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Goeckeritz CZ, Zheng X, Harkess A, Dresselhaus T. Widespread application of apomixis in agriculture requires further study of natural apomicts. iScience 2024; 27:110720. [PMID: 39280618 PMCID: PMC11399699 DOI: 10.1016/j.isci.2024.110720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/18/2024] Open
Abstract
Apomixis, or asexual reproduction through seeds, is frequent in nature but does not exist in any major crop species, yet the phenomenon has captivated researchers for decades given its potential for clonal seed production and plant breeding. A discussion on whether this field will benefit from the continued study of natural apomicts is warranted given the recent outstanding progress in engineering apomixis. Here, we summarize what is known about its genetic control and the status of applying synthetic apomixis in agriculture. We argue there is still much to be learned from natural apomicts, and learning from them is necessary to improve on current progress and guarantee the effective application of apomixis beyond the few genera it has shown promise in so far. Specifically, we stress the value of studying the repeated evolution of natural apomicts in a phylogenetic and comparative -omics context. Finally, we identify outstanding questions in the field and discuss how technological advancements can be used to help close these knowledge gaps. In particular, genomic resources are lacking for apomicts, and this must be remedied for widespread use of apomixis in agriculture.
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Affiliation(s)
| | - Xixi Zheng
- Cell Biology and Plant Biochemistry, University of Regensburg, 93040 Regensburg, Germany
| | - Alex Harkess
- HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, University of Regensburg, 93040 Regensburg, Germany
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2
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Bicknell R, Gaillard M, Catanach A, McGee R, Erasmuson S, Fulton B, Winefield C. Genetic mapping of the LOSS OF PARTHENOGENESIS locus in Pilosella piloselloides and the evolution of apomixis in the Lactuceae. FRONTIERS IN PLANT SCIENCE 2023; 14:1239191. [PMID: 37692427 PMCID: PMC10485273 DOI: 10.3389/fpls.2023.1239191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/01/2023] [Indexed: 09/12/2023]
Abstract
Pilosella piloselloides var. praealta (syn. P. praealta; Hieracium praealtum) is a versatile model used to study gametophytic apomixis. In this system apomixis is controlled by three loci: one that controls the avoidance of meiosis (LOA), one that controls the avoidance of fertilization (LOP) and a third that controls autonomous endosperm formation (AutE). Using a unique polyhaploid mapping approach the LOP locus was mapped to a 654 kb genomic interval syntenic to linkage group 8 of Lactuca sativa. Polyhaploids form through the gametophytic action of a dominant determinant at LOP, so the mapped region represents both a functional and a physical domain for LOP in P. piloselloides. Allele sequence divergence (ASD) analysis of the PARTHENOGENESIS (PAR) gene within the LOP locus revealed that dominant PAR alleles in Pilosella remain highly similar across the genus, whilst the recessive alleles are more divergent. A previous report noted that dominant PAR alleles in both Pilosella and Taraxacum are modified by the presence of a class II transposable element (TE) in the promoter of the gene. This observation was confirmed and further extended to the related genus Hieracium. Sufficient differences were noted in the structure and location of the TE elements to conclude that TE insertional events had occurred independently in the three genera. Measures of allele crossover amongst the polyhaploids revealed that P. piloselloides is an autopolyploid species with tetrasomic inheritance. It was also noted that the dominant determinant of LOP in P. piloselloides could transmit via a diploid gamete (pollen or egg) but not via a haploid gamete. Using this information, a model is presented of how gametophytic apomixis may have evolved in several members of the Lactuceae, a tribe of the Asteraceae.
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Affiliation(s)
- Ross Bicknell
- Department of Breeding and Genomics, The New Zealand Institute for Plant and Food Research Limited, Christchurch, New Zealand
| | - Marion Gaillard
- Department of Plant and Microbial Biology, University of Zürich, Zurich, Switzerland
| | - Andrew Catanach
- Department of Breeding and Genomics, The New Zealand Institute for Plant and Food Research Limited, Christchurch, New Zealand
| | - Robert McGee
- Department of Plant Science, McGill University, Lincoln, QC, Canada
| | - Sylvia Erasmuson
- Department of Breeding and Genomics, The New Zealand Institute for Plant and Food Research Limited, Christchurch, New Zealand
| | - Beatrice Fulton
- Department of Breeding and Genomics, The New Zealand Institute for Plant and Food Research Limited, Christchurch, New Zealand
| | - Christopher Winefield
- Department of Wine, