flowers and ratio of the dry mass of sexual to asexual propagules all decreased with increasing ploidy level. We additionally tested tetra- and pentaploids as to whether plants originating from different types of propagule (bulbils, seeds) differ in survivorship, growth and reproduction when growing with and without a competitor. Plants originating from bulbils had higher survivorship, were more robust, flowered earlier and produced more propagules when compared to plants originating from seeds and grown without competition. Under competition, differences in performance between plants originating from seeds and bulbils mostly disappeared, with higher survivorship only for plants originating from bulbils.
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Affiliation(s)
- M Fialová
- Plant Biosystematics and Ecology RG, Department of Botany, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - M Duchoslav
- Plant Biosystematics and Ecology RG, Department of Botany, Faculty of Science, Palacký University, Olomouc, Czech Republic
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20
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Godsoe W, Larson MA, Glennon KL, Segraves KA. Polyploidization in Heuchera cylindrica (Saxifragaceae) did not result in a shift in climatic requirements. AMERICAN JOURNAL OF BOTANY 2013; 100:496-508. [PMID: 23400493 DOI: 10.3732/ajb.1200275] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
PREMISE OF THE STUDY Polyploidization is a key factor involved in the diversification of plants. Although polyploids are commonly found, there remains controversy on the mechanisms that lead to their successful establishment. One major problem that has been identified is that newly formed polyploids lack mates of the appropriate ploidy level and may experience severely reduced fertility due to nonproductive intercytotype crosses. Niche differentiation has been proposed as a primary mechanism that can alleviate this reproductive disadvantage and facilitate polyploid establishment. Here we test whether the establishment of tetraploid cytotypes of Heuchera cylindrica (Saxifragaceae) is consistent with climatic niche differentiation. • METHODS We use a combination of field surveys, flow cytometry and species distribution models to: (1) examine the distribution of diploid and tetraploid cytotypes; and (2) determine whether tetraploid Heuchera cylindrica occupy climates that differ from those of its diploid progenitors. • KEY RESULTS The geographic distributions of diploid and tetraploid cytotypes are largely allopatric as an extensive survey of 636 plants from 43 locations failed to detect any populations with both cytotypes. Although diploids and tetraploids occur in different geographic areas, polyploid Heuchera cylindrica occur almost exclusively in environments that are predicted to be suitable to diploid populations. • CONCLUSIONS Climatic niche differentiation does not explain the geographic distribution of tetraploid Heuchera cylindrica. We propose instead that tetraploid lineages were able to establish by taking advantage of glacial retreat and expanding into previously unoccupied sites.
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Affiliation(s)
- William Godsoe
- Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
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Watching the grin fade: tracing the effects of polyploidy on different evolutionary time scales. Semin Cell Dev Biol 2013; 24:320-31. [PMID: 23466286 DOI: 10.1016/j.semcdb.2013.02.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 02/05/2013] [Accepted: 02/07/2013] [Indexed: 12/13/2022]
Abstract
Polyploidy, or whole-genome duplication (WGD), is a recurrent mutation both in cell lineages and over evolutionary time. By globally changing the relationship between gene copy number and other cellular entities, it can induce dramatic changes at the cellular and phenotypic level. Perhaps surprisingly, then, the insights that these events can bring to understanding other cellular features are not as well appreciated as they could be. In this review, we draw on examples of polyploidy from animals, plants and yeast to explore how investigations of polyploid cells have improved our understanding of the cell cycle, biological network complexity, metabolic phenotypes and tumor biology. We argue that the study of polyploidy across organisms, cell types, and time scales serves not only as a window into basic cell biology, but also as a basis for a predictive biology with applications ranging from crop improvement to treating cancer.
