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Rojek J, Ohad N. The phenomenon of autonomous endosperm in sexual and apomictic plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4324-4348. [PMID: 37155961 PMCID: PMC10433939 DOI: 10.1093/jxb/erad168] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 05/04/2023] [Indexed: 05/10/2023]
Abstract
Endosperm is a key nutritive tissue that supports the developing embryo or seedling, and serves as a major nutritional source for human and livestock feed. In sexually-reproducing flowering plants, it generally develops after fertilization. However, autonomous endosperm (AE) formation (i.e. independent of fertilization) is also possible. Recent findings of AE loci/ genes and aberrant imprinting in native apomicts, together with a successful initiation of parthenogenesis in rice and lettuce, have enhanced our understanding of the mechanisms bridging sexual and apomictic seed formation. However, the mechanisms driving AE development are not well understood. This review presents novel aspects related to AE development in sexual and asexual plants underlying stress conditions as the primary trigger for AE. Both application of hormones to unfertilized ovules and mutations that impair epigenetic regulation lead to AE development in sexual Arabidopsis thaliana, which may point to a common pathway for both phenomena. Apomictic-like AE development under experimental conditions can take place due to auxin-dependent gene expression and/or DNA methylation.
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Affiliation(s)
- Joanna Rojek
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Nir Ohad
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
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Spotting the Targets of the Apospory Controller TGS1 in Paspalum notatum. PLANTS 2022; 11:plants11151929. [PMID: 35893633 PMCID: PMC9332697 DOI: 10.3390/plants11151929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/27/2022] [Accepted: 06/30/2022] [Indexed: 11/17/2022]
Abstract
Sexuality and apomixis are interconnected plant reproductive routes possibly behaving as polyphenic traits under the influence of the environment. In the subtropical grass Paspalum notatum, one of the controllers of apospory, a main component of gametophytic apomixis reproduction, is TRIMETHYLGUANOSINE SYNTHASE 1 (TGS1), a multifunctional gene previously associated with RNA cleavage regulation (including mRNA splicing as well as rRNA and miRNA processing), transcriptional modulation and the establishment of heterochromatin. In particular, the downregulation of TGS1 induces a sexuality decline and the emergence of aposporous-like embryo sacs. The present work was aimed at identifying TGS1 target RNAs expressed during reproductive development of Paspalum notatum. First, we mined available RNA databases originated from spikelets of sexual and apomictic plants, which naturally display a contrasting TGS1 representation, to identify differentially expressed mRNA splice variants and miRNAs. Then, the role of TGS1 in the generation of these particular molecules was investigated in antisense tgs1 sexual lines. We found that CHLOROPHYLL A-B BINDING PROTEIN 1B-21 (LHC Ib-21, a component of the chloroplast light harvesting complex), QUI-GON JINN (QGJ, encoding a MAP3K previously associated with apomixis) and miR2275 (a meiotic 24-nt phasi-RNAs producer) are directly or indirectly targeted by TGS1. Our results point to a coordinated control exercised by signal transduction and siRNA machineries to induce the transition from sexuality to apomixis.
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Xu Y, Jia H, Tan C, Wu X, Deng X, Xu Q. Apomixis: genetic basis and controlling genes. HORTICULTURE RESEARCH 2022; 9:uhac150. [PMID: 36072837 PMCID: PMC9437720 DOI: 10.1093/hr/uhac150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/27/2022] [Indexed: 05/12/2023]
Abstract
Apomixis is the phenomenon of clonal reproduction by seed. As apomixis can produce clonal progeny with exactly the same genotype as the maternal plant, it has an important application in genotype fixation and accelerating agricultural breeding strategies. The introduction of apomixis to major crops would bring many benefits to agriculture, including permanent fixation of superior genotypes and simplifying the procedures of hybrid seed production, as well as purification and rejuvenation of crops propagated vegetatively. Although apomixis naturally occurs in more than 400 plant species, it is rare among the major crops. Currently, with better understanding of apomixis, some achievements have been made in synthetic apomixis. However, due to prevailing limitations, there is still a long way to go to achieve large-scale application of apomixis to crop breeding. Here, we compare the developmental features of apomixis and sexual plant reproduction and review the recent identification of apomixis genes, transposons, epigenetic regulation, and genetic events leading to apomixis. We also summarize the possible strategies and potential genes for engineering apomixis into crop plants.
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Affiliation(s)
- Yuantao Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Huihui Jia
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Chunming Tan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Xiaomeng Wu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
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Epigenetic Modifications in Plant Development and Reproduction. EPIGENOMES 2021; 5:epigenomes5040025. [PMID: 34968249 PMCID: PMC8715465 DOI: 10.3390/epigenomes5040025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/14/2021] [Accepted: 11/16/2021] [Indexed: 01/27/2023] Open
Abstract
Plants are exposed to highly fluctuating effects of light, temperature, weather conditions, and many other environmental factors throughout their life. As sessile organisms, unlike animals, they are unable to escape, hide, or even change their position. Therefore, the growth and development of plants are largely determined by interaction with the external environment. The success of this interaction depends on the ability of the phenotype plasticity, which is largely determined by epigenetic regulation. In addition to how environmental factors can change the patterns of genes expression, epigenetic regulation determines how genetic expression changes during the differentiation of one cell type into another and how patterns of gene expression are passed from one cell to its descendants. Thus, one genome can generate many ‘epigenomes’. Epigenetic modifications acquire special significance during the formation of gametes and plant reproduction when epigenetic marks are eliminated during meiosis and early embryogenesis and later reappear. However, during asexual plant reproduction, when meiosis is absent or suspended, epigenetic modifications that have arisen in the parental sporophyte can be transmitted to the next clonal generation practically unchanged. In plants that reproduce sexually and asexually, epigenetic variability has different adaptive significance. In asexuals, epigenetic regulation is of particular importance for imparting plasticity to the phenotype when, apart from mutations, the genotype remains unchanged for many generations of individuals. Of particular interest is the question of the possibility of transferring acquired epigenetic memory to future generations and its potential role for natural selection and evolution. All these issues will be discussed to some extent in this review.
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Carballo J, Zappacosta D, Selva JP, Caccamo M, Echenique V. Eragrostis curvula, a Model Species for Diplosporous Apomixis. PLANTS (BASEL, SWITZERLAND) 2021; 10:1818. [PMID: 34579351 PMCID: PMC8472828 DOI: 10.3390/plants10091818] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/16/2021] [Accepted: 08/26/2021] [Indexed: 11/16/2022]
Abstract
Eragrostis curvula (Schrad.) Ness is a grass with a particular apomictic embryo sac development called Eragrostis type. Apomixis is a type of asexual reproduction that produces seeds without fertilization in which the resulting progeny is genetically identical to the mother plant and with the potential to fix the hybrid vigour from more than one generation, among other advantages. The absence of meiosis and the occurrence of only two rounds of mitosis instead of three during embryo sac development make this model unique and suitable to be transferred to economically important crops. Throughout this review, we highlight the advances in the knowledge of apomixis in E. curvula using different techniques such as cytoembryology, DNA methylation analyses, small-RNA-seq, RNA-seq, genome assembly, and genotyping by sequencing. The main bulk of evidence points out that apomixis is inherited as a single Mendelian factor, and it is regulated by genetic and epigenetic mechanisms controlled by a complex network. With all this information, we propose a model of the mechanisms involved in diplosporous apomixis in this grass. All the genetic and epigenetic resources generated in E. curvula to study the reproductive mode changed its status from an orphan to a well-characterised species.
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Affiliation(s)
- Jose Carballo
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
| | - Diego Zappacosta
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, Bahía Blanca 8000, Argentina
| | - Juan Pablo Selva
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), San Juan 670, Bahía Blanca 8000, Argentina
| | - Mario Caccamo
- NIAB, 93 Lawrence Weaver Road, Cambridge CB3 0LE, UK;
| | - Viviana Echenique
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, Bahía Blanca 8000, Argentina
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A Review of Unreduced Gametes and Neopolyploids in Alfalfa: How to Fill the Gap between Well-Established Meiotic Mutants and Next-Generation Genomic Resources. PLANTS 2021; 10:plants10050999. [PMID: 34067689 PMCID: PMC8156078 DOI: 10.3390/plants10050999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/03/2021] [Accepted: 05/12/2021] [Indexed: 01/11/2023]
Abstract
The gene flow mediated by unreduced gametes between diploid and tetraploid plants of the Medicagosativa-coerulea-falcata complex is pivotal for alfalfa breeding. Sexually tetraploidized hybrids could represent the best way to exploit progressive heterosis simultaneously derived from gene diversity, heterozygosity, and polyploidy. Moreover, unreduced gametes combined with parthenogenesis (i.e., apomixis) would enable the cloning of plants through seeds, providing a unique opportunity for the selection of superior genotypes with permanently fixed heterosis. This reproductive strategy has never been detected in the genus Medicago, but features of apomixis, such as restitutional apomeiosis and haploid parthenogenesis, have been reported. By means of an original case study, we demonstrated that sexually tetraploidized plants maintain apomeiosis, but this trait is developmentally independent from parthenogenesis. Alfalfa meiotic mutants producing unreduced egg cells revealed a null or very low capacity for parthenogenesis. The overall achievements reached so far are reviewed and discussed along with the efforts and strategies made for exploiting reproductive mutants that express apomictic elements in alfalfa breeding programs. Although several studies have investigated the cytological mechanisms responsible for 2n gamete formation and the inheritance of this trait, only a very small number of molecular markers and candidate genes putatively linked to unreduced gamete formation have been identified. Furthermore, this scenario has remained almost unchanged over the last two decades. Here, we propose a reverse genetics approach, by exploiting the genomic and transcriptomic resources available in alfalfa. Through a comparison with 9 proteins belonging to Arabidopsis thaliana known for their involvement in 2n gamete production, we identified 47 orthologous genes and evaluated their expression in several tissues, paving the way for novel candidate gene characterization studies. An overall view on strategies suitable to fill the gap between well-established meiotic mutants and next-generation genomic resources is presented and discussed.
