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Setayeshnasab M, Sabzalian MR, Rahimmalek M. The relation between apomictic seed production and morpho-physiological characteristics in a world collection of castor bean (Ricinus communis L.). Sci Rep 2024; 14:5013. [PMID: 38424457 PMCID: PMC10904805 DOI: 10.1038/s41598-024-53700-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 02/03/2024] [Indexed: 03/02/2024] Open
Abstract
Ricinus communis is one of the most important oilseed plants with many medicinal and industrial applications. Variation in 30 genotypes of castor bean collected from different regions of the world was evaluated for two consecutive years and the difference in seed production with two different reproductive modes (including apomixis and open-pollination) was compared based on yield components, agronomic traits, and phytochemical properties. Results of data analysis demonstrated that castor bean has the ability for a wide range of apomixis for seed production and the highest percentages of apomixis ability in the first and second years were 86.3% and 92.31%, respectively. Apomixis ability had a high positive correlation with yield components, seed oil content, and the amount of leaf rutin. Two genotypes from Brazil and Syria revealed the highest phenolic content in the first and second years, respectively. In addition, the Afghanistan genotype in two modes of apomixis and open-pollination in the first year and the Syria and Yazd genotypes in apomixis and open-pollination modes, respectively, in the second year showed the highest content of seed fatty acids. It is possible to maintain superior genotypes of castor bean in terms of phytochemical traits, yield, and oil quality through apomixis reproduction.
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Affiliation(s)
- Maedeh Setayeshnasab
- Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, 84156-83111, Isfahan, Iran
| | - Mohammad R Sabzalian
- Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, 84156-83111, Isfahan, Iran.
| | - Mehdi Rahimmalek
- Department of Horticulture, College of Agriculture, Isfahan University of Technology, 84156-83111, Isfahan, Iran
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Cornaro L, Banfi C, Cucinotta M, Colombo L, van Dijk PJ. Asexual reproduction through seeds: the complex case of diplosporous apomixis. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:2462-2478. [PMID: 36794770 DOI: 10.1093/jxb/erad054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 02/07/2023] [Indexed: 06/06/2023]
Abstract
Apomixis is considered a potentially revolutionary tool to generate high-quality food at a lower cost and shorter developmental time due to clonal seed production through apomeiosis and parthenogenesis. In the diplosporous type of apomixis, meiotic recombination and reduction are circumvented either by avoiding or failing meiosis or by a mitotic-like division. Here, we review the literature on diplospory, from early cytological studies dating back to the late 19th century to recent genetic findings. We discuss diplosporous developmental mechanisms, including their inheritance. Furthermore, we compare the strategies adopted to isolate the genes controlling diplospory with those to produce mutants forming unreduced gametes. Nowadays, the dramatically improved technologies of long-read sequencing and targeted CRISPR/Cas mutagenesis justify the expectation that natural diplospory genes will soon be identified. Their identification will answer questions such as how the apomictic phenotype can be superimposed upon the sexual pathway and how diplospory genes have evolved. This knowledge will contribute to the application of apomixis in agriculture.
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Affiliation(s)
- Letizia Cornaro
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Camilla Banfi
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Mara Cucinotta
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Lucia Colombo
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Peter J van Dijk
- KeyGene N.V., Agro Business Park 90, 6708 PW Wageningen, The Netherlands
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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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Zappacosta D, Gallardo J, Carballo J, Meier M, Rodrigo JM, Gallo CA, Selva JP, Stein J, Ortiz JPA, Albertini E, Echenique V. A High-Density Linkage Map of the Forage Grass Eragrostis curvula and Localization of the Diplospory Locus. FRONTIERS IN PLANT SCIENCE 2019; 10:918. [PMID: 31354781 PMCID: PMC6640543 DOI: 10.3389/fpls.2019.00918] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 06/28/2019] [Indexed: 05/05/2023]
Abstract
Eragrostis curvula (Schrad.) Nees (weeping lovegrass) is an apomictic species native to Southern Africa that is used as forage grass in semiarid regions of Argentina. Apomixis is a mechanism for clonal propagation through seeds that involves the avoidance of meiosis to generate an unreduced embryo sac (apomeiosis), parthenogenesis, and viable endosperm formation in a fertilization-dependent or -independent manner. Here, we constructed the first saturated linkage map of tetraploid E. curvula using both traditional (AFLP and SSR) and high-throughput molecular markers (GBS-SNP) and identified the locus controlling diplospory. We also identified putative regulatory regions affecting the expressivity of this trait and syntenic relationships with genomes of other grass species. We obtained a tetraploid mapping population from a cross between a full sexual genotype (OTA-S) with a facultative apomictic individual of cv. Don Walter. Phenotypic characterization of F1 hybrids by cytoembryological analysis yielded a 1:1 ratio of apomictic vs. sexual plants (34:27, X 2 = 0.37), which agrees with the model of inheritance of a single dominant genetic factor. The final number of markers was 1,114 for OTA-S and 2,019 for Don Walter. These markers were distributed into 40 linkage groups per parental genotype, which is consistent with the number of E. curvula chromosomes (containing 2 to 123 markers per linkage group). The total length of the OTA-S map was 1,335 cM, with an average marker density of 1.22 cM per marker. The Don Walter map was 1,976.2 cM, with an average marker density of 0.98 cM/marker. The locus responsible for diplospory was mapped on Don Walter linkage group 3, with other 65 markers. QTL analyses of the expressivity of diplospory in the F1 hybrids revealed the presence of two main QTLs, located 3.27 and 15 cM from the diplospory locus. Both QTLs explained 28.6% of phenotypic variation. Syntenic analysis allowed us to establish the groups of homologs/homeologs for each linkage map. The genetic linkage map reported in this study, the first such map for E. curvula, is the most saturated map for the genus Eragrostis and one of the most saturated maps for a polyploid forage grass species.
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Affiliation(s)
- Diego Zappacosta
- Departamento de Agronomía, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Jimena Gallardo
- Departamento de Agronomía, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - José Carballo
- Departamento de Agronomía, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Mauro Meier
- Laboratorio Biotecnológico, Asociación de Cooperativas Argentinas Coop. Ltd., Pergamino, Argentina
| | - Juan Manuel Rodrigo
- Departamento de Agronomía, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Cristian A. Gallo
- Departamento de Agronomía, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Juan Pablo Selva
- Departamento de Agronomía, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Juliana Stein
- Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Zavalla, Argentina
| | - Juan Pablo A. Ortiz
- Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR, CONICET-UNR), Zavalla, Argentina
| | - Emidio Albertini
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy
- Emidio Albertini,
| | - Viviana Echenique
- Departamento de Agronomía, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Universidad Nacional del Sur, Bahía Blanca, Argentina
- *Correspondence: Viviana Echenique,
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Lee MS, Anderson EK, Stojšin D, McPherson MA, Baltazar B, Horak MJ, de la Fuente JM, Wu K, Crowley JH, Rayburn AL, Lee DK. Assessment of the potential for gene flow from transgenic maize (Zea mays L.) to eastern gamagrass (Tripsacum dactyloides L.). Transgenic Res 2017; 26:501-514. [PMID: 28466411 PMCID: PMC5504203 DOI: 10.1007/s11248-017-0020-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 04/24/2017] [Indexed: 10/24/2022]
Abstract
Eastern gamagrass (Tripsacum dactyloides L.) belongs to the same tribe of the Poaceae family as maize (Zea mays L.) and grows naturally in the same region where maize is commercially produced in the USA. Although no evidence exists of gene flow from maize to eastern gamagrass in nature, experimental crosses between the two species were produced using specific techniques. As part of environmental risk assessment, the possibility of transgene flow from maize to eastern gamagrass populations in nature was evaluated with the objectives: (1) to assess the seeds of eastern gamagrass populations naturally growing near commercial maize fields for the presence of a transgenic glyphosate-tolerance gene (cp4 epsps) that would indicate cross-pollination between the two species, and (2) to evaluate the possibility of interspecific hybridization between transgenic maize used as male parent and eastern gamagrass used as female parent. A total of 46,643 seeds from 54 eastern gamagrass populations collected in proximity of maize fields in Illinois, USA were planted in a field in 2014 and 2015. Emerged seedlings were treated with glyphosate herbicide and assessed for survival. An additional 48,000 seeds from the same 54 eastern gamagrass populations were tested for the presence of the cp4 epsps transgene markers using TaqMan® PCR method. The results from these trials showed that no seedlings survived the herbicide treatment and no seed indicated presence of the herbicide tolerant cp4 epsps transgene, even though these eastern gamagrass populations were exposed to glyphosate-tolerant maize pollen for years. Furthermore, no interspecific hybrid seeds were produced from 135 hand-pollination attempts involving 1529 eastern gamagrass spikelets exposed to maize pollen. Together, these results indicate that there is no evidence of gene flow from maize to eastern gamagrass in natural habitats. The outcome of this study should be taken in consideration when assessing for environmental risks regarding the consequence of gene flow from transgenic maize to its wild relatives.
