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Hörandl E. Apomixis and the paradox of sex in plants. ANNALS OF BOTANY 2024; 134:1-18. [PMID: 38497809 PMCID: PMC11161571 DOI: 10.1093/aob/mcae044] [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: 12/11/2023] [Accepted: 03/15/2024] [Indexed: 03/19/2024]
Abstract
BACKGROUND The predominance of sex in eukaryotes, despite the high costs of meiosis and mating, remains an evolutionary enigma. Many theories have been proposed, none of them being conclusive on its own, and they are, in part, not well applicable to land plants. Sexual reproduction is obligate in embryophytes for the great majority of species. SCOPE This review compares the main forms of sexual and asexual reproduction in ferns and angiosperms, based on the generation cycling of sporophyte and gametophyte (leaving vegetative propagation aside). The benefits of sexual reproduction for maintenance of genomic integrity in comparison to asexuality are discussed in the light of developmental, evolutionary, genetic and phylogenetic studies. CONCLUSIONS Asexual reproduction represents modifications of the sexual pathway, with various forms of facultative sexuality. For sexual land plants, meiosis provides direct DNA repair mechanisms for oxidative damage in reproductive tissues. The ploidy alternations of meiosis-syngamy cycles and prolonged multicellular stages in the haploid phase in the gametophytes provide a high efficiency of purifying selection against recessive deleterious mutations. Asexual lineages might buffer effects of such mutations via polyploidy and can purge the mutational load via facultative sexuality. The role of organelle-nuclear genome compatibility for maintenance of genome integrity is not well understood. In plants in general, the costs of mating are low because of predominant hermaphroditism. Phylogenetic patterns in the archaeplastid clade suggest that high frequencies of sexuality in land plants are concomitant with a stepwise increase of intrinsic and extrinsic stress factors. Furthermore, expansion of genome size in land plants would increase the potential mutational load. Sexual reproduction appears to be essential for keeping long-term genomic integrity, and only rare combinations of extrinsic and intrinsic factors allow for shifts to asexuality.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium), University of Göttingen, Göttingen, Germany
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Hojsgaard D, Nagel M, Feingold SE, Massa GA, Bradshaw JE. New Frontiers in Potato Breeding: Tinkering with Reproductive Genes and Apomixis. Biomolecules 2024; 14:614. [PMID: 38927018 PMCID: PMC11202281 DOI: 10.3390/biom14060614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/13/2024] [Accepted: 05/20/2024] [Indexed: 06/28/2024] Open
Abstract
Potato is the most important non-cereal crop worldwide, and, yet, genetic gains in potato have been traditionally delayed by the crop's biology, mostly the genetic heterozygosity of autotetraploid cultivars and the intricacies of the reproductive system. Novel site-directed genetic modification techniques provide opportunities for designing climate-smart cultivars, but they also pose new possibilities (and challenges) for breeding potato. As potato species show a remarkable reproductive diversity, and their ovules have a propensity to develop apomixis-like phenotypes, tinkering with reproductive genes in potato is opening new frontiers in potato breeding. Developing diploid varieties instead of tetraploid ones has been proposed as an alternative way to fill the gap in genetic gain, that is being achieved by using gene-edited self-compatible genotypes and inbred lines to exploit hybrid seed technology. In a similar way, modulating the formation of unreduced gametes and synthesizing apomixis in diploid or tetraploid potatoes may help to reinforce the transition to a diploid hybrid crop or enhance introgression schemes and fix highly heterozygous genotypes in tetraploid varieties. In any case, the induction of apomixis-like phenotypes will shorten the time and costs of developing new varieties by allowing the multi-generational propagation through true seeds. In this review, we summarize the current knowledge on potato reproductive phenotypes and underlying genes, discuss the advantages and disadvantages of using potato's natural variability to modulate reproductive steps during seed formation, and consider strategies to synthesize apomixis. However, before we can fully modulate the reproductive phenotypes, we need to understand the genetic basis of such diversity. Finally, we visualize an active, central role for genebanks in this endeavor by phenotyping properly genotyped genebank accessions and new introductions to provide scientists and breeders with reliable data and resources for developing innovations to exploit market opportunities.
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Affiliation(s)
- Diego Hojsgaard
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, Germany;
| | - Manuela Nagel
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, Germany;
| | - Sergio E. Feingold
- Laboratorio de Agrobiotecnología, EEA Balcarce-IPADS (UEDD INTA–CONICET), Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce B7620, Argentina; (S.E.F.); (G.A.M.)
| | - Gabriela A. Massa
- Laboratorio de Agrobiotecnología, EEA Balcarce-IPADS (UEDD INTA–CONICET), Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce B7620, Argentina; (S.E.F.); (G.A.M.)
- Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Balcarce B7620, Argentina
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Keller B, Alther B, Jiménez A, Koutroumpa K, Mora-Carrera E, Conti E. Island plants with newly discovered reproductive traits have higher capacity for uniparental reproduction, supporting Baker's law. Sci Rep 2024; 14:11392. [PMID: 38762587 PMCID: PMC11102434 DOI: 10.1038/s41598-024-62065-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 05/13/2024] [Indexed: 05/20/2024] Open
Abstract
Uniparental reproduction is advantageous when lack of mates limits outcrossing opportunities in plants. Baker's law predicts an enrichment of uniparental reproduction in habitats colonized via long-distance dispersal, such as volcanic islands. To test it, we analyzed reproductive traits at multiple hierarchical levels and compared seed-set after selfing and crossing experiments in both island and mainland populations of Limonium lobatum, a widespread species that Baker assumed to be self-incompatible because it had been described as pollen-stigma dimorphic, i.e., characterized by floral morphs differing in pollen-surface morphology and stigma-papillae shape that are typically self-incompatible. We discovered new types and combinations of pollen and stigma traits hitherto unknown in the literature on pollen-stigma dimorphism and a lack of correspondence between such combinations and pollen compatibility. Contrary to previous reports, we conclude that Limonium lobatum comprises both self-compatible and self-incompatible plants characterized by both known and previously undescribed combinations of reproductive traits. Most importantly, plants with novel combinations are overrepresented on islands, selfed seed-set is higher in islands than the mainland, and insular plants with novel pollen-stigma trait-combinations disproportionally contribute to uniparental reproduction on islands. Our results thus support Baker's law, connecting research on reproductive and island biology.
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Affiliation(s)
- Barbara Keller
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.
| | - Barbara Alther
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Ares Jiménez
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Konstantina Koutroumpa
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Botanischer Garten und Botanisches Museum Berlin (BGBM), Freie Universität Berlin, Berlin, Germany
| | - Emiliano Mora-Carrera
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Elena Conti
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
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Reutemann AV, Honfi AI, Karunarathne P, Eckers F, Hojsgaard DH, Martínez EJ. Comparative analysis of molecular and morphological diversity in two diploid Paspalum species (Poaceae) with contrasting mating systems. PLANT REPRODUCTION 2024; 37:15-32. [PMID: 37566236 DOI: 10.1007/s00497-023-00478-3] [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: 03/15/2023] [Accepted: 07/22/2023] [Indexed: 08/12/2023]
Abstract
KEY MESSAGE Interspecific comparison of two Paspalum species has demonstrated that mating systems (selfing and outcrossing) contribute to variation (genetically and morphologically) within species through similar but mutually exclusive processes. Mating systems play a key role in the genetic dynamics of populations. Studies show that populations of selfing plants have less genetic diversity than outcrossing plants. Yet, many such studies have ignored morphological diversity. Here, we compared the morphological and molecular diversity patterns in populations of two phylogenetically-related sexual diploids that differ in their mating system: self-sterile Paspalum indecorum and self-fertile P. pumilum. We assessed the morphological variation using 16 morpho-phenological characters and the molecular diversity using three combinations of AFLPs. We compared the morphological and molecular diversity within and among populations in each mating system. Contrary to expectations, selfers showed higher morphological variation within populations, mainly in vegetative and phenological traits, compared to outcrossers. The high morphological variation within populations of selfers led to a low differentiation among populations. At molecular level, selfing populations showed lower levels of genotypic and genetic diversity than outcrossing populations. As expected, selfers showed higher population structure than outcrossers (PhiST = 0.301 and PhiST = 0.108, respectively). Increased homozygous combinations for the same trait/locus enhance morphological variation and reduce molecular variation within populations in selfing P. pumilum. Thus, selfing outcomes are opposite when comparing morphological and molecular variation in P. pumilum. Meanwhile, pollen flow in obligate outcrossing populations of P. indecorum increases within-population molecular variation, but tends to homogenize phenotypes within-population. Pollen flow in obligate outcrossers tends to merge geographically closer populations; but isolation by distance can lead to a weak differentiation among distant populations of P. indecorum.
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Affiliation(s)
- A Verena Reutemann
- Instituto de Botánica del Nordeste (IBONE-CONICET-UNNE), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), 3400, Corrientes, Argentina
| | - Ana I Honfi
- Programa de Estudios Florísticos y Genética Vegetal, Instituto de Biología Subtropical (PEFyGV, IBS-UNaM-CONICET), 3300, Posadas, Argentina
| | - Piyal Karunarathne
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-Von-Haller Institute for Plant Sciences, University of Goettingen, 37073, Goettingen, Germany
- Institute for Population Genetics, Heinrich Heine University, 40225, Düsseldorf, Germany
| | - Fabiana Eckers
- Programa de Estudios Florísticos y Genética Vegetal, Instituto de Biología Subtropical (PEFyGV, IBS-UNaM-CONICET), 3300, Posadas, Argentina
| | - Diego H Hojsgaard
- Taxonomy and Evolutionary Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466, Gatersleben, Germany
| | - Eric J Martínez
- Instituto de Botánica del Nordeste (IBONE-CONICET-UNNE), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), 3400, Corrientes, Argentina.