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Carballo J, Zappacosta D, Marconi G, Gallardo J, Di Marsico M, Gallo CA, Caccamo M, Albertini E, Echenique V. Differential Methylation Patterns in Apomictic vs. Sexual Genotypes of the Diplosporous Grass Eragrostis curvula. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10050946. [PMID: 34068493 PMCID: PMC8150776 DOI: 10.3390/plants10050946] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 05/05/2023]
Abstract
DNA methylation is an epigenetic mechanism by which a methyl group is added to a cytosine or an adenine. When located in a gene/regulatory sequence it may repress or de-repress genes, depending on the context and species. Eragrostis curvula is an apomictic grass in which facultative genotypes increases the frequency of sexual pistils triggered by epigenetic mechanisms. The aim of the present study was to look for correlations between the reproductive mode and specific methylated genes or genomic regions. To do so, plants with contrasting reproductive modes were investigated through MCSeEd (Methylation Context Sensitive Enzyme ddRad) showing higher levels of DNA methylation in apomictic genotypes. Moreover, an increased proportion of differentially methylated positions over the regulatory regions were observed, suggesting its possible role in regulation of gene expression. Interestingly, the methylation pathway was also found to be self-regulated since two of the main genes (ROS1 and ROS4), involved in de-methylation, were found differentially methylated between genotypes with different reproductive behavior. Moreover, this work allowed us to detect several genes regulated by methylation that were previously found as differentially expressed in the comparisons between apomictic and sexual genotypes, linking DNA methylation to differences in reproductive mode.
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Affiliation(s)
- Jose Carballo
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, 8000 Bahía Blanca, Argentina; (J.C.); (D.Z.); (J.G.); (C.A.G.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, 8000 Bahía Blanca, Argentina
| | - Diego Zappacosta
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, 8000 Bahía Blanca, Argentina; (J.C.); (D.Z.); (J.G.); (C.A.G.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, 8000 Bahía Blanca, Argentina
| | - Gianpiero Marconi
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Jimena Gallardo
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, 8000 Bahía Blanca, Argentina; (J.C.); (D.Z.); (J.G.); (C.A.G.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, 8000 Bahía Blanca, Argentina
| | - Marco Di Marsico
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Cristian A. Gallo
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, 8000 Bahía Blanca, Argentina; (J.C.); (D.Z.); (J.G.); (C.A.G.)
| | - Mario Caccamo
- NIAB, 93 Lawrence Weaver Road, Cambridge CB3 0LE, UK;
| | - Emidio Albertini
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
- Correspondence: (E.A.); (V.E.); Tel.: +39-075-585-6206 (E.A.); +54-291-486-1124 (V.E.)
| | - Viviana Echenique
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, 8000 Bahía Blanca, Argentina; (J.C.); (D.Z.); (J.G.); (C.A.G.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, 8000 Bahía Blanca, Argentina
- Correspondence: (E.A.); (V.E.); Tel.: +39-075-585-6206 (E.A.); +54-291-486-1124 (V.E.)
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Ke Y, Podio M, Conner J, Ozias-Akins P. Single-cell transcriptome profiling of buffelgrass (Cenchrus ciliaris) eggs unveils apomictic parthenogenesis signatures. Sci Rep 2021; 11:9880. [PMID: 33972603 PMCID: PMC8110759 DOI: 10.1038/s41598-021-89170-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/15/2021] [Indexed: 12/04/2022] Open
Abstract
Apomixis, a type of asexual reproduction in angiosperms, results in progenies that are genetically identical to the mother plant. It is a highly desirable trait in agriculture due to its potential to preserve heterosis of F1 hybrids through subsequent generations. However, no major crops are apomictic. Deciphering mechanisms underlying apomixis becomes one of the alternatives to engineer self-reproducing capability into major crops. Parthenogenesis, a major component of apomixis, commonly described as the ability to initiate embryo formation from the egg cell without fertilization, also can be valuable in plant breeding for doubled haploid production. A deeper understanding of transcriptional differences between parthenogenetic and sexual or non-parthenogenetic eggs can assist with pathway engineering. By conducting laser capture microdissection-based RNA-seq on sexual and parthenogenetic egg cells on the day of anthesis, a de novo transcriptome for the Cenchrus ciliaris egg cells was created, transcriptional profiles that distinguish the parthenogenetic egg from its sexual counterpart were identified, and functional roles for a few transcription factors in promoting natural parthenogenesis were suggested. These transcriptome data expand upon previous gene expression studies and will be a resource for future research on the transcriptome of egg cells in parthenogenetic and sexual genotypes.
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Affiliation(s)
- Yuji Ke
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, GA, 31793, USA
| | - Maricel Podio
- Department of Horticulture, University of Georgia, Tifton, GA, 31793, USA
| | - Joann Conner
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, GA, 31793, USA.,Department of Horticulture, University of Georgia, Tifton, GA, 31793, USA
| | - Peggy Ozias-Akins
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, GA, 31793, USA. .,Department of Horticulture, University of Georgia, Tifton, GA, 31793, USA.
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Soliman M, Podio M, Marconi G, Di Marsico M, Ortiz JPA, Albertini E, Delgado L. Differential Epigenetic Marks Are Associated with Apospory Expressivity in Diploid Hybrids of Paspalum rufum. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10040793. [PMID: 33920644 PMCID: PMC8072704 DOI: 10.3390/plants10040793] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
Apomixis seems to emerge from the deregulation of preexisting genes involved in sexuality by genetic and/or epigenetic mechanisms. The trait is associated with polyploidy, but diploid individuals of Paspalum rufum can form aposporous embryo sacs and develop clonal seeds. Moreover, diploid hybrid families presented a wide apospory expressivity variation. To locate methylation changes associated with apomixis expressivity, we compare relative DNA methylation levels, at CG, CHG, and CHH contexts, between full-sib P. rufum diploid genotypes presenting differential apospory expressivity. The survey was performed using a methylation content-sensitive enzyme ddRAD (MCSeEd) strategy on samples at premeiosis/meiosis and postmeiosis stages. Based on the relative methylation level, principal component analysis and heatmaps, clearly discriminate samples with contrasting apospory expressivity. Differential methylated contigs (DMCs) showed 14% of homology to known transcripts of Paspalum notatum reproductive transcriptome, and almost half of them were also differentially expressed between apomictic and sexual samples. DMCs showed homologies to genes involved in flower growth, development, and apomixis. Moreover, a high proportion of DMCs aligned on genomic regions associated with apomixis in Setaria italica. Several stage-specific differential methylated sequences were identified as associated with apospory expressivity, which could guide future functional gene characterization in relation to apomixis success at diploid and tetraploid levels.
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Affiliation(s)
- Mariano Soliman
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
| | - Maricel Podio
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
| | - Gianpiero Marconi
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Marco Di Marsico
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Juan Pablo A. Ortiz
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
| | - Emidio Albertini
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Luciana Delgado
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
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A study of the heterochronic sense/antisense RNA representation in florets of sexual and apomictic Paspalum notatum. BMC Genomics 2021; 22:185. [PMID: 33726667 PMCID: PMC7962388 DOI: 10.1186/s12864-021-07450-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/18/2021] [Indexed: 11/10/2022] Open
Abstract
Background Apomixis, an asexual mode of plant reproduction, is a genetically heritable trait evolutionarily related to sexuality, which enables the fixation of heterozygous genetic combinations through the development of maternal seeds. Recently, reference floral transcriptomes were generated from sexual and apomictic biotypes of Paspalum notatum, one of the most well-known plant models for the study of apomixis. However, the transcriptome dynamics, the occurrence of apomixis vs. sexual expression heterochronicity across consecutive developmental steps and the orientation of transcription (sense/antisense) remain unexplored. Results We produced 24 Illumina TruSeq®/ Hiseq 1500 sense/antisense floral transcriptome libraries covering four developmental stages (premeiosis, meiosis, postmeiosis, and anthesis) in biological triplicates, from an obligate apomictic and a full sexual genotype. De novo assemblies with Trinity yielded 103,699 and 100,114 transcripts for the apomictic and sexual samples respectively. A global comparative analysis involving reads from all developmental stages revealed 19,352 differentially expressed sense transcripts, of which 13,205 (68%) and 6147 (32%) were up- and down-regulated in apomictic samples with respect to the sexual ones. Interestingly, 100 differentially expressed antisense transcripts were detected, 55 (55%) of them up- and 45 (45%) down-regulated in apomictic libraries. A stage-by-stage comparative analysis showed a higher number of differentially expressed candidates due to heterochronicity discrimination: the highest number of differential sense transcripts was detected at premeiosis (23,651), followed by meiosis (22,830), postmeiosis (19,100), and anthesis (17,962), while the highest number of differential antisense transcripts were detected at anthesis (495), followed by postmeiosis (164), meiosis (120) and premeiosis (115). Members of the AP2, ARF, MYB and WRKY transcription factor families, as well as the auxin, jasmonate and cytokinin plant hormone families appeared broadly deregulated. Moreover, the chronological expression profile of several well-characterized apomixis controllers was examined in detail. Conclusions This work provides a quantitative sense/antisense gene expression catalogue covering several subsequent reproductive developmental stages from premeiosis to anthesis for apomictic and sexual P. notatum, with potential to reveal heterochronic expression between reproductive types and discover sense/antisense mediated regulation. We detected a contrasting transcriptional and hormonal control in apomixis and sexuality as well as specific sense/antisense modulation occurring at the onset of parthenogenesis. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07450-3.