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22
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Suda J, Herben T. Ploidy frequencies in plants with ploidy heterogeneity: fitting a general gametic model to empirical population data. Proc Biol Sci 2013; 280:20122387. [PMID: 23193129 PMCID: PMC3574409 DOI: 10.1098/rspb.2012.2387] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/02/2012] [Indexed: 11/12/2022] Open
Abstract
Genome duplication (polyploidy) is a recurrent evolutionary process in plants, often conferring instant reproductive isolation and thus potentially leading to speciation. Outcome of the process is often seen in the field as different cytotypes co-occur in many plant populations. Failure of meiotic reduction during gametogenesis is widely acknowledged to be the main mode of polyploid formation. To get insight into its role in the dynamics of polyploidy generation under natural conditions, and coexistence of several ploidy levels, we developed a general gametic model for diploid-polyploid systems. This model predicts equilibrium ploidy frequencies as functions of several parameters, namely the unreduced gamete proportions and fertilities of higher ploidy plants. We used data on field ploidy frequencies for 39 presumably autopolyploid plant species/populations to infer numerical values of the model parameters (either analytically or using an optimization procedure). With the exception of a few species, the model fit was very high. The estimated proportions of unreduced gametes (median of 0.0089) matched published estimates well. Our results imply that conditions for cytotype coexistence in natural populations are likely to be less restrictive than previously assumed. In addition, rather simple models show sufficiently rich behaviour to explain the prevalence of polyploids among flowering plants.
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Affiliation(s)
- Jan Suda
- Faculty of Science, Department of Botany, Charles University in Prague, Benátská 2, 128 01 Praha 2, CzechRepublic
- Academy of Sciences of the Czech Republic, Institute of Botany, 252 43 Průhonice, CzechRepublic
| | - Tomáš Herben
- Faculty of Science, Department of Botany, Charles University in Prague, Benátská 2, 128 01 Praha 2, CzechRepublic
- Academy of Sciences of the Czech Republic, Institute of Botany, 252 43 Průhonice, CzechRepublic
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De Storme N, Copenhaver GP, Geelen D. Production of diploid male gametes in Arabidopsis by cold-induced destabilization of postmeiotic radial microtubule arrays. PLANT PHYSIOLOGY 2012; 160:1808-26. [PMID: 23096158 PMCID: PMC3510112 DOI: 10.1104/pp.112.208611] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 10/24/2012] [Indexed: 05/18/2023]
Abstract
Whole-genome duplication through the formation of diploid gametes is a major route for polyploidization, speciation, and diversification in plants. The prevalence of polyploids in adverse climates led us to hypothesize that abiotic stress conditions can induce or stimulate diploid gamete production. In this study, we show that short periods of cold stress induce the production of diploid and polyploid pollen in Arabidopsis (Arabidopsis thaliana). Using a combination of cytological and genetic analyses, we demonstrate that cold stress alters the formation of radial microtubule arrays at telophase II and consequently leads to defects in postmeiotic cytokinesis and cell wall formation. As a result, cold-stressed male meiosis generates triads, dyads, and monads that contain binuclear and polynuclear microspores. Fusion of nuclei in binuclear and polynuclear microspores occurs spontaneously before pollen mitosis I and eventually leads to the formation of diploid and polyploid pollen grains. Using segregation analyses, we also found that the majority of cold-induced dyads and triads are genetically equivalent to a second division restitution and produce diploid gametes that are highly homozygous. In a broader perspective, these findings offer insights into the fundamental mechanisms that regulate male gametogenesis in plants and demonstrate that their sensitivity to environmental stress has evolutionary significance and agronomic relevance in terms of polyploidization.
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Affiliation(s)
- Nico De Storme
- Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, 9000 Ghent, Belgium (N.D.S., D.G.); Department of Biology and Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599 (G.P.C.); and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599 (G.P.C.)
| | - Gregory P. Copenhaver
- Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, 9000 Ghent, Belgium (N.D.S., D.G.); Department of Biology and Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599 (G.P.C.); and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599 (G.P.C.)
| | - Danny Geelen
- Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, 9000 Ghent, Belgium (N.D.S., D.G.); Department of Biology and Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599 (G.P.C.); and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599 (G.P.C.)
