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Qu Y, Fernie AR, Liu J, Yan J. Doubled haploid technology and synthetic apomixis: Recent advances and applications in future crop breeding. MOLECULAR PLANT 2024; 17:1005-1018. [PMID: 38877700 DOI: 10.1016/j.molp.2024.06.005] [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: 11/27/2023] [Revised: 05/19/2024] [Accepted: 06/11/2024] [Indexed: 06/16/2024]
Abstract
Doubled haploid (DH) technology and synthetic apomixis approaches can considerably shorten breeding cycles and enhance breeding efficiency. Compared with traditional breeding methods, DH technology offers the advantage of rapidly generating inbred lines, while synthetic apomixis can effectively fix hybrid vigor. In this review, we focus on (i) recent advances in identifying and characterizing genes responsible for haploid induction (HI), (ii) the molecular mechanisms of HI, (iii) spontaneous haploid genome doubling, and (iv) crop synthetic apomixis. We also discuss the challenges and potential solutions for future crop breeding programs utilizing DH technology and synthetic apomixis. Finally, we provide our perspectives about how to integrate DH and synthetic apomixis for precision breeding and de novo domestication.
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Affiliation(s)
- Yanzhi Qu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan 430070, China
| | - Alisdair R Fernie
- Department of Molecular Physiology, Max- Planck- Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany; Center of Plant Systems Biology and Biotechnology, 4000 Plovdiv, Bulgaria
| | - Jie Liu
- Yazhouwan National Laboratory, Sanya 572024, China.
| | - Jianbing Yan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan 430070, China; Yazhouwan National Laboratory, Sanya 572024, China.
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2
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Hojsgaard D, Nagel M, Feingold SE, Massa GA, Bradshaw JE. New Frontiers in Potato Breeding: Tinkering with Reproductive Genes and Apomixis. Biomolecules 2024; 14:614. [PMID: 38927018 PMCID: PMC11202281 DOI: 10.3390/biom14060614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/13/2024] [Accepted: 05/20/2024] [Indexed: 06/28/2024] Open
Abstract
Potato is the most important non-cereal crop worldwide, and, yet, genetic gains in potato have been traditionally delayed by the crop's biology, mostly the genetic heterozygosity of autotetraploid cultivars and the intricacies of the reproductive system. Novel site-directed genetic modification techniques provide opportunities for designing climate-smart cultivars, but they also pose new possibilities (and challenges) for breeding potato. As potato species show a remarkable reproductive diversity, and their ovules have a propensity to develop apomixis-like phenotypes, tinkering with reproductive genes in potato is opening new frontiers in potato breeding. Developing diploid varieties instead of tetraploid ones has been proposed as an alternative way to fill the gap in genetic gain, that is being achieved by using gene-edited self-compatible genotypes and inbred lines to exploit hybrid seed technology. In a similar way, modulating the formation of unreduced gametes and synthesizing apomixis in diploid or tetraploid potatoes may help to reinforce the transition to a diploid hybrid crop or enhance introgression schemes and fix highly heterozygous genotypes in tetraploid varieties. In any case, the induction of apomixis-like phenotypes will shorten the time and costs of developing new varieties by allowing the multi-generational propagation through true seeds. In this review, we summarize the current knowledge on potato reproductive phenotypes and underlying genes, discuss the advantages and disadvantages of using potato's natural variability to modulate reproductive steps during seed formation, and consider strategies to synthesize apomixis. However, before we can fully modulate the reproductive phenotypes, we need to understand the genetic basis of such diversity. Finally, we visualize an active, central role for genebanks in this endeavor by phenotyping properly genotyped genebank accessions and new introductions to provide scientists and breeders with reliable data and resources for developing innovations to exploit market opportunities.
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Affiliation(s)
- Diego Hojsgaard
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, Germany;
| | - Manuela Nagel
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, Germany;
| | - Sergio E. Feingold
- Laboratorio de Agrobiotecnología, EEA Balcarce-IPADS (UEDD INTA–CONICET), Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce B7620, Argentina; (S.E.F.); (G.A.M.)
| | - Gabriela A. Massa
- Laboratorio de Agrobiotecnología, EEA Balcarce-IPADS (UEDD INTA–CONICET), Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce B7620, Argentina; (S.E.F.); (G.A.M.)
- Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Balcarce B7620, Argentina
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3
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Binmöller L, Volkert C, Kiefer C, Zühl L, Slawinska MW, Loreth A, Nauerth BH, Ibberson D, Martinez R, Mandakova TM, Zipper R, Schmidt A. Differential expression and evolutionary diversification of RNA helicases in Boechera sexual and apomictic reproduction. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2451-2469. [PMID: 38263359 DOI: 10.1093/jxb/erae026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 01/22/2024] [Indexed: 01/25/2024]
Abstract
In higher plants, sexual reproduction is characterized by meiosis of the first cells of the germlines, and double fertilization of the egg and central cell after gametogenesis. In contrast, in apomicts of the genus Boechera, meiosis is omitted or altered and only the central cell requires fertilization, while the embryo forms parthenogenetically from the egg cell. To deepen the understanding of the transcriptional basis underlying these differences, we applied RNA-seq to compare expression in reproductive tissues of different Boechera accessions. This confirmed previous evidence of an enrichment of RNA helicases in plant germlines. Furthermore, few RNA helicases were differentially expressed in female reproductive ovule tissues harboring mature gametophytes from apomictic and sexual accessions. For some of these genes, we further found evidence for a complex recent evolutionary history. This included a homolog of Arabidopsis thaliana FASCIATED STEM4 (FAS4). In contrast to AtFAS4, which is a single-copy gene, FAS4 is represented by three homologs in Boechera, suggesting a potential for subfunctionalization to modulate reproductive development. To gain first insights into functional roles of FAS4, we studied Arabidopsis lines carrying mutant alleles. This identified the crucial importance of AtFAS4 for reproduction, as we observed developmental defects and arrest during male and female gametogenesis.
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Affiliation(s)
- Laura Binmöller
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Christopher Volkert
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Christiane Kiefer
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Luise Zühl
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Magdalena W Slawinska
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Anna Loreth
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Berit H Nauerth
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - David Ibberson
- Deep Sequencing Core Facility, CellNetworks Excellence Cluster, Heidelberg University, Im Neuenheimer Feld 267, D-69120 Heidelberg, Germany
| | - Rafael Martinez
- Centre for Organismal Studies Heidelberg, Department of Developmental Biology, Heidelberg University, Im Neuenheimer Feld 230, D-69120, Heidelberg, Germany
| | - Terezie M Mandakova
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic
| | - Reinhard Zipper
- Institute of Biology, Plant Evolutionary Biology, University of Hohenheim, Garbenstrasse 30, D-70599 Stuttgart, Germany
| | - Anja Schmidt
- Centre for Organismal Studies Heidelberg, Department of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
- Institute of Biology, Plant Evolutionary Biology, University of Hohenheim, Garbenstrasse 30, D-70599 Stuttgart, Germany
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Xiong W, Risse J, Berke L, Zhao T, van de Geest H, Oplaat C, Busscher M, Ferreira de Carvalho J, van der Meer IM, Verhoeven KJF, Schranz ME, Vijverberg K. Phylogenomic analysis provides insights into MADS-box and TCP gene diversification and floral development of the Asteraceae, supported by de novo genome and transcriptome sequences from dandelion ( Taraxacum officinale). FRONTIERS IN PLANT SCIENCE 2023; 14:1198909. [PMCID: PMC10338227 DOI: 10.3389/fpls.2023.1198909] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 05/26/2023] [Indexed: 07/15/2023]
Abstract
The Asteraceae is the largest angiosperm family with more than 25,000 species. Individual studies have shown that MADS-box and TCP transcription factors are regulators of the development and symmetry of flowers, contributing to their iconic flower-head (capitulum) and floret. However, a systematic study of MADS-box and TCP genes across the Asteraceae is lacking. We performed a comparative analysis of genome sequences of 33 angiosperm species including our de novo assembly of diploid sexual dandelion (Taraxacum officinale) and 11 other Asteraceae to investigate the lineage-specific evolution of MADS-box and TCP genes in the Asteraceae. We compared the phylogenomic results of MADS-box and TCP genes with their expression in T. officinale floral tissues at different developmental stages to demonstrate the regulation of genes with Asteraceae-specific attributes. Here, we show that MADS-box MIKCc and TCP-CYCLOIDEA (CYC) genes have expanded in the Asteraceae. The phylogenomic analysis identified AGAMOUS-like (AG-like: SEEDSTICK [STK]-like), SEPALATA-like (SEP3-like), and TCP-PROLIFERATING CELL FACTOR (PCF)-like copies with lineage-specific genomic contexts in the Asteraceae, Cichorioideae, or dandelion. Different expression patterns of some of these gene copies suggest functional divergence. We also confirm the presence and revisit the evolutionary history of previously named “Asteraceae-Specific MADS-box genes (AS-MADS).” Specifically, we identify non-Asteraceae homologs, indicating a more ancient origin of this gene clade. Syntenic relationships support that AS-MADS is paralogous to FLOWERING LOCUS C (FLC) as demonstrated by the shared ancient duplication of FLC and SEP3.
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Affiliation(s)
- Wei Xiong
- Biosystematics Group, Wageningen University and Research, Wageningen, Netherlands
| | - Judith Risse
- Bioinformatics Group, Wageningen University and Research, Wageningen, Netherlands
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands
| | - Lidija Berke
- Biosystematics Group, Wageningen University and Research, Wageningen, Netherlands
| | - Tao Zhao
- Biosystematics Group, Wageningen University and Research, Wageningen, Netherlands
| | | | - Carla Oplaat
- Biosystematics Group, Wageningen University and Research, Wageningen, Netherlands
| | - Marco Busscher
- Biosystematics Group, Wageningen University and Research, Wageningen, Netherlands
- Bioscience, Wageningen University and Research, Wageningen, Netherlands
| | - Julie Ferreira de Carvalho
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands
| | | | - Koen J. F. Verhoeven
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands
| | - M. Eric Schranz
- Biosystematics Group, Wageningen University and Research, Wageningen, Netherlands
| | - Kitty Vijverberg
- Biosystematics Group, Wageningen University and Research, Wageningen, Netherlands
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Xu LY, Wu WT, Bi N, Yan ZJ, Yang F, Yang WJ, Yang JS. A cytological revisit on parthenogenetic Artemia and the deficiency of a meiosis-specific recombinase DMC1 in the possible transition from bisexuality to parthenogenesis. Chromosoma 2023:10.1007/s00412-023-00790-x. [PMID: 36939898 DOI: 10.1007/s00412-023-00790-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 02/20/2023] [Accepted: 02/27/2023] [Indexed: 03/21/2023]
Abstract
Although parthenogenesis is widespread in nature and known to have close relationships with bisexuality, the transitional mechanism is poorly understood. Artemia is an ideal model to address this issue because bisexuality and "contagious" obligate parthenogenesis independently exist in its congeneric members. In the present study, we first performed chromosome spreading and immunofluorescence to compare meiotic processes of Artemia adopting two distinct reproductive ways. The results showed that, unlike conventional meiosis in bisexual Artemia, meiosis II in parthenogenic Artemia is entirely absent and anaphase I is followed by a single mitosis-like equational division. Interspecific comparative transcriptomics showed that two central molecules in homologous recombination (HR), Dmc1 and Rad51, exhibited significantly higher expression in bisexual versus parthenogenetic Artemia. qRT-PCR indicated that the expression of both genes peaked at the early oogenesis and gradually decreased afterward. Knocking-down by RNAi of Dmc1 in unfertilized females of bisexual Artemia resulted in a severe deficiency of homologous chromosome pairing and produced univalents at the middle oogenesis stage, which was similar to that of parthenogenic Artemia, while in contrast, silencing Rad51 led to no significant chromosome morphological change. Our results indicated that Dmc1 is vital for HR in bisexual Artemia, and the deficiency of Dmc1 may be correlated with or even possibly one of core factors in the transition from bisexuality to parthenogenesis.