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Fiaz S, Wang X, Younas A, Alharthi B, Riaz A, Ali H. Apomixis and strategies to induce apomixis to preserve hybrid vigor for multiple generations. GM CROPS & FOOD 2021; 12:57-70. [PMID: 32877304 PMCID: PMC7553744 DOI: 10.1080/21645698.2020.1808423] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/06/2020] [Indexed: 11/16/2022]
Abstract
Hybrid seeds of several important crops with supreme qualities including yield, biotic and abiotic stress tolerance have been cultivated for decades. Thus far, a major challenge with hybrid seeds is that they do not have the ability to produce plants with the same qualities over subsequent generations. Apomixis, an asexual mode of reproduction by avoiding meiosis, exists naturally in flowering plants, and ultimately leads to seed production. Apomixis has the potential to preserve hybrid vigor for multiple generations in economically important plant genotypes. The evolution and genetics of asexual seed production are unclear, and much more effort will be required to determine the genetic architecture of this phenomenon. To fix hybrid vigor, synthetic apomixis has been suggested. The development of MiMe (mitosis instead of meiosis) genotypes has been utilized for clonal gamete production. However, the identification and parental origin of genes responsible for synthetic apomixis are little known and need further clarification. Genome modifications utilizing genome editing technologies (GETs), such as clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (cas), a reverse genetics tool, have paved the way toward the utilization of emerging technologies in plant molecular biology. Over the last decade, several genes in important crops have been successfully edited. The vast availability of GETs has made functional genomics studies easy to conduct in crops important for food security. Disruption in the expression of genes specific to egg cell MATRILINEAL (MTL) through the CRISPR/Cas genome editing system promotes the induction of haploid seed, whereas triple knockout of the Baby Boom (BBM) genes BBM1, BBM2, and BBM3 cause embryo arrest and abortion, which can be fully rescued by male-transmitted BBM1. The establishment of synthetic apomixis by engineering the MiMe genotype by genome editing of BBM1 expression or disruption of MTL leads to clonal seed production and heritability for multiple generations. In the present review, we discuss current developments related to the use of CRISPR/Cas technology in plants and the possibility of promoting apomixis in crops to preserve hybrid vigor. In addition, genetics, evolution, epigenetic modifications, and strategies for MiMe genotype development are discussed in detail.
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Affiliation(s)
- Sajid Fiaz
- Department of Plant Breeding and Genetics, The University of Haripur 22620 , Khyber Pakhtunkhwa, Pakistan
| | - Xiukang Wang
- College of Life Sciences, Yan'an University , Yan'an, Shaanxi, China
| | - Afifa Younas
- Department of Botany, Lahore College for Women University , Lahore, Pakistan
| | - Badr Alharthi
- College of Science and Engineering, Flinders University , Adelaide, Australia
- University College of Khurma, Taif University , Taif, Saudi Arabia
| | - Adeel Riaz
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences , Beijing, China
| | - Habib Ali
- Department of Agricultural Engineering, Khawaja Fareed University of Engineering and Information Technology , Rahim Yar Khan, Pakistan
- Department of Entomology, Sub-Campus Depalpur, University of Agriculture Faisalabad , Faisalabad, Pakistan
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Ortiz JPA, Pupilli F, Acuña CA, Leblanc O, Pessino SC. How to Become an Apomixis Model: The Multifaceted Case of Paspalum. Genes (Basel) 2020; 11:E974. [PMID: 32839398 PMCID: PMC7564465 DOI: 10.3390/genes11090974] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/12/2022] Open
Abstract
In the past decades, the grasses of the Paspalum genus have emerged as a versatile model allowing evolutionary, genetic, molecular, and developmental studies on apomixis as well as successful breeding applications. The rise of such an archetypal system progressed through integrative phases, which were essential to draw conclusions based on solid standards. Here, we review the steps adopted in Paspalum to establish the current body of knowledge on apomixis and provide model breeding programs for other agronomically important apomictic crops. In particular, we discuss the need for previous detailed cytoembryological and cytogenetic germplasm characterization; the establishment of sexual and apomictic materials of identical ploidy level; the development of segregating populations useful for inheritance analysis, positional mapping, and epigenetic control studies; the development of omics data resources; the identification of key molecular pathways via comparative gene expression studies; the accurate molecular characterization of genomic loci governing apomixis; the in-depth functional analysis of selected candidate genes in apomictic and model species; the successful building of a sexual/apomictic combined breeding scheme.
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Affiliation(s)
- Juan Pablo A. Ortiz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA Zavalla, Argentina;
| | - Fulvio Pupilli
- Institute of Biosciences and Bioresources (IBBR-CNR), 06128 Perugia, Italy;
| | - Carlos A. Acuña
- Instituto de Botánica del Nordeste (IBONE), CONICET, Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, 3400 Corrientes, Argentina;
| | - Olivier Leblanc
- UMR DIADE, IRD, Univ. Montpellier, 34090 Montpellier, France;
| | - Silvina C. Pessino
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA Zavalla, Argentina;
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13
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Rathore P, Raina SN, Kumar S, Bhat V. Retro-Element Gypsy-163 Is Differentially Methylated in Reproductive Tissues of Apomictic and Sexual Plants of Cenchrus ciliaris. Front Genet 2020; 11:795. [PMID: 32849800 PMCID: PMC7387646 DOI: 10.3389/fgene.2020.00795] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 07/03/2020] [Indexed: 11/18/2022] Open
Abstract
Apomixis, an asexual mode of reproduction through seeds, has immense scope for crop improvement due to its ability to fix hybrid vigor. In C. ciliaris, a predominantly apomictically reproducing range grass, apomixis is genetically controlled by an apospory-specific-genomic-region (ASGR) which is enriched with retrotransposons. Earlier studies showed insertional polymorphisms of a few ASGR-specific retrotransposons between apomictic and sexual plants of C. ciliaris. REs are mainly regulated at the transcriptional level through cytosine methylation. To understand the possible association of ASGR-specific retrotransposon to apomixis, the extent and pattern of differential methylation of Gy163 RE and its impact on transcription were investigated in two genotypes each of apomictic and sexual plants of C. ciliaris. We observed that Gy163 encodes for an integrase domain of RE Ty3-Gypsy, is differentially methylated between reproductive tissues of apomictic and sexual plants. However, leaf tissues did not exhibit differential methylation between apomictic and sexual plants. Among the three contexts (CG, CHG, and CHH) of cytosine methylation, the maximum variation was observed in CHH context in reproductive (at aposporous initial and mature embryo sac stages) tissues of apomictic plants implicating RdDM pathway in methylation of Gy163. Quantitative PCR analysis showed that Gy163 transcripts are expressed more in the reproductive tissues of apomictic plants compared to that in the sexual plants, which was negatively correlated with the methylation level. Thus, the study helps in understanding the role of RE present in ASGR in epigenetic regulation of apomictic mode of reproduction in C. ciliaris.
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Affiliation(s)
- Priyanka Rathore
- Department of Botany, Faculty of Science, University of Delhi, New Delhi, India
| | - Soom Nath Raina
- Amity Institute of Biotechnology, Amity University, Noida, India
| | - Suresh Kumar
- Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Vishnu Bhat
- Department of Botany, Faculty of Science, University of Delhi, New Delhi, India
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14
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Scheben A, Hojsgaard D. Can We Use Gene-Editing to Induce Apomixis in Sexual Plants? Genes (Basel) 2020; 11:E781. [PMID: 32664641 PMCID: PMC7397034 DOI: 10.3390/genes11070781] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 12/12/2022] Open
Abstract
Apomixis, the asexual formation of seeds, is a potentially valuable agricultural trait. Inducing apomixis in sexual crop plants would, for example, allow breeders to fix heterosis in hybrid seeds and rapidly generate doubled haploid crop lines. Molecular models explain the emergence of functional apomixis, i.e., apomeiosis + parthenogenesis + endosperm development, as resulting from a combination of genetic or epigenetic changes that coordinate altered molecular and developmental steps to form clonal seeds. Apomixis-like features and synthetic clonal seeds have been induced with limited success in the sexual plants rice and maize by using gene editing to mutate genes related to meiosis and fertility or via egg-cell specific expression of embryogenesis genes. Inducing functional apomixis and increasing the penetrance of apomictic seed production will be important for commercial deployment of the trait. Optimizing the induction of apomixis with gene editing strategies that use known targets as well as identifying alternative targets will be possible by better understanding natural genetic variation in apomictic species. With the growing availability of genomic data and precise gene editing tools, we are making substantial progress towards engineering apomictic crops.