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Affiliation(s)
- Moon-Sub Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Eric K Anderson
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Duška Stojšin
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Marc A McPherson
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Baltazar Baltazar
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Michael J Horak
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Juan Manuel de la Fuente
- Monsanto Company, Park Plaza Torre II, 504 Javier Barros Sierra Ave., Col. Santa Fe, Del. Alvaro Obregon, CP 01210, Mexico, DF, Mexico
| | - Kunsheng Wu
- Monsanto Company, 700 Chesterfield Parkway W., St. Louis, MO, 63017, USA
| | - James H Crowley
- Monsanto Company, 700 Chesterfield Parkway W., St. Louis, MO, 63017, USA
| | - A Lane Rayburn
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - D K Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA.
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Abstract
Apomixis, commonly defined as asexual reproduction through seed, is a reproductive trait that occurs in only a few minor crops, but would be highly valuable in major crops. Apomixis results in seed-derived progenies that are genetically identical to their maternal parent. The advantage of apomixis would lie in seed propagation of elite food, feed, and biofuel crops that are heterozygous such as hybrid corn and switchgrass or self-pollinating crops for which no commercial-scale hybrid production system is available. While hybrid plants often outperform parental lines in growth and higher yields, production of hybrid seed is accomplished through carefully controlled, labor intensive crosses. Both small farmers in developing countries who produce their own seed and commercial companies that market hybrid seed could benefit from the establishment of engineered apomixis in plants. In this chapter, we review what has been learned from studying natural apomicts and mutations in sexual plants leading to apomixis-like development, plus discuss how the components of apomixis could be successfully engineered in plants.
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Affiliation(s)
- Joann A Conner
- Horticulture Department, NESPAL/University of Georgia-Tifton Campus, 2356 Rainwater Road, Tifton, GA, 31794, USA.
| | - Peggy Ozias-Akins
- Horticulture Department, NESPAL/University of Georgia-Tifton Campus, 2356 Rainwater Road, Tifton, GA, 31794, USA
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia-Tifton Campus, Tifton, GA, USA
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Bicknell R, Catanach A, Hand M, Koltunow A. Seeds of doubt: Mendel's choice of Hieracium to study inheritance, a case of right plant, wrong trait. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2016; 129:2253-2266. [PMID: 27695890 PMCID: PMC5121183 DOI: 10.1007/s00122-016-2788-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 09/12/2016] [Indexed: 05/14/2023]
Abstract
KEY MESSAGE In this review, we explore Gregor Mendel's hybridization experiments with Hieracium , update current knowledge on apomictic reproduction and describe approaches now being used to develop true-breeding hybrid crops. From our perspective, it is easy to conclude that Gregor Mendel's work on pea was insightful, but his peers clearly did not regard it as being either very convincing or of much importance. One apparent criticism was that his findings only applied to pea. We know from a letter he wrote to Carl von Nägeli, a leading botanist, that he believed he needed to "verify, with other plants, the results obtained with Pisum". For this purpose, Mendel adopted Hieracium subgenus Pilosella, a phenotypically diverse taxon under botanical study at the time. What Mendel could not have known, however, is that the majority of these plants are not sexual plants like pea, but instead are facultatively apomictic. In these forms, the majority of seed arises asexually, and such progeny are, therefore, clones of the maternal parent. Mendel obtained very few hybrids in his Hieracium crosses, yet we calculate that he probably emasculated in excess of 5000 Hieracium florets to even obtain the numbers he did. Despite that effort, he was perplexed by the results, and they ultimately led him to conclude that "the hybrids of Hieracium show a behaviour exactly opposite to those of Pisum". Apomixis is now a topic of intense research interest, and in an ironic twist of history, Hieracium subgenus Pilosella has been developed as a molecular model to study this trait. In this paper, we explore further Mendel's hybridization experiments with Hieracium, update current knowledge on apomictic reproduction and describe approaches now being used to develop true-breeding hybrid crops.
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Affiliation(s)
- Ross Bicknell
- Plant and Food Research, Private Bag 4704, Christchurch, 8140, New Zealand
| | - Andrew Catanach
- Plant and Food Research, Private Bag 4704, Christchurch, 8140, New Zealand
| | - Melanie Hand
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Private Bag 2, Glen Osmond, SA, 5064, Australia
| | - Anna Koltunow
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Private Bag 2, Glen Osmond, SA, 5064, Australia.
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Neiman M, Sharbel TF, Schwander T. Genetic causes of transitions from sexual reproduction to asexuality in plants and animals. J Evol Biol 2014; 27:1346-59. [DOI: 10.1111/jeb.12357] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/17/2014] [Accepted: 02/18/2014] [Indexed: 11/30/2022]
Affiliation(s)
- M. Neiman
- Department of Biology; University of Iowa; Iowa City IA USA
| | - T. F. Sharbel
- Apomixis Research Group; Leibniz Institute of Plant Genetics and Crop Plant Research (IPK); Gatersleben Germany
| | - T. Schwander
- Department of Ecology and Evolution; University of Lausanne; Lausanne Switzerland
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Barcaccia G, Albertini E. Apomixis in plant reproduction: a novel perspective on an old dilemma. PLANT REPRODUCTION 2013; 26:159-79. [PMID: 23852378 PMCID: PMC3747320 DOI: 10.1007/s00497-013-0222-y] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 06/23/2013] [Indexed: 05/19/2023]
Abstract
Seed is one of the key factors of crop productivity. Therefore, a comprehension of the mechanisms underlying seed formation in cultivated plants is crucial for the quantitative and qualitative progress of agricultural production. In angiosperms, two pathways of reproduction through seed exist: sexual or amphimictic, and asexual or apomictic; the former is largely exploited by seed companies for breeding new varieties, whereas the latter is receiving continuously increasing attention from both scientific and industrial sectors in basic research projects. If apomixis is engineered into sexual crops in a controlled manner, its impact on agriculture will be broad and profound. In fact, apomixis will allow clonal seed production and thus enable efficient and consistent yields of high-quality seeds, fruits, and vegetables at lower costs. The development of apomixis technology is expected to have a revolutionary impact on agricultural and food production by reducing cost and breeding time, and avoiding the complications that are typical of sexual reproduction (e.g., incompatibility barriers) and vegetative propagation (e.g., viral transfer). However, the development of apomixis technology in agriculture requires a deeper knowledge of the mechanisms that regulate reproductive development in plants. This knowledge is a necessary prerequisite to understanding the genetic control of the apomictic process and its deviations from the sexual process. Our molecular understanding of apomixis will be greatly advanced when genes that are specifically or differentially expressed during embryo and embryo sac formation are discovered. In our review, we report the main findings on this subject by examining two approaches: i) analysis of the apomictic process in natural apomictic species to search for genes controlling apomixis and ii) analysis of gene mutations resembling apomixis or its components in species that normally reproduce sexually. In fact, our opinion is that a novel perspective on this old dilemma pertaining to the molecular control of apomixis can emerge from a cross-check among candidate genes in natural apomicts and a high-throughput analysis of sexual mutants.