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Affiliation(s)
- Lian-Ying Xu
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Wen-Tao Wu
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ning Bi
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zhi-Jun Yan
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Fan Yang
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Wei-Jun Yang
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jin-Shu Yang
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
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Roy AK, Chakraborti M, Radhakrishna A, Dwivedi KK, Srivastava MK, Saxena S, Paul S, Khare A, Malaviya DR, Kaushal P. Alien genome mobilization and fixation utilizing an apomixis mediated genome addition (AMGA) strategy in Pennisetum to improve domestication traits of P. squamulatum. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2022; 135:2555-2575. [PMID: 35726065 DOI: 10.1007/s00122-022-04138-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
An approach to release 'frozen' variability in apomictic species using sexuality of another species, eventually its utilization in crop improvement and de-novo domestication of crop wild relatives is presented. Pennisetum squamulatum, a secondary gene pool species of pearl millet (P. glaucum), harbours many desirable traits. However, it was neither utilized to improve pearl millet fodder traits nor improvement of its own domestication traits was attempted, due to the complexities of genomes and apomictic reproduction. To overcome this, we followed an Apomixis Mediated Genome Addition (AMGA) strategy and utilized the contrasting reproductive capacities (sexuality and apomixis) of both the species to access the otherwise un-available variability embedded in P. squamulatum. Segregating population of interspecific hybrids exhibited significant variability and heterosis for desired morphological, agronomical, and nutritional traits. Elite apomictic and perennial hybrids were evaluated in breeding trials, and eventually a novel grass cultivar was released for commercial cultivation in India. The performance of newly developed cultivar was superior to other adapted perennial grasses of arid and semi-arid rangelands. Through AMGA, the sexuality of one species was successfully utilized to 'release' the 'frozen' variability embedded in another species. Subsequently, the hybrids representing desirable trait combinations were again 'fixed' utilizing the apomixis alleles from the male parent in a back-and-forth apomixis-sexual-apomixis selection cycle. This study also demonstrated the potential of AMGA to improve crop relatives through genomes introgression as well as de novo domestication of new crops from wild species.
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Affiliation(s)
- A K Roy
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, 284003, India
| | - M Chakraborti
- ICAR - National Rice Research Institute, Cuttack, 753006, India
| | - A Radhakrishna
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, 284003, India
| | - K K Dwivedi
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, 284003, India
| | - M K Srivastava
- ICAR - Indian Institute of Soybean Research, Indore, 452001, India
| | - S Saxena
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, 284003, India
| | - S Paul
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, 284003, India
| | - Aarti Khare
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, 284003, India
| | - D R Malaviya
- ICAR - Indian Institute of Sugarcane Research, Lucknow, 226002, India
| | - P Kaushal
- ICAR - National Institute of Biotic Stress Management, Raipur, 493225, India.
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Abstract
The zygote is a totipotent structure that develops into an embryo with all of the cells needed to produce an entire plant. The BABY BOOM (BBM) transcription factor induces spontaneous asexual embryo development on plant organs when ectopically expressed. Although BBM is at the top of a transcriptional network that promotes asexual embryo development, little is known about its expression and role during zygotic embryogenesis. Here we show in Arabidopsis that BBM regulates the progression of zygotic embryo development and embryo patterning, and division and cellularization of the filial endosperm. In line with its role as a totipotency factor, ectopic BBM expression in the egg cell is also sufficient to induce haploid embryo development in Arabidopsis and dicot crops. The BABY BOOM (BBM) AINTEGUMENTA-LIKE (AIL) AP2/ERF domain transcription factor is a major regulator of plant cell totipotency, as it induces asexual embryo formation when ectopically expressed. Surprisingly, only limited information is available on the role of BBM during zygotic embryogenesis. Here we reexamined BBM expression and function in the model plant Arabidopsis thaliana (Arabidopsis) using reporter analysis and newly developed CRISPR mutants. BBM was expressed in the embryo from the zygote stage and also in the maternal (nucellus) and filial (endosperm) seed tissues. Analysis of CRISPR mutant alleles for BBM (bbm-cr) and the redundantly acting AIL gene PLETHORA2 (PLT2) (plt2-cr) uncovered individual roles for these genes in the timing of embryo progression. We also identified redundant roles for BBM and PLT2 in endosperm proliferation and cellularization and the maintenance of zygotic embryo development. Finally, we show that ectopic BBM expression in the egg cell of Arabidopsis and the dicot crops Brassica napus and Solanum lycopersicon is sufficient to bypass the fertilization requirement for embryo development. Together these results highlight roles for BBM and PLT2 in seed development and demonstrate the utility of BBM genes for engineering asexual embryo development in dicot species.