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Affiliation(s)
- Armin Scheben
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA;
| | - Diego Hojsgaard
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, 37073 Goettingen, Germany
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15
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Karunarathne P, Reutemann AV, Schedler M, Glücksberg A, Martínez EJ, Honfi AI, Hojsgaard DH. Sexual modulation in a polyploid grass: a reproductive contest between environmentally inducible sexual and genetically dominant apomictic pathways. Sci Rep 2020; 10:8319. [PMID: 32433575 PMCID: PMC7239852 DOI: 10.1038/s41598-020-64982-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 04/25/2020] [Indexed: 12/24/2022] Open
Abstract
In systems alternating between sexual and asexual reproduction, sex increases under unfavorable environmental conditions. In plants producing sexual and asexual (apomictic) seeds, studies on the influence of environmental factors on sex are equivocal. We used Paspalum intermedium to study environmental effects on the expression of sexual and apomictic developments, and on resulting reproductive fitness variables. Flow cytometric and embryological analyses were performed to characterize ploidy and reproductive modes, and effects of local climatic conditions on sexual and apomictic ovule and seed frequencies were determined. Seed set and germination data were collected and used to estimate reproductive fitness. Frequencies of sexual and apomictic ovules and seeds were highly variable within and among populations. Apomictic development exhibited higher competitive ability but lower overall fitness. Frequencies of sexual reproduction in facultative apomictic plants increased at lower temperatures and wider mean diurnal temperature ranges. We identified a two-fold higher fitness advantage of sexuality and a Tug of War between factors intrinsic to apomixis and environmental stressors promoting sexuality which influence the distribution of sex in apomictic populations. This points toward a crucial role of local ecological conditions in promoting a reshuffling of genetic variability that may be shaping the adaptative landscape in apomictic P. intermedium plants.
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Affiliation(s)
- Piyal Karunarathne
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, 37073, Goettingen, Germany.
- Georg-August University School of Science, University of Goettingen, Goettingen, Germany.
| | - Anna V Reutemann
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, 37073, Goettingen, Germany
- Instituto de Botánica del Nordeste (IBONE), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), CC209, 3400, Corrientes, Argentina
| | - Mara Schedler
- Instituto de Botánica del Nordeste (IBONE), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), CC209, 3400, Corrientes, Argentina
| | - Adriana Glücksberg
- Instituto de Botánica del Nordeste (IBONE), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), CC209, 3400, Corrientes, Argentina
| | - Eric J Martínez
- Instituto de Botánica del Nordeste (IBONE), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (FCA-UNNE), CC209, 3400, Corrientes, Argentina
| | - Ana I Honfi
- Programa de Estudios Florísticos y Genética Vegetal, Instituto de Biología Subtropical (CONICET-UNaM), Facultad de Ciencias Exactas, Químicas y Naturales, Universidad Nacional de Misiones, Rivadavia 2370, 3300, Posadas, Misiones, Argentina
| | - Diego H Hojsgaard
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, 37073, Goettingen, Germany.
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16
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Schinkel CCF, Syngelaki E, Kirchheimer B, Dullinger S, Klatt S, Hörandl E. Epigenetic Patterns and Geographical Parthenogenesis in the Alpine Plant Species Ranunculus kuepferi (Ranunculaceae). Int J Mol Sci 2020; 21:E3318. [PMID: 32392879 PMCID: PMC7247541 DOI: 10.3390/ijms21093318] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/31/2022] Open
Abstract
Polyploidization and the shift to apomictic reproduction are connected to changes in DNA cytosine-methylation. Cytosine-methylation is further sensitive to environmental conditions. We, therefore, hypothesize that DNA methylation patterns would differentiate within species with geographical parthenogenesis, i.e., when diploid sexual and polyploid apomictic populations exhibit different spatial distributions. On natural populations of the alpine plant Ranunculus kuepferi, we tested differences in methylation patterns across two cytotypes (diploid, tetraploid) and three reproduction modes (sexual, mixed, apomictic), and their correlation to environmental data and geographical distributions. We used methylation-sensitive amplified fragment-length polymorphism (methylation-sensitive AFLPs) and scored three types of epiloci. Methylation patterns differed independently between cytotypes versus modes of reproduction and separated three distinct combined groups (2x sexual + mixed, 4x mixed, and 4x apomictic), with differentiation of 4x apomicts in all epiloci. We found no global spatial autocorrelation, but instead correlations to elevation and temperature gradients in 22 and 36 epiloci, respectively. Results suggest that methylation patterns in R. kuepferi were altered by cold conditions during postglacial recolonization of the Alps, and by the concomitant shift to facultative apomixis, and by polyploidization. Obligate apomictic tetraploids at the highest elevations established a distinct methylation profile. Methylation patterns reflect an ecological gradient rather than the geographical differentiation.
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Affiliation(s)
- Christoph C. F. Schinkel
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspüle 2, 37073 Göttingen, Germany;
| | - Eleni Syngelaki
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspüle 2, 37073 Göttingen, Germany;
| | - Bernhard Kirchheimer
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria; (B.K.); (S.D.)
| | - Stefan Dullinger
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria; (B.K.); (S.D.)
| | - Simone Klatt
- Section Safety and Environmental Protection, University of Goettingen, Humboldtallee 15, 37073 Göttingen, Germany;
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, Untere Karspüle 2, 37073 Göttingen, Germany;
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17
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Hojsgaard D. Apomixis Technology: Separating the Wheat from the Chaff. Genes (Basel) 2020; 11:E411. [PMID: 32290084 PMCID: PMC7231277 DOI: 10.3390/genes11040411] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 02/06/2023] Open
Abstract
Projections indicate that current plant breeding approaches will be unable to incorporate the global crop yields needed to deliver global food security. Apomixis is a disruptive innovation by which a plant produces clonal seeds capturing heterosis and gene combinations of elite phenotypes. Introducing apomixis into hybrid cultivars is a game-changing development in the current plant breeding paradigm that will accelerate the generation of high-yield cultivars. However, apomixis is a developmentally complex and genetically multifaceted trait. The central problem behind current constraints to apomixis breeding is that the genomic configuration and molecular mechanism that initiate apomixis and guide the formation of a clonal seed are still unknown. Today, not a single explanation about the origin of apomixis offer full empirical coverage, and synthesizing apomixis by manipulating individual genes has failed or produced little success. Overall evidence suggests apomixis arise from a still unknown single event molecular mechanism with multigenic effects. Disentangling the genomic basis and complex genetics behind the emergence of apomixis in plants will require the use of novel experimental approaches benefiting from Next Generation Sequencing technologies and targeting not only reproductive genes, but also the epigenetic and genomic configurations associated with reproductive phenotypes in homoploid sexual and apomictic carriers. A comprehensive picture of most regulatory changes guiding apomixis emergence will be central for successfully installing apomixis into the target species by exploiting genetic modification techniques.
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Affiliation(s)
- Diego Hojsgaard
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, Georg-August-University of Göttingen, Untere Karspüle 2, D-37073-1 Göttingen, Germany
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18
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Controlling Apomixis: Shared Features and Distinct Characteristics of Gene Regulation. Genes (Basel) 2020; 11:genes11030329. [PMID: 32245021 PMCID: PMC7140868 DOI: 10.3390/genes11030329] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 02/06/2023] Open
Abstract
In higher plants, sexual and asexual reproduction through seeds (apomixis) have evolved as alternative strategies. As apomixis leads to the formation of clonal offspring, its great potential for agricultural applications has long been recognized. However, the genetic basis and the molecular control underlying apomixis and its evolutionary origin are to date not fully understood. Both in sexual and apomictic plants, reproduction is tightly controlled by versatile mechanisms regulating gene expression, translation, and protein abundance and activity. Increasing evidence suggests that interrelated pathways including epigenetic regulation, cell-cycle control, hormonal pathways, and signal transduction processes are relevant for apomixis. Additional molecular mechanisms are being identified that involve the activity of DNA- and RNA-binding proteins, such as RNA helicases which are increasingly recognized as important regulators of reproduction. Together with other factors including non-coding RNAs, their association with ribosomes is likely to be relevant for the formation and specification of the apomictic reproductive lineage. Subsequent seed formation appears to involve an interplay of transcriptional activation and repression of developmental programs by epigenetic regulatory mechanisms. In this review, insights into the genetic basis and molecular control of apomixis are presented, also taking into account potential relations to environmental stress, and considering aspects of evolution.