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Affiliation(s)
- Gianni Barcaccia
- Laboratory of Genetics and Genomics, DAFNAE, University of Padova, Campus of Agripolis, Viale dell’Università 16, 35020 Legnaro, Italy
| | - Emidio Albertini
- Department of Applied Biology, University of Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy
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Paul P, Awasthi A, Kumar S, Verma SK, Prasad R, Dhaliwal HS. Development of multiple embryos in polyembryonic insertional mutant OsPE of rice. PLANT CELL REPORTS 2012; 31:1779-1787. [PMID: 22790320 DOI: 10.1007/s00299-012-1291-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 04/20/2012] [Accepted: 05/20/2012] [Indexed: 06/01/2023]
Abstract
A T-DNA insertional mutant OsPE of rice gives twin and triplet seedlings in up to 20 % of the seeds. Detailed cytological and histological analysis of OsPE indicated normal male and female gametogenesis in the OsPE mutant. Confocal laser scanning microscopic (CLSM) analysis of the developing seeds of OsPE showed multiple embryo development in up to 60 % of the ovules. The multiple embryos, mostly twins and triplets, and rarely quadruplets, developed through sequential cleavage from a single zygotic embryo in each ovule. The reduced number of multiple seedlings compared with multiple embryos observed in CLSM study may be attributed to their inability to develop further due to competition in a single embryo sac. Key message Multiple seedlings in the OsPE mutant are due to sequential proliferation and cleavage of the zygotic embryos. The nucellar tissue was not involved in multiple embryo development.
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Affiliation(s)
- Priyanka Paul
- Department of Biotechnology, Indian Institute of Technology, Roorkee, 247 667, Uttaranchal, India.
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Selva JP, C. Pessino S, S. Meier M, C. Echenique V. Identification of Candidate Genes Related to Polyploidy and/or Apomixis in <i>Eragrostis curvula</i>. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/ajps.2012.33049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Two polyploid hybrids between cassava (Manihot esculenta) cultivar 307-2 and its wild relatives M. glaziovii and M. anomala, were studied to examine the relationship between ploidy level and the production of seeds without fertilization. A clearing method was applied to assess ovule sizes as an indication of multiembryony. The diploid cultivar 307-2 had regular 18 bivalents at meiotic metaphase 1 while the polyploid types showed chromosome configurations varying from 3 to 4 quadrivalents and 28 to 30 bivalents. A total of 14% of studied ovules of the polyploid hybrid involving M. glaziovii were multiebryonic, while the percentage of multiembryony was as low as 2% in the polyploid hybrid M. anomala×M. esculenta. Diploid hybrid types did not show any multi embryony. Adventitious embryos were found and documented for the first time in polyploid hybrids M. esculenta×M. glaziovii. The association of multiple embryo formation with ovary size and pollination showed that apomictic embryos form independently from fertilization. Simple iodized carmine stain for measuring pollen viability proved as efficient as the sophisticated Alexander method.
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Cloning plants by seeds: Inheritance models and candidate genes to increase fundamental knowledge for engineering apomixis in sexual crops. J Biotechnol 2011; 159:291-311. [PMID: 21906637 DOI: 10.1016/j.jbiotec.2011.08.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 08/16/2011] [Accepted: 08/17/2011] [Indexed: 01/02/2023]
Abstract
Apomixis is desirable in agriculture as a reproductive strategy for cloning plants by seeds. Because embryos derive from the parthenogenic development of apomeiotic egg cells, apomixis excludes fertilization in addition to meiotic segregation and recombination, resulting in offspring that are exact replicas of the parent. Introgression of apomixis from wild relatives to crop species and transformation of sexual genotypes into apomictically reproducing ones are long-held goals of plant breeding. In fact, it is generally accepted that the introduction of apomixis into agronomically important crops will have revolutionary implications for agriculture. This review deals with the current genetic and molecular findings that have been collected from model species to elucidate the mechanisms of apomeiosis, parthenogenesis and apomixis as a whole. Our goal is to critically determine whether biotechnology can combine key genes known to control the expression of the processes miming the main components of apomixis in plants. Two natural apomicts, as the eudicot Hypericum perforatum L. (St. John's wort) and the monocot Paspalum spp. (crowngrass), and the sexual model species Arabidopsis thaliana are ideally suited for such investigations at the genomic and biotechnological levels. Some novel views and original concepts have been faced on this review, including (i) the parallel between Y-chromosome and apomixis-bearing chromosome (e.g., comparative genomic analyses revealed common features as repression of recombination events, accumulation of transposable elements and degeneration of genes) from the most primitive (Hypericum-type) to the most advanced (Paspalum-type) in evolutionary terms, and (ii) the link between apomixis and gene-specific silencing mechanisms (i.e., likely based on chromatin remodelling factors), with merging lines of evidence regarding the role of auxin in cell fate specification of embryo sac and egg cell development in Arabidopsis. The production of engineered plants exhibiting apomictic-like phenotypes is critically reviewed and discussed.
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Aliyu OM, Schranz ME, Sharbel TF. Quantitative variation for apomictic reproduction in the genus Boechera (Brassicaceae). AMERICAN JOURNAL OF BOTANY 2010; 97:1719-31. [PMID: 21616805 DOI: 10.3732/ajb.1000188] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
PREMISE OF THE STUDY The evolution of asexual seed production (apomixis) from sexual relatives is a great enigma of plant biology. The genus Boechera is ideal for studying apomixis because of its close relation to Arabidopsis and the occurrence of sexual and apomictic species at low ploidy levels (diploid and triploid). Apomixis is characterized by three components: unreduced embryo-sac formation (apomeiosis), fertilization-independent embryogenesis (parthenogenesis), and functional endosperm formation (pseudogamy or autonomous endosperm formation). Understanding the variation in these traits within and between species has been hindered by the laborious histological analyses required to analyze large numbers of samples. • METHODS To quantify variability for the different components of apomictic seed development, we developed a high-throughput flow cytometric seed screen technique to measure embryo:endosperm ploidy in over 22000 single seeds derived from 71 accessions of diploid and triploid Boechera. • KEY RESULTS Three interrelated features were identified within and among Boechera species: (1) variation for most traits associated with apomictic seed formation, (2) three levels of apomeiosis expression (low, high, obligate), and (3) correlations between apomeiosis and parthenogenesis/pseudogamy. • CONCLUSIONS The data presented here provide a framework for choosing specific genotypes for correlations with large "omics" data sets being collected for Boechera to study population structure, gene flow, and evolution of specific traits. We hypothesize that low levels of apomeiosis represent an ancestral condition of Boechera, whereas high apomeiosis levels may have been induced by global gene regulatory changes associated with hybridization.
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Affiliation(s)
- Olawale M Aliyu
- Apomixis Research Group, Leibniz Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany
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16
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Schallau A, Arzenton F, Johnston AJ, Hähnel U, Koszegi D, Blattner FR, Altschmied L, Haberer G, Barcaccia G, Bäumlein H. Identification and genetic analysis of the APOSPORY locus in Hypericum perforatum L. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:773-84. [PMID: 20202173 DOI: 10.1111/j.1365-313x.2010.04188.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The introduction of apomixis - seed formation without fertilization - into crop plants is a long-held goal of breeding research, since it would allow for the ready fixation of heterozygosity. The genetic basis of apomixis, whether of the aposporous or the diplosporous type, is still only poorly understood. Hypericum perforatum (St John's wort), a plant with a small genome and a short generation time, can be aposporous and/or parthenogenetic, and so represents an interesting model dicot for apomixis research. Here we describe a genetic analysis which first defined and then isolated a locus (designated HAPPY for Hypericum APOSPORY) associated with apospory. Amplified fragment length polymorphism (AFLP) profiling was used to generate a cleaved amplified polymorphic sequence (CAPS) marker for HAPPY which co-segregated with apospory but not with parthenogenesis, showing that these two components of apomixis are independently controlled. Apospory was inherited as a dominant simplex gene at the tetraploid level. Part of the HAPPY sequence is homologous to the Arabidopsis thaliana gene ARI7 encoding the ring finger protein ARIADNE7. This protein is predicted to be involved in various regulatory processes, including ubiquitin-mediated protein degradation. While the aposporous and sexual alleles of the HAPPY component HpARI were co-expressed in many parts of the plant, the gene product of the apomict's allele is truncated. Cloning HpARI represents the first step towards the full characterization of HAPPY and the elucidation of the molecular mechanisms underlying apomixis in H. perforatum.
