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Rojek J, Ohad N. The phenomenon of autonomous endosperm in sexual and apomictic plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4324-4348. [PMID: 37155961 PMCID: PMC10433939 DOI: 10.1093/jxb/erad168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 05/04/2023] [Indexed: 05/10/2023]
Abstract
Endosperm is a key nutritive tissue that supports the developing embryo or seedling, and serves as a major nutritional source for human and livestock feed. In sexually-reproducing flowering plants, it generally develops after fertilization. However, autonomous endosperm (AE) formation (i.e. independent of fertilization) is also possible. Recent findings of AE loci/ genes and aberrant imprinting in native apomicts, together with a successful initiation of parthenogenesis in rice and lettuce, have enhanced our understanding of the mechanisms bridging sexual and apomictic seed formation. However, the mechanisms driving AE development are not well understood. This review presents novel aspects related to AE development in sexual and asexual plants underlying stress conditions as the primary trigger for AE. Both application of hormones to unfertilized ovules and mutations that impair epigenetic regulation lead to AE development in sexual Arabidopsis thaliana, which may point to a common pathway for both phenomena. Apomictic-like AE development under experimental conditions can take place due to auxin-dependent gene expression and/or DNA methylation.
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Affiliation(s)
- Joanna Rojek
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Nir Ohad
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
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2
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Hörandl E. Geographical Parthenogenesis in Alpine and Arctic Plants. PLANTS (BASEL, SWITZERLAND) 2023; 12:844. [PMID: 36840192 PMCID: PMC9959270 DOI: 10.3390/plants12040844] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
The term "Geographical parthenogenesis" describes the phenomenon that asexual organisms usually occupy larger and more northern distribution areas than their sexual relatives, and tend to colonize previously glaciated areas. Several case studies on alpine and arctic plants confirm the geographical pattern, but the causal factors behind the phenomenon are still unclear. Research of the last decade in several plant families has shed light on the question and evaluated some of the classical evolutionary theories. Results confirmed, in general, that the advantages of uniparental reproduction enable apomictic plants to re-colonize faster in larger and more northern distribution areas. Associated factors like polyploidy seem to contribute mainly to the spatial separation of sexual and asexual cytotypes. Ecological studies suggest a better tolerance of apomicts to colder climates and temperate extremes, whereby epigenetic flexibility and phenotypic plasticity play an important role in occupying ecological niches under harsh conditions. Genotypic diversity appears to be of lesser importance for the distributional success of asexual plants. Classical evolutionary theories like a reduced pressure of biotic interactions in colder climates and hence an advantage to asexuals (Red Queen hypothesis) did not gain support from studies on plants. However, it is also still enigmatic why sexual outcrossing remains the predominant mode of reproduction also in alpine floras. Constraints for the origin of apomixis might play a role. Interestingly, some studies suggest an association of sexuality with abiotic stresses. Light stress in high elevations might explain why most alpine plants retain sexual reproduction despite other environmental factors that would favor apomixis. Directions for future research will be given.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, 37073 Göttingen, Germany
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Chao YS, Ebihara A, Chiou WL, Tsai JM, Huang YW, Ranker TA. Reticulate evolution in the Pteris fauriei group (Pteridaceae). Sci Rep 2022; 12:9145. [PMID: 35650209 PMCID: PMC9159987 DOI: 10.1038/s41598-022-11390-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 04/14/2022] [Indexed: 11/10/2022] Open
Abstract
The Pteris fauriei group (Pteridaceae) has a wide distribution in Eastern Asia and includes 18 species with similar but varied morphology. We collected more than 300 specimens of the P. fauriei group and determined ploidy by flow cytometry and inferred phylogenies by molecular analyses of chloroplast and nuclear DNA markers. Our results reveal a complicated reticulate evolution, consisting of seven parental taxa and 58 hybrids. The large number of hybrid taxa have added significant morphological complexity to the group leading to difficult taxonomic issues. The hybrids generally had broader ranges and more populations than their parental taxa. Genetic combination of different pairs of parental species created divergent phenotypes of hybrids, exhibited by both morphological characteristics and ecological fidelities. Niche novelty could facilitate hybrid speciation. Apogamy is common in this group and potentially contributes to the sustainability of the whole group. We propose that frequent hybridizations among members of the P. fauriei group generate and maintain genetic diversity, via novel genetic combinations, niche differentiation, and apogamy.
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Affiliation(s)
- Yi-Shan Chao
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, 100, Shih-Chuan 1st Rd., Kaohsiung, 80708, Taiwan.
| | - Atsushi Ebihara
- Department of Botany, National Museum of Nature and Science, 4-1-1, Amakubo, Tsukuba-shi, Ibaraki, 305-0005, Japan
| | - Wen-Liang Chiou
- Taiwan Forestry Research Institute, 53 Nan-Hai Rd., Taipei, 100051, Taiwan
| | - Jer-Min Tsai
- Department of Information and Communication, Kun Shan University, 195, Kunda Rd., Tainan, 710303, Taiwan
| | - Yu-Wen Huang
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, 100, Shih-Chuan 1st Rd., Kaohsiung, 80708, Taiwan
| | - Tom A Ranker
- University of Hawai'i at Mānoa, School of Life Sciences, Honolulu, HI, 96822, USA
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Kocot D, Sitek E, Nowak B, Kołton A, Stachurska-Swakoń A, Towpasz K. The Effectiveness of the Sexual Reproduction in Selected Clonal and Nonclonal Species of the Genus Ranunculus. BIOLOGY 2022; 11:biology11010085. [PMID: 35053083 PMCID: PMC8772756 DOI: 10.3390/biology11010085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/14/2021] [Accepted: 01/03/2022] [Indexed: 11/24/2022]
Abstract
Simple Summary The genus Ranunculus (buttercup) includes over 600 species, some of which are endangered, e.g., Illyrian Buttercup. Knowledge of the reproductive biology of such species may be crucial for conservation action. For this purpose, six species with different reproduction modes (nonclonal reproducing sexually by seeds only, clonal propagating by seeds and additionally vegetatively and apomictic) were observed. Selected features related to the efficiency of sexual reproduction were described: pollen viability, number of fruit set, seed viability and germination. It has been shown that in clonal species, which include the Illyrian Buttercup, the efficiency of sexual reproduction is lower compared to nonclonal species. The results will support conservation action taken for this species. Abstract Generative processes have been evaluated in six European buttercup species in order to verify the hypothesis that the reproduction efficiency of clonal species is lower than that of nonclonal ones. The study covered common species (Ficaria verna, Ranunculus auricomus, R. bulbosus, R. cassubicus, R. lanuginosus) and the endangered R. illyricus. The following properties have been assessed: pollen viability (staining method), pollen grain germination and the pollen-tube elongation in pistil tissues (fluorescence microscopy), seed formation efficiency, seed viability (tetrazolium test) and germination ability by introducing factors interrupting dormancy (low temperature and gibberellin application). Additionally, the pistil morphology was documented for R. bulbosus, R. illyricus and R. cassubicus using SEM techniques. It was demonstrated that the reproductive efficiency, expressed as the production of viable seeds able to germinate, was significantly higher in the species reproducing sexually (especially in R. lanuginosus) compared to the clonal ones. However, the complexity observed leads to separation of an additional group (cluster) of apomictic species: R. auricomus and R. cassubicus, distinguished by the lowest pollen viability and a low ability of the seeds to germinate. In the vegetatively reproducing R. illyricus, the seed formation efficiency was just 13.2% despite the having highest number of pistils in its flowers. The developed seeds of this species observed in our experiment were viable, but in general effective methods to stimulate their germination have not been proposed yet. Here, the first comparative study concerning the biology of sexual reproduction of R. illyricus is presented in the context of its decreasing distribution in natural habitats.
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Affiliation(s)
- Dawid Kocot
- Department of Botany, Physiology and Plant Protection, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, 29 Listopada 54, 31-425 Krakow, Poland; (D.K.); (E.S.); (A.K.)
| | - Ewa Sitek
- Department of Botany, Physiology and Plant Protection, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, 29 Listopada 54, 31-425 Krakow, Poland; (D.K.); (E.S.); (A.K.)
| | - Barbara Nowak
- Department of Botany, Physiology and Plant Protection, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, 29 Listopada 54, 31-425 Krakow, Poland; (D.K.); (E.S.); (A.K.)
- Correspondence: ; Tel.: +48-126-6252-5198; Fax: +48-12-662-5266
| | - Anna Kołton
- Department of Botany, Physiology and Plant Protection, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, 29 Listopada 54, 31-425 Krakow, Poland; (D.K.); (E.S.); (A.K.)
| | - Alina Stachurska-Swakoń
- Department of Plant Ecology, Institute of Botany, Faculty of Biology, Jagiellonian University, Gronostajowa 3, 30-387 Krakow, Poland; (A.S.-S.); (K.T.)
| | - Krystyna Towpasz
- Department of Plant Ecology, Institute of Botany, Faculty of Biology, Jagiellonian University, Gronostajowa 3, 30-387 Krakow, Poland; (A.S.-S.); (K.T.)
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Genome Size, Cytotype Diversity and Reproductive Mode Variation of Cotoneaster integerrimus (Rosaceae) from the Balkans. PLANTS 2021; 10:plants10122798. [PMID: 34961270 PMCID: PMC8708406 DOI: 10.3390/plants10122798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 12/28/2022]
Abstract
Cotoneaster integerrimus represents a multiploid and facultative apomictic system of widely distributed mountain populations. We used flow cytometry to determine genome size, ploidy level, and reproduction mode variation of the Balkan populations, supplemented by analysis of nuclear microsatellites in order to address: (i) geographic distribution and variation of cytotypes among the populations; (ii) variation of reproduction mode and the frequency of sexuality; (iii) pathways of endosperm formation among the sampled polyploids and their endosperm balance requirements; (iv) genotypic diversity and geographic distribution of clonal lineages of polyploids. The prevalence of apomictic tetraploid cytotype followed by sexual diploids and extremely rare triploids was demonstrated. This prevalence of tetraploids affected the populations’ structure composed from clonal genotypes with varying proportions. The co-occurrence of diploids and tetraploids generated higher cytotype, reproductive mode, and genotypic diversity, but mixed-ploidy sites were extremely rare. The endosperm imbalance facilitates the development and the occurrence of intermediate triploids in mixed-ploidy populations, but also different tetraploid lineages elsewhere with unbalanced endosperm. All these results showed that the South European populations of C. integerrimus have higher levels of cytotype and reproductive diversity compared to the Central European ones. Therefore, the South European populations can be considered as a potential reservoir of regional and global diversity for this species.
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Dias ACC, Marinho RC, Sampaio DS, Bonetti AM, Oliveira PE. Clone worth? Genetic diversity in obligate apomictic Miconia albicans (Melastomataceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:743-748. [PMID: 33884736 DOI: 10.1111/plb.13273] [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: 10/02/2020] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
Apomixis is the asexual production of seeds by plants and, in theory, would render low genetic diversity and even clonal lineages. However, recent studies have shown otherwise, although is not always clear where the genetic diversity of obligate apomicts comes from. We evaluated the genetic diversity among sister seedlings of M. albicans, an obligate apomictic species in Cerrado, Neotropical Savannas in Central Brazil. A total of 50 seedlings from five individuals were analysed using ISSR primers. We obtained 107 fragments, all with good resolution, consistently observed and replicable. The percentage of polymorphic loci ranged from 28.04% to 33.64% and Shannon's information index (I) averaged 0.173. The expected heterozygosity (He) averaged 0.117, similar to the observed for populations of M. albicans and other selfed species. Only two seedlings showed the same genotype (possible clones), but most differed at least for five loci. Most of variance was among progenies (62%), but we found that 38% was within progenies. Genetic distances separated the progenies in two groups, and analogous analyses between individuals reconstructed the original progenies clustering. The results confirmed a relatively high genetic diversity among sister seedling of this obligatory apomictic plant and clones were rare. This diversity can be generated during development, probably by restitutional meiosis or other recombination processes. These differences may accumulate into lineages and populations well adapted to heterogenous Cerrado environment.