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Coexpression and Transcriptome analyses identify active Apomixis-related genes in Paspalum notatum leaves. BMC Genomics 2020; 21:78. [PMID: 31992196 PMCID: PMC6986084 DOI: 10.1186/s12864-020-6518-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 01/20/2020] [Indexed: 11/12/2022] Open
Abstract
Background Paspalum notatum exhibits both sexual and apomictic cytotypes and, thus, is considered a good model for studies of apomixis because it facilitates comparative approaches. In this work, transcriptome sequencing was used to compare contrasting P. notatum cytotypes to identify differential expression patterns and candidate genes involved in the regulation of expression of this trait. Results We built a comprehensive transcriptome using leaf and inflorescence from apomictic tetraploids and sexual diploids/tetraploids and a coexpression network based on pairwise correlations between transcript expression profiles. We identified genes exclusively expressed in each cytotype and genes differentially expressed between pairs of cytotypes. Gene Ontology enrichment analyses were performed to better interpret the data. We de novo assembled 114,306 reference transcripts. In total, 536 candidate genes possibly associated with apomixis were detected through statistical analyses of the differential expression data, and several interacting genes potentially linked to the apomixis-controlling region, genes that have already been reported in the literature, and their neighbors were transcriptionally related in the coexpression network. Conclusions Apomixis is a highly desirable trait in modern agriculture due to the maintenance of the characteristics of the mother plant in the progeny. The reference transcriptome, candidate genes and their coexpression network identified in this work represent rich resources for future grass breeding programs.
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Konate M, Wilkinson MJ, Taylor J, Scott ES, Berger B, Rodriguez Lopez CM. Greenhouse Spatial Effects Detected in the Barley ( Hordeum vulgare L.) Epigenome Underlie Stochasticity of DNA Methylation. FRONTIERS IN PLANT SCIENCE 2020; 11:553907. [PMID: 33013971 PMCID: PMC7511590 DOI: 10.3389/fpls.2020.553907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/24/2020] [Indexed: 05/10/2023]
Abstract
Environmental cues are known to alter the methylation profile of genomic DNA, and thereby change the expression of some genes. A proportion of such modifications may become adaptive by adjusting expression of stress response genes but others have been shown to be highly stochastic, even under controlled conditions. The influence of environmental flux on plants adds an additional layer of complexity that has potential to confound attempts to interpret interactions between environment, methylome, and plant form. We therefore adopt a positional and longitudinal approach to study progressive changes to barley DNA methylation patterns in response to salt exposure during development under greenhouse conditions. Methylation-sensitive amplified polymorphism (MSAP) and phenotypic analyses of nine diverse barley varieties were grown in a randomized plot design, under two salt treatments (0 and 75 mM NaCl). Combining environmental, phenotypic and epigenetic data analyses, we show that at least part of the epigenetic variability, previously described as stochastic, is linked to environmental micro-variations during plant growth. Additionally, we show that differences in methylation increase with time of exposure to micro-variations in environment. We propose that subsequent epigenetic studies take into account microclimate-induced epigenetic variability.
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Affiliation(s)
- Moumouni Konate
- Institut de l'Environnement et de Recherche Agricole (INERA), DRREA-Ouest, Bobo Dioulasso, Burkina Faso
| | - Michael J. Wilkinson
- Institute of Biological, Environmental and Rural Sciences, Penglais Campus, Aberystwyth, United Kingdom
- *Correspondence: Carlos Marcelino Rodriguez Lopez, ; Michael J. Wilkinson,
| | - Julian Taylor
- Biometry Hub, School of Agriculture, Food and Wine, Waite Research Institute, The University of Adelaide, Glen Osmond, SA, Australia
| | - Eileen S. Scott
- School of Agriculture, Food and Wine, Waite Research Institute, The University of Adelaide, Glen Osmond, SA, Australia
| | - Bettina Berger
- School of Agriculture, Food and Wine, Waite Research Institute, The University of Adelaide, Glen Osmond, SA, Australia
- The Plant Accelerator, Australian Plant Phenomics Facility, School of Agriculture, Food and Wine, Waite Research Institute, The University of Adelaide, Glen Osmond, SA, Australia
| | - Carlos Marcelino Rodriguez Lopez
- Environmental Epigenetics and Genetics Group, Department of Horticulture, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, United States
- *Correspondence: Carlos Marcelino Rodriguez Lopez, ; Michael J. Wilkinson,
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21
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Ortiz JPA, Leblanc O, Rohr C, Grisolia M, Siena LA, Podio M, Colono C, Azzaro C, Pessino SC. Small RNA-seq reveals novel regulatory components for apomixis in Paspalum notatum. BMC Genomics 2019; 20:487. [PMID: 31195966 PMCID: PMC6567921 DOI: 10.1186/s12864-019-5881-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/04/2019] [Indexed: 12/31/2022] Open
Abstract
Background Apomixis is considered an evolutionary deviation of the sexual reproductive pathway leading to the generation of clonal maternal progenies by seeds. Recent evidence from model and non-model species suggested that this trait could be modulated by epigenetic mechanisms involving small RNAs (sRNAs). Here we profiled floral sRNAs originated from apomictic and sexual Paspalum notatum genotypes in order to identify molecular pathways under epigenetic control that might be involved in the transition from sexuality to agamospermy. Results The mining of genes participating in sRNA-directed pathways from floral Paspalum transcriptomic resources showed these routes are functional during reproductive development, with several members differentially expressed in apomictic and sexual plants. Triplicate floral sRNA libraries derived from apomictic and a sexual genotypes were characterized by using high-throughput sequencing technology. EdgeR was apply to compare the number of sRNA reads between sexual and apomictic libraries that map over all Paspalum floral transcripts. A total of 1525 transcripts showed differential sRNA representation, including genes related to meiosis, plant hormone signaling, biomolecules transport, transcription control and cell cycle. Survey for miRNA precursors on transcriptome and genome references allowed the discovery of 124 entities, including 40 conserved and 8 novel ones. Fifty-six clusters were differentially represented in apomictic and sexual plants. All differentially expressed miRNAs were up-regulated in apomictic libraries but miR2275, which showed different family members with opposed representation. Examination of predicted miRNAs targets detected 374 potential candidates. Considering sRNA, miRNAs and target surveys together, 14 genes previously described as related with auxin metabolism, transport and signaling were detected, including AMINO ACID/AUXIN PERMEASE 15, IAA-AMIDO SYNTHETASE GH3–8, IAA30, miR160, miR167, miR164, miR319, ARF2, ARF8, ARF10, ARF12, AFB2, PROLIFERATING CELL FACTOR 6 and NITRATE TRANSPORTER 1.1. Conclusions This work provides a comprehensive survey of the sRNA differential representation in flowers of sexual and apomictic Paspalum notatum plants. An integration of the small RNA profiling data presented here and previous transcriptomic information suggests that sRNA-mediated regulation of auxin pathways is pivotal in promoting apomixis. These results will underlie future functional characterization of the molecular components mediating the switch from sexuality to apomixis. Electronic supplementary material The online version of this article (10.1186/s12864-019-5881-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Juan Pablo A Ortiz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Olivier Leblanc
- Institut de Recherche pour le Développement (IRD), Université de Montpellier, Montpellier, France
| | - Cristian Rohr
- Instituto de Agrobiotecnología de Rosario (INDEAR), Rosario, Argentina
| | - Mauricio Grisolia
- Instituto de Agrobiotecnología de Rosario (INDEAR), Rosario, Argentina
| | - Lorena A Siena
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Maricel Podio
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Carolina Colono
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Celeste Azzaro
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Silvina C Pessino
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina.
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Fei X, Shi J, Liu Y, Niu J, Wei A. The steps from sexual reproduction to apomixis. PLANTA 2019; 249:1715-1730. [PMID: 30963237 DOI: 10.1007/s00425-019-03113-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 02/18/2019] [Indexed: 05/03/2023]
Abstract
In this paper, an interaction model of apomixis-related genes was constructed to analyze the emergence of apomictic types. It is speculated that apomixis technology will be first implemented in gramineous plants. Apomixis (asexual seed formation) is a phenomenon in which a plant bypasses the most fundamental aspects of sexual reproduction-meiosis and fertilization-to form a viable seed. Plants can form seeds without fertilization, and the seed genotype is consistent with the female parent. The development of apomictic technology would be revolutionary for agriculture and for food production as it would reduce costs and breeding times and also avoid many complications typical of sexual reproduction (e.g. incompatibility barriers) and of vegetative propagation (e.g. viral transfer). The application of apomictic reproductive technology has the potential to revolutionize crop breeding. This article reviews recent advances in apomixis in cytology and molecular biology. The general idea of identifying apomixis was proposed and the process of the emergence of non-fusion types was discussed. To better understand the apomixis mechanism, an apomixis regulatory model was established. At the same time, the realization of apomixis technology is proposed, which provides reference for the research and application of apomixis.