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Affiliation(s)
- Anna Schallau
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466 Gatersleben, Germany
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Fenby N, Pu H, Pennell R, Praekelt U, Day R, Scott R. An uncoupling screen for autonomous embryo mutants in Arabidopsis thaliana. ACTA ACUST UNITED AC 2010; 23:255-64. [PMID: 20454908 DOI: 10.1007/s00497-010-0142-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 04/16/2010] [Indexed: 11/25/2022]
Abstract
Simple de novo screens in Arabidopsis thaliana have previously identified mutants that affect endosperm development but viable-embryo mutants have not been identified. Our strategy to identify autonomous embryo development was to uncouple embryo and endosperm fertilisation. This involved a male-sterile mutant population being crossed with a distinct pollen parent--the pollen was needed to initiate endosperm development and because it was distinct, the maternal progeny could be selected from the hybrid population. This process was refined over three stages, resulting in a viable approach to screen for autonomous embryo mutants. From 8,000 screened plants, a mutation was isolated in which the integument cells extended from the ovule and proliferated into a second complete twinned ovule. Some embryos from the mutant were normal but others developed fused cotyledons. In addition, a proportion of the progeny lacked paternal genes.
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Affiliation(s)
- Nick Fenby
- Department of Biology and Biochemistry, Bath University, Bath BA2 7AY, UK
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18
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Conner JA, Goel S, Gunawan G, Cordonnier-Pratt MM, Johnson VE, Liang C, Wang H, Pratt LH, Mullet JE, DeBarry J, Yang L, Bennetzen JL, Klein PE, Ozias-Akins P. Sequence analysis of bacterial artificial chromosome clones from the apospory-specific genomic region of Pennisetum and Cenchrus. PLANT PHYSIOLOGY 2008; 147:1396-411. [PMID: 18508959 PMCID: PMC2442526 DOI: 10.1104/pp.108.119081] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 05/25/2008] [Indexed: 05/18/2023]
Abstract
Apomixis, asexual reproduction through seed, is widespread among angiosperm families. Gametophytic apomixis in Pennisetum squamulatum and Cenchrus ciliaris is controlled by the apospory-specific genomic region (ASGR), which is highly conserved and macrosyntenic between these species. Thirty-two ASGR bacterial artificial chromosomes (BACs) isolated from both species and one ASGR-recombining BAC from P. squamulatum, which together cover approximately 2.7 Mb of DNA, were used to investigate the genomic structure of this region. Phrap assembly of 4,521 high-quality reads generated 1,341 contiguous sequences (contigs; 730 from the ASGR and 30 from the ASGR-recombining BAC in P. squamulatum, plus 580 from the C. ciliaris ASGR). Contigs containing putative protein-coding regions unrelated to transposable elements were identified based on protein similarity after Basic Local Alignment Search Tool X analysis. These putative coding regions were further analyzed in silico with reference to the rice (Oryza sativa) and sorghum (Sorghum bicolor) genomes using the resources at Gramene (www.gramene.org) and Phytozome (www.phytozome.net) and by hybridization against sorghum BAC filters. The ASGR sequences reveal that the ASGR (1) contains both gene-rich and gene-poor segments, (2) contains several genes that may play a role in apomictic development, (3) has many classes of transposable elements, and (4) does not exhibit large-scale synteny with either rice or sorghum genomes but does contain multiple regions of microsynteny with these species.
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Affiliation(s)
- Joann A Conner
- Department of Horticulture, University of Georgia, Tifton, Georgia 31793-0748, USA
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19
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Cervigni GDL, Paniego N, Pessino S, Selva JP, Díaz M, Spangenberg G, Echenique V. Gene expression in diplosporous and sexual Eragrostis curvula genotypes with differing ploidy levels. PLANT MOLECULAR BIOLOGY 2008; 67:11-23. [PMID: 18311543 DOI: 10.1007/s11103-008-9305-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Accepted: 01/31/2008] [Indexed: 05/04/2023]
Abstract
The molecular nature of gene expression during the initiation and progress of diplosporous apomixis is still unknown. Moreover, the basis of the close correlation between diplospory and polyploidy is not clarified yet. A comparative expression analysis was performed based on expressed sequence tags (ESTs) sequencing and differential display in an Eragrostis curvula diplosporous tetraploid genotype (T, 4x apo), a sexual diploid derivative obtained from tissue culture (D, 2x sex) and an artificial sexual tetraploid obtained from the diploid seeds after colchicine treatment (C, 4x sex). From a total of 8,884 unigenes sequenced from inflorescence-derived libraries, 112 (1.26%) showed significant differential expression in individuals with different ploidy level and/or variable reproductive mode. Independent comparisons between plants with different reproductive mode (same ploidy) or different ploidy level (same reproductive mode) allowed the identification of genes modulated in response to diplosporous development or polyploidization, respectively. Surprisingly, a group of genes (Group 3) were differentially expressed or silenced only in the 4x sex plant, presenting similar levels of expression in the 4x apo and the 2x sex genotypes. A group of randomly selected differential genes was validated by QR-PCR. Differential display analysis showed that in general the 4x apo and 4x sex expression profiles were more related and different from the 2x sex one, but confirmed the existence of Group 3-type genes, in both inflorescences and leaves. The possible biological significance for the occurrence of this particular group of genes is discussed. In silico mapping onto the rice genome was used to identify candidates mapping to the region syntenic to the diplospory locus.
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Affiliation(s)
- Gerardo D L Cervigni
- Centro de Recursos Naturales Renovables de la Zona Semiárida- CONICET, Camino de La Carrindanga Km 7,0, Bahia Blanca, Argentina
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20
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Affiliation(s)
- Peggy Ozias-Akins
- Department of Horticulture, University of Georgia Tifton Campus, Tifton, Georgia;
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21
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Ge Y, He G, Wang Z, Guo D, Qin R, Li R. GISH and BAC-FISH study of apomictic Beta M14. ACTA ACUST UNITED AC 2007; 50:242-50. [PMID: 17447032 DOI: 10.1007/s11427-007-0018-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Accepted: 11/30/2006] [Indexed: 11/30/2022]
Abstract
Apomixis is a means of asexual reproduction by which plants produce embryos without fertilization and meiosis, therefore the embryo is of clonal and maternal origin. Interspecific hybrids between diploid B. vulgaris (2n=2x=18) and tetraploid B. corolliflora (2n=4x=36) were established, and then back-crossed with B. vulgaris. Among their offspring, monosomic addition line M14 (2n=2x=18+1) was selected because of the apomictic phenotype. We documented chromosome transmission from B. corolliflora into M14 by using genomic in situ hybridization (GISH). Suppression of cross-hybridization by blocking DNA was not necessary, indicating that the investigated Beta genome contains sufficient species-specific DNA, thus enabling the determination of genomic composition of the hybrids. We analyzed BAC microarrays of B. corolliflora chromosome 9 by using fluorescence-specific mRNA of B. vulgaris and Beta M14. BAC clones 16-M11 and 26-L15 were detected as fluorescence-specifics of BAC DNA of Beta M14. Then both BAC clones 16-M11 and 26-L15 were in situ hybridized to M14 chromosomes. The two hybridized BAC clones were located close to the telomere region of the long arm of a single chromosome 9, and showed hemizygosity. The results of BAC microarrays showed that these developments of embryo and endosperm have conservative expression patterns, indicating that sexual reproduction and apomixis have an interrelated pathway with common regulatory components and that the induction of a modified sexual reproduction program may enable the manifestation of apomixis in Beta species. It would be sufficient for the expression of apomixes with those apomictic-specific genes on chromosome 9 of B. corolliflora.