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Affiliation(s)
- A C C Dias
- Universidade Federal de Uberlândia, Instituto de Biotecnologia - IBTEC, Uberlândia, MG, Brazil
| | - R C Marinho
- Universidade Federal de Uberlândia, Instituto de Biologia - INBIO, Uberlândia, MG, Brazil
| | - D S Sampaio
- Universidade Federal de Uberlândia, Instituto de Biologia - INBIO, Uberlândia, MG, Brazil
| | - A M Bonetti
- Universidade Federal de Uberlândia, Instituto de Biotecnologia - IBTEC, Uberlândia, MG, Brazil
| | - P E Oliveira
- Universidade Federal de Uberlândia, Instituto de Biologia - INBIO, Uberlândia, MG, Brazil
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Mráz P, Mrázová V. Greater reproductive assurance of asexual plant compared with sexual relative in a low-density sympatric population: Experimental evidence for pollen limitation. J Evol Biol 2021; 34:1503-1509. [PMID: 34331325 DOI: 10.1111/jeb.13910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/07/2021] [Accepted: 07/20/2021] [Indexed: 11/30/2022]
Abstract
High reproductive assurance is regarded as a key advantage of uniparentally reproducing organisms for establishing a new population. This demographic benefit should especially be relevant for plants with autonomous apomixis, that is those which produce seeds completely independently from mates and pollinators. Indeed, many autonomous apomicts occupy larger distributional ranges when compared to their sexual relatives, showing geographical parthenogenesis patterns. However, uniparental reproduction advantage has only rarely been quantified in natural populations and results provided a mixed support, partly because allopatric sexual and asexual populations were exposed to different environmental and pollination conditions causing considerable between-population variation in the level of reproductive assurance. Here, we compared the level and stability of reproductive assurance between sexual self-incompatible and asexual autonomously apomictic plants of Hieracium alpinum (Asteraceae) cultivated in a sympatric low-density population with two levels of spatial clumping of sexual plants. Overall, we found that the realized seed set (i.e. proportion of well-developed seeds per capitulum) of asexuals was ca. 3 times greater than that of sexuals (83% vs. 27%), whereas the variance of this trait expressed as coefficient of variation was ca. 4 times smaller in asexuals compared with sexuals (19% vs. 83%). Solitary sexual plants had more than 2 times lower realized seed set when compared to clumps composed of two spatially close (20-30 cm) sexual plants (13% vs. 34%). Our study provides experimental evidence for benefit of uniparental reproduction of asexuals in a sympatric situation when the availability of mates is limited. This, together with unpredictability of pollinator environment could provide autonomous apomicts with an ultimate demographic superiority during colonization reflected in geographical parthenogenesis observed in this species.
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Affiliation(s)
- Patrik Mráz
- Herbarium Collections and Department of Botany, Charles University, Praha, Czechia
| | - Viera Mrázová
- Herbarium Collections and Department of Botany, Charles University, Praha, Czechia
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Karbstein K, Tomasello S, Hodač L, Lorberg E, Daubert M, Hörandl E. Moving beyond assumptions: Polyploidy and environmental effects explain a geographical parthenogenesis scenario in European plants. Mol Ecol 2021; 30:2659-2675. [PMID: 33871107 DOI: 10.1111/mec.15919] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 11/28/2022]
Abstract
Geographical parthenogenesis (GP) describes the phenomenon that apomicts tend to have larger distribution areas and/or occur at higher altitudes or latitudes compared to sexual relatives. However, the complex effects of genome-wide heterozygosity, ploidy, reproduction mode (sexual vs. apomictic), and environment shaping GP of plants are still not well understood. We ascertained ploidy and reproduction mode by flow cytometry of 221 populations, and added genomic RADseq data (maximum 33,165 loci) of 80 taxa of the Ranunculus auricomus polyploid plant complex in temperate Europe. We observed 7% mainly diploid sexual, 28% facultative apomictic (mean sexuality 7.1%), and 65% obligate apomictic populations. Sexuals occupied a more southern, smaller distribution area, whereas apomicts expanded their range to higher latitudes. Within the complex, we detected three main genetic clusters and highly reticulate relationships. A genetically-informed path analysis using GLMMs revealed several significant relationships. Sexuality of populations (percent of sexual seeds) was higher in diploids compared to polyploids, associated with more petals, and similar between forests and open habitats. In contrast to other apomictic plant complexes, sexuality was mainly positively correlated to solar radiation and isothermality, which fits the southern distribution. We found up to three times higher heterozygosity in polyploids compared to diploids, and generally more heterozygous individuals in forests compared with open habitats. Interestingly, we revealed a previously unknown positive association between heterozygosity and temperature seasonality, suggesting a higher resistance of polyploids to more extreme climatic conditions. We provide empirical evidence for intrinsic and extrinsic factors shaping the GP pattern in a polyploid plant complex.
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Affiliation(s)
- Kevin Karbstein
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Göttingen, Germany.,Georg-August University School of Science (GAUSS), University of Göttingen, Göttingen, Germany
| | - Salvatore Tomasello
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Göttingen, Germany
| | - Ladislav Hodač
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Göttingen, Germany
| | - Ellen Lorberg
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Göttingen, Germany
| | - Mareike Daubert
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Göttingen, Germany.,Institute of Biology and Environmental Sciences, Carl von Ossietzky University, Oldenburg, Germany
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Göttingen, Germany
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Zhang Y, Wu H, Hörandl E, de Oliveira Franca R, Wang L, Hao J. Autonomous apomixis in Praxelis clematidea (Asteraceae: Eupatorieae), an invasive alien plant. AOB PLANTS 2021; 13:plab007. [PMID: 33859809 PMCID: PMC8035972 DOI: 10.1093/aobpla/plab007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 01/23/2021] [Indexed: 06/06/2023]
Abstract
Understanding the reproductive mechanisms of invasive alien species can lay the foundation for effective control measures. Praxelis clematidea is a triploid neotropical Asteraceae species that is invasive in China and other countries. However, few studies have focused on its reproductive biology. In this study, flow cytometric seed screening (FCSS) was used to identify and confirm the reproductive mode of the species. The development of ovules, anthers, and mega- and microgametophytes was observed using a clearing method and differential interference contrast microscopy. Pollen viability was measured using the Benzidine test and Alexander's stain. Pollen morphology was observed via fluorescence microscopy after sectioning the disk florets and staining with water-soluble aniline blue or 4'6-diamidino-2-phenylindole nuclei dyes. Controlled pollination experiments were conducted on four populations in China to examine the breeding system and to confirm autonomous apomixis. The reproductive mode was found to be autonomous apomixis without pseudogamy, according to FCSS. Megaspore mother cells developed directly into eight-nucleate megagametophytes without meiosis, conforming to Antennaria-type diplospory. The unreduced egg cells developed into embryos through parthenogenesis, while the endosperm was formed by the fusion of two unreduced polar nuclei. Pollen viability was very low (0.82 ± 0.57 % and 0.36 ± 0.44 %) as measured by the Benzidine test and Alexander's stain, respectively. The majority of the pollen grains were empty and had neither cytoplasm nor nuclei. The seed set was >90 % for all treatments of open pollination, bagging and emasculated capitula. Mature cypselae developed in capitula that were emasculated before flowering, which confirmed that the breeding system of P. clematidea was autonomous apomixis. The present study is the first report of autonomous apomixis in P. clematidea in China. Antennaria-type autonomous apomixis in P. clematidea greatly increases the probability of successful colonisation and dispersal of P. clematidea into new areas, which likely contributes to its high invasion potential. Effective control measures should be implemented to prevent autonomous (pollen-independent) seed production.
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Affiliation(s)
- Yuhuan Zhang
- School of Biology and Food Engineering, Changshu Institute of Technology, Nansanhuanlu 99, Changshu 215500, Jiangsu Province, China
- College of Life Sciences, Northwest Normal University, No. 967, Anningxi Road, Lanzhou City 730070, Gansu Province, China
| | - Hairong Wu
- Guangzhou Customs Technology Center, No. 66, Huacheng Avenue, Guangzhou 51062, Guangdong Province, China
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspuele 2, 37073 Goettingen, Germany
| | - Rafael de Oliveira Franca
- Programa de Pós-graduação em Biologia Comparada, Universidade Estadual de Maringá, 87020-900 Maringá, Paraná, Brazil
| | - LiXin Wang
- School of Biology and Food Engineering, Changshu Institute of Technology, Nansanhuanlu 99, Changshu 215500, Jiangsu Province, China
| | - Jianhua Hao
- School of Biology and Food Engineering, Changshu Institute of Technology, Nansanhuanlu 99, Changshu 215500, Jiangsu Province, China
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Khanday I, Sundaresan V. Plant zygote development: recent insights and applications to clonal seeds. CURRENT OPINION IN PLANT BIOLOGY 2021; 59:101993. [PMID: 33422964 DOI: 10.1016/j.pbi.2020.101993] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/11/2020] [Accepted: 12/15/2020] [Indexed: 05/22/2023]
Abstract
In flowering plants, haploid gametes - an egg cell and a sperm cell fuse to form the first diploid cell - the zygote. The zygote is the progenitor stem cell that gives rise to all the embryonic and post embryonic tissues and organs. Unlike animals, both maternal and paternal gene products participate in the initial development of zygotes in plants. Here, we discuss recent advances in understanding of the zygotic transition and embryo initiation in angiosperms, including the role of parental contributions to gene expression in the zygote. We further discuss utilization of this knowledge in agricultural biotechnology through synthetic apomixis. Parthenogenesis obtained by manipulation of embryogenic factors, combined with mutations that bypass meiosis, enables clonal propagation of hybrid crops through seeds.
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Affiliation(s)
- Imtiyaz Khanday
- Department of Plant Biology, University of California, Davis, CA, USA; Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Venkatesan Sundaresan
- Department of Plant Biology, University of California, Davis, CA, USA; Innovative Genomics Institute, University of California, Berkeley, CA, USA; Department of Plant Sciences, University of California, Davis, CA, USA.
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11
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Pérez YDJ, Angulo MB, Honfi A, Dematteis M. Embryology and fertility of the natural tetraploid Lessingianthus plantaginoides (Asteraceae, Vernonieae): taxonomic implications. RODRIGUÉSIA 2021. [DOI: 10.1590/2175-7860202172080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abstract Lessingianthus plantaginoides (Vernonieae, Asteraceae) is a small natural tetraploid shrub that inhabits rocky highlands from South America. The population studied inhabits and covers an extensive region of a private reserve with high local biodiversity and animal and plant endemisms. With the purpose of providing insights into the cyto-embryology of this tetraploid species, the aims of this study were: to perform an ontogenetic study of the male and female gametophytes of L. plantaginoides; to carry out detailed meiotic analysis and evaluate the fertility of this species; to document and provide highlights on taxonomic implications of their reproductive aspects. Lessingianthus plantaginoides presented the following male and female gametophyte traits: dicotyledonous type of anther wall development, tetrahedral tetrads, 3-celled mature pollen grains; development of the chalazal megaspore, monosporic embryo sac and Polygonum type of megagametophyte development. The meiotic behavior was regular, the spores were tetrads of equal size and the pollen grains were highly stainable. Lessingianthus plantaginoides is a highly diplodized autotetraploid that reproduces sexually and has high meiotic regularity; which is apparently responsible for its colonization potential. It now seems certain that polyploid speciation plays a significant role in the establishment and diversification of the genus.
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Affiliation(s)
| | - Maria Betiana Angulo
- Instituto de Botánica del Nordeste, Argentina; Facultad de Ciencias Exactas y Naturales y Agrimensura (UNNE), Argentina
| | - Ana Honfi
- Universidad Nacional de Misiones, Argentina
| | - Massimiliano Dematteis
- Instituto de Botánica del Nordeste, Argentina; Facultad de Ciencias Exactas y Naturales y Agrimensura (UNNE), Argentina
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Karbstein K, Rahmsdorf E, Tomasello S, Hodač L, Hörandl E. Breeding system of diploid sexuals within the Ranunculus auricomus complex and its role in a geographical parthenogenesis scenario. Ecol Evol 2020; 10:14435-14450. [PMID: 33391726 PMCID: PMC7771175 DOI: 10.1002/ece3.7073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 12/26/2022] Open
Abstract
The larger distribution area of asexuals compared with their sexual relatives in geographical parthenogenesis (GP) scenarios has been widely attributed to the advantages of uniparental reproduction and polyploidy. However, potential disadvantages of sexuals due to their breeding system have received little attention so far. Here, we study the breeding system of five narrowly distributed sexual lineages of Ranunculus notabilis s.l. (R. auricomus complex) and its effects on outcrossing, inbreeding, female fitness, and heterozygosity. We performed selfing and intra- and interlineage crossings by bagging 481 flowers (59 garden individuals) followed by germination experiments. We compared seed set and germination rates, and related them to genetic distance and genome-wide heterozygosity (thousands of RADseq loci). Selfings (2.5%) unveiled a significantly lower seed set compared with intra- (69.0%) and interlineage crossings (69.5%). Seed set of intra- (65%) compared to interpopulation crossings (78%) was significantly lower. In contrast, all treatments showed comparable germination rates (32%-43%). Generalized linear regressions between seed set and genetic distance revealed positive relationships in general and between lineages, and a negative one within lineages. Seed set was the main decisive factor for female fitness. Germination rates were not related to genetic distance at any level, but were positively associated with heterozygosity in interlineage crossings. Experiments confirmed full crossability and predominant outcrossing among sexual R. notabilis s.l. lineages. However, up to 5% (outliers 15%-31%) of seeds were formed by selfing, probably due to semi-self-compatibility in a multi-locus gametophytic SI system. Less seed set in intrapopulation crossings, and higher seed set and germination rates from crossings of genetically more distant and heterozygous lineages (interlineage) indicate negative inbreeding and positive outbreeding effects. In GP scenarios, sexual species with small and/or isolated populations can suffer from decreased female fitness due to their breeding system. This factor, among others, probably limits range expansion of sexuals.
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Affiliation(s)
- Kevin Karbstein
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium)Institute for Plant SciencesUniversity of GöttingenGöttingenGermany
- Georg‐August University School of Science (GAUSS)University of GöttingenGöttingenGermany
| | - Elisabeth Rahmsdorf
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium)Institute for Plant SciencesUniversity of GöttingenGöttingenGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
| | - Salvatore Tomasello
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium)Institute for Plant SciencesUniversity of GöttingenGöttingenGermany
| | - Ladislav Hodač
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium)Institute for Plant SciencesUniversity of GöttingenGöttingenGermany
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium)Institute for Plant SciencesUniversity of GöttingenGöttingenGermany
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Chasing the Apomictic Factors in the Ranunculus auricomus Complex: Exploring Gene Expression Patterns in Microdissected Sexual and Apomictic Ovules. Genes (Basel) 2020; 11:genes11070728. [PMID: 32630035 PMCID: PMC7397075 DOI: 10.3390/genes11070728] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/10/2020] [Accepted: 06/27/2020] [Indexed: 12/24/2022] Open
Abstract
Apomixis, the asexual reproduction via seeds, is associated to polyploidy and hybridization. To identify possible signatures of apomixis, and possible candidate genes underlying the shift from sex to apomixis, microarray-based gene expression patterns of live microdissected ovules at four different developmental stages were compared between apomictic and sexual individuals of the Ranunculus auricomus complex. Following predictions from previous work on mechanisms underlying apomixis penetrance and expressivity in the genus, gene expression patterns were classified into three categories based on their relative expression in apomicts compared to their sexual parental ancestors. We found evidence of misregulation and differential gene expression between apomicts and sexuals, with the highest number of differences detected during meiosis progression and emergence of aposporous initial (AI) cells, a key developmental stage in the ovule of apomicts where a decision between divergent reproductive pathways takes place. While most of the differentially expressed genes (DEGs) could not be annotated, gene expression was classified into transgressive, parent of origin and ploidy effects. Genes related to gametogenesis and meiosis demonstrated patterns reflective of transgressive and genome dosage effects, which support the hypothesis of a dominant factor controlling apomixis in Ranunculus and modulated by secondary modifiers. Three genes with probable functions in sporogenesis and gametogenesis development are identified and characterized for future studies.
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14
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Abstract
Gametophytic apomixis is a way of asexual plant reproduction by seeds. It should be advantageous under stressful high altitude or latitude environment where short growing seasons, low temperatures, low pollinator activity or unstable weather may hamper sexual reproduction. However, this hypothesis remains largely untested. Here, we assess the reproductive mode in 257 species belonging to 45 families from the world’s broadest alpine belt (2800–6150 m) in NW Himalayas using flow cytometric seed screen. We found only 12 apomictic species, including several members of Poaceae (Festuca, Poa and Stipa), Rosaceae (Potentilla) and Ranunculaceae (Halerpestes, Ranunculus), which are families typical for high apomict frequency. However, several apomictic species were newly discovered, including the first known apomictic species from the family Biebersteiniaceae (Biebersteinia odora), and first apomicts from the genera Stipa (Stipa splendens) and Halerpestes (Halerpestes lancifolia). Apomicts showed no preference for higher elevations, even in these extreme Himalayan alpine habitats. Additional trait-based analyses revealed that apomicts differed from sexuals in comprising more rhizomatous graminoids and forbs, higher soil moisture demands, sharing the syndrome of dominant species with broad geographical and elevation ranges typical for the late-successional habitats. Apomicts differ from non-apomicts in greater ability of clonal propagation and preference for wetter, more productive habitats.
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15
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Alonso‐Marcos H, Nardi FD, Scheffknecht S, Tribsch A, Hülber K, Dobeš C. Difference in reproductive mode rather than ploidy explains niche differentiation in sympatric sexual and apomictic populations of Potentilla puberula. Ecol Evol 2019; 9:3588-3598. [PMID: 30988899 PMCID: PMC6434561 DOI: 10.1002/ece3.4992] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/16/2019] [Accepted: 01/23/2019] [Indexed: 01/02/2023] Open
Abstract
Apomicts tend to have larger geographical distributional ranges and to occur in ecologically more extreme environments than their sexual progenitors. However, the expression of apomixis is typically linked to polyploidy. Thus, it is a priori not clear whether intrinsic effects related to the change in the reproductive mode or rather in the ploidy drive ecological differentiation. We used sympatric sexual and apomictic populations of Potentilla puberula to test for ecological differentiation. To distinguish the effects of reproductive mode and ploidy on the ecology of cytotypes, we compared the niches (a) of sexuals (tetraploids) and autopolyploid apomicts (penta-, hepta-, and octoploids) and (b) of the three apomictic cytotypes. We based comparisons on a ploidy screen of 238 populations along a latitudinal transect through the Eastern European Alps and associated bioclimatic, and soil and topographic data. Sexual tetraploids preferred primary habitats at drier, steeper, more south-oriented slopes, while apomicts mostly occurred in human-made habitats with higher water availability. Contrariwise, we found no or only marginal ecological differentiation among the apomictic higher ploids. Based on the pronounced ecological differences found between sexuals and apomicts, in addition to the lack of niche differentiation among cytotypes of the same reproductive mode, we conclude that reproductive mode rather than ploidy is the main driver of the observed differences. Moreover, we compared our system with others from the literature, to stress the importance of identifying alternative confounding effects (such as hybrid origin). Finally, we underline the relevance of studying ecological parthenogenesis in sympatry, to minimize the effects of differential migration abilities.
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Affiliation(s)
- Henar Alonso‐Marcos
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Flavia Domizia Nardi
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
- Department of BiosciencesUniversity of SalzburgSalzburgAustria
| | - Susanne Scheffknecht
- Institute of BotanyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Andreas Tribsch
- Department of BiosciencesUniversity of SalzburgSalzburgAustria
| | - Karl Hülber
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Christoph Dobeš
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
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16
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Mráz P, Zdvořák P, Hartmann M, Štefánek M, Chrtek J. Can obligate apomixis and more stable reproductive assurance explain the distributional successes of asexual triploids in Hieracium alpinum (Asteraceae)? PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:227-236. [PMID: 30369009 DOI: 10.1111/plb.12930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/24/2018] [Indexed: 06/08/2023]
Abstract
Although reproductive assurance has been suggested to be one of the most important factors shaping the differential distributional patterns between sexuals and asexuals (geographic parthenogenesis), it has only rarely been studied in natural populations of vascular plants with autonomous apomixis. Moreover, there are almost no data concerning the putative relationship between the level of apomictic versus sexual plant reproduction on one hand, and reproductive assurance on the other. We assessed the level of sexual versus apomictic reproduction in diploid and triploid plants of Hieracium alpinum across its distributional range using flow cytometric analyses of seeds, and compared the level of potential and realized seed set, i.e. reproductive assurance, between the two cytotypes under field and greenhouse conditions. Flow cytometric screening of embryos and endosperms of more than 4,100 seeds showed that diploids produced solely diploid progeny sexually, while triploids produced triploid progeny by obligate apomixis. Potential fruit set was much the same in diploids and triploids from the field and the greenhouse experiment. While in the pollination-limited environment in the greenhouse apomictic triploids had considerably higher realized fruit set than sexual diploids, there was no significant difference between cytotypes under natural conditions. In addition, sexuals varied to a significantly larger extent in realized fruit set than asexuals under both natural and greenhouse conditions. Our results indicate that triploid plants reproduce by obligate apomixis, assuring more stable and predictable fruit reproduction when compared to sexual diploids. This advantage could provide apomictic triploids with a superior colonisation ability, mirrored in a strong geographic parthenogenesis pattern observed in this species.
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Affiliation(s)
- P Mráz
- Herbarium and Department of Botany, Charles University, Praha, Czech Republic
| | - P Zdvořák
- Herbarium and Department of Botany, Charles University, Praha, Czech Republic
| | - M Hartmann
- Herbarium and Department of Botany, Charles University, Praha, Czech Republic
| | - M Štefánek
- Herbarium and Department of Botany, Charles University, Praha, Czech Republic
| | - J Chrtek
- Herbarium and Department of Botany, Charles University, Praha, Czech Republic
- Institute of Botany of the Czech Academy of Sciences, Průhonice, Czech Republic
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León-Martínez G, Vielle-Calzada JP. Apomixis in flowering plants: Developmental and evolutionary considerations. Curr Top Dev Biol 2019; 131:565-604. [DOI: 10.1016/bs.ctdb.2018.11.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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18
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Samaniego F, Kolár F, Urfus T, Barragán Á, Romoleroux K. Determination of apomixis by flow cytometry in two species of Lachemilla (Rosaceae) in Ecuador. NEOTROPICAL BIODIVERSITY 2018. [DOI: 10.1080/23766808.2018.1542785] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Affiliation(s)
- Fernanda Samaniego
- Herbario QCA - Pontificia Universidad Catolica del Ecuador, Quito, Ecuador
| | | | - Tomas Urfus
- Fyziologicky Ustav Akademie Ved Ceske Republiky, Pruhonice, Czech republic
| | - Álvaro Barragán
- Museo QCAZ - Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Katya Romoleroux
- Herbario QCA - Pontificia Universidad Catolica del Ecuador, Quito, Ecuador
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19
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Kirchheimer B, Wessely J, Gattringer A, Hülber K, Moser D, Schinkel CCF, Appelhans M, Klatt S, Caccianiga M, Dellinger A, Guisan A, Kuttner M, Lenoir J, Maiorano L, Nieto‐Lugilde D, Plutzar C, Svenning J, Willner W, Hörandl E, Dullinger S, Thrall P. Reconstructing geographical parthenogenesis: effects of niche differentiation and reproductive mode on Holocene range expansion of an alpine plant. Ecol Lett 2018; 21:392-401. [PMID: 29349850 PMCID: PMC5888191 DOI: 10.1111/ele.12908] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/23/2017] [Accepted: 11/27/2017] [Indexed: 12/25/2022]
Abstract
Asexual taxa often have larger ranges than their sexual progenitors, particularly in areas affected by Pleistocene glaciations. The reasons given for this 'geographical parthenogenesis' are contentious, with expansion of the ecological niche or colonisation advantages of uniparental reproduction assumed most important in case of plants. Here, we parameterized a spread model for the alpine buttercup Ranunculus kuepferi and reconstructed the joint Holocene range expansion of its sexual and apomictic cytotype across the European Alps under different simulation settings. We found that, rather than niche broadening or a higher migration rate, a shift of the apomict's niche towards colder conditions per se was crucial as it facilitated overcoming of topographical barriers, a factor likely relevant for many alpine apomicts. More generally, our simulations suggest potentially strong interacting effects of niche differentiation and reproductive modes on range formation of related sexual and asexual taxa arising from their differential sensitivity to minority cytotype disadvantage.
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Affiliation(s)
- Bernhard Kirchheimer
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Johannes Wessely
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Andreas Gattringer
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Karl Hülber
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Dietmar Moser
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Christoph C. F. Schinkel
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium)University of GoettingenUntere Karspüle 237073Göttingen
| | - Marc Appelhans
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium)University of GoettingenUntere Karspüle 237073Göttingen
| | - Simone Klatt
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium)University of GoettingenUntere Karspüle 237073Göttingen
| | - Marco Caccianiga
- Department of BiosciencesUniversity of MilanVia Giovanni Celoria 2620133MilanItaly
| | - Agnes Dellinger
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Antoine Guisan
- Department of Ecology & EvolutionBiophoreUniversity of Lausanne1015LausanneSwitzerland
- Institute of Earth Surface DynamicsGeopolisUniversity of Lausanne1015LausanneSwitzerland
| | - Michael Kuttner
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Jonathan Lenoir
- UR «Ecologie et Dynamique des Systèmes Anthropisés» (EDYSAN, FRE 3498 CNRS)Jules Verne University of Picardie1 Rue des LouvelsF‐80037Amiens Cedex 1France
| | - Luigi Maiorano
- Department of Biology and BiotechnologiesSapienza University of RomeViale dell'Università 32RomeItaly
| | - Diego Nieto‐Lugilde
- Departamento de BotánicaEcología y Fisiología VegetalUniversidad de Córdoba14071CórdobaSpain
| | - Christoph Plutzar
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
| | - Jens‐Christian Svenning
- Section for Ecoinformatics & BiodiversityDepartment of BioscienceAarhus UniversityNy Munkegade 114‐1168000Aarhus CDenmark
| | - Wolfgang Willner
- Vienna Institute for Nature Conservation and AnalysesGießergasse 6/71090ViennaAustria
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium)University of GoettingenUntere Karspüle 237073Göttingen
| | - Stefan Dullinger
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 141030ViennaAustria
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20
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Dias ACC, Serra AC, Sampaio DS, Borba EL, Bonetti AM, Oliveira PE. Unexpectedly high genetic diversity and divergence among populations of the apomictic Neotropical tree Miconia albicans. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:244-251. [PMID: 29069536 DOI: 10.1111/plb.12654] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 10/20/2017] [Indexed: 06/07/2023]
Abstract
Since tropical trees often have long generation times and relatively small reproductive populations, breeding systems and genetic variation are important for population viability and have consequences for conservation. Miconia albicans is an obligate, diplosporous, apomictic species widespread in the Brazilian Cerrado, the savanna areas in central Brazil and elsewhere in the Neotropics. The genetic variability would be, theoretically, low within these male-sterile and possibly clonal populations, although some variation would be expected due to recombination during restitutional meiosis. We used ISSR markers to assess genetic diversity of M. albicans and to compare with other tropical trees, including invasive species of Melastomataceae. A total of 120 individuals from six populations were analysed using ten ISSR primers, which produced 153 fully reproducible fragments. The populations of M. albicans presented mean Shannon's information index (I) of 0.244 and expected heterozygosity (He ) of 0.168. Only two pairs of apparently clonal trees were identified, and genetic diversity was relatively high. A hierarchical amova for all ISSR datasets showed that 74% of the variance was found among populations, while only 26% of the variance was found within populations of this species. Multivariate and Bayesian analyses indicated marked separation between the studied populations. The genetic diversity generated by restitutional meiosis, polyploidy and possibly other genome changes may explain the morpho-physiological plasticity and the ability of these plants to differentiate and occupy such a wide territory and different environmental conditions. Producing enormous amounts of bird-dispersed fruits, M. albicans possess weedy potential that may rival other Melastomataceae alien invaders.