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Affiliation(s)
- Xitong Fei
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Jingwei Shi
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Yulin Liu
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Jinshuang Niu
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Anzhi Wei
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China.
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Albertini E, Barcaccia G, Carman JG, Pupilli F. Did apomixis evolve from sex or was it the other way around? JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2951-2964. [PMID: 30854543 DOI: 10.1093/jxb/erz109] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/25/2019] [Indexed: 05/20/2023]
Abstract
In angiosperms, there are two pathways of reproduction through seeds: sexual, or amphimictic, and asexual, or apomictic. The essential feature of apomixis is that an embryo in an ovule is formed autonomously. It may form from a cell of the nucellus or integuments in an otherwise sexual ovule, a process referred to as adventitious embryony. Alternatively, the embryo may form by parthenogenesis from an unreduced egg that forms in an unreduced embryo sac. The latter may form from an ameiotic megasporocyte, in which case it is referred to as diplospory, or from a cell of the nucellus or integument, in which case it is referred to as apospory. Progeny of apomictic plants are generally identical to the mother plant. Apomixis has been seen over the years as either a gain- or loss-of-function over sexuality, implying that the latter is the default condition. Here, we consider an additional point of view, that apomixis may be anciently polyphenic with sex and that both reproductive phenisms involve anciently canalized components of complex molecular processes. This polyphenism viewpoint suggests that apomixis fails to occur in obligately sexual eukaryotes because genetic or epigenetic modifications have silenced the primitive sex apomixis switch and/or disrupted molecular capacities for apomixis. In eukaryotes where sex and apomixis are clearly polyphenic, apomixis exponentially drives clonal fecundity during reproductively favorable conditions, while stress induces sex for stress-tolerant spore or egg formation. The latter often guarantees species survival during environmentally harsh seasons.
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Affiliation(s)
- Emidio Albertini
- Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, Italy
| | - Gianni Barcaccia
- Laboratory of Genomics, Department of Agronomy, Food, Natural Resources, Animals and the Environment (DAFNAE), University of Padova Legnaro, PD, Italy
| | - John G Carman
- Department of Plants, Soils and Climate, Utah State University, Logan, Utah, USA
| | - Fulvio Pupilli
- Institute of Biosciences and Bioresources, Research Division of Perugia, National Research Council (CNR), Perugia, Italy
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Hojsgaard D, Hörandl E. The Rise of Apomixis in Natural Plant Populations. FRONTIERS IN PLANT SCIENCE 2019; 10:358. [PMID: 31001296 PMCID: PMC6454013 DOI: 10.3389/fpls.2019.00358] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 03/07/2019] [Indexed: 05/04/2023]
Abstract
Apomixis, the asexual reproduction via seed, has many potential applications for plant breeding by maintaining desirable genotypes over generations. Since most major crops do not express natural apomixis, it is useful to understand the origin and maintenance of apomixis in natural plant systems. Here, we review the state of knowledge on origin, establishment and maintenance of natural apomixis. Many studies suggest that hybridization, either on diploid or polyploid cytotypes, is a major trigger for the formation of unreduced female gametophytes, which represents the first step toward apomixis, and must be combined to parthenogenesis, the development of an unfertilized egg cell. Nevertheless, fertilization of endosperm is still needed for most apomictic plants. Coupling of these three steps appears to be a major constraint for shifts to natural apomixis. Adventitious embryony is another developmental pathway toward apomixis. Establishment of a newly arisen apomictic lineage is often fostered by side-effects of polyploidy. Polyploidy creates an immediate reproductive barrier against the diploid parental and progenitor populations; it can cause a breakdown of genetic self-incompatibility (SI) systems which is needed to establish self-fertility of pseudogamous apomictic lineages; and finally, polyploidy could indirectly help to establish an apomictic cytotype in a novel ecological niche by increasing adaptive potentials of the plants. This step may be followed by a phase of diversification and range expansion, mostly described as geographical parthenogenesis. The utilization of apomixis in crops must consider the potential risks of pollen transfer and introgression into sexual crop fields, which might be overcome by using pollen-sterile or cleistogamous variants. Another risk is the escape into natural vegetation and potential invasiveness of apomictic plants which needs careful management and consideration of ecological conditions.
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Galla G, Siena LA, Ortiz JPA, Baumlein H, Barcaccia G, Pessino SC, Bellucci M, Pupilli F. A Portion of the Apomixis Locus of Paspalum Simplex is Microsyntenic with an Unstable Chromosome Segment Highly Conserved Among Poaceae. Sci Rep 2019; 9:3271. [PMID: 30824748 PMCID: PMC6397161 DOI: 10.1038/s41598-019-39649-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 01/16/2019] [Indexed: 01/04/2023] Open
Abstract
The introgression of apomixis in major seed crops, would guarantee self-seeding of superior heterotic seeds over generations. In the grass species Paspalum simplex, apomixis is controlled by a single locus in which recombination is blocked. In the perspective of isolating the genetic determinants of apomixis, we report data on sequencing, in silico mapping and expression analysis of some of the genes contained in two cloned genomic regions of the apomixis locus of P. simplex. In silico mapping allowed us to identify a conserved synteny group homoeologous to the apomixis locus, located on a telomeric position of chromosomes 12, 8, 3 and 4 of rice, Sorghum bicolor, Setaria italica and Brachypodium distachyum, respectively, and on a more centromeric position of maize chromosome 1. Selected genes of the apomixis locus expressed sense and antisense transcripts in reproductively committed cells of sexual and apomictic ovules. Some of the genes considered here expressed apomixis-specific allelic variants which showed partial non-overlapping expression patterns with alleles shared by sexual and apomictic reproductive phenotypes. Our findings open new routes for the isolation of the genetic determinants of apomixis and, in perspective, for its introgression in crop grasses.
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Affiliation(s)
- Giulio Galla
- Department of Agriculture Food Natural resources Animals and Environment (DAFNAE), University of Padova, 35020, Legnaro (PD), Italy
| | - Lorena A Siena
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET-UNR, Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Juan Pablo A Ortiz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET-UNR, Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Helmut Baumlein
- The Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466, Gatersleben, Germany
| | - Gianni Barcaccia
- Department of Agriculture Food Natural resources Animals and Environment (DAFNAE), University of Padova, 35020, Legnaro (PD), Italy
| | - Silvina C Pessino
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET-UNR, Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Michele Bellucci
- Institute of Biosciences and Bioresources (IBBR), National Research Council (CNR), 06128, Perugia, Italy
| | - Fulvio Pupilli
- Institute of Biosciences and Bioresources (IBBR), National Research Council (CNR), 06128, Perugia, Italy.
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Colono C, Ortiz JPA, Permingeat HR, Souza Canada ED, Siena LA, Spoto N, Galdeano F, Espinoza F, Leblanc O, Pessino SC. A Plant-Specific TGS1 Homolog Influences Gametophyte Development in Sexual Tetraploid Paspalum notatum Ovules. FRONTIERS IN PLANT SCIENCE 2019; 10:1566. [PMID: 31850040 PMCID: PMC6895069 DOI: 10.3389/fpls.2019.01566] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 11/08/2019] [Indexed: 05/04/2023]
Abstract
Aposporous apomictic plants form clonal maternal seeds by inducing the emergence of non-reduced (2n) embryo sacs in the ovule nucellus and the development of embryos by parthenogenesis. In previous work, we reported a plant-specific TRIMETHYLGUANOSINE SYNTHASE 1 (TGS1) gene (PN_TGS1-like) showing expression levels positively correlated with sexuality rates in facultative apomictic Paspalum notatum. PN_ TGS1-like displayed contrasting in situ hybridization patterns in apomictic and sexual plant ovules from premeiosis to anthesis. Here we transformed sexual P. notatum with a TGS1-like antisense construction under a constitutive promoter, in order to produce lines with reduced transcript representation. Antisense plants developed prominent trichomes on the adaxial leaf surface, a trait absent from control genotypes. Reproductive development analysis revealed occasional formation of twin ovules. While control individuals typically displayed a single meiotic embryo sac per ovule, antisense lines showed 12.93-15.79% of ovules bearing extra nuclei, which can be assigned to aposporous-like embryo sacs (AES-like) or, alternatively, to gametophytes with a misguided cell fate development. Moreover, around 8.42-9.52% of ovules showed what looked like a combination of meiotic and aposporous-like sacs. Besides, 32.5% of ovules at early developmental stages displayed nucellar cells with prominent nuclei resembling apospory initials (AIs), which surrounded the megaspore mother cell (MMC) or the MMC-derived meiotic products. Two or more concurrent meiosis events were never detected, which suggest a non-reduced nature for the extra nuclei observed in the mature ovules, unless they were generated by proliferation and misguided differentiation of the legitimate meiotic products. The antisense lines produced a similar amount of viable even-sized pollen with respect to control genotypes, and formed an equivalent full seed set (∼9% of total seeds) after self-pollination. Flow cytometry analyses of caryopses derived from antisense lines revealed that all full seeds had originated from meiotic embryo sacs (i.e. by sexuality). A reduction of 25.55% in the germination percentage was detected when comparing antisense lines with controls. Our results indicate that PN_ TGS1-like influences ovule, gametophyte and possibly embryo development.