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Affiliation(s)
- Yan Ge
- Key Laboratory of Biochemistry and Molecular Biology, College of Life Sciences, Heilongjiang University, Harbin 150080, China
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22
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Schranz ME, Kantama L, de Jong H, Mitchell-Olds T. Asexual reproduction in a close relative of Arabidopsis: a genetic investigation of apomixis in Boechera (Brassicaceae). THE NEW PHYTOLOGIST 2006; 171:425-38. [PMID: 16866948 DOI: 10.1111/j.1469-8137.2006.01765.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Understanding apomixis (asexual reproduction through seeds) is of great interest to both plant breeders and evolutionary biologists. The genus Boechera is an excellent system for studying apomixis because of its close relationship to Arabidopsis, the occurrence of apomixis at the diploid level, and its potentially simple inheritance by transmission of a heterochromatic (Het) chromosome. Diploid sexual Boechera stricta and diploid apomictic Boechera divaricarpa (carrying a Het chromosome) were crossed. Flow cytometry, karyotype analysis, genomic in situ hybridization, pollen staining and seed-production measurements were used to analyse the parents and resulting F1, F2 and selected F3 and test-cross (TC) generations. The F1 plant was a low-fertility triploid that produced a swarm of aneuploid and polyploid F2 progeny. Two of the F2 plants were fertile near-tetraploids, and analysis of their F3 and TC progeny revealed that they were sexual and genomically stabilized. The apomictic phenotype was not transmitted by genetic crossing as a single dominant locus on the Het chromosome, suggesting a complex genetic control of apomixis that has implications for future genetic and evolutionary analyses in this group.
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Affiliation(s)
- M Eric Schranz
- Department of Genetics and Evolution, Max Planck Institute for Chemical Ecology, Hans Knoll Strasse 6, D-07745 Jena, Germany.
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23
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Matzk F, Prodanovic S, Bäumlein H, Schubert I. The Inheritance of apomixis in Poa pratensis confirms a five locus model with differences in gene expressivity and penetrance. THE PLANT CELL 2005; 17:13-24. [PMID: 15608334 PMCID: PMC544486 DOI: 10.1105/tpc.104.027359] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2004] [Accepted: 10/22/2004] [Indexed: 05/20/2023]
Abstract
The genetic control of apomixis was studied in numerous segregating progenies originated from intercrossing and selfing of obligate sexual and facultative apomictic parents in Poa pratensis by means of the flow cytometric seed screen. The data support a novel model with five major genes required to control asexual seed formation: the Apospory initiator (Ait) gene, the Apospory preventer (Apv) gene, a Megaspore development (Mdv) gene, the Parthenogenesis initiator (Pit) gene, and the Parthenogenesis preventer (Ppv) gene. Differences in expressivity and interactions of these genes are responsible for the wide variation of the mode of reproduction. Apospory and parthenogenesis as well as the initiator and preventer genes of these components segregate independently. The genotypes with the highest expressivity of apospory and parthenogenesis were assigned as Ait-/apvapv/Pit-/ppvppv, those with intermediate expressivity as Ait-/Apv-/Pit-/Ppv-, and those with low expressivity as aitait/apvapv/pitpit/ppvppv. Among the self progenies of obligate sexual individuals, plants with a low capacity for apospory and/or parthenogenesis occurred, indicating that the sexual parents were heterozygous for the preventer genes and homozygous for the recessive initiator alleles (aitait/Apv-/pitpit/Ppv-). The dominant allele Ait exhibits incomplete penetrance. The degree of expressivity of apospory and parthenogenesis was constant among several harvest years of F1 plants.
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Affiliation(s)
- Fritz Matzk
- Institut für Pflanzengenetik und Kulturpflanzenforschung, 06466 Gatersleben, Germany.
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24
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Pessino SC, Evans C, Ortiz JPA, Armstead I, Valle CBD, Hayward MD. A Genetic Map of the Apospory-Region in Brachiaria Hybrids: Identification of two Markers Closely Associated with the Trait. Hereditas 2004. [DOI: 10.1111/j.1601-5223.1998.00153.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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26
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Vijverberg K, Van Der Hulst RGM, Lindhout P, Van Dijk PJ. A genetic linkage map of the diplosporous chromosomal region in Taraxacum officinale (common dandelion; Asteraceae). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2004; 108:725-32. [PMID: 14564398 DOI: 10.1007/s00122-003-1474-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2003] [Accepted: 09/10/2003] [Indexed: 05/09/2023]
Abstract
In this study, we mapped the diplosporous chromosomal region in Taraxacum officinale, by using amplified fragment length polymorphism technology (AFLP) in 73 plants from a segregating population. Taraxacum serves as a model system to investigate the genetics, ecology, and evolution of apomixis. The genus includes sexual diploid as well as apomictic polyploid, mostly triploid, plants. Apomictic Taraxacum is diplosporous, parthenogenetic, and has autonomous endosperm formation. Previous studies have indicated that these three apomixis elements are controlled by more than one locus in Taraxacum and that diplospory inherits as a dominant, monogenic trait ( Ddd; DIP). A bulked segregant analysis provided 34 AFLP markers that were linked to DIP and were, together with two microsatellite markers, used for mapping the trait. The map length was 18.6 cM and markers were found on both sides of DIP, corresponding to 5.9 and 12.7 cM, respectively. None of the markers completely co-segregated with DIP. Eight markers were selected for PCR-based marker development, of which two were successfully converted. In contrast to all other mapping studies of apomeiosis to date, our results showed no evidence for suppression of recombination around the DIP locus in Taraxacum. No obvious evidence for sequence divergence between the DIP and non- DIP homologous loci was found, and no hemizygosity at the DIP locus was detected. These results may indicate that apomixis is relatively recent in Taraxacum.
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Affiliation(s)
- K Vijverberg
- Centre for Terrestrial Ecology, Netherlands Institute of Ecology, Boterhoeksestraat 48, 6666 GA Heteren, The Netherlands.
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27
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Ozias-Akins P, Akiyama Y, Hanna WW. Molecular characterization of the genomic region linked with apomixis in Pennisetum/Cenchrus. Funct Integr Genomics 2003; 3:94-104. [PMID: 12827522 DOI: 10.1007/s10142-003-0084-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2002] [Revised: 04/11/2003] [Accepted: 04/15/2003] [Indexed: 10/26/2022]
Abstract
Apomixis is defined as asexual reproduction through seeds, although this outcome can be achieved by multiple pathways. Since little is known about the molecular control of these pathways, how they might intersect is also a mystery. Two of these pathways in the grass family, diplospory and apospory, are receiving attention from molecular biologists. Apospory in Pennisetum/Cenchrus, two genera of panicoid grasses, results in the formation of four-nucleate embryo sacs that lack antipodals. Sexual reproduction frequently aborts so that the resulting seed is composed of (1) a parthenogenetically derived embryo that is genetically identical to the mother and (2) endosperm formed through pseudogamy. The transmission of apomixis is associated with the transfer of a linkage block on a single chromosome. This linkage block contains repetitive sequences as well as hemizygous, low-copy DNA sequences. Fluorescence in situ hybridization has demonstrated that these DNA regions occur on only a single chromosome, but not its homologs, in the polyploid apomicts studied. Features of the apomixis-associated region resemble those of other chromosomal segments isolated from recombination and replete with "selfish" DNAs.