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Affiliation(s)
- A C C Dias
- Universidade Federal de Uberlândia, Instituto de Genética e Bioquímica, Uberlândia, Brazil
| | - A C Serra
- Universidade Federal de Uberlândia, Instituto de Biologia, Uberlândia, Brazil
| | - D S Sampaio
- Universidade Federal de Uberlândia, Instituto de Biologia, Uberlândia, Brazil
| | - E L Borba
- Departamento Botânica, Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Belo Horizonte, Minas Gerais, Brazil
| | - A M Bonetti
- Universidade Federal de Uberlândia, Instituto de Genética e Bioquímica, Uberlândia, Brazil
| | - P E Oliveira
- Universidade Federal de Uberlândia, Instituto de Biologia, Uberlândia, Brazil
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Schinkel CCF, Kirchheimer B, Dullinger S, Geelen D, De Storme N, Hörandl E. Pathways to polyploidy: indications of a female triploid bridge in the alpine species Ranunculus kuepferi (Ranunculaceae). PLANT SYSTEMATICS AND EVOLUTION = ENTWICKLUNGSGESCHICHTE UND SYSTEMATIK DER PFLANZEN 2017; 303:1093-1108. [PMID: 29081576 PMCID: PMC5640749 DOI: 10.1007/s00606-017-1435-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 06/14/2017] [Indexed: 05/05/2023]
Abstract
Polyploidy is one of the most important evolutionary processes in plants. In natural populations, polyploids usually emerge from unreduced gametes which either fuse with reduced ones, resulting in triploid offspring (triploid bridge), or with other unreduced gametes, resulting in tetraploid embryos. The frequencies of these two pathways, and male versus female gamete contributions, however, are largely unexplored. Ranunculus kuepferi occurs with diploid, triploid and autotetraploid cytotypes in the Alps, whereby diploids are mostly sexual, while tetraploids are facultative apomicts. To test for the occurrence of polyploidization events by triploid bridge, we investigated 551 plants of natural populations via flow cytometric seed screening. We assessed ploidy shifts in the embryo to reconstruct female versus male gamete contributions to polyploid embryo and/or endosperm formation. Seed formation via unreduced egg cells (BIII hybrids) occurred in all three cytotypes, while only in one case both gametes were unreduced. Polyploids further formed seeds with reduced, unfertilized egg cells (polyhaploids and aneuploids). Pollen was highly variable in diameter, but only pollen >27 μm was viable, whereby diploids produced higher proportions of well-developed pollen. Pollen size was not informative for the formation of unreduced pollen. These results suggest that a female triploid bridge via unreduced egg cells is the major pathway toward polyploidization in R. kuepferi, maybe as a consequence of constraints of endosperm development. Triploids resulting from unreduced male gametes were not observed, which explains the lack of obligate sexual tetraploid individuals and populations. Unreduced egg cell formation in diploids represents the first step toward apomixis.
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Affiliation(s)
- Christoph C. F. Schinkel
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspüle 2, 37073 Göttingen, Germany
| | - Bernhard Kirchheimer
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Stefan Dullinger
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Danny Geelen
- Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Nico De Storme
- Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspüle 2, 37073 Göttingen, Germany
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22
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Schinkel CCF, Kirchheimer B, Dullinger S, Geelen D, De Storme N, Hörandl E. Pathways to polyploidy: indications of a female triploid bridge in the alpine species Ranunculus kuepferi (Ranunculaceae). PLANT SYSTEMATICS AND EVOLUTION = ENTWICKLUNGSGESCHICHTE UND SYSTEMATIK DER PFLANZEN 2017; 303:1093-1108. [PMID: 29081576 DOI: 10.1007/s00606-017-1435-1436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 06/14/2017] [Indexed: 05/20/2023]
Abstract
Polyploidy is one of the most important evolutionary processes in plants. In natural populations, polyploids usually emerge from unreduced gametes which either fuse with reduced ones, resulting in triploid offspring (triploid bridge), or with other unreduced gametes, resulting in tetraploid embryos. The frequencies of these two pathways, and male versus female gamete contributions, however, are largely unexplored. Ranunculus kuepferi occurs with diploid, triploid and autotetraploid cytotypes in the Alps, whereby diploids are mostly sexual, while tetraploids are facultative apomicts. To test for the occurrence of polyploidization events by triploid bridge, we investigated 551 plants of natural populations via flow cytometric seed screening. We assessed ploidy shifts in the embryo to reconstruct female versus male gamete contributions to polyploid embryo and/or endosperm formation. Seed formation via unreduced egg cells (BIII hybrids) occurred in all three cytotypes, while only in one case both gametes were unreduced. Polyploids further formed seeds with reduced, unfertilized egg cells (polyhaploids and aneuploids). Pollen was highly variable in diameter, but only pollen >27 μm was viable, whereby diploids produced higher proportions of well-developed pollen. Pollen size was not informative for the formation of unreduced pollen. These results suggest that a female triploid bridge via unreduced egg cells is the major pathway toward polyploidization in R. kuepferi, maybe as a consequence of constraints of endosperm development. Triploids resulting from unreduced male gametes were not observed, which explains the lack of obligate sexual tetraploid individuals and populations. Unreduced egg cell formation in diploids represents the first step toward apomixis.
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Affiliation(s)
- Christoph C F Schinkel
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspüle 2, 37073 Göttingen, Germany
| | - Bernhard Kirchheimer
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Stefan Dullinger
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Danny Geelen
- Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Nico De Storme
- Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspüle 2, 37073 Göttingen, Germany
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23
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Schinkel CCF, Kirchheimer B, Dellinger AS, Klatt S, Winkler M, Dullinger S, Hörandl E. Correlations of polyploidy and apomixis with elevation and associated environmental gradients in an alpine plant. AOB PLANTS 2016; 8:plw064. [PMID: 27594702 PMCID: PMC5091893 DOI: 10.1093/aobpla/plw064] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/29/2016] [Indexed: 05/20/2023]
Abstract
Apomictic plants expand their geographical distributions more to higher elevations compared to their sexual progenitors. It was so far unclear whether this tendency is related to mode of reproduction itself or represents a side effect of polyploidy. Apomixis is advantageous for range expansions as no mating partners and pollinators are needed (Baker's rule). Polyploidy is thought to infer fitness advantages and a higher vigour that would enable plants to adjust better to more extreme climatic conditions. However, little is known about actual performance of plants at higher elevations. We analyzed 81 populations of Ranunculus kuepferi from the whole distribution area in the European Alps to quantify apomictic versus sexual seed formation via flow cytometric seed screening. Seed set and vegetative growth were measured as fitness parameters. All parameters were correlated to geographical distribution, elevation, temperature and precipitation. Flow cytometric seed screening revealed predominantly obligate sexuality (88.9 %) and facultative apomixis in diploid populations, while tetraploid populations are predominantly facultative (65.4 %) to obligate apomictic. Apomictic seed formation correlated significantly to higher elevations, which explains also the observed niche shift to lower temperatures. However, within the tetraploid range, there is no apparent correlation of degree of facultative apomixis to geographical distance. Apomixis appeared in diploids three times independently in separated, otherwise sexual populations in the southwestern refugial areas of the Alps. Diploid apomixis was not successful in range expansions, and obligate sexual polyploids were not observed. Polyploidy may relate to cold tolerance as an adaptation to conditions at high elevations, where diploid sexuals have no fitness advantage. Instead, facultative apomixis may have aided colonization of higher elevations and range expansions in the Alps without mate and pollinator limitation, but did not necessarily involve long-distance dispersal. A direct influence of low temperatures on unreduced gamete formation cannot be ruled out.
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Affiliation(s)
- Christoph C F Schinkel
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium), Georg-August-University of Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany
| | - Bernhard Kirchheimer
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Agnes S Dellinger
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Simone Klatt
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium), Georg-August-University of Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany
| | - Manuela Winkler
- GLORIA co-ordination, University of Natural Resources and Life Sciences Vienna, Centre for Global Change and Sustainability, Vienna, Austria
| | - Stefan Dullinger
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium), Georg-August-University of Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany
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Tilquin A, Kokko H. What does the geography of parthenogenesis teach us about sex? Philos Trans R Soc Lond B Biol Sci 2016; 371:20150538. [PMID: 27619701 PMCID: PMC5031622 DOI: 10.1098/rstb.2015.0538] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/16/2016] [Indexed: 11/12/2022] Open
Abstract
Theory predicts that sexual reproduction is difficult to maintain if asexuality is an option, yet sex is very common. To understand why, it is important to pay attention to repeatably occurring conditions that favour transitions to, or persistence of, asexuality. Geographic parthenogenesis is a term that has been applied to describe a large variety of patterns where sexual and related asexual forms differ in their geographic distribution. Often asexuality is stated to occur in a habitat that is, in some sense, marginal, but the interpretation differs across studies: parthenogens might not only predominate near the margin of the sexuals' distribution, but might also extend far beyond the sexual range; they may be disproportionately found in newly colonizable areas (e.g. areas previously glaciated), or in habitats where abiotic selection pressures are relatively stronger than biotic ones (e.g. cold, dry). Here, we review the various patterns proposed in the literature, the hypotheses put forward to explain them, and the assumptions they rely on. Surprisingly, few mathematical models consider geographic parthenogenesis as their focal question, but all models for the evolution of sex could be evaluated in this framework if the (often ecological) causal factors vary predictably with geography. We also recommend broadening the taxa studied beyond the traditional favourites.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Anaïs Tilquin
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland Centre of Excellence in Biological Interactions, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Hanna Kokko
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland Centre of Excellence in Biological Interactions, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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Hersh E, Grimm J, Whitton J. Attack of the clones: reproductive interference between sexuals and asexuals in the Crepis agamic complex. Ecol Evol 2016; 6:6473-6483. [PMID: 27777723 PMCID: PMC5058521 DOI: 10.1002/ece3.2353] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/30/2016] [Accepted: 07/04/2016] [Indexed: 02/02/2023] Open
Abstract
Negative reproductive interactions are likely to be strongest between close relatives and may be important in limiting local coexistence. In plants, interspecific pollen flow is common between co-occurring close relatives and may serve as the key mechanism of reproductive interference. Agamic complexes, systems in which some populations reproduce through asexual seeds (apomixis), while others reproduce sexually, provide an opportunity to examine effects of reproductive interference in limiting coexistence. Apomictic populations experience little or no reproductive interference, because apomictic ovules cannot receive pollen from nearby sexuals. Oppositely, apomicts produce some viable pollen and can exert reproductive interference on sexuals by siring hybrids. In the Crepis agamic complex, sexuals co-occur less often with other members of the complex, but apomicts appear to freely co-occur with one another. We identified a mixed population and conducted a crossing experiment between sexual diploid C. atribarba and apomictic polyploid C. barbigera using pollen from sexual diploids and apomictic polyploids. Seed set was high for all treatments, and as predicted, diploid-diploid crosses produced all diploid offspring. Diploid-polyploid crosses, however, produced mainly polyploidy offspring, suggesting that non-diploid hybrids can be formed when the two taxa meet. Furthermore, a small proportion of seeds produced in open-pollinated flowers was also polyploid, indicating that polyploid hybrids are produced under natural conditions. Our results provide evidence for asymmetric reproductive interference, with pollen from polyploid apomicts contributing to reduce the recruitment of sexual diploids in subsequent generations. Existing models suggest that these mixed sexual-asexual populations are likely to be transient, eventually leading to eradication of sexual individuals from the population.