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Underwood CJ, Mercier R. Engineering Apomixis: Clonal Seeds Approaching the Fields. ANNUAL REVIEW OF PLANT BIOLOGY 2022; 73:201-225. [PMID: 35138881 DOI: 10.1146/annurev-arplant-102720-013958] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Apomixis is a form of reproduction leading to clonal seeds and offspring that are genetically identical to the maternal plant. While apomixis naturally occurs in hundreds of plant species distributed across diverse plant families, it is absent in major crop species. Apomixis has a revolutionary potential in plant breeding, as it could allow the instant fixation and propagation though seeds of any plant genotype, most notably F1 hybrids. Mastering and implementing apomixis would reduce the cost of hybrid seed production, facilitate new types of hybrid breeding, and make it possible to harness hybrid vigor in crops that are not presently cultivated as hybrids. Synthetic apomixis can be engineered by combining modifications of meiosis and fertilization. Here, we review the current knowledge and recent major achievements toward the development of efficient apomictic systems usable in agriculture.
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Affiliation(s)
- Charles J Underwood
- Department of Chromosome Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany; ,
| | - Raphael Mercier
- Department of Chromosome Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany; ,
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9
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Chumakov MI, Mazilov SI. Genetic Control of Maize Gynogenesis. RUSS J GENET+ 2022. [DOI: 10.1134/s1022795422040044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Yin PP, Tang LP, Zhang XS, Su YH. Options for Engineering Apomixis in Plants. FRONTIERS IN PLANT SCIENCE 2022; 13:864987. [PMID: 35371148 PMCID: PMC8967160 DOI: 10.3389/fpls.2022.864987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 02/24/2022] [Indexed: 06/14/2023]
Abstract
In plants, embryogenesis and reproduction are not strictly dependent on fertilization. Several species can produce embryos in seeds asexually, a process known as apomixis. Apomixis is defined as clonal asexual reproduction through seeds, whereby the progeny is identical to the maternal genotype, and provides valuable opportunities for developing superior cultivars, as its induction in agricultural crops can facilitate the development and maintenance of elite hybrid genotypes. In this review, we summarize the current understanding of apomixis and highlight the successful introduction of apomixis methods into sexual crops. In addition, we discuss several genes whose overexpression can induce somatic embryogenesis as candidate genes to induce parthenogenesis, a unique reproductive method of gametophytic apomixis. We also summarize three schemes to achieve engineered apomixis, which will offer more opportunities for the realization of apomictic reproduction.
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11
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Li M, Wrobel-Marek J, Heidmann I, Horstman A, Chen B, Reis R, Angenent GC, Boutilier K. Auxin biosynthesis maintains embryo identity and growth during BABY BOOM-induced somatic embryogenesis. PLANT PHYSIOLOGY 2022; 188:1095-1110. [PMID: 34865162 PMCID: PMC8825264 DOI: 10.1093/plphys/kiab558] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 11/03/2021] [Indexed: 05/18/2023]
Abstract
Somatic embryogenesis is a type of plant cell totipotency where embryos develop from nonreproductive (vegetative) cells without fertilization. Somatic embryogenesis can be induced in vitro by auxins, and by ectopic expression of embryo-expressed transcription factors like the BABY BOOM (BBM) AINTEGUMENTA-LIKE APETALA2/ETHYLENE RESPONSE FACTOR domain protein. These different pathways are thought to converge to promote auxin response and biosynthesis, but the specific roles of the endogenous auxin pathway in somatic embryogenesis induction have not been well-characterized. Here we show that BBM transcriptionally regulates the YUCCA3 (YUC3) and YUC8 auxin biosynthesis genes during BBM-mediated somatic embryogenesis in Arabidopsis (Arabidopsis thaliana) seedlings. BBM induced local and ectopic YUC3 and YUC8 expression in seedlings, which coincided with increased DR5 auxin response and indole-3-acetic acid (IAA) biosynthesis and with ectopic expression of the WOX2 embryo reporter. YUC-driven auxin biosynthesis was required for BBM-mediated somatic embryogenesis, as the number of embryogenic explants was reduced by ca. 50% in yuc3 yuc8 mutants and abolished after chemical inhibition of YUC enzyme activity. However, a detailed YUC inhibitor time-course study revealed that YUC-dependent IAA biosynthesis is not required for the re-initiation of totipotent cell identity in seedlings. Rather, YUC enzymes are required later in somatic embryo development for the maintenance of embryo identity and growth. This study resolves a long-standing question about the role of endogenous auxin biosynthesis in transcription factor-mediated somatic embryogenesis and also provides an experimental framework for understanding the role of endogenous auxin biosynthesis in other in planta and in vitro embryogenesis systems.
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Affiliation(s)
- Mengfan Li
- Bioscience, Wageningen University and Research, Wageningen, 6700 AA, Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen, 6700 AP, Netherlands
| | - Justyna Wrobel-Marek
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Katowice, 40-032, Poland
| | - Iris Heidmann
- Bioscience, Wageningen University and Research, Wageningen, 6700 AA, Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen, 6700 AP, Netherlands
- Enza Zaden Research and Development B.V, Enkhuizen, 1602 DB, The Netherlands
| | - Anneke Horstman
- Bioscience, Wageningen University and Research, Wageningen, 6700 AA, Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen, 6700 AP, Netherlands
| | - Baojian Chen
- Bioscience, Wageningen University and Research, Wageningen, 6700 AA, Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen, 6700 AP, Netherlands
| | - Ricardo Reis
- Bioscience, Wageningen University and Research, Wageningen, 6700 AA, Netherlands
| | - Gerco C Angenent
- Bioscience, Wageningen University and Research, Wageningen, 6700 AA, Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen, 6700 AP, Netherlands
| | - Kim Boutilier
- Bioscience, Wageningen University and Research, Wageningen, 6700 AA, Netherlands
- Author for communication:
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12
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Palumbo F, Draga S, Vannozzi A, Lucchin M, Barcaccia G. Trends in Apomixis Research: The 10 Most Cited Research Articles Published in the Pregenomic and Genomic Eras. FRONTIERS IN PLANT SCIENCE 2022; 13:878074. [PMID: 35599856 PMCID: PMC9115752 DOI: 10.3389/fpls.2022.878074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/14/2022] [Indexed: 05/12/2023]
Abstract
Apomixis, or asexual reproduction by seed, represents an easy shortcut for life cycle renewal based on maternal embryo production without ploidy reduction (meiosis) and ploidy restitution (syngamy). Although the first studies officially published on this topic in scientific journals date back to the early 1930s, the identification and introduction of genes involved in asexual reproduction in species of agronomic interest still represent a major challenge. Through a bibliometric analysis of the research programs implemented in apomixis over the last 40 years, the present study was aimed to discuss not only the main findings achieved but also the investigational methods and model species used. We split the critical survey of the most cited original articles into pregenomic and genomic eras to identify potential trends and depict scenarios that have emerged in the scientific community working on apomixis, as well as to determine any correlation between the exponential increase in acquired basic knowledge and the development of advanced analytical technologies. This review found a substantial stagnation in the use of the same model species, with few exceptions, for at least 40 years. In contrast, the development of new molecular techniques, genomic platforms, and repositories has directly affected the approaches used in research, which has been directed toward an increasingly focused study of the genetic and epigenetic determinants of apomixis.
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Underwood CJ, Vijverberg K, Rigola D, Okamoto S, Oplaat C, Camp RHMOD, Radoeva T, Schauer SE, Fierens J, Jansen K, Mansveld S, Busscher M, Xiong W, Datema E, Nijbroek K, Blom EJ, Bicknell R, Catanach A, Erasmuson S, Winefield C, van Tunen AJ, Prins M, Schranz ME, van Dijk PJ. A PARTHENOGENESIS allele from apomictic dandelion can induce egg cell division without fertilization in lettuce. Nat Genet 2022; 54:84-93. [PMID: 34992267 DOI: 10.1038/s41588-021-00984-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 11/03/2021] [Indexed: 01/21/2023]
Abstract
Apomixis, the clonal formation of seeds, is a rare yet widely distributed trait in flowering plants. We have isolated the PARTHENOGENESIS (PAR) gene from apomictic dandelion that triggers embryo development in unfertilized egg cells. PAR encodes a K2-2 zinc finger, EAR-domain protein. Unlike the recessive sexual alleles, the dominant PAR allele is expressed in egg cells and has a miniature inverted-repeat transposable element (MITE) transposon insertion in the promoter. The MITE-containing promoter can invoke a homologous gene from sexual lettuce to complement dandelion LOSS OF PARTHENOGENESIS mutants. A similar MITE is also present in the promoter of the PAR gene in apomictic forms of hawkweed, suggesting a case of parallel evolution. Heterologous expression of dandelion PAR in lettuce egg cells induced haploid embryo-like structures in the absence of fertilization. Sexual PAR alleles are expressed in pollen, suggesting that the gene product releases a block on embryogenesis after fertilization in sexual species while in apomictic species PAR expression triggers embryogenesis in the absence of fertilization.
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Affiliation(s)
- Charles J Underwood
- Keygene N.V., Wageningen, the Netherlands
- Department of Chromosome Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Kitty Vijverberg
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
- Naturalis Biodiversity Center, Radboud University, Nijmegen, the Netherlands
| | | | - Shunsuke Okamoto
- Keygene N.V., Wageningen, the Netherlands
- Takii & Co. Ltd, Plant Breeding and Experiment Station, Konan Shiga, Japan
| | - Carla Oplaat
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
- National Reference Centre of Plant Health, National Plant Protection Organization, Wageningen, the Netherlands
| | | | | | | | | | - Kim Jansen
- Keygene N.V., Wageningen, the Netherlands
| | | | - Marco Busscher
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
| | - Wei Xiong
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
| | | | | | | | - Ross Bicknell
- New Zealand Institute for Plant & Food Research, Lincoln, New Zealand
| | - Andrew Catanach
- New Zealand Institute for Plant & Food Research, Lincoln, New Zealand
| | - Sylvia Erasmuson
- New Zealand Institute for Plant & Food Research, Lincoln, New Zealand
| | | | | | | | - M Eric Schranz
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands.
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Bhowmik P, Bilichak A. Advances in Gene Editing of Haploid Tissues in Crops. Genes (Basel) 2021; 12:1410. [PMID: 34573392 PMCID: PMC8468125 DOI: 10.3390/genes12091410] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/07/2021] [Accepted: 09/09/2021] [Indexed: 01/14/2023] Open
Abstract
Emerging threats of climate change require the rapid development of improved varieties with a higher tolerance to abiotic and biotic factors. Despite the success of traditional agricultural practices, novel techniques for precise manipulation of the crop's genome are needed. Doubled haploid (DH) methods have been used for decades in major crops to fix desired alleles in elite backgrounds in a short time. DH plants are also widely used for mapping of the quantitative trait loci (QTLs), marker-assisted selection (MAS), genomic selection (GS), and hybrid production. Recent discoveries of genes responsible for haploid induction (HI) allowed engineering this trait through gene editing (GE) in non-inducer varieties of different crops. Direct editing of gametes or haploid embryos increases GE efficiency by generating null homozygous plants following chromosome doubling. Increased understanding of the underlying genetic mechanisms responsible for spontaneous chromosome doubling in haploid plants may allow transferring this trait to different elite varieties. Overall, further improvement in the efficiency of the DH technology combined with the optimized GE could accelerate breeding efforts of the major crops.