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Ptáček J, Ekrt L, Hornych O, Urfus T. Interploidy gene flow via a 'pentaploid bridge' and ploidy reduction in Cystopteris fragilis fern complex (Cystopteridaceae: Polypodiales). PLANT REPRODUCTION 2023; 36:321-331. [PMID: 37532893 DOI: 10.1007/s00497-023-00476-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 07/15/2023] [Indexed: 08/04/2023]
Abstract
KEY MESSAGE Our results indicate the existence of interploidy gene flow in Cystopteris fragilis, resulting in sexual triploid and diploid gametophytes from pentaploid parents. Similar evolutionary dynamics might operate in other fern complexes and need further investigation. Polyploidization and hybridization are a key evolutionary processes in ferns. Here, we outline an interploidy gene flow pathway operating in the polyploid Cystopteris fragilis complex. The conditions necessary for the existence of this pathway were tested. A total of 365 C. fragilis individuals were collected covering representatives of all three predominant ploidy levels (tetraploid, pentaploid, and hexaploid), cultivated, had their ploidy level estimated by flow cytometry, and their spores collected. The spores, as well as gametophytes and sporophytes established from them, were analysed by flow cytometry. Spore abortion rate was also estimated. In tetraploids, we observed the formation of unreduced (tetraploid) spores (ca 2%). Collected pentaploid individuals indicate ongoing hybridization between ploidy levels. Pentaploids formed up to 52% viable spores, ca 79% of them reduced, i.e. diploid and triploid. Reduced spores formed viable gametophytes, and, in the case of triploids, filial hexaploid sporophytes, showing evidence of sexual reproduction. Some tetraploid sporophytes reproduce apomictically (based on uniform ploidy of their metagenesis up to filial sporophytes). Triploid and diploid gametophytes from pentaploid parents are able to mate among themselves, or with "normal" reduced gametophytes from the sexual tetraploid sporophytes (the dominant ploidy level in the sporophytes in this populations), to produce tetraploid, pentaploid, and hexaploid sporophytes, allowing for geneflow from the pentaploids to both the tetraploid and hexaploid populations. Similar evolutionary dynamics might operate in other fern complexes and need further investigation.
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Affiliation(s)
- Jan Ptáček
- Department of Botany, Faculty of Science, Charles University, Benátská 2, , 128 00, Praha, Czech Republic
| | - Libor Ekrt
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
| | - Ondřej Hornych
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
| | - Tomáš Urfus
- Department of Botany, Faculty of Science, Charles University, Benátská 2, , 128 00, Praha, Czech Republic.
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6
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Bala M, Rehana S, Singh MP. Self-incompatibility: a targeted, unexplored pre-fertilization barrier in flower crops of Asteraceae. JOURNAL OF PLANT RESEARCH 2023; 136:587-612. [PMID: 37452973 DOI: 10.1007/s10265-023-01480-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 07/03/2023] [Indexed: 07/18/2023]
Abstract
Asteraceae (synonym as Compositae) is one of the largest angiosperm families among flowering plants comprising one-tenth of all agri-horticultural species grown across various habitats except in Antarctica. These are commercially utilized as cut and loose flowers as well as pot and bedding plants in landscape gardens due to their unique floral traits. Consequently, ineffective seed setting and presence of an intraspecific reproductive barrier known as self-incompatibility (SI) severely reduces the effectiveness of hybridization and self-fertilization by traditional crossing. There have been very few detailed studies of pollen-stigma interactions in this family. Moreover, about 63% of Aster species can barely self-fertilize due to self-incompatibility (SI). The chrysanthemum (Chrysanthemum × morifolium) is one of the most economically important ornamental plants in the Asteraceae family which hugely shows incompatibility. Reasons for the low fertility and reproductive capacity of species are still indefinite or not clear. Hence, the temporal pattern of inheritance of self-incompatibility and its effect on reproductive biology needs to be investigated further to improve the breeding efficiency. This review highlights the self-incompatible (SI) system operating in important Astraceous (ornamental) crops which are adversely affected by this mechanism along with different physiological and molecular techniques involved in breaking down self-incompatibility.
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Affiliation(s)
- Madhu Bala
- Department of Floriculture and Landscaping, Punjab Agricultural University, Ludhiana, Punjab, 141 004, India.
| | - Shaik Rehana
- Department of Floriculture and Landscaping, Punjab Agricultural University, Ludhiana, Punjab, 141 004, India
| | - Mohini Prabha Singh
- Department of Floriculture and Landscaping, Punjab Agricultural University, Ludhiana, Punjab, 141 004, India
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Wang N, Cao S, Liu Z, Xiao H, Hu J, Xu X, Chen P, Ma Z, Ye J, Chai L, Guo W, Larkin RM, Xu Q, Morrell PL, Zhou Y, Deng X. Genomic conservation of crop wild relatives: A case study of citrus. PLoS Genet 2023; 19:e1010811. [PMID: 37339133 DOI: 10.1371/journal.pgen.1010811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 06/01/2023] [Indexed: 06/22/2023] Open
Abstract
Conservation of crop wild relatives is critical for plant breeding and food security. The lack of clarity on the genetic factors that lead to endangered status or extinction create difficulties when attempting to develop concrete recommendations for conserving a citrus wild relative: the wild relatives of crops. Here, we evaluate the conservation of wild kumquat (Fortunella hindsii) using genomic, geographical, environmental, and phenotypic data, and forward simulations. Genome resequencing data from 73 accessions from the Fortunella genus were combined to investigate population structure, demography, inbreeding, introgression, and genetic load. Population structure was correlated with reproductive type (i.e., sexual and apomictic) and with a significant differentiation within the sexually reproducing population. The effective population size for one of the sexually reproducing subpopulations has recently declined to ~1,000, resulting in high levels of inbreeding. In particular, we found that 58% of the ecological niche overlapped between wild and cultivated populations and that there was extensive introgression into wild samples from cultivated populations. Interestingly, the introgression pattern and accumulation of genetic load may be influenced by the type of reproduction. In wild apomictic samples, the introgressed regions were primarily heterozygous, and genome-wide deleterious variants were hidden in the heterozygous state. In contrast, wild sexually reproducing samples carried a higher recessive deleterious burden. Furthermore, we also found that sexually reproducing samples were self-incompatible, which prevented the reduction of genetic diversity by selfing. Our population genomic analyses provide specific recommendations for distinct reproductive types and monitoring during conservation. This study highlights the genomic landscape of a wild relative of citrus and provides recommendations for the conservation of crop wild relatives.
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Affiliation(s)
- Nan Wang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
- State Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Shuo Cao
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
- State Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Zhongjie Liu
- State Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Hua Xiao
- State Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Jianbing Hu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
| | - Xiaodong Xu
- State Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
- Hubei Hongshan Laboratory, Wuhan, China
| | - Peng Chen
- Institute of Horticultural Research, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Zhiyao Ma
- State Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Junli Ye
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
| | - Lijun Chai
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
| | - Wenwu Guo
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
- Hubei Hongshan Laboratory, Wuhan, China
| | - Robert M Larkin
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
- Hubei Hongshan Laboratory, Wuhan, China
| | - Qiang Xu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
- Hubei Hongshan Laboratory, Wuhan, China
| | - Peter L Morrell
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Yongfeng Zhou
- State Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
- State Key Laboratory of Tropical Crop Breeding, Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - Xiuxin Deng
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, China
- Hubei Hongshan Laboratory, Wuhan, China
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Schedler M, Reutemann AV, Hojsgaard DH, Zilli AL, Brugnoli EA, Galdeano F, Acuña CA, Honfi AI, Martínez EJ. Alternative Evolutionary Pathways in Paspalum Involving Allotetraploidy, Sexuality, and Varied Mating Systems. Genes (Basel) 2023; 14:1137. [PMID: 37372317 DOI: 10.3390/genes14061137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/17/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023] Open
Abstract
The genetic systems of Paspalum species have not been extensively studied. We analyzed the ploidy, reproductive mode, mating system, and fertility of four Paspalum species-Paspalum durifolium, Paspalum ionanthum, Paspalum regnellii, and Paspalum urvillei. An analysis of 378 individuals from 20 populations of northeastern Argentina was conducted. All populations of the four Paspalum species were pure tetraploid and had a sexual and stable reproductive mode. However, some populations of P. durifolium and P. ionanthum showed low levels of apospory. Populations of P. durifolium and P. ionanthum had low seed sets under self-pollination but were fertile under open pollination, showing that self-incompatibility likely caused self-sterility. In contrast, populations of P. regnellii or P. urvillei showed no evidence of apospory, and seed sets in both self- and open pollination conditions were high, suggesting that they are self-compatible due to the absence of pollen-pistil molecular incompatibility mechanisms. The evolutionary origin of the four Paspalum species could explain these differences. This study supplies valuable insights into the genetic systems of Paspalum species, which could have implications for their conservation and management.
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Affiliation(s)
- Mara Schedler
- Instituto de Botánica del Nordeste (IBONE-UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Corrientes 3400, Corrientes, Argentina
| | - Anna Verena Reutemann
- Instituto de Botánica del Nordeste (IBONE-UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Corrientes 3400, Corrientes, Argentina
| | - Diego Hernán Hojsgaard
- Taxonomy & Evolutionary Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Gatersleben, Germany
| | - Alex Leonel Zilli
- Instituto de Botánica del Nordeste (IBONE-UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Corrientes 3400, Corrientes, Argentina
| | - Elsa Andrea Brugnoli
- Instituto de Botánica del Nordeste (IBONE-UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Corrientes 3400, Corrientes, Argentina
| | - Florencia Galdeano
- Instituto de Botánica del Nordeste (IBONE-UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Corrientes 3400, Corrientes, Argentina
| | - Carlos Alberto Acuña
- Instituto de Botánica del Nordeste (IBONE-UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Corrientes 3400, Corrientes, Argentina
| | - Ana Isabel Honfi
- Programa de Estudios Florísticos y Genética Vegetal, Instituto de Biología Subtropical (PEFyGV, IBS-UNaM-CONICET), Posadas 3300, Misiones, Argentina
| | - Eric Javier Martínez
- Instituto de Botánica del Nordeste (IBONE-UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), Corrientes 3400, Corrientes, Argentina
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Geometric Morphometric Versus Genomic Patterns in a Large Polyploid Plant Species Complex. BIOLOGY 2023; 12:biology12030418. [PMID: 36979110 PMCID: PMC10045763 DOI: 10.3390/biology12030418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023]
Abstract
Plant species complexes represent a particularly interesting example of taxonomically complex groups (TCGs), linking hybridization, apomixis, and polyploidy with complex morphological patterns. In such TCGs, mosaic-like character combinations and conflicts of morphological data with molecular phylogenies present a major problem for species classification. Here, we used the large polyploid apomictic European Ranunculus auricomus complex to study relationships among five diploid sexual progenitor species and 75 polyploid apomictic derivate taxa, based on geometric morphometrics using 11,690 landmarked objects (basal and stem leaves, receptacles), genomic data (97,312 RAD-Seq loci, 48 phased target enrichment genes, 71 plastid regions) from 220 populations. We showed that (1) observed genomic clusters correspond to morphological groupings based on basal leaves and concatenated traits, and morphological groups were best resolved with RAD-Seq data; (2) described apomictic taxa usually overlap within trait morphospace except for those taxa at the space edges; (3) apomictic phenotypes are highly influenced by parental subgenome composition and to a lesser extent by climatic factors; and (4) allopolyploid apomictic taxa, compared to their sexual progenitor, resemble a mosaic of ecological and morphological intermediate to transgressive biotypes. The joint evaluation of phylogenomic, phenotypic, reproductive, and ecological data supports a revision of purely descriptive, subjective traditional morphological classifications.
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Hajrudinović-Bogunić A, Frajman B, Schönswetter P, Siljak-Yakovlev S, Bogunić F. Apomictic Mountain Whitebeam (Sorbus austriaca, Rosaceae) Comprises Several Genetically and Morphologically Divergent Lineages. BIOLOGY 2023; 12:biology12030380. [PMID: 36979072 PMCID: PMC10045669 DOI: 10.3390/biology12030380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/04/2023]
Abstract
The interplay of polyploidisation, hybridization, and apomixis contributed to the exceptional diversity of Sorbus (Rosaceae), giving rise to a mosaic of genetic and morphological entities. The Sorbus austriaca species complex from the mountains of Central and South-eastern Europe represents an allopolyploid apomictic system of populations that originated following hybridisation between S. aria and S. aucuparia. However, the mode and frequency of such allopolyploidisations and the relationships among different, morphologically more or less similar populations that have often been described as different taxa remain largely unexplored. We used amplified fragment length polymorphism (AFLP) fingerprinting, plastid DNA sequencing, and analyses of nuclear microsatellites, along with multivariate morphometrics and ploidy data, to disentangle the relationships among populations within this intricate complex. Our results revealed a mosaic of genetic lineages—many of which have not been taxonomically recognised—that originated via multiple allopolyploidisations. The clonal structure within and among populations was then maintained via apomixis. Our results thus support previous findings that hybridisation, polyploidization, and apomixis are the main drivers of Sorbus diversification in Europe.
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Affiliation(s)
| | - Božo Frajman
- Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
- Correspondence: (B.F.); (F.B.)
| | - Peter Schönswetter
- Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Sonja Siljak-Yakovlev
- Ecologie Systématique Evolution, CNRS, Université Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400 Orsay, France
| | - Faruk Bogunić
- Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina
- Correspondence: (B.F.); (F.B.)
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11
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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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12
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Silva DM, Luna ALL, Souza CS, Nunes YRF, Fonseca RS, Azevedo IFPD. Sexual and reproductive systems of woody species in
vereda
are distributed according to the life form and habitat occurrence. AUSTRAL ECOL 2022. [DOI: 10.1111/aec.13235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Danila Moreira Silva
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
| | - Andressa Laís Lacerda Luna
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
| | - Camila Silveira Souza
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
- Laboratório de Ecologia Vegetal, Departamento de Biologia Geral Universidade Estadual de Montes Claros Montes Claros Brazil
| | - Yule Roberta Ferreira Nunes
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
- Laboratório de Ecologia Vegetal, Departamento de Biologia Geral Universidade Estadual de Montes Claros Montes Claros Brazil
| | - Rúbia Santos Fonseca
- Instituto de Ciências Agrárias Universidade Federal de Minas Gerais, Bairro Universitário Montes Claros Brazil
| | - Islaine Franciely Pinheiro de Azevedo
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
- Laboratório de Ecologia Vegetal, Departamento de Biologia Geral Universidade Estadual de Montes Claros Montes Claros Brazil
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13
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Hornych O, Férová A, Hori K, Košnar J, Ekrt L. Apomictic fern fathers: an experimental approach to the reproductive characteristics of sexual, apomict, and hybrid fern gametophytes. AMERICAN JOURNAL OF BOTANY 2022; 109:628-644. [PMID: 35072270 DOI: 10.1002/ajb2.1817] [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: 05/05/2021] [Revised: 01/05/2022] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
PREMISE Apomixis and hybridization are two essential and complementary factors in the evolution of plants, including ferns. Hybridization combines characteristics from different species, while apomixis conserves features within a lineage. When combined, these two processes result in apo-sex hybrids. The conditions leading to the formation of these hybrids are poorly understood in ferns. METHODS We cultivated spores from 66 fern samples (43 apomicts, 7 apo-sex hybrids, and 16 sexuals), and measured their development in vitro over 16 weeks. We evaluated germination, lateral meristem formation rates, sexual expression, and production of sporophytes and then compared ontogenetic patterns among the three groups. RESULTS The three examined groups formed antheridia (male gametangia) but differed in overall gametophyte development. Sexual species created archegonia (female, 86% of viable samples), but no sporophytes. Apomicts rarely created nonfunctional archegonia (8%) but usually produced apogamous sporophytes (75%). Surprisingly, apomictic and sexual species showed similar development speed. The sexually reproducing parents of viable studied hybrids formed about twice as many meristic gametophytes as the apomictic parents (39% vs. 20%, respectively). CONCLUSIONS We present the most thorough comparison of gametangial development of sexual and apomictic ferns, to date. Despite expectations, apomictic reproduction might not lead to earlier sporophyte formation. Apomicts produce functional sperm and thus can contribute this type of gamete to their hybrids. The development patterns found in the parents of hybrids indicate a possible increase of hybridization rates by antheridiogens. The apo-sex hybrids always inherit the apomictic reproductive strategy and are thus capable of self-perpetuation.
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Affiliation(s)
- Ondřej Hornych
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
| | - Alžběta Férová
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
| | - Kiyotaka Hori
- The Kochi prefectural Makino Botanical Garden, Godaisan 4200-6, Kochi, 781-8125, Japan
| | - Jiří Košnar
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
| | - Libor Ekrt
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
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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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15
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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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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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17
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Janas AB, Szeląg Z, Musiał K. In search of female sterility causes in the tetraploid and pentaploid cytotype of Pilosella brzovecensis (Asteraceae). JOURNAL OF PLANT RESEARCH 2021; 134:803-810. [PMID: 33813645 PMCID: PMC8245384 DOI: 10.1007/s10265-021-01290-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 03/26/2021] [Indexed: 06/12/2023]
Abstract
Within the agamic Pilosella complex, apomixis (asexual reproduction through seed) involves apospory, parthenogenesis, and autonomous endosperm development. Observations of reproductive biology in P. brzovecensis throughout four growing seasons in the garden have shown that both tetraploid and pentaploid plants of this species do not produce viable seeds and reproduce exclusively vegetatively by underground stolons. The reasons for the seed development failure were unknown, therefore our research focused on the analysis of reproductive events in the ovules of this taxon. We found that apospory was initiated in the ovules of both cytotypes. Multiple aposporous initial (AI) cells differentiated in close proximity to the megaspore mother cell (MMC) and suppressed megasporogenesis at the stage of early prophase I. However, none of the AI cells was able to further develop into a multi-nucleate aposporous embryo sac (AES) due to the inhibition of mitotic divisions. It was unusual that callose was accumulated in the walls of AI cells and its synthesis was most likely associated with a response to the dysfunction of these cells. Callose is regarded as the isolating factor and its surprising deposition in the ovules of P. brzovecensis may signal disruption of reproductive processes that cause premature termination of the aposporous development pathway and ultimately lead to ovule sterility. The results of our embryological analysis may be the basis for undertaking advanced molecular studies aimed at fully understanding of the causes of female sterility in P. brzovecensis.
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Affiliation(s)
- Agnieszka Barbara Janas
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, Gronostajowa 9, 30-387, Cracow, Poland.
- The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239, Cracow, Poland.
| | - Zbigniew Szeląg
- Institute of Biology, Pedagogical University of Cracow, Podchorążych 2, 30-084, Cracow, Poland
| | - Krystyna Musiał
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, Gronostajowa 9, 30-387, Cracow, Poland
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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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Sharples MT, Bentz PC, Manzitto-Tripp EA. Evolution of apetaly in the cosmopolitan genus Stellaria. AMERICAN JOURNAL OF BOTANY 2021; 108:869-882. [PMID: 33982285 DOI: 10.1002/ajb2.1650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 12/29/2020] [Indexed: 05/22/2023]
Abstract
PREMISE Apetaly is widespread across distantly related lineages of flowering plants and is associated with abiotic (or self-) pollination. It is particularly prevalent in the carnation family, and the cosmopolitan genus Stellaria contains many lineages that are hypothesized to have lost petals from showy petalous ancestors. But the pollination biology of apetalous species of Stellaria remains unclear. METHODS Using a substantial species-level sampling (~92% of known taxonomic diversity), we describe the pattern of petal evolution within Stellaria using ancestral character state reconstructions. To help shed light on the reproductive biology of apetalous Stellaria, we conducted a field experiment at an alpine tundra site in the southern Rocky Mountains to test whether an apetalous species (S. irrigua) exhibits higher levels of selfing than a sympatric, showy petalous congener (S. longipes). RESULTS Analyses indicated that the ancestor of Stellaria was likely showy petalous and that repeated, parallel reductions of petals occurred in clades across much of the world, with uncommon reversal back to showy petals. Field experiments supported high rates of selfing in the apetalous species and high rates of outcrossing in the petalous species. CONCLUSIONS Petal loss is rampant across major clades of Stellaria and is potentially linked with self-pollination worldwide. Self-pollination occurs within the buds in S. irrigua, and high propensities for this and other forms of selfing known in many other taxa of arctic-alpine habitats may reflect erratic availability of pollinators.
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Affiliation(s)
- Mathew T Sharples
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, 80309, USA
| | - Philip C Bentz
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, 80309, USA
- Department of Plant Biology, University of Georgia, Athens, Georgia, 30602, USA
| | - Erin A Manzitto-Tripp
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, 80309, USA
- Museum of Natural History, COLO Herbarium, University of Colorado, Boulder, Colorado, 80309, USA
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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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21
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Mau M, Liiving T, Fomenko L, Goertzen R, Paczesniak D, Böttner L, Sharbel TF. The spread of infectious asexuality through haploid pollen. THE NEW PHYTOLOGIST 2021; 230:804-820. [PMID: 33421128 DOI: 10.1111/nph.17174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 12/26/2020] [Indexed: 05/16/2023]
Abstract
The mechanisms of initiation and transmission of apomixis (asexual reproduction through seeds) in natural plant populations are important for understanding the evolution of reproductive variation. Here, we used the phylogenetic diversity of the genus Boechera (Brassicaceae), together with natural diversity in pollen types produced by apomictic lines, to test whether hybridization triggers the transition to asexuality, and whether a 'triploid bridge' is required for the formation of polyploid apomicts. We performed crosses between diploid sexual recipient and diploid apomictic donor lines and tested whether the mating system (interspecific hybridization vs intraspecific outcrossing) or pollen type (haploid vs diploid) influenced the transmission of apomixis from diploid apomictic donors into sexual recipients. We used genetic markers and flow cytometric analyses of embryo and endosperm in seeds to infer the reproductive mode. Within a single generation, initiation of both diploid and polyploid apomixis in sexual Boechera can occur. Diploid apomixis is transmitted through haploid pollen (infectious asexuality) and polyploids can form through multiple pathways. The three functional elements of apomixis occasionally segregate. Variation in pollen ploidy and the segregation of apomixis elements drive reproductive diversity of hybrids and outcrosses and can be utilized for apomixis initiation in crop breeding programs.
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Affiliation(s)
- Martin Mau
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
- Global Institute for Food Security, University of Saskatchewan, 110 Gymnasium Place, Saskatoon, SK, S7N5C2, Canada
| | - Tiina Liiving
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
- Global Institute for Food Security, University of Saskatchewan, 110 Gymnasium Place, Saskatoon, SK, S7N5C2, Canada
| | - Liza Fomenko
- Global Institute for Food Security, University of Saskatchewan, 110 Gymnasium Place, Saskatoon, SK, S7N5C2, Canada
| | - Richard Goertzen
- Global Institute for Food Security, University of Saskatchewan, 110 Gymnasium Place, Saskatoon, SK, S7N5C2, Canada
| | - Dorota Paczesniak
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
- Global Institute for Food Security, University of Saskatchewan, 110 Gymnasium Place, Saskatoon, SK, S7N5C2, Canada
| | - Laura Böttner
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
| | - Timothy F Sharbel
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
- Global Institute for Food Security, University of Saskatchewan, 110 Gymnasium Place, Saskatoon, SK, S7N5C2, Canada
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22
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Marinho RC, Mendes-Rodrigues C, Bonetti AM, Oliveira PE. Stomatal size, ploidy and polyembryony in Eriotheca Stellate Trichome Species Complex (Bombacoideae - Malvaceae) in the Cerrados of Brazil. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:91-99. [PMID: 32853431 DOI: 10.1111/plb.13177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 07/31/2020] [Indexed: 06/11/2023]
Abstract
Geographic parthenogenesis, range expansion of apomictic plants after climate changes, has been described for Northern Hemisphere gametophytic apomicts. But similar trends have been observed for sporophytic apomicts of Cerrado, the savannas in Brazil. Eriotheca pubescens is a common Cerrado tree, an agamic complex of either hexaploid/polyembryonic apomicts or tetraploid/monoembryonic sexual individuals. Some populations have been described as a new species, Eriotheca estevesiae, all included in the Eriotheca Stellate Trichome Species Complex (ESTSC). Since breeding systems and ploidy are clearly associated with polyembryony and stomatal size, we used these ancillary features to map the reproductive and ploidy level traits of E. pubescens and E. estevesiae. Leaves and seeds were collected from individuals of 19 populations. Seeds were evaluated for the presence of polyembryony and leaves for stomatal measurements. Eight populations were monoembryonic while another eight were polyembryonic and for other three, the embryonic pattern was not readily verified. E. pubescens polyembryonic and hexaploid populations formed a homogeneous group, but monoembryonic plants were more variable. E. estevesiae populations were monoembryonic with smaller stomata. In contrast, some E. pubescens monoembryonic populations further south presented larger stomata. Despite these outliers, possibly mixed populations, stomatal size and embryonic pattern differed from northern to southern populations. Embryonic pattern and stomatal size indicated that northernmost populations of Eriotheca STSC (E. estevesiae) are diploid and sexual. Southernmost populations, mostly polyembryonic and with large stomata, are hexaploid and apomictic. This is in agreement with geographic parthenogenesis and range expansion of apomictic lineages to southern habitats available after the last glacial maximum.
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Affiliation(s)
- R C Marinho
- Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia, Brazil
- Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Brazil
| | - C Mendes-Rodrigues
- Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Brazil
- Faculdade de Medicina, Universidade Federal de Uberlândia, Uberlândia, Brazil
| | - A M Bonetti
- Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia, Brazil
| | - P E Oliveira
- Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Brazil
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23
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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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24
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Nardi FD, Hülber K, Moser D, Alonso‐Marcos H, Tribsch A, Dobeš C. Occurrence of apomictic conspecifics and ecological preferences rather than colonization history govern the geographic distribution of sexual Potentilla puberula. Ecol Evol 2020; 10:7306-7319. [PMID: 32760530 PMCID: PMC7391561 DOI: 10.1002/ece3.6455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/20/2020] [Accepted: 05/11/2020] [Indexed: 11/24/2022] Open
Abstract
The geographic distribution of sexual-apomictic taxa (i.e., comprising individuals usually reproducing either sexually or asexually via seeds) is traditionally thought to be driven by their ecological preferences and colonization histories. Where sexuals and apomicts get into contact with each other, competitive and reproductive interactions can interfere with these factors, an aspect which hitherto received little attention in biogeographic studies. We disentangled and quantified the relative effects of the three factors on the distribution of tetraploid sexuals in Potentilla puberula in a latitudinal transect through the Eastern European Alps, in which they are codistributed with penta-, hepta-, and octoploid apomictic conspecifics. Effects were explored by means of binomial generalized linear regression models combining a single with a multiple predictor approach. Postglacial colonization history was inferred from population genetic variation (AFLPs and cpDNA) and quantified using a cost distance metric. The study was based on 235 populations, which were purely sexual, purely apomictic, or of mixed reproductive mode. The occurrence of apomicts explained most of the variation in the distribution of sexuals (31%). Specifically, the presence of sexual tetraploids was negatively related to the presence of each of the three apomictic cytotypes. Effects of ecological preferences were substantial too (7% and 12% of the total variation explained by ecological preferences alone, or jointly with apomicts' occurrence, respectively). In contrast, colonization history had negligible effects on the occurrence of sexuals. Taken together, our results highlight the potentially high impact of reproductive interactions on the geographic distribution of sexual and apomictic conspecifics and that resultant mutual exclusion interrelates to ecological differentiation, a situation potentially promoting their local coexistence.
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Affiliation(s)
- Flavia Domizia Nardi
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
- Department of BiosciencesUniversity of SalzburgSalzburgAustria
| | - Karl Hülber
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Dietmar Moser
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Henar Alonso‐Marcos
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Andreas Tribsch
- Department of BiosciencesUniversity of SalzburgSalzburgAustria
| | - Christoph Dobeš
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
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25
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Hodač L, Klatt S, Hojsgaard D, Sharbel TF, Hörandl E. A little bit of sex prevents mutation accumulation even in apomictic polyploid plants. BMC Evol Biol 2019; 19:170. [PMID: 31412772 PMCID: PMC6694583 DOI: 10.1186/s12862-019-1495-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 08/08/2019] [Indexed: 01/30/2023] Open
Abstract
Background In the absence of sex and recombination, genomes are expected to accumulate deleterious mutations via an irreversible process known as Muller’s ratchet, especially in the case of polyploidy. In contrast, no genome-wide mutation accumulation was detected in a transcriptome of facultative apomictic, hexaploid plants of the Ranunculus auricomus complex. We hypothesize that mutations cannot accumulate in flowering plants with facultative sexuality because sexual and asexual development concurrently occurs within the same generation. We assume a strong effect of purging selection on reduced gametophytes in the sexual developmental pathway because previously masked recessive deleterious mutations would be exposed to selection. Results We test this hypothesis by modeling mutation elimination using apomictic hexaploid plants of the R. auricomus complex. To estimate mean recombination rates, the mean number of recombinants per generation was calculated by genotyping three F1 progeny arrays with six microsatellite markers and character incompatibility analyses. We estimated the strength of purging selection in gametophytes by calculating abortion rates of sexual versus apomictic development at the female gametophyte, seed and offspring stage. Accordingly, we applied three selection coefficients by considering effects of purging selection against mutations on (1) male and female gametophytes in the sexual pathway (additive, s = 1.000), (2) female gametophytes only (s = 0.520), and (3) on adult plants only (sporophytes, s = 0.212). We implemented recombination rates into a mathematical model considering the three different selection coefficients, and a genomic mutation rate calculated from genome size of our plants and plant-specific mutation rates. We revealed a mean of 6.05% recombinants per generation. This recombination rate eliminates mutations after 138, 204 or 246 generations, depending on the respective selection coefficients (s = 1.000, 0.520, and 0.212). Conclusions Our results confirm that the empirically observed frequencies of facultative recombination suffice to prevent accumulation of deleterious mutations via Muller’s ratchet even in a polyploid genome. The efficiency of selection is in flowering plants strongly increased by acting on the haplontic (reduced) gametophyte stage. Electronic supplementary material The online version of this article (10.1186/s12862-019-1495-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ladislav Hodač
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Goettingen, Germany
| | - Simone Klatt
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Goettingen, Germany
| | - Diego Hojsgaard
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Goettingen, Germany
| | - Timothy F Sharbel
- Global Institute for Food Security, University of Saskatchewan, Saskatoon, Canada
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Goettingen, Germany.
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26
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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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27
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Bräuning S, Catanach A, Lord JM, Bicknell R, Macknight RC. Comparative transcriptome analysis of the wild-type model apomict Hieracium praealtum and its loss of parthenogenesis (lop) mutant. BMC PLANT BIOLOGY 2018; 18:206. [PMID: 30249189 PMCID: PMC6154955 DOI: 10.1186/s12870-018-1423-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 09/10/2018] [Indexed: 05/23/2023]
Abstract
BACKGROUND Asexual seed formation (apomixis) has been observed in diverse plant families but is rare in crop plants. The generation of apomictic crops would revolutionize agriculture, as clonal seed production provides a low cost and efficient way to produce hybrid seed. Hieracium (Asteraceae) is a model system for studying the molecular components of gametophytic apomixis (asexual seed reproduction). RESULTS In this study, a reference transcriptome was produced from apomictic Hieracium undergoing the key apomictic events of apomeiosis, parthenogenesis and autonomous endosperm development. In addition, transcriptome sequences from pre-pollination and post-pollination stages were generated from a loss of parthenogenesis (lop) mutant accession that exhibits loss of parthenogenesis and autonomous endosperm development. The transcriptome is composed of 147,632 contigs, 50% of which were annotated with orthologous genes and their probable function. The transcriptome was used to identify transcripts differentially expressed during apomictic and pollination dependent (lop) seed development. Gene Ontology enrichment analysis of differentially expressed transcripts showed that an important difference between apomictic and pollination dependent seed development was the expression of genes relating to epigenetic gene regulation. Genes that mark key developmental stages, i.e. aposporous embryo sac development and seed development, were also identified through their enhanced expression at those stages. CONCLUSION The production of a comprehensive floral reference transcriptome for Hieracium provides a valuable resource for research into the molecular basis of apomixis and the identification of the genes underlying the LOP locus.
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Affiliation(s)
- Sophia Bräuning
- Department of Biochemistry, University of Otago, 710 Cumberland St, Dunedin, 9016 New Zealand
- Department of Botany, University of Otago, 464 Great King St, Dunedin, 9016 New Zealand
| | - Andrew Catanach
- New Zealand Institute for Plant and Food Research, Gerald St, Lincoln, 7608 New Zealand
| | - Janice M. Lord
- Department of Botany, University of Otago, 464 Great King St, Dunedin, 9016 New Zealand
| | - Ross Bicknell
- New Zealand Institute for Plant and Food Research, Gerald St, Lincoln, 7608 New Zealand
| | - Richard C. Macknight
- Department of Biochemistry, University of Otago, 710 Cumberland St, Dunedin, 9016 New Zealand
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28
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Nakonechnaya OV, Kalachev AV. Pollen ultrastructure in Aristolochia manshuriensis and A. contorta (Aristolochiaceae). PROTOPLASMA 2018; 255:1309-1316. [PMID: 29511834 DOI: 10.1007/s00709-018-1230-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 02/19/2018] [Indexed: 06/08/2023]
Abstract
Pollen ultrastructure has been studied in two relict and rare species of the genus Aristolochia, A. contorta Bunge and A. manshuriensis Kom. (Aristolochiaceae). Both species have inaperturate, spheroidal, sometimes distally monocolpate or distally bicolpate pollen grains. The equatorial and polar axes of pollen grain in A. manshuriensis are 48.5 and 44.0 μm, respectively. The percentage of defective pollen grains in A. manshuriensis is 3.4%. The fossulate, perforated exine is up to 2.3 μm in thickness; the sexine and the nexine are almost equal in thickness. In A. contorta, the equatorial axis of pollen grain is 36.6 μm: the defectiveness percentage, 24.5%. The exine is verrucate, up to 0.3 μm in thickness, while the sexine is two to three times thicker than the nexine. The pollen germination experiments have shown that pollen of A. manshuriensis, in contrast to A. contorta, can germinate in 10-20% sucrose at 22°С. These data and the high percentage of pollen defectiveness in A. contorta indicate that the androecium function in this species is reduced. The reduction of the androecium function is evidenced by a small amount of pollen grains in anthers or empty anthers and a high percentage of defective pollen grains.
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Affiliation(s)
- O V Nakonechnaya
- Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences, Pr. 100 let Vladivostoku 159, Vladivostok, Russian Federation, 690022.
| | - A V Kalachev
- National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, ul. Palchevskogo 17, Vladivostok, Russian Federation, 690041
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29
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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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Zhang S, Liang M, Wang N, Xu Q, Deng X, Chai L. Reproduction in woody perennial Citrus: an update on nucellar embryony and self-incompatibility. PLANT REPRODUCTION 2018; 31:43-57. [PMID: 29457194 DOI: 10.1007/s00497-018-0327-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 02/14/2018] [Indexed: 05/22/2023]
Abstract
Review on citrus reproduction. Citrus is one of the most important and widely grown fruit crops. It possesses several special reproductive characteristics, such as nucellar embryony and self-incompatibility. The special phenomenon of nucellar embryony in citrus, also known as the polyembryony, is a kind of sporophytic apomixis. During the past decade, the emergence of novel technologies and the construction of multiple citrus reference genomes have facilitated rapid advances to our understanding of nucellar embryony. Indeed, several research teams have preliminarily determined the genetic basis of citrus apomixis. On the other hand, the phenomenon of self-incompatibility that promotes genetic diversity by rejecting self-pollen and accepting non-self-pollen is difficult to study in citrus because the long juvenile period of citrus presents challenges to identifying candidate genes that control this phenomenon. In this review, we focus on advances to our understanding of reproduction in citrus from the last decade and discuss priorities for the coming decade.
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Affiliation(s)
- Siqi Zhang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), MOA, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Mei Liang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), MOA, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Nan Wang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), MOA, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Qiang Xu
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), MOA, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), MOA, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Lijun Chai
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), MOA, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
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31
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Dobeš C, Scheffknecht S, Fenko Y, Prohaska D, Sykora C, Hülber K. Asymmetric reproductive interference: The consequences of cross-pollination on reproductive success in sexual-apomictic populations of Potentilla puberula (Rosaceae). Ecol Evol 2017; 8:365-381. [PMID: 29321878 PMCID: PMC5756837 DOI: 10.1002/ece3.3684] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 10/03/2017] [Accepted: 11/08/2017] [Indexed: 11/16/2022] Open
Abstract
Apomixis evolves from a sexual background and usually is linked to polyploidization. Pseudogamous gametophytic apomicts, which require a fertilization to initiate seed development, of various ploidy levels frequently co‐occur with their lower‐ploid sexual ancestors, but the stability of such mixed populations is affected by reproductive interferences mediated by cross‐pollination. Thereby, reproductive success of crosses depends on the difference in ploidy levels of mating partners, that is, on tolerance of deviation from the balanced ratio of maternal versus paternal genomes. Quality of pollen can further affect reproductive success in intercytotype pollinations. Cross‐fertilization, however, can be avoided by selfing which may be induced upon pollination with mixtures of self‐ and cross‐pollen (i.e., mentor effects). We tested for reproductive compatibility of naturally co‐occurring tetraploid sexuals and penta‐ to octoploid apomicts in the rosaceous species Potentilla puberula by means of controlled crosses. We estimated the role of selfing as a crossing barrier and effects of self‐ and cross‐pollen quality as well as maternal: paternal genomic ratios in the endosperm on reproductive success. Cross‐fertilization of sexuals by apomicts was not blocked by selfing, and seed set was reduced in hetero‐ compared to homoploid crosses. Thereby, seed set was negatively related to deviations from balanced parental genomic ratios in the endosperm. In contrast, seed set in the apomictic cytotypes was not reduced in hetero‐ compared to homoploid crosses. Thus, apomictic cytotypes either avoided intercytotype cross‐fertilization through selfing, tolerated intercytotype cross‐fertilizations without negative effects on reproductive success, or even benefitted from higher pollen quality in intercytotype pollinations. Our experiment provides evidence for asymmetric reproductive interference, in favor of the apomicts, with significantly reduced seed set of sexuals in cytologically mixed populations, whereas seed set in apomicts was not affected. Incompleteness of crossing barriers further indicated at least partial losses of a parental genomic endosperm balance requirement.
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Affiliation(s)
- Christoph Dobeš
- Department of Forest Genetics Austrian Research Centre for Forests Vienna Austria
| | - Susanne Scheffknecht
- Department of Pharmacognosy and Pharmacobotany University of Vienna Vienna Austria
| | - Yulia Fenko
- Department of Pharmacognosy and Pharmacobotany University of Vienna Vienna Austria
| | - Dagmar Prohaska
- Department of Pharmacognosy and Pharmacobotany University of Vienna Vienna Austria
| | - Christina Sykora
- Department of Pharmacognosy and Pharmacobotany University of Vienna Vienna Austria
| | - Karl Hülber
- Division of Conservation Biology, Vegetation Ecology and Landscape Ecology Department of Botany and Biodiversity Research University of Vienna Vienna Austria.,Vienna Institute for Nature Conservation and Analyses Vienna Austria
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De novo transcriptome sequencing and assembly from apomictic and sexual Eragrostis curvula genotypes. PLoS One 2017; 12:e0185595. [PMID: 29091722 PMCID: PMC5665505 DOI: 10.1371/journal.pone.0185595] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 09/15/2017] [Indexed: 11/19/2022] Open
Abstract
A long-standing goal in plant breeding has been the ability to confer apomixis to agriculturally relevant species, which would require a deeper comprehension of the molecular basis of apomictic regulatory mechanisms. Eragrostis curvula (Schrad.) Nees is a perennial grass that includes both sexual and apomictic cytotypes. The availability of a reference transcriptome for this species would constitute a very important tool toward the identification of genes controlling key steps of the apomictic pathway. Here, we used Roche/454 sequencing technologies to generate reads from inflorescences of E. curvula apomictic and sexual genotypes that were de novo assembled into a reference transcriptome. Near 90% of the 49568 assembled isotigs showed sequence similarity to sequences deposited in the public databases. A gene ontology analysis categorized 27448 isotigs into at least one of the three main GO categories. We identified 11475 SSRs, and several of them were assayed in E curvula germoplasm using SSR-based primers, providing a valuable set of molecular markers that could allow direct allele selection. The differential contribution to each library of the spliced forms of several transcripts revealed the existence of several isotigs produced via alternative splicing of single genes. The reference transcriptome presented and validated in this work will be useful for the identification of a wide range of gene(s) related to agronomic traits of E. curvula, including those controlling key steps of the apomictic pathway in this species, allowing the extrapolation of the findings to other plant species.
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Hamston TJ, Wilson RJ, de Vere N, Rich TCG, Stevens JR, Cresswell JE. Breeding system and spatial isolation from congeners strongly constrain seed set in an insect-pollinated apomictic tree: Sorbus subcuneata (Rosaceae). Sci Rep 2017; 7:45122. [PMID: 28338049 PMCID: PMC5364488 DOI: 10.1038/srep45122] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 02/16/2017] [Indexed: 02/07/2023] Open
Abstract
In plants, apomixis results in the production of clonal offspring via seed and can provide reproductive assurance for isolated individuals. However, many apomicts require pollination to develop functional endosperm for successful seed set (pseudogamy) and therefore risk pollination-limitation, particularly in self-incompatible species that require heterospecific pollen. We used microsatellite paternity analysis and hand pollinations to investigate pollen-limitation in Sorbus subcuneata, a threatened endemic tree that co-occurs with its congener, S. admonitor. We confirmed that S. subcuneata is an obligate pseudogamous apomict, but open-pollinated flowers rarely produced seed (flower-to-seed conversion < 1%) even though they rapidly accumulated pollen on their stigmas. Manual heterospecific pollination by S. admonitor resulted in a high flower-to-seed conversion rate (65%), however, we estimate that the ratio of self: heterospecific pollination in open-pollinated flowers was at least 22:1. Despite the efficacy of heterospecific pollination, the contribution of S. admonitor trees to paternity in seed from open-pollinated flowers of S. subcuneata decreased rapidly with the spatial separation between paternal and maternal trees. Conservation efforts aimed at maintaining species with this breeding system must therefore manage the congeners in tandem which will also maintain the potential for rare heterospecific fertilisation that typically cause rapid diversification in these lineages.
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Affiliation(s)
- Tracey J Hamston
- Biosciences, University of Exeter, Exeter, Devon, UK.,Whitley Wildlife Conservation Trust, Paignton Zoo, Paignton, UK
| | | | - Natasha de Vere
- National Botanic Garden of Wales, Llanarthne, UK.,Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, UK
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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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Mirzaghaderi G, Hörandl E. The evolution of meiotic sex and its alternatives. Proc Biol Sci 2016; 283:20161221. [PMID: 27605505 PMCID: PMC5031655 DOI: 10.1098/rspb.2016.1221] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/16/2016] [Indexed: 12/23/2022] Open
Abstract
Meiosis is an ancestral, highly conserved process in eukaryotic life cycles, and for all eukaryotes the shared component of sexual reproduction. The benefits and functions of meiosis, however, are still under discussion, especially considering the costs of meiotic sex. To get a novel view on this old problem, we filter out the most conserved elements of meiosis itself by reviewing the various modifications and alterations of modes of reproduction. Our rationale is that the indispensable steps of meiosis for viability of offspring would be maintained by strong selection, while dispensable steps would be variable. We review evolutionary origin and processes in normal meiosis, restitutional meiosis, polyploidization and the alterations of meiosis in forms of uniparental reproduction (apomixis, apomictic parthenogenesis, automixis, selfing) with a focus on plants and animals. This overview suggests that homologue pairing, double-strand break formation and homologous recombinational repair at prophase I are the least dispensable elements, and they are more likely optimized for repair of oxidative DNA damage rather than for recombination. Segregation, ploidy reduction and also a biparental genome contribution can be skipped for many generations. The evidence supports the theory that the primary function of meiosis is DNA restoration rather than recombination.
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Affiliation(s)
- Ghader Mirzaghaderi
- Department of Agronomy and Plant Breeding, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants, Georg-August-University of Göttingen, Göttingen, Germany
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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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Płachno BJ, Świątek P, Kozieradzka-Kiszkurno M, Majeský Ľ, Marciniuk J, Stolarczyk P. Are obligatory apomicts invested in the pollen tube transmitting tissue? Comparison of the micropyle ultrastructure between sexual and apomictic dandelions (Asteraceae, Lactuceae). PROTOPLASMA 2015; 252:1325-33. [PMID: 25652809 PMCID: PMC4561075 DOI: 10.1007/s00709-015-0765-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/20/2015] [Indexed: 05/07/2023]
Abstract
With the exception of the sunflower, little information concerning the micropyle ultrastructure of the family Asteraceae is available. The aim of our study was to compare the micropyle structure in amphimictic and apomictic dandelions. Ultrastructural studies using buds and flowers during anthesis have been done on the micropyle of the sexual and apomictic Taraxacum. In all of the species that were examined, the micropylar canal was completely filled with ovule transmitting tissue and the matrix that was produced by these cells. The ovule transmitting tissue was connected to the ovarian transmitting tissue. The micropyle was asymmetrical because the integument epidermis that forms the transmitting tissue was only on the funicular side. There was a cuticle between the obturator cells and epidermal cells on the other side of integument. The micropylar transmitting tissue cells and theirs matrix reached the synergid apex. The cytoplasm of the transmitting tissue cells was especially rich in rough endoplasmic reticulum (ER), dictyosomes, and mitochondria. No major differences were detected between the micropyle structure of the amphimictic and apomictic species; thus, a structural reduction of obturator does not exist. The ovule transmitting tissue is still active in apomictic dandelions despite the presence of the embryo and endosperm. Differences and similarities between the micropyle structure in the Asteraceae that have been studied to date are discussed.
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Affiliation(s)
- Bartosz J Płachno
- Department of Plant Cytology and Embryology, Jagiellonian University in Kraków, Kraków, 9 Gronostajowa St., 30-387, Kraków, Poland,
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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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40
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Grossenbacher D, Briscoe Runquist R, Goldberg EE, Brandvain Y. Geographic range size is predicted by plant mating system. Ecol Lett 2015; 18:706-13. [PMID: 25980327 DOI: 10.1111/ele.12449] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 02/13/2015] [Accepted: 04/09/2015] [Indexed: 11/30/2022]
Abstract
Species' geographic ranges vary enormously, and even closest relatives may differ in range size by several orders of magnitude. With data from hundreds of species spanning 20 genera in 15 families, we show that plant species that autonomously reproduce via self-pollination consistently have larger geographic ranges than their close relatives that generally require two parents for reproduction. Further analyses strongly implicate autonomous self-fertilisation in causing this relationship, as it is not driven by traits such as polyploidy or annual life history whose evolution is sometimes correlated with selfing. Furthermore, we find that selfers occur at higher maximum latitudes and that disparity in range size between selfers and outcrossers increases with time since their evolutionary divergence. Together, these results show that autonomous reproduction--a critical biological trait that eliminates mate limitation and thus potentially increases the probability of establishment--increases range size.
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Affiliation(s)
- Dena Grossenbacher
- Department of Plant Biology, University of Minnesota, St. Paul, MN, 55108, USA
| | | | - Emma E Goldberg
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, 55108, USA
| | - Yaniv Brandvain
- Department of Plant Biology, University of Minnesota, St. Paul, MN, 55108, USA
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41
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Ahrens CW, James EA. Range-wide genetic analysis reveals limited structure and suggests asexual patterns in the rare forbSenecio macrocarpus. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12512] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Collin W. Ahrens
- Royal Botanic Gardens Melbourne; Birdwood Ave South Yarra Vic. 3141 Australia
| | - Elizabeth A. James
- Royal Botanic Gardens Melbourne; Birdwood Ave South Yarra Vic. 3141 Australia
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42
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Yin D, Zhu X, Jiang L, Zhang J, Zeng Y, Wu R. A reciprocal cross design to map the genetic architecture of complex traits in apomictic plants. THE NEW PHYTOLOGIST 2015; 205:1360-1367. [PMID: 25354995 DOI: 10.1111/nph.13128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/11/2014] [Indexed: 06/04/2023]
Abstract
Many higher plants of economic and biological importance undergo apomixis in which the maternal tissue of the ovule forms a seed, without experiencing meiosis and fertilization. This feature of apomixis has made it difficult to perform linkage mapping which relies on meiotic recombination. Here, we describe a computational model for mapping quantitative trait loci (QTLs) that control complex traits in apomictic plants. The model is founded on the mixture model-based likelihood in which maternal genotypes are dissolved into two possible components generated by meiotic and apomictic processes, respectively. The EM algorithm was implemented to discern meiotic and apomictic genotypes and, therefore, allow the marker-QTL linkage relationship to be estimated. By capitalizing on reciprocal crosses, the model is renovated to estimate and test imprinting effects of QTLs, providing a better gateway to characterize the genetic architecture of complex traits. The model was validated through computer simulation and further demonstrated for its usefulness by analyzing a real data for an apomictic woody plant. The model has for the first time provided a unique tool for genetic mapping in apomictic plants.
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Affiliation(s)
- Danni Yin
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Xuli Zhu
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Libo Jiang
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Jian Zhang
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
- Yuanpeng Genome Institute of Jiangsu, Nantong, Jiangsu, 226531, China
| | - Yanru Zeng
- The Nurturing Station for the State Key Laboratory of Subtropical Silviculture, Zhejiang Agricultural and Forestry University, Lin'an, Zhejiang, 311300, China
| | - Rongling Wu
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
- Center for Statistical Genetics, The Pennsylvania State University, Hershey, PA, 17033, USA
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43
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Hojsgaard D, Hörandl E. A little bit of sex matters for genome evolution in asexual plants. FRONTIERS IN PLANT SCIENCE 2015; 6:82. [PMID: 25750646 PMCID: PMC4335465 DOI: 10.3389/fpls.2015.00082] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 02/01/2015] [Indexed: 05/10/2023]
Abstract
Genome evolution in asexual organisms is theoretically expected to be shaped by various factors: first, hybrid origin, and polyploidy confer a genomic constitution of highly heterozygous genotypes with multiple copies of genes; second, asexuality confers a lack of recombination and variation in populations, which reduces the efficiency of selection against deleterious mutations; hence, the accumulation of mutations and a gradual increase in mutational load (Muller's ratchet) would lead to rapid extinction of asexual lineages; third, allelic sequence divergence is expected to result in rapid divergence of lineages (Meselson effect). Recent transcriptome studies on the asexual polyploid complex Ranunculus auricomus using single-nucleotide polymorphisms confirmed neutral allelic sequence divergence within a short time frame, but rejected a hypothesis of a genome-wide accumulation of mutations in asexuals compared to sexuals, except for a few genes related to reproductive development. We discuss a general model that the observed incidence of facultative sexuality in plants may unmask deleterious mutations with partial dominance and expose them efficiently to purging selection. A little bit of sex may help to avoid genomic decay and extinction.
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Affiliation(s)
- Diego Hojsgaard
- *Correspondence: Diego Hojsgaard and Elvira Hörandl, Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, Georg-August University of Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany e-mail: ;
| | - Elvira Hörandl
- *Correspondence: Diego Hojsgaard and Elvira Hörandl, Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, Georg-August University of Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany e-mail: ;
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44
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Płachno BJ, Musiał K, Swiątek P, Tuleja M, Marciniuk J, Grabowska-Joachimiak A. Synergids and filiform apparatus in the sexual and apomictic dandelions from section Palustria (Taraxacum, Asteraceae). PROTOPLASMA 2014; 251:211-7. [PMID: 23974526 PMCID: PMC3893458 DOI: 10.1007/s00709-013-0539-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 08/08/2013] [Indexed: 05/07/2023]
Abstract
An evolutionary trend to reduce "unnecessary costs" associated with the sexual reproduction of their amphimictic ancestors, which may result in greater reproductive success, has been observed among the obligatory apomicts. However, in the case of the female gametophyte, knowledge about this trend in apomicts is not sufficient because most of the ultrastructural studies of the female gametophyte have dealt with amphimictic angiosperms. In this paper, we tested the hypothesis that, in contrast to amphimictic plants, synergids in apomictic embryo sacs do not form a filiform apparatus. We compared the synergid structure in two dandelions from sect. Palustria: the amphimictic diploid Taraxacum tenuifolium and the apomictic tetraploid, male-sterile Taraxacum brandenburgicum. Synergids in both species possessed a filiform apparatus. In T. brandenburgicum, both synergids persisted for a long time without any degeneration, in spite of the presence of an embryo and endosperm. We propose that the persistent synergids in apomicts may play a role in the transport of nutrients to the embryo.
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Affiliation(s)
- Bartosz J Płachno
- Department of Plant Cytology and Embryology, Jagiellonian University, 9 Gronostajowa St., 30-387, Cracow, Poland,
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45
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Hörandl E, Hadacek F. The oxidative damage initiation hypothesis for meiosis. PLANT REPRODUCTION 2013; 26:351-367. [PMID: 23995700 DOI: 10.1007/s00497-013-0234-237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 08/17/2013] [Indexed: 05/20/2023]
Abstract
The maintenance of sexual reproduction in eukaryotes is still a major enigma in evolutionary biology. Meiosis represents the only common feature of sex in all eukaryotic kingdoms, and thus, we regard it a key issue for discussing its function. Almost all asexuality modes maintain meiosis either in a modified form or as an alternative pathway, and facultatively apomictic plants increase frequencies of sexuality relative to apomixis after abiotic stress. On the physiological level, abiotic stress causes oxidative stress. We hypothesize that repair of oxidative damage on nuclear DNA could be a major driving force in the evolution of meiosis. We present a hypothetical model for the possible redox chemistry that underlies the binding of the meiosis-specific protein Spo11 to DNA. During prophase of meiosis I, oxidized sites at the DNA molecule are being targeted by the catalytic tyrosine moieties of Spo11 protein, which acts like an antioxidant reducing the oxidized target. The oxidized tyrosine residues, tyrosyl radicals, attack the phosphodiester bonds of the DNA backbone causing DNA double strand breaks that can be repaired by various mechanisms. Polyploidy in apomictic plants could mitigate oxidative DNA damage and decrease Spo11 activation. Our hypothesis may contribute to explaining various enigmatic phenomena: first, DSB formation outnumbers crossovers and, thus, effective recombination events by far because the target of meiosis may be the removal of oxidative lesions; second, it offers an argument for why expression of sexuality is responsive to stress in many eukaryotes; and third, repair of oxidative DNA damage turns meiosis into an essential characteristic of eukaryotic reproduction.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic Botany, Albrecht-Haller-Institute for Plant Sciences, Georg-August-University of Göttingen, Untere Karspüle 2, 37073, Göttingen, Germany,
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46
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Hörandl E, Hadacek F. The oxidative damage initiation hypothesis for meiosis. PLANT REPRODUCTION 2013; 26:351-367. [PMID: 23995700 DOI: 10.1007s0049701302347/s00497-013-0234-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 08/17/2013] [Indexed: 05/27/2023]
Abstract
The maintenance of sexual reproduction in eukaryotes is still a major enigma in evolutionary biology. Meiosis represents the only common feature of sex in all eukaryotic kingdoms, and thus, we regard it a key issue for discussing its function. Almost all asexuality modes maintain meiosis either in a modified form or as an alternative pathway, and facultatively apomictic plants increase frequencies of sexuality relative to apomixis after abiotic stress. On the physiological level, abiotic stress causes oxidative stress. We hypothesize that repair of oxidative damage on nuclear DNA could be a major driving force in the evolution of meiosis. We present a hypothetical model for the possible redox chemistry that underlies the binding of the meiosis-specific protein Spo11 to DNA. During prophase of meiosis I, oxidized sites at the DNA molecule are being targeted by the catalytic tyrosine moieties of Spo11 protein, which acts like an antioxidant reducing the oxidized target. The oxidized tyrosine residues, tyrosyl radicals, attack the phosphodiester bonds of the DNA backbone causing DNA double strand breaks that can be repaired by various mechanisms. Polyploidy in apomictic plants could mitigate oxidative DNA damage and decrease Spo11 activation. Our hypothesis may contribute to explaining various enigmatic phenomena: first, DSB formation outnumbers crossovers and, thus, effective recombination events by far because the target of meiosis may be the removal of oxidative lesions; second, it offers an argument for why expression of sexuality is responsive to stress in many eukaryotes; and third, repair of oxidative DNA damage turns meiosis into an essential characteristic of eukaryotic reproduction.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic Botany, Albrecht-Haller-Institute for Plant Sciences, Georg-August-University of Göttingen, Untere Karspüle 2, 37073, Göttingen, Germany,
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47
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Hörandl E, Hadacek F. The oxidative damage initiation hypothesis for meiosis. PLANT REPRODUCTION 2013; 26:351-67. [PMID: 23995700 PMCID: PMC3825497 DOI: 10.1007/s00497-013-0234-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 08/17/2013] [Indexed: 05/21/2023]
Abstract
The maintenance of sexual reproduction in eukaryotes is still a major enigma in evolutionary biology. Meiosis represents the only common feature of sex in all eukaryotic kingdoms, and thus, we regard it a key issue for discussing its function. Almost all asexuality modes maintain meiosis either in a modified form or as an alternative pathway, and facultatively apomictic plants increase frequencies of sexuality relative to apomixis after abiotic stress. On the physiological level, abiotic stress causes oxidative stress. We hypothesize that repair of oxidative damage on nuclear DNA could be a major driving force in the evolution of meiosis. We present a hypothetical model for the possible redox chemistry that underlies the binding of the meiosis-specific protein Spo11 to DNA. During prophase of meiosis I, oxidized sites at the DNA molecule are being targeted by the catalytic tyrosine moieties of Spo11 protein, which acts like an antioxidant reducing the oxidized target. The oxidized tyrosine residues, tyrosyl radicals, attack the phosphodiester bonds of the DNA backbone causing DNA double strand breaks that can be repaired by various mechanisms. Polyploidy in apomictic plants could mitigate oxidative DNA damage and decrease Spo11 activation. Our hypothesis may contribute to explaining various enigmatic phenomena: first, DSB formation outnumbers crossovers and, thus, effective recombination events by far because the target of meiosis may be the removal of oxidative lesions; second, it offers an argument for why expression of sexuality is responsive to stress in many eukaryotes; and third, repair of oxidative DNA damage turns meiosis into an essential characteristic of eukaryotic reproduction.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematic Botany, Albrecht-Haller-Institute for Plant Sciences, Georg-August-University of Göttingen, Untere Karspüle 2, 37073, Göttingen, Germany,
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48
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Dobeš C, Milosevic A, Prohaska D, Scheffknecht S, Sharbel TF, Hülber K. Reproductive differentiation into sexual and apomictic polyploid cytotypes in Potentilla puberula (Potentilleae, Rosaceae). ANNALS OF BOTANY 2013; 112:1159-68. [PMID: 23960045 PMCID: PMC3783232 DOI: 10.1093/aob/mct167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 06/06/2013] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS Intraspecific reproductive differentiation into sexual and apomictic cytotypes of differing ploidy is a common phenomenon. However, mechanisms enabling the maintenance of both reproductive modes and integrity of cytotypes in sympatry are as yet poorly understood. This study examined the association of sexual and apomictic seed formation with ploidy as well as gene flow towards sexuals within populations of purely polyploid Potentilla puberula. METHODS The study is based on 22 populations representing various combinations of five polyploid cytotypes (tetraploid-octoploid) from East Tyrol, Austria. Embryo ploidy and the endosperm/embryo ploidy ratio obtained by a flow cytometric seed screen were used to infer reproductive modes of seed formation and to calculate the male and female genomic contributions to the embryo and endosperm. Self-incompatibility (SI) patterns were assessed and a new indirect approach was used to test for the occurrence of intercytotype matings based on the variation in the male genomic contribution to sexually derived embryos on the level of developed seed. KEY RESULTS Tetraploids formed seeds almost exclusively via sexual reproduction, whereas penta- to octoploids were preferentially apomictic. Non-random distribution of reproductive modes within maternal plants further revealed a tendency to separate the sexual from the apomictic mode among individuals. Self-incompatibility of sexuals indicated functionality of the gametophytic SI system despite tetraploidy of the nuclear genome. We found no indication for significant cross-fertilization of tetraploids by the high polyploids. CONCLUSIONS The study revealed a rare example of intraspecific differentiation into sexual and apomictic cytotypes at the polyploid level. The integrity of the sexual tetraploids was maintained due to reproductive isolation from the apomictic higher polyploids. Functionality of the gametophytic SI system suggested that the tetraploids are functional diploids.
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Key Words
- Apomixis, endosperm, European Alps, FCSS, flow cytometry, pollen, polyploidy, Potentilla puberula, reproductive isolation, Rosaceae, sexual reproduction
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Affiliation(s)
- Ch. Dobeš
- Department of Pharmacognosy, Pharmacobotany, University of Vienna,
Althanstrasse 14, 1090 Vienna, Austria
| | - A. Milosevic
- Department of Pharmacognosy, Pharmacobotany, University of Vienna,
Althanstrasse 14, 1090 Vienna, Austria
| | - D. Prohaska
- Department of Pharmacognosy, Pharmacobotany, University of Vienna,
Althanstrasse 14, 1090 Vienna, Austria
| | - S. Scheffknecht
- Department of Pharmacognosy, Pharmacobotany, University of Vienna,
Althanstrasse 14, 1090 Vienna, Austria
| | - T. F. Sharbel
- Apomixis Research Group, Leibniz-Institute for plant genetics and crop
research (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany
| | - K. Hülber
- Department of Conservation Biology, Vegetation Ecology and Landscape
Ecology, University of Vienna, Rennweg 14, 1030 Vienna, Austria
- Vienna Institute for Nature Conservation & Analyses, Giessergasse
6/7, 1090 Vienna, Austria
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49
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Sampaio DS, Bittencourt NS, Oliveira PE. Mating in the pseudogamic apomictic Anemopaegma acutifolium DC: another case of pseudo-self-compatibility in Bignoniaceae? PLANT BIOLOGY (STUTTGART, GERMANY) 2013; 15:919-924. [PMID: 23126331 DOI: 10.1111/j.1438-8677.2012.00692.x] [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: 06/25/2012] [Accepted: 09/11/2012] [Indexed: 06/01/2023]
Abstract
Self-compatibility in apomictic pseudogamic species is considered fundamental to assure reproduction by seeds in extreme situations, making apomictic species more advantageous than sexual ones in these scenarios. Anemopaegma acutifolium is a polyploidy, apomictic sporophytic species with no endosperm development in ovules of unpollinated pistils, which indicates obligate pseudogamy. Thus, the aim of the present work is to study the breeding system and post-pollination events to test if there is similar pseudogamous development irrespective of pollination treatment. We analysed fruit and seed set obtained in controlled experimental pollinations, as well as embryo number per seed, and the progress of ovule penetration, fertilisation and early endosperm development between self- and cross-pollinated pistils. We found that the species is self-fertile and that spontaneous selfing fruit set is also possible, although emasculated flowers never form fruits. Selfed pistils were as efficient as crossed ones for all parameters analysed, except for a delay in endosperm development observed in the former that may be an effect of the late-acting self-incompatibility. Therefore, the avoidance of selfed pistil abortion seems to be promoted by the presence of adventitious embryos and a normal endosperm. We conclude that A. acutifolium shows apomixis-related pseudo-self-compatibility, as in other self-fertile apomictic species of Bignoniaceae, which confer reproductive assurance and increases fruit-set and persistence ability in fast-changing tropical habitats.
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Affiliation(s)
- D S Sampaio
- Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil
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50
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Musiał K, Płachno BJ, Świątek P, Marciniuk J. Anatomy of ovary and ovule in dandelions (Taraxacum, Asteraceae). PROTOPLASMA 2013; 250:715-22. [PMID: 23001751 PMCID: PMC3659273 DOI: 10.1007/s00709-012-0455-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 09/11/2012] [Indexed: 05/10/2023]
Abstract
The genus Taraxacum Wigg. (Asteraceae) forms a polyploid complex within which there are strong links between the ploidy level and the mode of reproduction. Diploids are obligate sexual, whereas polyploids are usually apomictic. The paper reports on a comparative study of the ovary and especially the ovule anatomy in the diploid dandelion T. linearisquameum and the triploid T. gentile. Observations with light and electron microscopy revealed no essential differences in the anatomy of both the ovary and ovule in the examined species. Dandelion ovules are anatropous, unitegmic and tenuinucellate. In both sexual and apomictic species, a zonal differentiation of the integument is characteristic of the ovule. In the integumentary layers situated next to the endothelium, the cell walls are extremely thick and PAS positive. Data obtained from TEM indicate that these special walls have an open spongy structure and their cytoplasm shows evidence of gradual degeneration. Increased deposition of wall material in the integumentary cells surrounding the endothelium takes place especially around the chalazal pole of the embryo sac as well as around the central cell. In contrast, the integumentary cells surrounding the micropylar region have thin walls and exhibit a high metabolic activity. The role of the thick-walled integumentary layers in the dandelion ovule is discussed. We also consider whether this may be a feature of taxonomic importance.
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Affiliation(s)
- K Musiał
- Department of Plant Cytology and Embryology, Jagiellonian University, Grodzka 52, 31-044, Krakow, Poland.
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