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Affiliation(s)
- Evan Hersh
- Department of Botany and Biodiversity Research CentreThe University of British Columbia6270 University BoulevardVancouverBritish ColumbiaCanadaV6T 1Z4
| | - Jaime Grimm
- Department of Botany and Biodiversity Research CentreThe University of British Columbia6270 University BoulevardVancouverBritish ColumbiaCanadaV6T 1Z4
- Present address: Department of BiologyMcGill University1205 Dr. Penfield AvenueMontrealQuébecCanadaH3A 1B1
| | - Jeannette Whitton
- Department of Botany and Biodiversity Research CentreThe University of British Columbia6270 University BoulevardVancouverBritish ColumbiaCanadaV6T 1Z4
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Dellinger AS, Essl F, Hojsgaard D, Kirchheimer B, Klatt S, Dawson W, Pergl J, Pyšek P, van Kleunen M, Weber E, Winter M, Hörandl E, Dullinger S. Niche dynamics of alien species do not differ among sexual and apomictic flowering plants. THE NEW PHYTOLOGIST 2016; 209:1313-23. [PMID: 26508329 PMCID: PMC4950116 DOI: 10.1111/nph.13694] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 08/31/2015] [Indexed: 05/20/2023]
Abstract
Biological invasions can be associated with shifts of the species' climatic niches but the incidence of such shifts is under debate. The reproductive system might be a key factor controlling such shifts because it influences a species' evolutionary flexibility. However, the link between reproductive systems and niche dynamics in plant invasions has been little studied so far. We compiled global occurrence data sets of 13 congeneric sexual and apomictic species pairs, and used principal components analysis (PCA) and kernel smoothers to compare changes in climatic niche optima, breadths and unfilling/expansion between native and alien ranges. Niche change metrics were compared between sexual and apomictic species. All 26 species showed changes in niche optima and/or breadth and 14 species significantly expanded their climatic niches. However, we found no effect of the reproductive system on niche dynamics. Instead, species with narrower native niches showed higher rates of niche expansion in the alien ranges. Our results suggest that niche shifts are frequent in plant invasions but evolutionary potential may not be of major importance for such shifts. Niche dynamics rather appear to be driven by changes of the realized niche without adaptive change of the fundamental climatic niche.
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Affiliation(s)
- Agnes S. Dellinger
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 14Vienna1030Austria
| | - Franz Essl
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 14Vienna1030Austria
| | - Diego Hojsgaard
- Department of Systematics, Biodiversity and Evolution of PlantsGeorg‐August‐University of GöttingenUntere Karspüle 2Göttingen37073Germany
| | - Bernhard Kirchheimer
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 14Vienna1030Austria
| | - Simone Klatt
- Department of Systematics, Biodiversity and Evolution of PlantsGeorg‐August‐University of GöttingenUntere Karspüle 2Göttingen37073Germany
| | - Wayne Dawson
- EcologyUniversity of KonstanzUniversitätsstrasse 10Konstanz78457Germany
| | - Jan Pergl
- Institute of BotanyDepartment of Invasion EcologyThe Czech Academy of SciencesPrůhoniceCZ‐252 43Czech Republic
| | - Petr Pyšek
- Institute of BotanyDepartment of Invasion EcologyThe Czech Academy of SciencesPrůhoniceCZ‐252 43Czech Republic
- Department of EcologyFaculty of ScienceCharles University in PragueViničná 7CZ‐128 44Prague 2Czech Republic
| | - Mark van Kleunen
- EcologyUniversity of KonstanzUniversitätsstrasse 10Konstanz78457Germany
| | - Ewald Weber
- Institute of Biochemistry and BiologyUniversity of PotsdamMaulbeerallee 1Potsdam14469Germany
| | - Marten Winter
- German Centre for Integrative Biodiversity Research (iDiv)Halle‐Jena‐LeipzigGermany
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of PlantsGeorg‐August‐University of GöttingenUntere Karspüle 2Göttingen37073Germany
| | - Stefan Dullinger
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 14Vienna1030Austria
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Róis AS, Sádio F, Paulo OS, Teixeira G, Paes AP, Espírito-Santo D, Sharbel TF, Caperta AD. Phylogeography and modes of reproduction in diploid and tetraploid halophytes of Limonium species (Plumbaginaceae): evidence for a pattern of geographical parthenogenesis. ANNALS OF BOTANY 2016; 117:37-50. [PMID: 26424783 PMCID: PMC4701142 DOI: 10.1093/aob/mcv138] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/22/2015] [Accepted: 07/28/2015] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS The genus Limonium (Plumbaginaceae) has long been recognized to have sexual and apomictic (asexual seed formation) modes of reproduction. This study aimed to elucidate phylogeographical patterns and modes of reproduction in diploid and tetraploid Limonium species, namely three putative sexual diploid species with morphological affinities (L. nydeggeri, L. ovalifolium, L. lanceolatum) and three related, probably apomict tetraploid species (L. binervosum, L. dodartii, L. multiflorum). METHODS cpDNA diversity and differentiation between natural populations of the species were investigated using two chloroplast sequence regions (trnL intron and trnL-trnF intergenic spacer). Floral heteromorphies, ovule cytoembryological analyses and pollination and crossing tests were performed in representative species of each ploidy group, namely diploid L. ovalifolium and tetraploid L. multiflorum, using plants from greenhouse collections. KEY RESULTS AND CONCLUSIONS Genetic analyses showed that diploid species have a higher haplotype diversity and a higher number of unique (endemic) haplotypes than tetraploid species. Network analysis revealed correlations between cpDNA haplotype distribution and ploidy groups, species groups and geographical origin, and haplotype sharing within and among species with distinct ploidy levels. Reproductive biology analyses showed that diploid L. ovalifolium mainly forms meiotically reduced tetrasporic embryo sacs of Gagea ova, Adoxa and Drusa types. Limonium multiflorum, however, has only unreduced, diplosporic (apomictic) embryo sacs of Rudbeckia type, and autonomous apomictic development seems to occur. Taken together, the findings provide evidence of a pattern of 'geographical parthenogenesis' in which quaternary climatic oscillations appear to be involved in the geographical patterns of coastal diploid and tetraploid Limonium species.
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Affiliation(s)
- Ana Sofia Róis
- Centro de Investigação em Agronomia, Alimentos, Ambiente e Paisagem (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (ULisboa), Tapada da Ajuda, 1349-017 Lisboa, Portugal
| | - Flávio Sádio
- Centro de Investigação em Agronomia, Alimentos, Ambiente e Paisagem (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (ULisboa), Tapada da Ajuda, 1349-017 Lisboa, Portugal
| | - Octávio S Paulo
- cE3c - Centre for Ecology Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa (ULisboa), Campo Grande, 1649-003 Lisboa, Portugal
| | - Generosa Teixeira
- cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Farmácia, Universidade de Lisboa (ULisboa), Avenida Professor Gama Pinto, 1649-003 Lisboa, Portugal
| | - Ana Paula Paes
- Centro de Investigação em Agronomia, Alimentos, Ambiente e Paisagem (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (ULisboa), Tapada da Ajuda, 1349-017 Lisboa, Portugal
| | - Dalila Espírito-Santo
- Centro de Investigação em Agronomia, Alimentos, Ambiente e Paisagem (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (ULisboa), Tapada da Ajuda, 1349-017 Lisboa, Portugal, Research Network in Biodiversity and Evolutionary Biology (InBIO), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (ULisboa), Tapada da Ajuda, 1349-017 Lisboa, Portugal and
| | - Timothy F Sharbel
- Apomixis Research Group, Department of Cytogenetics and Genome Analysis, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Gatersleben, Germany
| | - Ana D Caperta
- Centro de Investigação em Agronomia, Alimentos, Ambiente e Paisagem (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (ULisboa), Tapada da Ajuda, 1349-017 Lisboa, Portugal, Research Network in Biodiversity and Evolutionary Biology (InBIO), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (ULisboa), Tapada da Ajuda, 1349-017 Lisboa, Portugal and
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Maia FR, Varassin IG, Goldenberg R. Apomixis does not affect visitation to flowers of Melastomataceae, but pollen sterility does. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:132-138. [PMID: 26152277 DOI: 10.1111/plb.12364] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 07/01/2015] [Indexed: 06/04/2023]
Abstract
Apomixis is an asexual seed reproduction mechanism thorough which embryos are originated from material tissues inside the ovules, without precedent fertilisation. It allows plants to colonise new habitats, even in places where flower visitors are scarce or where plants are isolate. Apomixis seems to be related to pollen sterility and, in species with flowers that offer pollen as a reward for pollinators, the amount or quality of the pollen offered by these species may influence the amount of the visits and specific composition of the visitors. In order to test this hypothesis, we studied breeding systems of 16 species of Melastomataceae and their flower visitors, evaluating composition and abundance of the visits to apomictic and sexual species. Apomictic plants with no viable pollen or with pollen with low viability did not receive visits from pollinators, and consequently probably produce strictly apomictic fruits. On the other hand, apomictic and sexual plants with high pollen viability do receive visits; in this case, apomictic plants may produce fruits and seeds through both sexual and apomictic methods. The species composition of insects visiting Melastomataceae with high pollen viability was similar, regardless of whether the plants were apomictic or not. It seems that pollen viability levels are important to determine visits to the flowers irrespective of breeding system.
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Affiliation(s)
- F R Maia
- Departamento de Botânica, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - I G Varassin
- Departamento de Botânica, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - R Goldenberg
- Departamento de Botânica, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
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Ardehed A, Johansson D, Schagerström E, Kautsky L, Johannesson K, Pereyra RT. Complex spatial clonal structure in the macroalgae Fucus radicans with both sexual and asexual recruitment. Ecol Evol 2015; 5:4233-45. [PMID: 26664675 PMCID: PMC4667831 DOI: 10.1002/ece3.1629] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 07/03/2015] [Accepted: 07/08/2015] [Indexed: 11/19/2022] Open
Abstract
In dioecious species with both sexual and asexual reproduction, the spatial distribution of individual clones affects the potential for sexual reproduction and local adaptation. The seaweed Fucus radicans, endemic to the Baltic Sea, has separate sexes, but new attached thalli may also form asexually. We mapped the spatial distribution of clones (multilocus genotypes, MLGs) over macrogeographic (>500 km) and microgeographic (<100 m) scales in the Baltic Sea to assess the relationship between clonal spatial structure, sexual recruitment, and the potential for natural selection. Sexual recruitment was predominant in some areas, while in others asexual recruitment dominated. Where clones of both sexes were locally intermingled, sexual recruitment was nevertheless low. In some highly clonal populations, the sex ratio was strongly skewed due to dominance of one or a few clones of the same sex. The two largest clones (one female and one male) were distributed over 100–550 km of coast and accompanied by small and local MLGs formed by somatic mutations and differing by 1–2 mutations from the large clones. Rare sexual events, occasional long‐distance migration, and somatic mutations contribute new genotypic variation potentially available to natural selection. However, dominance of a few very large (and presumably old) clones over extensive spatial and temporal scales suggested that either these have superior traits or natural selection has only been marginally involved in the structuring of genotypes.
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Affiliation(s)
- Angelica Ardehed
- Department of Biology and Environmental Sciences University of Gothenburg Box 463, SE 405 30 Gothenburg Sweden
| | - Daniel Johansson
- Department of Biology and Environmental Sciences University of Gothenburg Box 463, SE 405 30 Gothenburg Sweden
| | - Ellen Schagerström
- Department of Ecology, Environment and Plant Sciences Stockholm University SE 106 91 Stockholm Sweden
| | - Lena Kautsky
- Department of Ecology, Environment and Plant Sciences Stockholm University SE 106 91 Stockholm Sweden
| | - Kerstin Johannesson
- Department of Marine Sciences-Tjärnö University of Gothenburg SE 452 96 Strömstad Sweden
| | - Ricardo T Pereyra
- Department of Marine Sciences-Tjärnö University of Gothenburg SE 452 96 Strömstad Sweden
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Hajrudinović A, Siljak-Yakovlev S, Brown SC, Pustahija F, Bourge M, Ballian D, Bogunić F. When sexual meets apomict: genome size, ploidy level and reproductive mode variation of Sorbus aria s.l. and S. austriaca (Rosaceae) in Bosnia and Herzegovina. ANNALS OF BOTANY 2015; 116:301-12. [PMID: 26113635 PMCID: PMC4512196 DOI: 10.1093/aob/mcv093] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/23/2015] [Accepted: 05/07/2015] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS Allopolyploidy and intraspecific heteroploid crosses are associated, in certain groups, with changes in the mating system. The genus Sorbus represents an appropriate model to study the relationships between ploidy and reproductive mode variations. Diploid S. aria and tetraploid apomictic S. austriaca were screened for ploidy and mating system variations within pure and sympatric populations in order to gain insights into their putative causalities. METHODS Flow cytometry was used to assess genome size and ploidy level among 380 S. aria s.l. and S. austriaca individuals from Bosnia and Herzegovina, with 303 single-seed flow cytometric seed screenings being performed to identify their mating system. Pollen viability and seed set were also determined. KEY RESULTS Flow cytometry confirmed the presence of di-, tri- and tetraploid cytotype mixtures in mixed-ploidy populations of S. aria and S. austriaca. No ploidy variation was detected in single-species populations. Diploid S. aria mother plants always produced sexually originated seeds, whereas tetraploid S. austriaca as well as triploid S. aria were obligate apomicts. Tetraploid S. aria preserved sexuality in a low portion of plants. A tendency towards a balanced 2m : 1p parental genome contribution to the endosperm was shared by diploids and tetraploids, regardless of their sexual or asexual origin. In contrast, most triploids apparently tolerated endosperm imbalance. CONCLUSIONS Coexistence of apomictic tetraploids and sexual diploids drives the production of novel polyploid cytotypes with predominantly apomictic reproductive modes. The data suggest that processes governing cytotype diversity and mating system variation in Sorbus from Bosnia and Herzegovina are probably parallel to those in other diversity hotspots of this genus. The results represent a solid contribution to knowledge of the reproduction of Sorbus and will inform future investigations of the molecular and genetic mechanisms involved in triggering and regulating cytotype diversity and alteration of reproductive modes.