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Affiliation(s)
- Pankaj Bhowmik
- Aquatic and Crop Resource Development, National Research Council of Canada, Saskatoon, SK S7N 0W9, Canada;
| | - Andriy Bilichak
- Agriculture and Agri-Food Canada, Morden Research and Development Centre, Morden, MB R6M 1Y5, Canada
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Belyaeva EV, Elkonin LA, Vladimirova AA, Panin VM. Manifestation of apomictic potentials in the line AS-3 of Sorghum bicolor (L.) Moench. PLANTA 2021; 254:37. [PMID: 34309737 DOI: 10.1007/s00425-021-03681-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 07/08/2021] [Indexed: 06/13/2023]
Abstract
AS-3 line of Sorghum bicolor possesses functional components of apomixis-apospory, parthenogenesis and autonomous endospermogenesis. The data obtained indicate efficiency of selection for apomixis components in diploid species of cultivated crops. Apomixis (seed formation without fertilization) is one of most attractive phenomena in plant biology. In this paper, we provide the results of long-term selection for apomixis components in the progeny of grain sorghum (Sorghum bicolor (L.) Moench) hybrid plants with male sterility mutation. Selection was carried out for a high frequency of aposporous embryo sacs (ESs), autonomous pro-embryos, and the presence of maternal-type plants in test crosses with the line Volzhskoe-4v (V4v) homozygous for the Rs1 genes determining the red color of the leaves and stem of the hybrids. As a result of using this approach, the line, AS-3, was created, in which the frequency of ovaries with parthenogenetic embryos reached 42-45%. The autonomous development of embryos and endosperm was observed in the panicles of each of the 10 cytologically studied plants of this line. The frequency of parthenogenesis positively correlated with the high average daily air temperature during the first five out of 10 days preceding the onset of flowering (r = 0.75; P > 0.01). Genotyping of the plants from the progeny of hand-emasculated panicles of AS-3 pollinated with V4v performed using co-dominant SSR markers revealed that the F1 hybrids carrying the Rs1 gene (chromosome 6) possessed both paternal and maternal alleles of Sb1-10 (chromosome 4) and Xtxp320 (chromosome 10) markers, while in the maternal-type plants (rs1rs1), only the maternal alleles of these markers were present. In the endosperm of the kernels from which the maternal-type seedlings were obtained, only the maternal alleles were present, while in the endosperm of the kernels that produced hybrid seedlings, both the paternal and maternal alleles were observed. The data obtained indicate the presence of functional components of apomixis (apospory, parthenogenesis, autonomous endospermogenesis) in the grain sorghum line AS-3, and the efficiency of selection for apomixis in functionally diploid species of cultivated crops.
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Affiliation(s)
- Elena V Belyaeva
- Department of Biotechnology, Federal Center of Agriculture Research of the South-East Region, Saratov, 410010, Russia
| | - Lev A Elkonin
- Department of Biotechnology, Federal Center of Agriculture Research of the South-East Region, Saratov, 410010, Russia.
| | - Anastasia A Vladimirova
- Department of Biotechnology, Federal Center of Agriculture Research of the South-East Region, Saratov, 410010, Russia
| | - Valery M Panin
- Department of Biotechnology, Federal Center of Agriculture Research of the South-East Region, Saratov, 410010, Russia
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Thondehaalmath T, Kulaar DS, Bondada R, Maruthachalam R. Understanding and exploiting uniparental genome elimination in plants: insights from Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:4646-4662. [PMID: 33851980 DOI: 10.1093/jxb/erab161] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
Uniparental genome elimination (UGE) refers to the preferential exclusion of one set of the parental chromosome complement during embryogenesis following successful fertilization, giving rise to uniparental haploid progeny. This artificially induced phenomenon was documented as one of the consequences of distant (wide) hybridization in plants. Ten decades since its discovery, attempts to unravel the molecular mechanism behind this process remained elusive due to a lack of genetic tools and genomic resources in the species exhibiting UGE. Hence, its successful adoption in agronomic crops for in planta (in vivo) haploid production remains implausible. Recently, Arabidopsis thaliana has emerged as a model system to unravel the molecular basis of UGE. It is now possible to simulate the genetic consequences of distant crosses in an A. thaliana intraspecific cross by a simple modification of centromeres, via the manipulation of the centromere-specific histone H3 variant gene, CENH3. Thus, the experimental advantages conferred by A. thaliana have been used to elucidate and exploit the benefits of UGE in crop breeding. In this review, we discuss developments and prospects of CENH3 gene-mediated UGE and other in planta haploid induction strategies to illustrate its potential in expediting plant breeding and genetics in A. thaliana and other model plants.
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Affiliation(s)
- Tejas Thondehaalmath
- School of Biology, Indian Institute of Science Education and Research (IISER)- Thiruvananthapuram, Vithura, Kerala, India
| | - Dilsher Singh Kulaar
- School of Biology, Indian Institute of Science Education and Research (IISER)- Thiruvananthapuram, Vithura, Kerala, India
| | - Ramesh Bondada
- School of Biology, Indian Institute of Science Education and Research (IISER)- Thiruvananthapuram, Vithura, Kerala, India
| | - Ravi Maruthachalam
- School of Biology, Indian Institute of Science Education and Research (IISER)- Thiruvananthapuram, Vithura, Kerala, India
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Dresselhaus T, Jürgens G. Comparative Embryogenesis in Angiosperms: Activation and Patterning of Embryonic Cell Lineages. ANNUAL REVIEW OF PLANT BIOLOGY 2021; 72:641-676. [PMID: 33606951 DOI: 10.1146/annurev-arplant-082520-094112] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Following fertilization in flowering plants (angiosperms), egg and sperm cells unite to form the zygote, which generates an entire new organism through a process called embryogenesis. In this review, we provide a comparative perspective on early zygotic embryogenesis in flowering plants by using the Poaceae maize and rice as monocot grass and crop models as well as Arabidopsis as a eudicot model of the Brassicaceae family. Beginning with the activation of the egg cell, we summarize and discuss the process of maternal-to-zygotic transition in plants, also taking recent work on parthenogenesis and haploid induction into consideration. Aspects like imprinting, which is mainly associated with endosperm development and somatic embryogenesis, are not considered. Controversial findings about the timing of zygotic genome activation as well as maternal versus paternal contribution to zygote and early embryo development are highlighted. The establishment of zygotic polarity, asymmetric division, and apical and basal cell lineages represents another chapter in which we also examine and compare the role of major signaling pathways, cell fate genes, and hormones in early embryogenesis. Except for the model Arabidopsis, little is known about embryopatterning and the establishment of the basic body plan in angiosperms. Using available in situ hybridization, RNA-sequencing, and marker data, we try to compare how and when stem cell niches are established. Finally, evolutionary aspects of plant embryo development are discussed.
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Affiliation(s)
- Thomas Dresselhaus
- Department of Cell Biology and Plant Biochemistry, University of Regensburg, D-93053 Regensburg, Germany;
| | - Gerd Jürgens
- Department of Cell Biology, Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany
- Center for Plant Molecular Biology, University of Tübingen, D-72076 Tübingen, Germany;
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Proceedings of the 7th Series of Seminars on Advances in Apomixis Research. PLANTS 2021; 10:plants10030565. [PMID: 33802754 PMCID: PMC8002402 DOI: 10.3390/plants10030565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 03/14/2021] [Accepted: 03/15/2021] [Indexed: 11/17/2022]
Abstract
These proceedings contain the abstracts for the presentations given at the 7th biennial Seminars on Advances in Apomixis Research, held virtually on 2-3 and 9 December 2020. The first day hosted the kick-off meeting of the EU-funded Mechanisms of Apomictic Development (MAD) project, while the remaining days were dedicated to oral presentations and in-depth exchanges on the latest progress in the field of apomixis and plant reproductive biology research.
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Corral-Martínez P, Siemons C, Horstman A, Angenent GC, de Ruijter N, Boutilier K. Live Imaging of embryogenic structures in Brassica napus microspore embryo cultures highlights the developmental plasticity of induced totipotent cells. PLANT REPRODUCTION 2020; 33:143-158. [PMID: 32651727 PMCID: PMC7648746 DOI: 10.1007/s00497-020-00391-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/29/2020] [Indexed: 05/10/2023]
Abstract
In vitro embryo development is highly plastic; embryo cell fate can be re-established in tissue culture through different pathways. In most angiosperms, embryo development from the single-celled zygote follows a defined pattern of cell divisions in which apical (embryo proper) and basal (root and suspensor) cell fates are established within the first cell divisions. By contrast, embryos that are induced in vitro in the absence of fertilization show a less regular initial cell division pattern yet develop into histodifferentiated embryos that can be converted into seedlings. We used the Brassica napus microspore embryogenesis system, in which the male gametophyte is reprogrammed in vitro to form haploid embryos, to identify the developmental fates of the different types of embryogenic structures found in culture. Using time-lapse imaging of LEAFY COTYLEDON1-expressing cells, we show that embryogenic cell clusters with very different morphologies are able to form haploid embryos. The timing of surrounding pollen wall (exine) rupture is a major determinant of cell fate in these clusters, with early exine rupture leading to the formation of suspensor-bearing embryos and late rupture to suspensorless embryos. In addition, we show that embryogenic callus, which develops into suspensor-bearing embryos, initially expresses transcripts associated with both basal- and apical-embryo cell fates, suggesting that these two cell fates are fixed later in development. This study reveals the inherent plasticity of in vitro embryo development and identifies new pathways by which embryo cell fate can be established.
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Affiliation(s)
- Patricia Corral-Martínez
- Plant Development Systems, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, P.O. Box 633, 6700 AP, Wageningen, The Netherlands
- Cell Biology Group, COMAV Institute, Universitat Politècnica de València (UPV), Camino de Vera, s/n. 46022, València, Spain
| | - Charlotte Siemons
- Plant Development Systems, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, P.O. Box 633, 6700 AP, Wageningen, The Netherlands
| | - Anneke Horstman
- Plant Development Systems, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, P.O. Box 633, 6700 AP, Wageningen, The Netherlands
| | - Gerco C Angenent
- Plant Development Systems, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- Laboratory of Molecular Biology, Wageningen University and Research, P.O. Box 633, 6700 AP, Wageningen, The Netherlands
| | - Norbert de Ruijter
- Laboratory of Cell Biology, Wageningen University and Research, P.O. Box 633, 6700 AP, Wageningen, The Netherlands
- Wageningen Light Microscopy Centre, Wageningen University and Research, P.O. Box 633, 6700 AP, Wageningen, The Netherlands
| | - Kim Boutilier
- Plant Development Systems, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands.
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Zhang Z, Conner J, Guo Y, Ozias-Akins P. Haploidy in Tobacco Induced by PsASGR-BBML Transgenes via Parthenogenesis. Genes (Basel) 2020; 11:E1072. [PMID: 32932590 PMCID: PMC7564442 DOI: 10.3390/genes11091072] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/10/2020] [Accepted: 09/10/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Engineering apomixis in sexually reproducing plants has been long desired because of the potential to fix hybrid vigor. Validating the functionality of genes originated from apomictic species that contribute to apomixis upon transfer to sexually reproducing species is an important step. The PsASGR-BABYBOOM-like (PsASGR-BBML) gene from Pennisetum squamulatum confers parthenogenesis in this apomict, and its functionality was demonstrated in several sexually reproducing monocots but not in any dicots. METHODS We introduced the PsASGR-BBML gene regulated by egg cell-specific promoters, either AtDD45 or AtRKD2, into tobacco, and analyzed progeny of the transgenic lines resulting from self-pollination and crossing by flow cytometry. RESULTS We identified haploid progeny at a frequency lower than 1% in the AtDD45pro lines, while at a frequency of 9.3% for an octoploid (2n = 8x) AtRKD2pro line. Haploid production in the T2 generation, derived from the tetraploid T1 offspring of this original octoploid AtRKD2pro line, was also observed. Pollinated by homozygous transgenic tobacco carrying a DsRed marker gene, 4x progeny of the AtRKD2pro line yielded parthenogenetic embryos identified as DsRed negative. We verified that the DsRed negative seedlings recovered were haploid (2x). CONCLUSION The PsASGR-BBML gene regulated by egg cell-specific promoters could enable parthenogenesis in tobacco, a dicotyledon species.
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Affiliation(s)
| | | | | | - Peggy Ozias-Akins
- Department of Horticulture and Institute of Plant Breeding, Genetics & Genomics, University of Georgia, Tifton, GA 31793, USA; (Z.Z.); (J.C.); (Y.G.)
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Van Dijk PJ, Op den Camp R, Schauer SE. Genetic Dissection of Apomixis in Dandelions Identifies a Dominant Parthenogenesis Locus and Highlights the Complexity of Autonomous Endosperm Formation. Genes (Basel) 2020; 11:genes11090961. [PMID: 32825294 PMCID: PMC7565526 DOI: 10.3390/genes11090961] [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: 07/20/2020] [Revised: 08/07/2020] [Accepted: 08/18/2020] [Indexed: 01/17/2023] Open
Abstract
Apomixis in the common dandelion (Taraxacum officinale) consists of three developmental components: diplospory (apomeiosis), parthenogenesis, and autonomous endosperm development. The genetic basis of diplospory, which is inherited as a single dominant factor, has been previously elucidated. To uncover the genetic basis of the remaining components, a cross between a diploid sexual seed parent and a triploid apomictic pollen donor was made. The resulting 95 triploid progeny plants were genotyped with co-dominant simple-sequence repeat (SSR) markers and phenotyped for apomixis as a whole and for the individual apomixis components using Nomarski Differential Interference Contrast (DIC) microscopy of cleared ovules and seed flow cytometry. From this, a new SSR marker allele was discovered that was closely linked to parthenogenesis and unlinked to diplospory. The segregation of apomixis as a whole does not differ significantly from a three-locus model, with diplospory and parthenogenesis segregating as unlinked dominant loci. Autonomous endosperm is regularly present without parthenogenesis, suggesting that the parthenogenesis locus does not also control endosperm formation. However, the high recovery of autonomous endosperm is inconsistent with this phenotype segregating as the third dominant locus. These results highlight the genetic complexity underlying apomixis in the dandelion and underline the challenge of introducing autonomous apomixis into sexual crops.
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Affiliation(s)
- Peter J. Van Dijk
- Keygene N.V., Agro Business Park 90, 6708 PW Wageningen, The Netherlands;
- Correspondence: ; Tel.: +31-317-466-866
| | - Rik Op den Camp
- Keygene N.V., Agro Business Park 90, 6708 PW Wageningen, The Netherlands;
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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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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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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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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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Ozias-Akins P, Conner JA. Clonal Reproduction through Seeds in Sight for Crops. Trends Genet 2020; 36:215-226. [PMID: 31973878 DOI: 10.1016/j.tig.2019.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/27/2019] [Accepted: 12/10/2019] [Indexed: 10/25/2022]
Abstract
Apomixis or asexual reproduction through seeds, enables the preservation of hybrid vigor. Hybrids are heterozygous and segregate for genotype and phenotype upon sexual reproduction. While apomixis, that is, clonal reproduction, is intuitively antithetical to diversity, it is rarely obligate and actually provides a mechanism to recover and maintain superior hybrid gene combinations for which sexual reproduction would reveal deleterious alleles in less fit genotypes. Apomixis, widespread across flowering plant orders, does not occur in major crop species, yet its introduction could add a valuable tool to the breeder's toolbox. In the past decade, discovery of genetic mechanisms regulating meiosis, embryo and endosperm development have facilitated proof-of-concept for the synthesis of apomixis, bringing apomictic crops closer to reality.
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Affiliation(s)
- Peggy Ozias-Akins
- Department of Horticulture and Institute of Plant Breeding and Genomics, University of Georgia, Tifton, GA 31793, USA.
| | - Joann A Conner
- Department of Horticulture and Institute of Plant Breeding and Genomics, University of Georgia, Tifton, GA 31793, USA
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