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Affiliation(s)
- Peggy Ozias-Akins
- Department of Horticulture, University of Georgia Tifton Campus, Tifton, GA 31793-0748, USA.
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Jessup RW, Burson BL, Burow O, Wang YW, Chang C, Li Z, Paterson AH, Hussey MA. Segmental allotetraploidy and allelic interactions in buffelgrass (Pennisetum ciliare (L.) Link syn. Cenchrus ciliaris L.) as revealed by genome mapping. Genome 2003; 46:304-13. [PMID: 12723046 DOI: 10.1139/g03-005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Linkage analyses increasingly complement cytological and traditional plant breeding techniques by providing valuable information regarding genome organization and transmission genetics of complex polyploid species. This study reports a genome map of buffelgrass (Pennisetum ciliare (L.) Link syn. Cenchrus ciliaris L.). Maternal and paternal maps were constructed with restriction fragment length polymorphisms (RFLPs) segregating in 87 F1 progeny from an intraspecific cross between two heterozygous genotypes. A survey of 862 heterologous cDNAs and gDNAs from across the Poaceae, as well as 443 buffelgrass cDNAs, yielded 100 and 360 polymorphic probes, respectively. The maternal map included 322 RFLPs, 47 linkage groups, and 3464 cM, whereas the paternal map contained 245 RFLPs, 42 linkage groups, and 2757 cM. Approximately 70 to 80% of the buffelgrass genome was covered, and the average marker spacing was 10.8 and 11.3 cM on the respective maps. Preferential pairing was indicated between many linkage groups, which supports cytological reports that buffelgrass is a segmental allotetraploid. More preferential pairing (disomy) was found in the maternal than paternal parent across linkage groups (55 vs. 38%) and loci (48 vs. 15%). Comparison of interval lengths in 15 allelic bridges indicated significantly less meiotic recombination in paternal gametes. Allelic interactions were detected in four regions of the maternal map and were absent in the paternal map.
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Affiliation(s)
- R W Jessup
- Department of Soil and Crop Sciences, Texas A & M University, College Station, TX 77843, U.S.A
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29
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Goel S, Chen Z, Conner JA, Akiyama Y, Hanna WW, Ozias-Akins P. Delineation by fluorescence in situ hybridization of a single hemizygous chromosomal region associated with aposporous embryo sac formation in Pennisetum squamulatum and Cenchrus ciliaris. Genetics 2003; 163:1069-82. [PMID: 12663545 PMCID: PMC1462501 DOI: 10.1093/genetics/163.3.1069] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Apomixis is a means of asexual reproduction by which plants produce embryos without meiosis and fertilization; thus the embryo is of clonal, maternal origin. We previously reported molecular markers showing no recombination with the trait for aposporous embryo sac development in Pennisetum squamulatum and Cenchrus ciliaris, and the collective single-dose alleles defined an apospory-specific genomic region (ASGR). Fluorescence in situ hybridization (FISH) was used to confirm that the ASGR is a hemizygous genomic region and to determine its chromosomal position with respect to rDNA loci and centromere repeats. We also documented chromosome transmission from P. squamulatum in several backcrosses (BCs) with P. glaucum using genomic in situ hybridization (GISH). One to three complete P. squamulatum chromosomes were detected in BC(6), but only one of the three hybridized with the ASGR-linked markers. In P. squamulatum and in all BCs examined, the apospory-linked markers were located in the distal region of the short arm of a single chromosome. All alien chromosomes behaved as univalents during meiosis and segregated randomly in BC(3) and later BC generations, but presence of the ASGR-carrier chromosome alone was sufficient to confer apospory. FISH results support our hypotheses that hemizygosity, proximity to centromeric sequences, and chromosome structure may all play a role in low recombination in the ASGR.
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Affiliation(s)
- Shailendra Goel
- Department of Horticulture, University of Georgia, Tifton, Georgia 31793-0748, USA
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30
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Abstract
Previous studies on the inheritance of aposporous apomixis in bahiagrass showed a wide range of segregation ratios in crosses involving sexual and aposporous apomictic plants. The F1 progenies were classified through a visual progeny test carried out on few F2 plants. The number of sexual F1s highly exceeded the apomictics leading to the conclusion that apomixis was controlled by a few recessive genes. The present study examines the inheritance of apospory in bahiagrass. A sexual plant was self-pollinated and crossed with an aposporous apomictic plant as pollen donor. Backcross and F2 progenies were obtained in several combinations. All self-pollinated sexual plants or sexual x sexual crosses produced progenies free of apospory. All crosses involving a sexual and an apomictic plant produced approximately three times more apospory-free plants than plants with apospory. Bahiagrass is of autotetraploid origin and hence is expected to display tetrasomic inheritance. The most widely accepted genetic model for inheritance of apospory in tropical grasses is a single dominant gene with tetrasomic inheritance. In the present experiments none of the apospory-free F1s segregated for the apospory trait indicating that it is most likely a dominant character. However, the observed results fit better a modified model: tetrasomic inheritance of a single dominant gene with pleiotropic effect and incomplete penetrance. The excess of apospory-free plants in the F1 progeny could be ascribed to some distortion in the segregation pattern due to a pleiotropic lethal effect of the dominant A allele with incomplete penetrance. Alternatively, partial lethality of factors linked to aposporous gene may account for segregation distortion against apospory.
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Affiliation(s)
- E J Martínez
- Instituto de Botánica del Nordeste, Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Corrientes, Argentina
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Blakey CA, Goldman SL, Dewald CL. Apomixis in Tripsacum: comparative mapping of a multigene phenomenon. Genome 2001; 44:222-30. [PMID: 11341732 DOI: 10.1139/g00-105] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A relationship has been established between the expression of apomixis in natural polyploids of Tripsacum dactyloides and fertility as measured by percent seed set. Thus, fertility may be reliably used as a defining phenotype for apomixis when scoring the progeny from diploid (2n = 2x = 36) x tetraploid (2n = 4x = 72) crosses in Tripsacum. By exploiting the relationship between apomixis and fertility, as defined by seed set, analyses were performed on a set of related second-generation triploid populations segregating for apomixis. These populations were derived from sexual (diploid) x apomictic (tetraploid) crosses. Six out of 25 genome-dispersed restriction fragment length polymorphism (RFLP) markers co-segregate with fertility. Five of these markers were previously reported and include: php20855, tda48, tda53, umc62, and umc83, and are linked to Tripsacum genetic linkage groups F, I, H, L, and A, respectively. Significantly, we report here the syntenic relationships of the maize chromosome intervals to Tripsacum that segregate for numerous meiosis-specific and fertility-associated genes. Utilizing RFLP locus comparative mapping based on conservation of chromosome (genic) regions between related species, it may be concluded that the genes controlling fertility have been preserved in both Tripsacum and maize. A sixth marker, umc166, has also been shown to co-segregate with fertility and is conserved in both grass species. Specifically, umc166 is linked to Tripsacum linkage group D and, by syntenic comparison, to the short arm of maize chromosome 5. Encoded within this marked interval is the gene Ameiotic1 (Am1) whose function is required for the initiation of meiosis in both micro- and megaspore mother cells and whose absence of expression in the female is, in all likelihood, a prerequisite for the expression of apomixis.