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Affiliation(s)
- Carolina Colono
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Juan Pablo A. Ortiz
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Hugo R. Permingeat
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | | | - Lorena A. Siena
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Nicolás Spoto
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Florencia Galdeano
- Genetics Laboratory, IBONE, CONICET, Universidad Nacional del Nordeste, Corrientes, Argentina
| | - Francisco Espinoza
- Genetics Laboratory, IBONE, CONICET, Universidad Nacional del Nordeste, Corrientes, Argentina
| | | | - Silvina C. Pessino
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
- *Correspondence: Silvina C. Pessino,
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Mancini M, Permingeat H, Colono C, Siena L, Pupilli F, Azzaro C, de Alencar Dusi DM, de Campos Carneiro VT, Podio M, Seijo JG, González AM, Felitti SA, Ortiz JPA, Leblanc O, Pessino SC. The MAP3K-Coding QUI-GON JINN ( QGJ) Gene Is Essential to the Formation of Unreduced Embryo Sacs in Paspalum. FRONTIERS IN PLANT SCIENCE 2018; 9:1547. [PMID: 30405677 PMCID: PMC6207905 DOI: 10.3389/fpls.2018.01547] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/03/2018] [Indexed: 05/20/2023]
Abstract
Apomixis is a clonal mode of reproduction via seeds, which results from the failure of meiosis and fertilization in the sexual female reproductive pathway. In previous transcriptomic surveys, we identified a mitogen-activated protein kinase kinase kinase (N46) displaying differential representation in florets of sexual and apomictic Paspalum notatum genotypes. Here, we retrieved and characterized the N46 full cDNA sequence from sexual and apomictic floral transcriptomes. Phylogenetic analyses showed that N46 was a member of the YODA family, which was re-named QUI-GON JINN (QGJ). Differential expression in florets of sexual and apomictic plants was confirmed by qPCR. In situ hybridization experiments revealed expression in the nucellus of aposporous plants' ovules, which was absent in sexual plants. RNAi inhibition of QGJ expression in two apomictic genotypes resulted in significantly reduced rates of aposporous embryo sac formation, with respect to the level detected in wild type aposporous plants and transformation controls. The QGJ locus segregated independently of apospory. However, a probe derived from a related long non-coding RNA sequence (PN_LNC_QGJ) revealed RFLP bands cosegregating with the Paspalum apospory-controlling region (ACR). PN_LNC_QGJ is expressed in florets of apomictic plants only. Our results indicate that the activity of QGJ in the nucellus of apomictic plants is necessary to form non-reduced embryo sacs and that a long non-coding sequence with regulatory potential is similar to sequences located within the ACR.
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Affiliation(s)
- Micaela Mancini
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Hugo Permingeat
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Carolina Colono
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Lorena Siena
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Fulvio Pupilli
- Istituto di Bioscienze e BioRisorse, Consiglio Nazionale delle Ricerche, Perugia, Italy
| | - Celeste Azzaro
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | | | | | - Maricel Podio
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - José Guillermo Seijo
- Instituto de Botánica del Nordeste, CONICET-UNNE, Corrientes, Argentina
- Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Corrientes, Argentina
| | - Ana María González
- Instituto de Botánica del Nordeste, CONICET-UNNE, Corrientes, Argentina
- Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Corrientes, Argentina
| | - Silvina A. Felitti
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | - Juan Pablo A. Ortiz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
| | | | - Silvina C. Pessino
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-UNR, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina
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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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Hojsgaard D. Transient Activation of Apomixis in Sexual Neotriploids May Retain Genomically Altered States and Enhance Polyploid Establishment. FRONTIERS IN PLANT SCIENCE 2018; 9:230. [PMID: 29535745 PMCID: PMC5834478 DOI: 10.3389/fpls.2018.00230] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 02/09/2018] [Indexed: 05/19/2023]
Abstract
Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step mechanism of cell fusions between ubiquitous (reduced) and rare (unreduced) gametes. The primary fusion event creates an intermediate triploid individual with unbalanced genome sets, a situation of genomic-shock characterized by gene expression dysregulation, high dosage sensitivity, disturbed cell divisions, and physiological and reproductive attributes drastically altered. This near-sterile neotriploid must produce (even) eupolyploids through secondary fusion events to restore genome steadiness, meiotic balance, and fertility required for the demographic establishment of a nascent lineage. Natural conditions locate several difficulties to polyploid establishment, including the production of highly unbalanced and rarely unreduced (euploid) gametes, frequency-dependent disadvantages (minority cytotype exclusion), severe fitness loss, and ecological competition with diploid parents. Persistence and adaptation of neopolyploids depend upon genetic and phenotypic novelty coupled to joint selective forces that preserve shock-induced genomic changes (subgenome homeolog partitioning) and drive meiotic (reproductive) stabilization and ecological diversification. Thus, polyploid establishment through the triploid bridge is a feasible but not ubiquitous process that requires a number of low-probability events and singular circumstances. Yet, frequencies of polyploids suggest that polyploid establishment is a pervasive process. To explain this disparity, and supported in experimental evidence, I propose that situations like hybridization and ploidy-state transitions associated to genomic shock and substantial developmental alterations can transiently activate apomixis as a mechanism to halt genomic instability and cancel factors restraining neopolyploid's sexual fertility, particularly in triploids. Apomixis -as a temporal alternative to sex- skip meiosis and syngamy, and thus can freeze genomic attributes, avoid unbalanced chromosomal segregation and increase the formation of unreduced euploid gametes, elude frequency-dependent reproductive disadvantages by parthenogenetic development of the embryo and permissive development of endosperm during seed formation, and increase the effective population size of the neopolyploid lineage favoring the formation rate of eupolyploids compared to aneuploids. The subsequent action of genome resilience mechanisms that alleviate transcriptomic shock and selection upon gene interactions might restore a stable meiosis and sexual fertility within few generations, as observed in synthetic polyploids. Alternatively, provided that resilience mechanisms fail, the neopolyploid might retain apomixis and hold genomically and transcriptionally altered states for many generations.
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Affiliation(s)
- Diego Hojsgaard
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, Georg August University of Göttingen, Göttingen, Germany
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The vesicle trafficking regulator PN_SCD1 is demethylated and overexpressed in florets of apomictic Paspalum notatum genotypes. Sci Rep 2018; 8:3030. [PMID: 29445151 PMCID: PMC5812994 DOI: 10.1038/s41598-018-21220-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 01/31/2018] [Indexed: 01/01/2023] Open
Abstract
Apomixis (asexual reproduction through seeds) is considered a deviation of the sexual reproductive pathway leading to the development of clonal progenies genetically identical to the mother plant. Here we used the Methylation-Sensitive Amplification Polymorphism (MSAP) technique to characterize cytosine methylation patterns occurring in florets of sexual and aposporous Paspalum notatum genotypes, in order to identify epigenetically-controlled genes putatively involved in apomixis development. From twelve polymorphic MSAP-derived sequences, one (PN_6.6, later renamed PN_SCD1) was selected due to its relevant annotation and differential representation in apomictic and sexual floral transcriptome libraries. PN_SCD1 encodes the DENN domain/WD repeat-containing protein SCD1, which interacts with RAB GTPases- and/or MAPKs to promote specialized cell division, functions in clathrin-mediated membrane transport and acts as potential substrate receptor of CUL4 E3 ubiquitin ligases. Quantitative RT-PCR and comparative RNAseq analyses of laser microdissected nucellar cells confirmed PN_SCD1 upregulation in florets of apomictic plants and revealed that overexpression takes place just before the onset of apospory initials. Moreover, we found that several SCD1 molecular partners are expressed in P. notatum florets and upregulated in apomictic plants. Our results disclosed a specific vesicle trafficking molecular pathway epigenetically modulated during apomixis.
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31
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Taşkin KM, Özbilen A, Sezer F, Hürkan K, Güneş Ş. Structure and expression of dna methyltransferase genes from apomictic and sexual Boechera species. Comput Biol Chem 2017; 67:15-21. [PMID: 28038368 DOI: 10.1016/j.compbiolchem.2016.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 09/30/2016] [Accepted: 12/09/2016] [Indexed: 10/20/2022]
Abstract
In this study, we determined the structure of DNA methyltransferase (DNMT) genes in apomict and sexual Boechera species and investigated the expression levels during seed development. Protein and DNA sequences of diploid sexual Boechera stricta DNMT genes obtained from Phytozome 10.3 were used to identify the homologues in apomicts, Boechera holboellii and Boechera divaricarpa. Geneious R8 software was used to map the short-paired reads library of B. holboellii whole genome or B. divaricarpa transcriptome reads to the reference gene sequences. We determined three DNMT genes; for Boechera spp. METHYLTRANSFERASE1 (MET1), CHROMOMETHYLASE 3 (CMT3) and DOMAINS REARRANGED METHYLTRANSFERASE 1/2 (DRM2). We examined the structure of these genes with bioinformatic tools and compared with other DNMT genes in plants. We also examined the levels of expression in silique tissues after fertilization by semi-quantitative PCR. The structure of DNMT proteins in apomict and sexual Boechera species share common features. However, the expression levels of DNMT genes were different in apomict and sexual Boechera species. We found that DRM2 was upregulated in apomictic Boechera species after fertilization. Phylogenetic trees showed that three genes are conserved among green algae, monocotyledons and dicotyledons. Our results indicated a deregulation of DNA methylation machinery during seed development in apomicts.