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Affiliation(s)
- Alma Hajrudinović
- Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina
| | - Sonja Siljak-Yakovlev
- CNRS, Université Paris-Sud, AgroParisTech, UMR 8079, Ecologie, Systématique, Evolution, Bât. 360, 91450 Orsay, France and
| | - Spencer C Brown
- Pôle de Biologie Cellulaire, Imagif, Centre de Recherche de Gif (FRC3115), CNRS, Saclay Plant Sciences, 91198, Gif-sur-Yvette Cedex, France
| | - Fatima Pustahija
- Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina
| | - Mickael Bourge
- Pôle de Biologie Cellulaire, Imagif, Centre de Recherche de Gif (FRC3115), CNRS, Saclay Plant Sciences, 91198, Gif-sur-Yvette Cedex, France
| | - Dalibor Ballian
- Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina
| | - Faruk Bogunić
- Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina,
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Hojsgaard D, Klatt S, Baier R, Carman JG, Hörandl E. Taxonomy and Biogeography of Apomixis in Angiosperms and Associated Biodiversity Characteristics. CRITICAL REVIEWS IN PLANT SCIENCES 2014; 33:414-427. [PMID: 27019547 PMCID: PMC4786830 DOI: 10.1080/07352689.2014.898488] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Apomixis in angiosperms is asexual reproduction from seed. Its importance to angiospermous evolution and biodiversity has been difficult to assess mainly because of insufficient taxonomic documentation. Thus, we assembled literature reporting apomixis occurrences among angiosperms and transferred the information to an internet database (http://www.apomixis.uni-goettingen.de). We then searched for correlations between apomixis occurrences and well-established measures of taxonomic diversity and biogeography. Apomixis was found to be taxonomically widespread with no clear tendency to specific groups and to occur with sexuality at all taxonomic levels. Adventitious embryony was the most frequent form (148 genera) followed by apospory (110) and diplospory (68). All three forms are phylogenetically scattered, but this scattering is strongly associated with measures of biodiversity. Across apomictic-containing orders and families, numbers of apomict-containing genera were positively correlated with total numbers of genera. In general, apomict-containing orders, families, and subfamilies of Asteraceae, Poaceae, and Orchidaceae were larger, i.e., they possessed more families or genera, than non-apomict-containing orders, families or subfamilies. Furthermore, many apomict-containing genera were found to be highly cosmopolitan. In this respect, 62% occupy multiple geographic zones. Numbers of genera containing sporophytic or gametophytic apomicts decreased from the tropics to the arctic, a trend that parallels general biodiversity. While angiosperms appear to be predisposed to shift from sex to apomixis, there is also evidence of reversions to sexuality. Such reversions may result from genetic or epigenetic destabilization events accompanying hybridization, polyploidy, or other cytogenetic alterations. Because of increased within-plant genetic and genomic heterogeneity, range expansions and diversifications at the species and genus levels may occur more rapidly upon reversion to sexuality. The significantly-enriched representations of apomicts among highly diverse and geographically-extensive taxa, from genera to orders, support this conclusion.
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Affiliation(s)
- Diego Hojsgaard
- Georg August University Göttingen, Albrecht-von-Haller Institute for Plant Sciences, Department of Systematic Botany, Göttingen, Germany
| | - Simone Klatt
- Georg August University Göttingen, Albrecht-von-Haller Institute for Plant Sciences, Department of Systematic Botany, Göttingen, Germany
| | - Roland Baier
- Gesellschaft für wissenschaftliche Datenverarbeitung mbH Göttingen (GWDG), Arbeitsgruppe Anwendungs- und Informationssysteme, Göttingen, Germany
| | - John G. Carman
- Plants, Soils and Climate Department, Utah State University, Logan, UT, USA
| | - Elvira Hörandl
- Georg August University Göttingen, Albrecht-von-Haller Institute for Plant Sciences, Department of Systematic Botany, Göttingen, Germany
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Molins MP, Corral JM, Aliyu OM, Koch MA, Betzin A, Maron JL, Sharbel TF. Biogeographic variation in genetic variability, apomixis expression and ploidy of St. John's wort (Hypericum perforatum) across its native and introduced range. ANNALS OF BOTANY 2014; 113:417-27. [PMID: 24344138 PMCID: PMC3906961 DOI: 10.1093/aob/mct268] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 09/26/2013] [Indexed: 05/18/2023]
Abstract
BACKGROUND AND AIMS St. John's wort (Hypericum perforatum) is becoming an important model plant system for investigations into ecology, reproductive biology and pharmacology. This study investigates biogeographic variation for population genetic structure and reproduction in its ancestral (European) and introduced (North America) ranges. METHODS Over 2000 individuals from 43 localities were analysed for ploidy, microsatellite variation (19 loci) and reproduction (flow cytometric seed screen). Most individuals were tetraploid (93%), while lower frequencies of hexaploid (6%), diploid (<1%) and triploid (<1%) individuals were also identified. KEY RESULTS A flow cytometric analysis of 24 single seeds per individual, and five individuals per population demonstrated opposite patterns between ploidy types, with tetraploids producing more apomictic (73%) than sexual (24%) seed, while hexaploids produced more sexual (73%) than apomictic (23%) seed. As hexaploids are derived from tetraploids, these data imply that gene dosage, in addition to the effects of hybridization, influences the switch from apomictic to sexual reproduction. No significant differences in seed production were found between Europe and North America. An analysis of population structure based upon microsatellite profiling demonstrated three major genetic clusters in Europe, whose distribution was reflective of Pleistocene glaciation (e.g. refugia) and post-glacial recolonization of Europe. CONCLUSIONS The presence of pure and mixed populations representing all three genetic clusters in North America demonstrates that H. perforatum was introduced multiple times onto the continent, followed by gene flow between the different gene pools. Taken together, the data presented here suggest that plasticity in reproduction has no influence on the invasive potential of H. perforatum.
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Affiliation(s)
- Marta Puente Molins
- Apomixis research group, Leibniz Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany
| | - José M. Corral
- Apomixis research group, Leibniz Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany
| | - Olawale Mashood Aliyu
- Apomixis research group, Leibniz Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany
| | - Marcus A. Koch
- Centre for Organismal Studies Heidelberg (COS Heidelberg), Department of Biodiversity and Plant Systematics/Botanic Garden and Herbarium Heidelberg (HEID), University of Heidelberg, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Anja Betzin
- Centre for Organismal Studies Heidelberg (COS Heidelberg), Department of Biodiversity and Plant Systematics/Botanic Garden and Herbarium Heidelberg (HEID), University of Heidelberg, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - John L. Maron
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Timothy F. Sharbel
- Apomixis research group, Leibniz Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany
- For correspondence. E-mail
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Kharrat-Souissi A, Siljak-Yakovlev S, Brown SC, Baumel A, Torre F, Chaieb M. The polyploid nature of Cenchrus ciliaris L. (Poaceae) has been overlooked: new insights for the conservation and invasion biology of this species – a review. RANGELAND JOURNAL 2014. [DOI: 10.1071/rj13043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Climate change, associated with increased aridity, and high grazing pressure by livestock results in the scarcity and loss of perennial Poaceae in arid ecosystems. The species threatened by this include Cenchrus ciliaris L., a native perennial grass of the tropical and sub-tropical arid rangelands of Africa and Western Asia and now introduced in Central and South America, and Australia. This species reproduces predominantly through aposporous apomixis although sexual individuals have been occasionally identified. Cenchrus ciliaris is characterised by a significant, heritable, phenotypic polymorphism and three ploidy levels including tetraploids (2n = 4x = 36), pentaploids (2n = 5x = 45) and hexaploids (2n = 6x = 54). Under water-deficit conditions, C. ciliaris shows plasticity in growth characteristics and aboveground biomass. This phenotypic plasticity has led to the identification of genotypic-associated responses conferring more productivity. This underlines the importance of conserving the genetic diversity of C. ciliaris in order to ensure the persistence of the vegetation cover in the arid ecosystems in which it occurs. Observations from cytogenetic and molecular data converge to underline the possibility of sexual reproduction, recombination and gene flow within and between populations of C. ciliaris. Genetic mechanisms, such as polyploidy, hybridisation between ploidy levels and apomixes, are generating and then maintaining the diversity of C. ciliaris. This review emphasises the role of polyploidy in the evolutionary development of C. ciliaris and how it may be a crucial factor for its conservation in some countries and its weedy nature in others.
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Dobeš C, Lückl A, Hülber K, Paule J. Prospects and limits of the flow cytometric seed screen--insights from Potentilla sensu lato (Potentilleae, Rosaceae). THE NEW PHYTOLOGIST 2013; 198:605-616. [PMID: 23425259 PMCID: PMC3618378 DOI: 10.1111/nph.12149] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 12/14/2012] [Indexed: 05/03/2023]
Abstract
The flow cytometric seed screen allows for identification of reproductive modes of seed formation and inference of the ploidy of contributing gametes. However, the lack of a mathematical formalization to infer male/female genomic contributions, and the prerequisite of a binucleate female contribution to the endosperm limits its applicability. We evaluated this assumption combining a DNA-based progeny survey with a comparison of the cytology of reproductive pathways co-occurring within single individuals representing 14 Potentilleae species from six phylogenetic lineages. A numerical framework valid for sexual and pseudogamous taxa was developed, enabling quantification of female and male genomes contributing to embryo and endosperm independent of gametophyte origins, numbers of sperm involved and ploidy of parents. The inference strongly depended on accurate peak index estimation. The endosperm of Potentilleae species received a binucleate female contribution in five evolutionary lineages whereas endosperm formation remained uncertain in the Tormentillae. A modified flow cytometric seed screen protocol was developed to cope with low endosperm contents. Evolutionary conservation of a binucleate female contribution to the endosperm suggested wide applicability of flow cytometric seed screen - at least in the Potentilleae. However, alternative progeny surveys and precise embryo/endosperm ploidy estimates are required for a comprehensive understanding of the cytology of seed formation.
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Affiliation(s)
- Christoph Dobeš
- Department of Pharmacognosy, Pharmacobotany, University of ViennaAlthanstrasse 14, A–1090, Vienna, Austria
| | - Andrea Lückl
- Department of Pharmacognosy, Pharmacobotany, University of ViennaAlthanstrasse 14, A–1090, Vienna, Austria
| | - Karl Hülber
- Department of Conservation Biology, Vegetation and Landscape Ecology, University of ViennaRennweg 14, A–1030, Vienna, Austria
- Vienna Institute for Nature Conservation & AnalysesGiessergasse 6/7, A-1090, Vienna, Austria
| | - Juraj Paule
- Department of Botany and Molecular Evolution, Senckenberg Research Institute & Biodiversity and Climate Research Centre (BiK-F)Senckenberganlage 25, D–60325, Frankfurt am Main, Germany
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Pellicer J, Clermont S, Houston L, Rich TCG, Fay MF. Cytotype diversity in the Sorbus complex (Rosaceae) in Britain: sorting out the puzzle. ANNALS OF BOTANY 2012; 110:1185-93. [PMID: 22922587 PMCID: PMC3478048 DOI: 10.1093/aob/mcs185] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 07/09/2012] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Large-scale ploidy surveys using flow cytometry have become an essential tool to study plant genome dynamics and to gain insight into the mechanisms and genetic barriers framing ploidy diversity. As an ideal complement to traditional techniques such as chromosome counting, the analysis of cytotype diversity in plant systems such as Sorbus provides primary investigation into the potential patterns and evolutionary implications of hybrid speciation. METHODS Ploidy was assessed by means of relative nuclear DNA content using propidium iodide flow cytometry in 474 Sorbus samples collected from 65 populations in southern Wales and South-West England. Statistical tests were applied to evaluate the utility of this technique to confidently discriminate ploidy in the genus. KEY RESULTS Flow cytometric profiles revealed the presence of four cytotypes (2x, 3x, 4x and 5x), confirming in many cases chromosome counts previously reported and demonstrating cytotype heterogeneity within specific Sorbus aggregates. Diploid cytotypes were restricted to the potential parental species and homoploid hybrids. Most of the samples processed were polyploid. The occurrence of the pentaploid cytotype had previously only been reported from a single specimen; it is now confirmed for two taxa occurring at different sites. CONCLUSIONS Flow cytometry results obtained have proved useful in shedding light on the taxonomy of several controversial taxa and in confirming the presence of cytoypes which occur at very low frequencies. Notably, the coexistence of several cytotypes in Sorbus populations has probably been facilitated by the overlapping distribution of many of the species studied, which might also explain the high incidence of potential hybrid apomictic polyploids. These results will provide a solid baseline for molecular research aiming to better understand the genetic pathways controlling the formation and establishment of polyploid Sorbus.