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Affiliation(s)
- C A Blakey
- Department of Biology, Ball State University, Muncie, IN 47306, USA
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Barcaccia G, Albertini E, Rosellini D, Tavoletti S, Veronesi F. Inheritance and mapping of 2n-egg production in diploid alfalfa. Genome 2000; 43:528-37. [PMID: 10902718 DOI: 10.1139/g00-017] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The production of eggs with the sporophytic chromosome number (2n eggs) in diploid alfalfa (Medicago spp.) is mainly associated with the absence of cytokinesis after restitutional meiosis. The formation of 2n eggs through diplosporic apomeiosis has also been documented in a diploid mutant of M. sativa subsp. falcata (L.) Arcang. (2n = 2x = 16), named PG-F9. Molecular tagging of 2n-egg formation appears to be an essential step towards marker-assisted breeding and map-based cloning strategies aimed at investigating and manipulating reproductive mutants of the M. sativa complex. We made controlled crosses between PG-F9 and three wild type plants of M. sativa subsp. coerulea (Less.) Schm. (2n = 2x = 16) and then hand-pollinated the F1 progenies with tetraploid plants of M. sativa subsp. sativa L. (2n = 4x = 32). As a triploid embryo block prevents the formation of 3x progenies in alfalfa because of endosperm imbalance, and owing to the negligible selfing rate, seed set in 2x-4x crosses was used to discriminate the genetic capacity for 2n-egg production. F1 plants that exhibited null or very low seed sets were classified as normal egg producers and plants with high seed sets as 2n-egg producers. A bulked segregant analysis (BSA) with RAPD (random amplified polymorphic DNA), ISSR (inter-simple sequence repeat), and AFLP (amplified fragment length polymorphism) markers was employed to identify a genetic linkage group related to the 2n-egg trait using one of the three F1 progenies. This approach enabled us to detect a paternal ISSR marker of 610 bp, generated by primer (CA)8-GC, located 9.8 cM from a putative gene (termed Tne1, two-n-eggs) that in its recessive form determines 2n eggs and a 30% recombination genomic window surrounding the target locus. Eight additional RAPD and AFLP markers, seven of maternal, and one of paternal origin, significantly co-segregated with the trait under investigation. The minimum number of quantitative trait loci (QTLs) controlling seed set in 2x-4x crosses was estimated by ANOVA and regression analysis. Four maternal and three paternal independent molecular markers significantly affected the trait. A paternal RAPD marker allele, mapped in the same linkage group of Tne1, explained 43% of the variation for seed set in 2x-4x crosses indicating the presence of a major QTL. A map of the PG-F9 chromosome regions carrying the minor genes that determine the expression level of 2n eggs was constructed using selected RAPD and AFLP markers. Two of these genes were linked to previously mapped RFLP loci belonging to groups 1 and 8. Molecular and genetic evidence support the involvement of at least five genes.
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Affiliation(s)
- G Barcaccia
- Dipartimento di Agronomia Ambientale e Produzioni Vegetali, University of Padova, Legnaro, Italy.
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Noyes RD, Rieseberg LH. Two Independent Loci Control Agamospermy (Apomixis) in the Triploid Flowering Plant Erigeron annuus. Genetics 2000; 155:379-90. [PMID: 10790411 PMCID: PMC1461076 DOI: 10.1093/genetics/155.1.379] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Asexual seed production (agamospermy) via gametophytic apomixis in flowering plants typically involves the formation of an unreduced megagametophyte (via apospory or diplospory) and the parthenogenetic development of the unreduced egg cell into an embryo. Agamospermy is almost exclusively restricted to polyploids. In this study, the genetic basis of agamospermy was investigated in a segregating population of 130 F1's from a cross between triploid (2n = 27) agamospermous Erigeron annuus and sexual diploid (2n = 18) E. strigosus. Correlations between markers and phenotypes and linkage analysis were performed on 387 segregating amplified fragment length polymorphisms (AFLPs). Results show that four closely linked markers with polysomic inheritance are significantly associated with parthenogenesis and that 11 cosegregating markers with univalent inheritance are completely associated with diplospory. This indicates that diplospory and parthenogenesis are unlinked and inherited independently. Further, the absence of agamospermy in diploid F1's appears to be best explained by a combination of recessive-lethal gametophytic selection against the parthenogenetic locus and univalent inheritance of the region bearing diplospory. These results may have major implications for attempts to manipulate agamospermy for agricultural purposes and for interpreting the evolution of the trait.
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Affiliation(s)
- R D Noyes
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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Bicknell RA, Borst NK, Koltunow AM. Monogenic inheritance of apomixis in two Hieracium species with distinct developmental mechanisms. Heredity (Edinb) 2000; 84 ( Pt 2):228-37. [PMID: 10762393 DOI: 10.1046/j.1365-2540.2000.00663.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apomixis, the asexual formation of seed, has been known in angiosperms for more than a century yet the genetic mechanisms that control this trait remain poorly understood. Most members of the genus Hieracium are apomicts, forming predominantly asexual seed. Some purely sexual forms, however, also exist. In this paper we present a study of the inheritance of apomixis using two apomictic species of Hieracium which utilize very different forms of megagametogenesis. In both cases the progeny inherited apomixis as a monogenic, dominant trait that could be transferred by both haploid and diploid male gametes. In common with observations from other systems, no diploid apomictic progeny were recovered from these crosses. This appears to have been caused by selection against the survival of diploid zygotes, rather than against the mediation of haploid gametes as has been noted in other systems. Crosses between the two apomicts showed that the dominant determinants in the two forms examined were closely linked, possibly allelic. The significance of these data is discussed with respect to current theories on the associative link between gametophytic apomixis and polyploidy.
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Affiliation(s)
- R A Bicknell
- Crop and Food Research, Private Bag 4704, Christchurch, New Zealand.
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Noyes RD. Diplospory and Parthenogenesis in Sexual x Agamospermous (Apomictic ) Erigeron (Asteraceae) Hybrids. INTERNATIONAL JOURNAL OF PLANT SCIENCES 2000; 161:1-12. [PMID: 10648190 DOI: 10.1086/314238] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Segregation for asexual seed production was evaluated for 130 experimental F1 hybrids resulting from a cross between diploid (2n=18) sexual Erigeron strigosus and triploid (2n=27) agamospermous Erigeron annuus. Paternity of hybrids was documented using 13 RAPD markers. The distribution of F1 chromosome numbers is bimodal, centering on diploid and triploid ploidal levels but with underrepresentation of diploids. Diplosporous versus meiotic megagametophyte development was ascertained microscopically for >/=100 ovules per plant. Diplospory ranges from 0% to 100% among all progeny but is uniformly low (0%-3%) for 17 diploid hybrids. The inheritance of diplospory in Erigeron appears to be best explained by a one-locus-two-allele polysomic model with selection against gametes homozygous for diplospory. Parthenogenesis, estimated via seed counts, ranges from 0% to 60% and apparently is contingent upon diplospory, as seed production was absent or very low in predominantly meiotic hybrids. However, the absence of parthenogenesis in many highly diplosporous hybrids indicates that these two aspects of agamospermous development are not strictly associated. The segregation of both diplospory and parthenogenesis in this population will permit further genetic dissection of these traits with molecular marker-based analyses.
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Poggio L, Confalonieri V, Comas C, Cuadrado A, Jouve N, Naranjo CA. Genomic in situ hybridization (GISH) of Tripsacum dactyloides and Zea mays ssp. mays with B chromosomes. Genome 1999. [DOI: 10.1139/g98-157] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Genomic affinities between Tripsacum dactyloides (2n = 72) and Zea mays ssp. mays (2n = 20 + 5 B) were analyzed through GISH (genomic in situ hybridization) to ascertain the degree of chromosome homology between the two genera. Mitotic cells of T. dactyloides were simultaneously probed with total genomic DNA from Z. mays ssp .mays (2n = 20) and with rDNA (pTA71). A disperse pattern of hybridization signal among all 72 chromosomes, corresponding to maize total DNA, and six strong fluorescent signals due to the rDNA probe hybridizing on 3 chromosome pairs of T. dactyloides were observed. Mitotic chromosomes from Z. mays ssp. mays (2n = 20 + 5 B) were hybridized with a maize line that lacked B chromosomes and knobs and with total DNA from T. dactyloides. The knobless line of maize hybridized intensely on all chromosomes except for some regions where the probe bound less. Tripsacum dactyloides bound intensely on one terminal region of each B chromosome and to some regions of chromosome pairs 2, 6, and 8. These regions are DAPI positive and coincide with regions that displayed lower affinity with the probe from the knobless maize line. The possible significance of these results is discussed briefly.Key words: Tripsacum dactyloides, Zea mays ssp. mays, maize B chromosomes, genomic in situ hybridization, GISH.