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Osabe K, Kawanabe T, Sasaki T, Ishikawa R, Okazaki K, Dennis ES, Kazama T, Fujimoto R. Multiple mechanisms and challenges for the application of allopolyploidy in plants. Int J Mol Sci 2012; 13:8696-8721. [PMID: 22942729 PMCID: PMC3430260 DOI: 10.3390/ijms13078696] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 07/04/2012] [Accepted: 07/04/2012] [Indexed: 11/16/2022] Open
Abstract
An allopolyploid is an individual having two or more complete sets of chromosomes derived from different species. Generation of allopolyploids might be rare because of the need to overcome limitations such as co-existing populations of parental lines, overcoming hybrid incompatibility, gametic non-reduction, and the requirement for chromosome doubling. However, allopolyploids are widely observed among plant species, so allopolyploids have succeeded in overcoming these limitations and may have a selective advantage. As techniques for making allopolyploids are developed, we can compare transcription, genome organization, and epigenetic modifications between synthesized allopolyploids and their direct parental lines or between several generations of allopolyploids. It has been suggested that divergence of transcription caused either genetically or epigenetically, which can contribute to plant phenotype, is important for the adaptation of allopolyploids.
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Affiliation(s)
- Kenji Osabe
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Plant Industry, Canberra, ACT 2601, Australia; E-Mails: (K.O.); (E.S.D.)
| | - Takahiro Kawanabe
- Watanabe Seed Co., Ltd, Machiyashiki, Misato-cho, Miyagi 987-8607, Japan; E-Mail:
| | - Taku Sasaki
- Watanabe Seed Co., Ltd, Machiyashiki, Misato-cho, Miyagi 987-8607, Japan; E-Mail:
| | - Ryo Ishikawa
- Laboratory of Plant Breeding, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8510, Japan; E-Mail:
- Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney, Norwich, NR4 7UH, UK; E-Mail:
| | - Keiichi Okazaki
- Graduate School of Science and Technology, Niigata University, Ikarashi-ninocho, Niigata 950-2181, Japan; E-Mail:
| | - Elizabeth S. Dennis
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Plant Industry, Canberra, ACT 2601, Australia; E-Mails: (K.O.); (E.S.D.)
| | - Tomohiko Kazama
- Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai 981-8555, Japan; E-Mail:
| | - Ryo Fujimoto
- Graduate School of Science and Technology, Niigata University, Ikarashi-ninocho, Niigata 950-2181, Japan; E-Mail:
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Trávníček P, Dočkalová Z, Rosenbaumová R, Kubátová B, Szeląg Z, Chrtek J. Bridging global and microregional scales: ploidy distribution in Pilosella echioides (Asteraceae) in central Europe. ANNALS OF BOTANY 2011; 107:443-54. [PMID: 21208933 PMCID: PMC3043935 DOI: 10.1093/aob/mcq260] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 11/02/2010] [Accepted: 11/24/2010] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS A detailed knowledge of cytotype distribution can provide important insights into the evolutionary history of polyploid systems. This study aims to explore the spatial distribution of different cytotypes in Pilosella echioides at various spatial scales (from the whole distributional range to the population level) and to outline possible evolutionary scenarios for the observed geographic pattern. METHODS DNA-ploidy levels were estimated using DAPI flow cytometry in 4410 individuals of P. echioides from 46 populations spread over the entire distribution range in central Europe. Special attention was paid to the cytotype structure in the most ploidy-diverse population in south-west Moravia. KEY RESULTS Five different cytotypes (2x, 3x, 4x, 5x and 6x) were found, the last being recorded for the first time. Although ploidy-uniform (di- or tetraploid) sites clearly prevailed, nearly one-quarter of the populations investigated harboured more (up to all five) cytotypes. Whereas penta- and hexaploids constituted only a minority of the samples, a striking predominance of the triploid cytotype was observed in several populations. CONCLUSIONS The representative sampling confirmed previous data on cytotype distribution, i.e. the spatial aggregation of mixed-ploidy populations in south-west Moravia and Lower Austria and the predominance of ploidy-uniform populations in other parts of the area investigated. Recurrent origin of polyploids from diploid progenitors via unreduced gametes and their successful establishment are considered the key factors promoting intrapopulational ploidy mixture ('primary hybrid zones'). As an alternative to the generally accepted theory of cytotype co-existence based on the development of different means of inter-ploidy reproductive isolation, it is suggested that a long-term ploidy mixture can also be maintained in free-mating populations provided that the polyploids originate with a sufficient frequency. In addition, the prevalence (or subdominance) of the triploid cytotype in several mixed-ploidy populations represents the first evidence of such a phenomenon in plant systems with exclusively sexual reproduction.
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Affiliation(s)
- Pavel Trávníček
- Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
- Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic
| | - Zuzana Dočkalová
- Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
| | - Radka Rosenbaumová
- Department of Botany, Natural History Museum, National Museum, CZ-193 00 Prague - Horní Počernice, Czech Republic
| | - Barbora Kubátová
- Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic
- Biotechnological Centre, Faculty of Agriculture, University of South Bohemia, CZ-370 05 České Budějovice, Czech Republic
| | - Zbigniew Szeląg
- Institute of Botany, Jagiellonian University, Kopernika 31, PL-315 01 Kraków, Poland
| | - Jindřich Chrtek
- Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
- Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic
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Saitoh K, Chen WJ, Mayden RL. Extensive hybridization and tetrapolyploidy in spined loach fish. Mol Phylogenet Evol 2010; 56:1001-10. [DOI: 10.1016/j.ympev.2010.04.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 04/14/2010] [Accepted: 04/16/2010] [Indexed: 12/15/2022]
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Duchoslav M, Šafářová L, Krahulec F. Complex distribution patterns, ecology and coexistence of ploidy levels of Allium oleraceum (Alliaceae) in the Czech Republic. ANNALS OF BOTANY 2010; 105:719-35. [PMID: 20363760 PMCID: PMC2859911 DOI: 10.1093/aob/mcq035] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 10/05/2009] [Accepted: 01/21/2010] [Indexed: 05/19/2023]
Abstract
BACKGROUND AND AIMS Despite extensive study of polyploidy, its origin, and ecogeographical differences between polyploids and their diploid progenitors, few studies have addressed ploidy-level structure and patterns of ecogeographical differentiation at various spatial scales using detailed sampling procedures. The pattern of coexistence of polyploids in the geophyte Allium oleraceum at the landscape and locality scale and their ecology were studied. METHODS Flow cytometry and root-tip squashes were used to identify the ploidy level of 4347 plants from 325 populations sampled from the Czech Republic using a stratified random sampling procedure. Ecological differentiation among ploidy levels was tested by comparing sets of environmental variables recorded at each locality. KEY RESULTS Across the entire sampling area, pentaploids (2n = 5x = 40) predominated, while hexaploids (2n = 6x = 48) and tetraploids (2n = 4x = 32) were less frequent. The distribution of tetra- and hexaploids was partially sympatric (in the eastern part) to parapatric (in the western part of the Czech Republic) whereas pentaploids were sympatric with other cytotypes. Plants of different ploidy levels were found to be ecologically differentiated and the ruderal character of cytotypes increased in the direction 4x --> 5x --> 6x with the largest realized niche differences between tetra- and hexaploids. Most populations contained only one ploidy level (77 %), 22 % had two (all possible combinations) and 1 % were composed of three ploidy levels. The majority of 4x + 5x and 5x + 6x mixed populations occurred in sympatry with uniform populations of the participating cytotypes in sites with ecologically heterogeneous or marginal environment, suggesting secondary contact between cytotypes. Some mixed 4x + 6x populations dominated by tetraploids being sympatric and intermixed with uniform 4x populations might represent primary zones of cytotype contact. Almost no mixed accessions were observed on the fine spatial scale in mixed populations. CONCLUSIONS The results provide evidence for adaptive differences among ploidy levels, which may contribute to their complex distribution pattern. The prevalence of asexual reproduction, limited dispersal and equilibrium-disrupting processes may support local coexistence of cytotypes.
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Affiliation(s)
- Martin Duchoslav
- Department of Botany, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc, Czech Republic
| | - Lenka Šafářová
- Department of Botany, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc, Czech Republic
| | - František Krahulec
- Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
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Dilkes BP, Spielman M, Weizbauer R, Watson B, Burkart-Waco D, Scott RJ, Comai L. The maternally expressed WRKY transcription factor TTG2 controls lethality in interploidy crosses of Arabidopsis. PLoS Biol 2008; 6:2707-20. [PMID: 19071961 PMCID: PMC2596861 DOI: 10.1371/journal.pbio.0060308] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 10/29/2008] [Indexed: 11/18/2022] Open
Abstract
The molecular mechanisms underlying lethality of F1 hybrids between diverged parents are one target of speciation research. Crosses between diploid and tetraploid individuals of the same genotype can result in F1 lethality, and this dosage-sensitive incompatibility plays a role in polyploid speciation. We have identified variation in F1 lethality in interploidy crosses of Arabidopsis thaliana and determined the genetic architecture of the maternally expressed variation via QTL mapping. A single large-effect QTL, DR. STRANGELOVE 1 (DSL1), was identified as well as two QTL with epistatic relationships to DSL1. DSL1 affects the rate of postzygotic lethality via expression in the maternal sporophyte. Fine mapping placed DSL1 in an interval encoding the maternal effect transcription factor TTG2. Maternal parents carrying loss-of-function mutations in TTG2 suppressed the F1 lethality caused by paternal excess interploidy crosses. The frequency of cellularization in the endosperm was similarly affected by both natural variation and ttg2 loss-of-function mutants. The simple genetic basis of the natural variation and effects of single-gene mutations suggests that F1 lethality in polyploids could evolve rapidly. Furthermore, the role of the sporophytically active TTG2 gene in interploidy crosses indicates that the developmental programming of the mother regulates the viability of interploidy hybrid offspring.
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Affiliation(s)
- Brian P Dilkes
- Section of Plant Biology and Genome Center, University of California Davis, Davis, California, United States of America
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Melissa Spielman
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Renate Weizbauer
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Brian Watson
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Diana Burkart-Waco
- Section of Plant Biology and Genome Center, University of California Davis, Davis, California, United States of America
| | - Rod J Scott
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Luca Comai
- Section of Plant Biology and Genome Center, University of California Davis, Davis, California, United States of America
- Department of Biology, University of Washington, Seattle, Washington, United States of America
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Genetic and embryological evidences of apomixis at the diploid level in Paspalum rufum support recurrent auto-polyploidization in the species. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s00497-008-0080-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
Reproductive isolation via apomixis is one way for newly created cytotypes to persist and coexist with other cytotypes. Arnica cordifolia (Asteraceae) has both triploid and tetraploid cytotypes co-occurring in many locations. The rate of apomixis in each cytotype was explored as a mechanism for the maintenance of sympatric cytotypes. Flow cytometry was used on both adults and seeds from mixed cytotype populations to estimate reproductive mode and to evaluate the relationship between cytotype frequency and reproductive success. Flowering time was surveyed to look for temporal reproductive isolation between cytotypes. Both triploids and tetraploids can be asexual. Apomixis in A. cordifolia is usually autonomous, not pseudogamous as previously thought. Sexual reproduction appears to be uncommon. The minority cytotype in each population does not produce fewer seeds, confirming that minority cytotype exclusion is unlikely to occur via reproductive disadvantage. Triploids flowered earlier than tetraploids, but with much overlap. Asexual reproduction is an important factor promoting the coexistence of cytotypes in this system. Other mechanisms maintaining populations of sympatric cytotypes are not well studied or understood and warrant further investigation.
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Affiliation(s)
- Rebecca Hufft Kao
- University of California Santa Cruz, EE Biology, EMS A316, 1156 High St., Santa Cruz, CA 95064, USA
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Yamauchi A. FORMULATION OF COMPETITION BETWEEN SEXUAL AND SELFING FORMS. Evolution 2006. [DOI: 10.1554/05-675.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Polyploids - organisms that have multiple sets of chromosomes - are common in certain plant and animal taxa, and can be surprisingly stable. The evidence that has emerged from genome analyses also indicates that many other eukaryotic genomes have a polyploid ancestry, suggesting that both humans and most other eukaryotes have either benefited from or endured polyploidy. Studies of polyploids soon after their formation have revealed genetic and epigenetic interactions between redundant genes. These interactions can be related to the phenotypes and evolutionary fates of polyploids. Here, I consider the advantages and challenges of polyploidy, and its evolutionary potential.
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Affiliation(s)
- Luca Comai
- Department of Biology, Box 355325, University of Washington, Seattle, Washington 98195, USA.
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