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Affiliation(s)
- Jaume Pellicer
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
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Cires E, Cuesta C, Vargas P, Fernández Prieto JA. Unravelling the evolutionary history of the polyploid complexRanunculus parnassiifolius(Ranunculaceae). Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01968.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eduardo Cires
- Departamento de Biología de Organismos y Sistemas; Universidad de Oviedo; Catedrático Rodrigo Uría s/n 33071 Oviedo Spain
| | - Candela Cuesta
- Departamento de Biología de Organismos y Sistemas; Universidad de Oviedo; Catedrático Rodrigo Uría s/n 33071 Oviedo Spain
- Department of Plant Systems Biology; VIB; Technologiepark 927 9052 Ghent Belgium
| | - Pablo Vargas
- Real Jardín Botánico de Madrid; CSIC; Plaza Murillo 2 28014 Madrid Spain
| | - José Antonio Fernández Prieto
- Departamento de Biología de Organismos y Sistemas; Universidad de Oviedo; Catedrático Rodrigo Uría s/n 33071 Oviedo Spain
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dos Santos APM, Fracasso CM, Luciene dos Santos M, Romero R, Sazima M, Oliveira PE. Reproductive biology and species geographical distribution in the Melastomataceae: a survey based on New World taxa. ANNALS OF BOTANY 2012; 110:667-79. [PMID: 22751617 PMCID: PMC3400453 DOI: 10.1093/aob/mcs125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
BACKGROUND AND AIMS Apomictic plants are less dependent on pollinator services and able to occupy more diverse habitats than sexual species. However, such assumptions are based on temperate species, and comparable evaluation for species-rich Neotropical taxa is lacking. In this context, the Melastomataceae is a predominantly Neotropical angiosperm family with many apomictic species, which is common in the Campos Rupestres, endemism-rich vegetation on rocky outcrops in central Brazil. In this study, the breeding system of some Campo Rupestre Melastomataceae was evaluated, and breeding system studies for New World species were surveyed to test the hypothesis that apomixis is associated with wide distributions, whilst sexual species have more restricted areas. METHODS The breeding systems of 20 Campo Rupestre Melastomataceae were studied using hand pollinations and pollen-tube growth analysis. In addition, breeding system information was compiled for 124 New World species of Melastomataceae with either wide (>1000 km) or restricted distributions. KEY RESULTS Most (80 %) of the Campo Rupestre species studied were self-compatible. Self-incompatibility in Microlicia viminalis was associated with pollen-tube arrest in the style, as described for other Melastomataceae, but most self-incompatible species analysed showed pollen-tube growth to the ovary irrespective of pollination treatment. Apomictic species showed lower pollen viability and were less frequent among the Campo Rupestre plants. Among the New World species compiled, 43 were apomictic and 77 sexual (24 self-incompatible and 53 self-compatible). Most apomictic (86 %) and self-incompatible species (71 %) presented wide distributions, whilst restricted distributions predominate only among the self-compatible ones (53 %). CONCLUSIONS Self-compatibility and dependence on biotic pollination were characteristic of Campo Rupestre and narrowly distributed New World Melastomataceae species, whilst apomictics are widely distributed. This is, to a certain extent, similar to the geographical parthenogenesis pattern of temperate apomictics.
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Affiliation(s)
- Ana Paula Milla dos Santos
- Universidade de São Paulo, Escola de Enfermagem de Ribeirão Preto, Av. Bandeirantes 3900, 14040-902, Ribeirão Preto, SP, Brasil
| | - Carla Magioni Fracasso
- Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Biologia Vegetal, Caixa Postal 6109, 13083-970, Campinas, SP, Brasil
| | - Mirley Luciene dos Santos
- Universidade Estadual de Goiás, Unidade Universitária de Ciências Exatas e Tecnológicas, Caixa Postal 459, 75001-970, Anápolis, GO, Brasil
| | - Rosana Romero
- Universidade Federal de Uberlândia, Instituto de Biologia, 38402-020 Uberlândia, MG, Brasil
| | - Marlies Sazima
- Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Biologia Vegetal, Caixa Postal 6109, 13083-970, Campinas, SP, Brasil
| | - Paulo Eugênio Oliveira
- Universidade Federal de Uberlândia, Instituto de Biologia, 38402-020 Uberlândia, MG, Brasil
- For correspondence. E-mail
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Hörandl E, Dobeš C, Suda J, Vít P, Urfus T, Temsch EM, Cosendai AC, Wagner J, Ladinig U. Apomixis is not prevalent in subnival to nival plants of the European Alps. ANNALS OF BOTANY 2011; 108:381-90. [PMID: 21724654 PMCID: PMC3143052 DOI: 10.1093/aob/mcr142] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 04/28/2011] [Indexed: 05/19/2023]
Abstract
BACKGROUND AND AIMS High alpine environments are characterized by short growing seasons, stochastic climatic conditions and fluctuating pollinator visits. These conditions are rather unfavourable for sexual reproduction of flowering plants. Apomixis, asexual reproduction via seed, provides reproductive assurance without the need of pollinators and potentially accelerates seed development. Therefore, apomixis is expected to provide selective advantages in high-alpine biota. Indeed, apomictic species occur frequently in the subalpine to alpine grassland zone of the European Alps, but the mode of reproduction of the subnival to nival flora was largely unknown. METHODS The mode of reproduction in 14 species belonging to seven families was investigated via flow cytometric seed screen. The sampling comprised 12 species typical for nival to subnival plant communities of the European Alps without any previous information on apomixis (Achillea atrata, Androsace alpina, Arabis caerulea, Erigeron uniflorus, Gnaphalium hoppeanum, Leucanthemopsis alpina, Oxyria digyna, Potentilla frigida, Ranunculus alpestris, R. glacialis, R. pygmaeus and Saxifraga bryoides), and two high-alpine species with apomixis reported from other geographical areas (Leontopodium alpinum and Potentilla crantzii). KEY RESULTS Flow cytometric data were clearly interpretable for all 46 population samples, confirming the utility of the method for broad screenings on non-model organisms. Formation of endosperm in all species of Asteraceae was documented. Ratios of endosperm : embryo showed pseudogamous apomixis for Potentilla crantzii (ratio approx. 3), but sexual reproduction for all other species (ratios approx. 1·5). CONCLUSIONS The occurrence of apomixis is not correlated to high altitudes, and cannot be readily explained by selective forces due to environmental conditions. The investigated species have probably other adaptations to high altitudes to maintain reproductive assurance via sexuality. We hypothesize that shifts to apomixis are rather connected to frequencies of polyploidization than to ecological conditions.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic and Evolutionary Botany, Faculty of Life Sciences, University of Vienna, A-1030 Vienna, Austria.
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CIRES EDUARDO, CUESTA CANDELA, REVILLA MARÍAÁNGELES, FERNÁNDEZ PRIETO JOSÉANTONIO. Intraspecific genome size variation and morphological differentiation of Ranunculus parnassifolius (Ranunculaceae), an Alpine-Pyrenean-Cantabrian polyploid group. Biol J Linn Soc Lond 2010. [DOI: 10.1111/j.1095-8312.2010.01517.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hörandl E. The evolution of self-fertility in apomictic plants. SEXUAL PLANT REPRODUCTION 2010; 23:73-86. [PMID: 20165965 PMCID: PMC2854795 DOI: 10.1007/s00497-009-0122-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 11/03/2009] [Indexed: 11/28/2022]
Abstract
Self-fertilization and apomixis have often been seen as alternative evolutionary strategies of flowering plants that are advantageous for colonization scenarios and in bottleneck situations. Both traits have multiple origins, but different genetic control mechanisms; possible connections between the two phenomena have long been overlooked. Most apomictic plants, however, need a fertilization of polar nuclei for normal seed development (pseudogamy). If self-pollen is used for this purpose, self-compatibility is a requirement for successful pollen tube growth. Apomictic lineages usually evolve from sexual self-incompatible outcrossing plants, but pseudogamous apomicts frequently show a breakdown of self-incompatibility. Two possible pathways may explain the evolution of SC: (1) Polyploidy not only may trigger gametophytic apomixis, but also may result in a partial breakdown of SI systems. (2) Alternatively, frequent pseudo self-compatibility (PSC) via aborted pollen may induce selfing of pseudogamous apomicts (mentor effects). Self-fertile pseudogamous genotypes will be selected for within mixed sexual-apomictic populations because of avoidance of interploidal crosses; in founder situations, SC provides reproductive assurance independent from pollinators and mating partners. SI pseudogamous genotypes will be selected against in mixed populations because of minority cytotype problems and high pollen discounting; in founder populations, SI reactions among clone mates will reduce seed set. Selection for SC genotypes will eliminate SI unless the apomict maintains a high genotypic diversity and thus a diversity of S-alleles within a population, or shifts to pollen-independent autonomous apomixis. The implications of a breakdown of SI in apomictic plants for evolutionary questions and for agricultural sciences are being discussed.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic and Evolutionary Botany, Faculty of Life Sciences, University of Vienna, Rennweg 14, 1030, Vienna, Austria.
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Abstract
Self-fertilization and apomixis have often been seen as alternative evolutionary strategies of flowering plants that are advantageous for colonization scenarios and in bottleneck situations. Both traits have multiple origins, but different genetic control mechanisms; possible connections between the two phenomena have long been overlooked. Most apomictic plants, however, need a fertilization of polar nuclei for normal seed development (pseudogamy). If self-pollen is used for this purpose, self-compatibility is a requirement for successful pollen tube growth. Apomictic lineages usually evolve from sexual self-incompatible outcrossing plants, but pseudogamous apomicts frequently show a breakdown of self-incompatibility. Two possible pathways may explain the evolution of SC: (1) Polyploidy not only may trigger gametophytic apomixis, but also may result in a partial breakdown of SI systems. (2) Alternatively, frequent pseudo self-compatibility (PSC) via aborted pollen may induce selfing of pseudogamous apomicts (mentor effects). Self-fertile pseudogamous genotypes will be selected for within mixed sexual-apomictic populations because of avoidance of interploidal crosses; in founder situations, SC provides reproductive assurance independent from pollinators and mating partners. SI pseudogamous genotypes will be selected against in mixed populations because of minority cytotype problems and high pollen discounting; in founder populations, SI reactions among clone mates will reduce seed set. Selection for SC genotypes will eliminate SI unless the apomict maintains a high genotypic diversity and thus a diversity of S-alleles within a population, or shifts to pollen-independent autonomous apomixis. The implications of a breakdown of SI in apomictic plants for evolutionary questions and for agricultural sciences are being discussed.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic and Evolutionary Botany, Faculty of Life Sciences, University of Vienna, Rennweg 14, 1030, Vienna, Austria.
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Cosendai AC, Hörandl E. Cytotype stability, facultative apomixis and geographical parthenogenesis in Ranunculus kuepferi (Ranunculaceae). ANNALS OF BOTANY 2010; 105:457-70. [PMID: 20100695 PMCID: PMC2826254 DOI: 10.1093/aob/mcp304] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 10/12/2009] [Accepted: 11/23/2009] [Indexed: 05/18/2023]
Abstract
BACKGROUND AND AIMS Asexual organisms are more widespread in previously glaciated areas than their sexual relatives ('geographical parthenogenesis'). In plants, this pattern is probably dependent on reproductive isolation and stability of cytotypes within their respective distribution areas. Both partial apomixis and introgressive hybridization potentially destabilize the spatial separation of sexual and apomictic populations. The wide distribution of apomicts may be further enhanced by uniparental reproduction which is advantageous for colonization. These factors are studied in the alpine species Ranunculus kuepferi. METHODS Geographical distribution, diversity and mode of reproduction of cytotypes were assessed using flow cytometry and flow cytometric seed screening on samples from 59 natural populations of Ranunculus kuepferi. Seed set of cytotypes was compared in the wild. KEY RESULTS Diploid sexuals are confined to the south-western parts of the Alps, while tetraploid apomicts dominate in previously glaciated and in geographically isolated areas despite a significantly lower fertility. Other cytotypes (3x, 5x and 6x) occur mainly in the sympatric zone, but without establishing populations. The tetraploids are predominantly apomictic, but also show a partial apomixis via an uncoupling of apomeiosis and parthenogenesis in the seed material. Both pseudogamy and autonomous endosperm formation are observed which may enhance uniparental reproduction. CONCLUSIONS Diploids occupy a glacial relic area and resist introgression of apomixis, probably because of a significantly higher seed set. Among the polyploids, only apomictic tetraploids form stable populations; the other cytotypes arising from partial apomixis fail to establish, probably because of minority cytotype disadvantages. Tetraploid apomicts colonize previously devastated and also distant areas via long-distance dispersal, confirming Baker's law of an advantage of uniparental reproduction. It is concluded that stability of cytotypes and of modes of reproduction are important factors for establishing a pattern of geographical parthenogenesis.