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Ozias-Akins P, Roche D, Hanna WW. Tight clustering and hemizygosity of apomixis-linked molecular markers in Pennisetum squamulatum implies genetic control of apospory by a divergent locus that may have no allelic form in sexual genotypes. Proc Natl Acad Sci U S A 1998; 95:5127-32. [PMID: 9560240 PMCID: PMC20225 DOI: 10.1073/pnas.95.9.5127] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Apomixis is a naturally occurring mode of reproduction that results in embryo formation without the involvement of meiosis or fertilization of the egg. Seed-derived progeny of an apomictic plant are genetically identical to the maternal parent. We are studying a form of apomixis called apospory that occurs in the genus Pennisetum, a taxon in the grass family. A cultivated member of this genus, pearl millet (Pennisetum glaucum), reproduces sexually. A wild relative of pearl millet, Pennisetum squamulatum, that is an obligate aposporous species, is cross-compatible with pearl millet when used as a pollen donor in the interspecific cross. We present herein the genetic mapping of 13 molecular markers in an interspecific hybrid population of 397 individuals that segregates for apomixis and sexuality. Surprisingly, 12 of the 13 markers strictly cosegregated with aposporous embryo sac development, clearly defining a contiguous apospory-specific genomic region in which no genetic recombination was detected. Lack of or suppression of recombination may be coincidentally associated with the chromosomal context of the apomixis locus or it may be a consequence of its evolution that is essential for preservation of gene function as has been previously shown in studies of complex loci in both plant and animal species.
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Affiliation(s)
- P Ozias-Akins
- Department of Horticulture, University of Georgia Coastal Plain Experiment Station, Tifton, GA 31793-0748, USA.
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Grimanelli D, Leblanc O, Espinosa E, Perotti E, González de León D, Savidan Y. Non-Mendelian transmission of apomixis in maize-Tripsacum hybrids caused by a transmission ratio distortion. Heredity (Edinb) 1998; 80 ( Pt 1):40-7. [PMID: 9474775 DOI: 10.1046/j.1365-2540.1998.00264.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Apomixis is a mode of asexual reproduction through seeds. The apomictic process bypasses both meiosis and egg cell fertilization, producing offspring that are exact genetic replicas of the mother plant. In the Tripsacum agamic complex, all polyploids reproduce through the diplosporous type of apomixis, and diploids are sexual. In this paper, molecular markers linked with diplospory were used to analyse various generations of maize-Tripsacum hybrids and backcross derivatives and to derive a model for the inheritance of diplosporous reproduction. The results suggest that the gene or genes controlling apomixis in Tripsacum are linked with a segregation distorter-type system promoting the elimination of the apomixis alleles when transmitted through haploid gametes. Hence, this model offers an explanation of the relationship between apomixis and polyploidy. The evolutionary importance of this mechanism, which protects the diploid level from being invaded by apomixis, is discussed.
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Affiliation(s)
- D Grimanelli
- ORSTOM, Institut Français de Recherche Scientifique pour le Développement en Coopération, Mexico DF, Mexico.
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Grimanelli D, Leblanc O, Espinosa E, Perotti E, González de León D, Savidan Y. Mapping diplosporous apomixis in tetraploid Tripsacum: one gene or several genes? Heredity (Edinb) 1998; 80 ( Pt 1):33-9. [PMID: 9474774 DOI: 10.1046/j.1365-2540.1998.00263.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Polyploids in Tripsacum, a wild relative of maize, reproduce through the diplosporous type of apomixis, an asexual mode of reproduction through seeds. Diplosporous apomixis involves both the failure of meiosis and the parthenogenetic development of the unreduced gametes, resulting in progenies that are exact genetic copies of the mother plant. Apomixis is believed to be controlled by one single dominant allele, responsible for the whole developmental process. Construction of a linkage map for the chromosome controlling diplosporous apomixis in Tripsacum was carried out in both tetraploid-apomictic and diploid-sexual Tripsacum species using maize restriction fragment length polymorphism (RFLP) probes. A high level of collinearity was observed between the Tripsacum chromosome carrying the control of apomixis and a duplicated segment in the maize genome. In the apomictic tetraploid, there was a strong restriction to recombination, as compared to the corresponding genomic segment in sexual plants and maize. This suggests that apomixis, although inherited as a single Mendelian allele, might really be controlled by a cluster of linked loci. The analysis also revealed the tetrasomic nature of the inheritance of the chromosomal segment controlling apomixis, which contradicts the usually accepted hypothesis of an allopolyploid origin of apomictic species. The implications of these data for the transfer of apomixis into cultivated crops are discussed, and a new approach to studying the genetics of apomixis, based on comparative mapping, is proposed.
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Affiliation(s)
- D Grimanelli
- ORSTOM, Institut Français de Recherche Scientifique pour le Développement en Coopération, Mexico DF, Mexico.
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Iridoid glycoside and allozyme variation within and among populations of Plantago rhodosperma decne. (Plantaginaceae). BIOCHEM SYST ECOL 1997. [DOI: 10.1016/s0305-1978(97)00040-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Nybom H. DNA fingerprinting—A useful tool in the taxonomy of apomictic plant groups. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf02815374] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kindiger B, Bai D, Sokolov V. Assignment of a gene(s) conferring apomixis in Tripsacum to a chromosome arm: cytological and molecular evidence. Genome 1996; 39:1133-41. [PMID: 8983184 DOI: 10.1139/g96-143] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Attempts are underway to locate and transfer genes conferring diplosporous apomixis from Tripsacum to maize. The objective of this study was to evaluate several apomictic and sexual maize-Tripsacum hybrids for the presence or absence of Tripsacum chromosomes, PCR-RAPD generated markers, and RFLP markers that would have an association with apomictic development. Cytological and molecular analysis resulted in the identification of the Tripsacum chromosome arm carrying the gene(s) conferring diplosporous apomixis. Evaluations made on apomictic sexually derived maize + Tripsacum addition lines and an apomictic line possessing a Mz6L-Tr16L translocation were used to establish the location of the gene(s). Results of the study indicate that the successful transfer of a single Tripsacum chromosome is all that is necessary to maintain apomictic reproduction in a maize background. Additional use of this material may facilitate the development of an apomictic maize prototype and the eventual isolation of the gene(s).
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Affiliation(s)
- B Kindiger
- United States Department of Agriculture, Southern Plains Range Research Station, Woodward, OK 73801, USA
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Brock RD, Pryor AJ. An unstable minichromosome generates variegated oil yellow maize seedlings. Chromosoma 1996; 104:575-84. [PMID: 8662250 DOI: 10.1007/bf00352297] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
An unstable minichromosome comprising part of the short arm of chromosome 10 of maize was recovered from an oil yellow variegated plant as a consequence of gamma irradiation of pollen. The cytological and gene dosage observations are consistent with the minichromosome being a partial isochromosome, which lags at mitotic and meiotic anaphase. Loss of the minichromosome, which carries two doses of the +gene, causes phenotypic variegation in otherwise yellow lethal (Oy/Oy or Oy/oy) and olive (Oy/+ or oy/oy) genotypes. The minichromosome was transmitted to 8.1% of progeny via the pollen and 0.5% via the egg. Variations in the number and size of the minichromosome were recovered in progeny from a large test cross designed to test the feasibility for the detection of genetic variants including apomicts. No apomicts were recovered. All progeny with the appropriate maternal olive phenotype and the paternally derived coloured aleurone proved to be haploids. The recovery of a large minichromosome provides evidence for rare pairing and exchange with the short arm of chromosome 10. The variants of chromosome 10S generated from this programme provide useful material for further cytological, genetic and molecular analysis.
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Affiliation(s)
- R D Brock
- CSIRO, Division of Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
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