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Affiliation(s)
- Kemal Melik Taşkin
- Çanakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Biology, 17100 Çanakkale, Turkey.
| | - Aslıhan Özbilen
- Çanakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Biology, 17100 Çanakkale, Turkey
| | - Fatih Sezer
- Çanakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Biology, 17100 Çanakkale, Turkey
| | - Kaan Hürkan
- Çanakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Biology, 17100 Çanakkale, Turkey
| | - Şebnem Güneş
- Çanakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Biology, 17100 Çanakkale, Turkey
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Galla G, Zenoni S, Avesani L, Altschmied L, Rizzo P, Sharbel TF, Barcaccia G. Pistil Transcriptome Analysis to Disclose Genes and Gene Products Related to Aposporous Apomixis in Hypericum perforatum L. FRONTIERS IN PLANT SCIENCE 2017; 8:79. [PMID: 28203244 PMCID: PMC5285387 DOI: 10.3389/fpls.2017.00079] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/13/2017] [Indexed: 05/19/2023]
Abstract
Unlike sexual reproduction, apomixis encompasses a number of reproductive strategies, which permit maternal genome inheritance without genetic recombination and syngamy. The key biological features of apomixis are the circumvention of meiosis (i.e., apomeiosis), the differentiation of unreduced embryo sacs and egg cells, and their autonomous development in functional embryos through parthenogenesis, and the formation of viable endosperm either via fertilization-independent means or following fertilization with a sperm cell. Despite the importance of apomixis for breeding of crop plants and although much research has been conducted to study this process, the genetic control of apomixis is still not well understood. Hypericum perforatum is becoming an attractive model system for the study of aposporous apomixis. Here we report results from a global gene expression analysis of H. perforatum pistils collected from sexual and aposporous plant accessions for the purpose of identifying genes, biological processes and molecular functions associated with the aposporous apomixis pathway. Across two developmental stages corresponding to the expression of aposporous apomeiosis and parthenogenesis in ovules, a total of 224 and 973 unigenes were found to be significantly up- and down-regulated with a fold change ≥ 2 in at least one comparison, respectively. Differentially expressed genes were enriched for multiple gene ontology (GO) terms, including cell cycle, DNA metabolic process, and single-organism cellular process. For molecular functions, the highest scores were recorded for GO terms associated with DNA binding, DNA (cytosine-5-)-methyltransferase activity and heterocyclic compound binding. As deregulation of single components of the sexual developmental pathway is believed to be a trigger of the apomictic reproductive program, all genes involved in sporogenesis, gametogenesis and response to hormonal stimuli were analyzed in great detail. Overall, our data suggest that phenotypic expression of apospory is concomitant with the modulation of key genes involved in the sexual reproductive pathway. Furthermore, based on gene annotation and co-expression, we underline a putative role of hormones and key actors playing in the RNA-directed DNA methylation pathway in regulating the developmental changes occurring during aposporous apomixis in H. perforatum.
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Affiliation(s)
- Giulio Galla
- Laboratory of Genomics, Department of Agronomy, Food, Natural Resources, Animals and Environment, University of PadovaPadova, Italy
- *Correspondence: Giulio Galla
| | - Sara Zenoni
- Department of Biotechnology, University of VeronaVerona, Italy
| | - Linda Avesani
- Department of Biotechnology, University of VeronaVerona, Italy
| | - Lothar Altschmied
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Paride Rizzo
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
- Department of Breeding Research, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Timothy F. Sharbel
- Department of Breeding Research, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Gianni Barcaccia
- Laboratory of Genomics, Department of Agronomy, Food, Natural Resources, Animals and Environment, University of PadovaPadova, Italy
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Siena LA, Ortiz JPA, Calderini O, Paolocci F, Cáceres ME, Kaushal P, Grisan S, Pessino SC, Pupilli F. An apomixis-linked ORC3-like pseudogene is associated with silencing of its functional homolog in apomictic Paspalum simplex. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:1965-78. [PMID: 26842983 DOI: 10.1093/jxb/erw018] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Apomixis in plants consists of asexual reproduction by seeds. Here we characterized at structural and functional levels an apomixis-linked sequence of Paspalum simplex homologous to subunit 3 of the ORIGIN RECOGNITION COMPLEX (ORC3). ORC is a multiprotein complex which controls DNA replication and cell differentiation in eukaryotes. Three PsORC3 copies were identified, each one characterized by a specific expression profile. Of these, PsORC3a, specific for apomictic genotypes, is a pseudogene that was poorly and constitutively expressed in all developmental stages of apomictic flowers, whereas PsORC3b, the putative functional gene in sexual flowers, showed a precise time-related regulation. Sense transcripts of PsORC3 were expressed in the female cell lineage of both apomictic and sexual reproductive phenotypes, and in aposporous initials. Although strong expression was detected in sexual early endosperm, no expression was present in the apomictic endosperm. Antisense PsORC3 transcripts were revealed exclusively in apomictic germ cell lineages. Defective orc3 mutants of rice and Arabidopsis showed normal female gametophytes although the embryo and endosperm were arrested at early phases of development. We hypothesize that PsORC3a is associated with the down-regulation of its functional homolog and with the development of apomictic endosperm which deviates from the canonical 2(maternal):1(paternal) genome ratio.
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Affiliation(s)
- Lorena A Siena
- Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina
| | - Juan Pablo A Ortiz
- Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina
| | - Ornella Calderini
- Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy
| | - Francesco Paolocci
- Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy
| | - Maria E Cáceres
- Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy
| | - Pankaj Kaushal
- Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy
| | - Simone Grisan
- Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy
| | - Silvina C Pessino
- Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina
| | - Fulvio Pupilli
- Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy
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Shah JN, Kirioukhova O, Pawar P, Tayyab M, Mateo JL, Johnston AJ. Depletion of Key Meiotic Genes and Transcriptome-Wide Abiotic Stress Reprogramming Mark Early Preparatory Events Ahead of Apomeiotic Transition. FRONTIERS IN PLANT SCIENCE 2016; 7:1539. [PMID: 27833618 PMCID: PMC5080521 DOI: 10.3389/fpls.2016.01539] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 09/30/2016] [Indexed: 05/19/2023]
Abstract
Molecular dissection of apomixis - an asexual reproductive mode - is anticipated to solve the enigma of loss of meiotic sex, and to help fixing elite agronomic traits. The Brassicaceae genus Boechera comprises of both sexual and apomictic species, permitting comparative analyses of meiotic circumvention (apomeiosis) and parthenogenesis. Whereas previous studies reported local transcriptome changes during these events, it remained unclear whether global changes associated with hybridization, polyploidy and environmental adaptation that arose during evolution of Boechera might serve as (epi)genetic regulators of early development prior apomictic initiation. To identify these signatures during vegetative stages, we compared seedling RNA-seq transcriptomes of an obligate triploid apomict and a diploid sexual, both isolated from a drought-prone habitat. Uncovered were several genes differentially expressed between sexual and apomictic seedlings, including homologs of meiotic genes ASYNAPTIC 1 (ASY1) and MULTIPOLAR SPINDLE 1 (MPS1) that were down-regulated in apomicts. An intriguing class of apomict-specific deregulated genes included several NAC transcription factors, homologs of which are known to be transcriptionally reprogrammed during abiotic stress in other plants. Deregulation of both meiotic and stress-response genes during seedling stages might possibly be important in preparation for meiotic circumvention, as similar transcriptional alteration was discernible in apomeiotic floral buds too. Furthermore, we noted that the apomict showed better tolerance to osmotic stress in vitro than the sexual, in conjunction with significant upregulation of a subset of NAC genes. In support of the current model that DNA methylation epigenetically regulates stress, ploidy, hybridization and apomixis, we noted that ASY1, MPS1 and NAC019 homologs were deregulated in Boechera seedlings upon DNA demethylation, and ASY1 in particular seems to be repressed by global DNA methylation exclusively in the apomicts. Variability in stress and transcriptional response in a diploid apomict, which is geographically distinct from the triploid apomict, pinpoints both common and independent features of apomixis evolution. Our study provides a molecular frame-work to investigate how the adaptive traits associated with the evolutionary history of apomicts co-adapted with meiotic gene deregulation at early developmental stage, in order to predate meiotic recombination, which otherwise is thought to be favorable in stress and low-fitness conditions.
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Affiliation(s)
- Jubin N. Shah
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Olga Kirioukhova
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Pallavi Pawar
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Muhammad Tayyab
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Juan L. Mateo
- Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
- *Correspondence: Amal J. Johnston, ; Juan L. Mateo,
| | - Amal J. Johnston
- Laboratory of Germline Genetics & Evo-Devo, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
- *Correspondence: Amal J. Johnston, ; Juan L. Mateo,
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