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Affiliation(s)
| | - Elvira Hörandl
- Department of Systematic and Evolutionary Botany, Faculty Centre for Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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Hoffmann MH, von Hagen KB, Hörandl E, Röser M, Tkach NV. SOURCES OF THE ARCTIC FLORA: ORIGINS OF ARCTIC SPECIES IN RANUNCULUS AND RELATED GENERA. INTERNATIONAL JOURNAL OF PLANT SCIENCES 2010; 171:90-106. [PMID: 20582248 PMCID: PMC2892301 DOI: 10.1086/647918] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The arctic biome is a relatively young ecosystem with ~2300 species of vascular plants. We studied the genus Ranunculus as an example of the origin and evolution of the arctic flora. For this purpose we used molecular phylogenetic and clock analyses based on evaluation of nuclear ITS and chloroplast matK-trnK DNA sequences in 194 taxa of Ranunculus and closely related genera. Taxa occurring in the Arctic arose form seven phylogenetic lineages of Ranunculus and also in the genera Coptidium and Halerpestes. Two clades of Ranunculus are species-rich in the Arctic, i.e., Ranunculus sect. Ranunculus and R. sect. Auricomus (both from R. subg. Ranunculus), but this is due to a number of arctic "microtaxa" morphologically barely separate from R. acris in the former clade and the widely agamospermic species complex of R. auricomus in the latter. Lineages with species adapted to wetlands or aquatic habitats are significant groups represented in the arctic flora (R. subg. Ranunculus sectt. Flammula and Hecatonia/Xanthobatrachium, R. subg. Batrachium, genus Coptidium) but show no clear signs of radiation in the Arctic or the northern boreal zone, except for sectt. Hecatonia/Xanthobatrachium, with R. hyperboreus and R. sceleratus subsp. reptabundus. Astonishingly few of the otherwise numerous lineages of Ranunculus with distributions in the higher mountain systems of Eurasia and North America have acted as "founding sources" for the arctic flora. The only clear example is that of the arctic-alpine R. glacialis and the Beringian R. chamissonis from the lineage of subg. R. sectt. Aconitifolii/Crymodes, although there might be others in sect. Auricomus not recovered in the current molecular data. Lineages that gave rise to arctic taxa diverged from each other from the early Miocene (R. glacialis/R. chamissonis, Coptidium, lineages in Halerpestes) and continued at an even rate throughout the Tertiary. There are no signs that the intense climate changes of the late Pliocene and the Quaternary substantially accelerated or impeded diversification in Ranunculus. Only the crown group split of R. acris and its relatives is clearly of Quaternary age. A detailed comparison concerning morphology, karyology, and life form excludes fundamental differences between taxa of Ranunculus in the Arctic and their respective closest relatives in regions south of it. Ecological traits, e.g., preferences for dry or moist soils or growth in open and sheltered conditions, also do not differ between arctic and nonarctic̣ taxa. Migration into the Arctic thus started from different phylogenetic lineages and at different times, without development of obvious special traits in the adaptation to arctic environments. This recurrent pattern in Ranunculus differs from that seen in other arctic genera, e.g., Artemisia, in which special traits of adaptation to arctic environments are found. In Ranunculus, the origin of the open arctic biome primarily favored range expansions of taxa/species already adapted to wet habitats in cold areas and depending on rapid dispersal.
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Affiliation(s)
- Matthias H. Hoffmann
- Geobotanik und Botanischer Garten, Martin-Luther-Universität Halle-Wittenberg, Institut für Biologie, Am Kirchtor 3, 06108 Halle, Germany
| | - K. Bernhard von Hagen
- Geobotanik und Botanischer Garten, Martin-Luther-Universität Halle-Wittenberg, Institut für Biologie, Am Kirchtor 3, 06108 Halle, Germany
| | - Elvira Hörandl
- Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Martin Röser
- Geobotanik und Botanischer Garten, Martin-Luther-Universität Halle-Wittenberg, Institut für Biologie, Am Kirchtor 3, 06108 Halle, Germany
| | - Natalia V. Tkach
- Geobotanik und Botanischer Garten, Martin-Luther-Universität Halle-Wittenberg, Institut für Biologie, Am Kirchtor 3, 06108 Halle, Germany
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Hörandl E, Greilhuber J, Klímová K, Paun O, Temsch E, Emadzade K, Hodálová I. Reticulate evolution and taxonomic concepts in the Ranunculus auricomus complex (Ranunculaceae): insights from analysis of morphological, karyological and molecular data. TAXON 2009; 58:1194-1215. [PMID: 20401184 PMCID: PMC2855680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
The Ranunculus auricomus complex is an interesting model system for studying the evolution and diversity of apomictic polyploid complexes. It comprises hundreds of agamospecies, usually referred to two distinct morphotypes (traditionally named "R. auricomus" and "R. cassubicus") which are connected by several intermediate forms. Here we try to elucidate the evolution of apomictic "cassubicus" morphotypes and we test criteria for different classification concepts by combining the information of molecular phylogenetic, morphological, karyological and population genetic data (AFLPs, amplified fragment length polymorphism). Phylogenetic analysis based on sequences of the nrDNA ITS and plastid data (matK, trnk, psbJ-psbA) suggest a deep split between the diploid sexual species R. notabilis ("auricomus" morphotype) from the closely related allopatric taxa R. cassubicifolius and R. carpaticola ("cassubicus"). The apomictic "cassubicus" morphotypes are not monophyletic, as one, R. hungaricus, groups with R. notabilis, which may be due to hybrid origin. Morphometric studies and ploidy level determinations via Feulgen densitometry show a transition from 4x R. hungaricus to the 6x apomictic hybrid derivatives of R. cassubicifolius and R. carpaticola. In two accessions, AFLPs and flow cytometric data suggest local gene flow among different apomictic polyploid morphotypes. Frequent facultative sexuality of apomicts may increase genetic diversity by continuous formation of new cytotypes, local hybridization and introgression, which obstructs the fixation of distinct agamospecies. We conclude that "R. cassubicus" and "R. auricomus" cannot be regarded as species but should be treated as either informal groups, or as (notho)taxa at the sectional level. To reflect the different evolutionary processes involved, we propose a separate classification of the sexual species, R. notabilis and the closely related species pair R. cassubicifolius and R. carpaticola. Based on these well-defined biological species, the apomictic biotypes can be classified as nothotaxa.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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Hörandl E, Greilhuber J, Klímová K, Paun O, Temsch E, Emadzade K, Hodálová I. Reticulate evolution and taxonomic concepts in the Ranunculus auricomus complex (Ranunculaceae): insights from analysis of morphological, karyological and molecular data. TAXON 2009; 58:1194-1215. [PMID: 20401184 DOI: 10.1002/tax.584012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The Ranunculus auricomus complex is an interesting model system for studying the evolution and diversity of apomictic polyploid complexes. It comprises hundreds of agamospecies, usually referred to two distinct morphotypes (traditionally named "R. auricomus" and "R. cassubicus") which are connected by several intermediate forms. Here we try to elucidate the evolution of apomictic "cassubicus" morphotypes and we test criteria for different classification concepts by combining the information of molecular phylogenetic, morphological, karyological and population genetic data (AFLPs, amplified fragment length polymorphism). Phylogenetic analysis based on sequences of the nrDNA ITS and plastid data (matK, trnk, psbJ-psbA) suggest a deep split between the diploid sexual species R. notabilis ("auricomus" morphotype) from the closely related allopatric taxa R. cassubicifolius and R. carpaticola ("cassubicus"). The apomictic "cassubicus" morphotypes are not monophyletic, as one, R. hungaricus, groups with R. notabilis, which may be due to hybrid origin. Morphometric studies and ploidy level determinations via Feulgen densitometry show a transition from 4x R. hungaricus to the 6x apomictic hybrid derivatives of R. cassubicifolius and R. carpaticola. In two accessions, AFLPs and flow cytometric data suggest local gene flow among different apomictic polyploid morphotypes. Frequent facultative sexuality of apomicts may increase genetic diversity by continuous formation of new cytotypes, local hybridization and introgression, which obstructs the fixation of distinct agamospecies. We conclude that "R. cassubicus" and "R. auricomus" cannot be regarded as species but should be treated as either informal groups, or as (notho)taxa at the sectional level. To reflect the different evolutionary processes involved, we propose a separate classification of the sexual species, R. notabilis and the closely related species pair R. cassubicifolius and R. carpaticola. Based on these well-defined biological species, the apomictic biotypes can be classified as nothotaxa.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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Abstract
Sexual reproduction implies high costs, but it is difficult to give evidence for evolutionary advantages that would explain the predominance of meiotic sex in eukaryotes. A combinational theory discussing evolution, maintenance and loss of sex may resolve the problem. The main function of sex is the restoration of DNA and consequently a higher quality of offspring. Recombination at meiosis evolved, perhaps, as a repair mechanism of DNA strand damages. This mechanism is most efficient for DNA restoration in multicellular eukaryotes, because the initial cell starts with a re-optimized genome, which is passed to all the daughter cells. Meiosis acts also as creator of variation in haploid stages, in which selection can purge most efficiently deleterious mutations. A prolonged diploid phase buffers the effects of deleterious recessive alleles as well as epigenetic defects and is thus optimal for prolonged growth periods. For complex multicellular organisms, the main advantage of sexuality is thus the alternation of diploid and haploid stages, combining advantages of both. A loss of sex is constrained by several, partly group-specific, developmental features. Hybridization may trigger shifts from sexual to asexual reproduction, but crossing barriers of the parental sexual species limit this process. For the concerted break-up of meiosis-outcrossing cycles plus silencing of secondary features, various group-specific changes in the regulatory system may be required. An establishment of asexuals requires special functional modifications and environmental opportunities. Costs for maintenance of meiotic sex are consequently lower than a shift to asexual reproduction.
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Hörandl E, Temsch EM. Introgression of apomixis into sexual species is inhibited by mentor effects and ploidy barriers in the Ranunculus auricomus complex. ANNALS OF BOTANY 2009; 104:81-9. [PMID: 19386790 PMCID: PMC2706732 DOI: 10.1093/aob/mcp093] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 03/09/2009] [Accepted: 03/20/2009] [Indexed: 05/03/2023]
Abstract
BACKGROUND AND AIMS Apomictic plants maintain functional pollen, and via pollination the genetic factors controlling apomixis can be potentially transferred to congeneric sexual populations. In contrast, the sexual individuals do not fertilize apomictic plants which produce seeds without fertilization of the egg cells. This unidirectional introgressive hybridization is expected finally to replace sexuality by apomixis and is thought to be a causal factor for the wide geographical distribution of apomictic complexes. Nevertheless, this process may be inhibited by induced selfing (mentor effects) of otherwise self-incompatible sexual individuals. Here whether mentor effects or actual cross-fertilization takes place between diploid sexual and polyploid apomictic cytotypes in the Ranunculus auricomus complex was tested via experimental crosses. METHODS Diploid sexual mother plants were pollinated with tetra- and hexaploid apomictic pollen donators by hand, and the amount of well-developed seed compared with aborted seed was evaluated. The reproductive pathways were assessed in the well-developed seed via flow cytometric seed screen (FCSS). KEY RESULTS The majority of seed was aborted; the well-developed seeds have resulted from both mentor effects and cross-fertilization at very low frequencies (1.3 and 1.6 % of achenes, respectively). Pollination by 4x apomictic pollen plants results more frequently in cross-fertilization, whereas pollen from 6x plants more frequently induced mentor effects. CONCLUSIONS It is concluded that introgression of apomixis into sexual populations is limited by ploidy barriers in the R. auricomus complex, and to a minor extent by mentor effects. In mixed populations, sexuality cannot be replaced by apomixis because the higher fertility of sexual populations still compensates the low frequencies of potential introgression of apomixis.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria.
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Hörandl E. EVOLUTIONARY IMPLICATIONS OF SELF-COMPATIBILITY AND REPRODUCTIVE FITNESS IN THE APOMICTIC RANUNCULUS AURICOMUS POLYPLOID COMPLEX (RANUNCULACEAE). INTERNATIONAL JOURNAL OF PLANT SCIENCES 2008; 169:1219-1228. [PMID: 20396408 PMCID: PMC2854825 DOI: 10.1086/591980] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Uniparental reproduction has often been regarded as advantageous for colonization. In pseudogamous a pomicts, reproduction via single individuals requires self-pollination and consequently self-compatibility (SC) for production of viable seeds. SC and reproductive fitness have been studied in diploid and polyploid taxa of the Ranunculus auricomus complex via pollinator exclusion tests, assessment of seed set, and germination rates. Reproductive fitness of sexuals exceeds that of apomicts and of F(1) hybrids but may fluctuate more strongly between years than is the case in apomicts. Diploid sexual taxa and also their F(1) hybrids are completely self-incompatible (SI). Auto-polyploid sexual cytotypes are also predominantly SI, which may have restricted their range expansion. The observed breakdown of SI in the rather widespread allohexaploid apomicts may be explained by initial partial SC inherited from semi-self-compatible ancestors and strong selection for SC genotypes. It is concluded that higher reproductive fitness of sexuals may help to maintain sexual populations when cross-pollination is available, whereas SC in apomicts may be advantageous in temporally and spatially unstable environments and also for colonization events. Results suggest that SC in connection with pseudogamous apomixis is an important factor for the observed distribution pattern of geographical parthenogenesis.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria
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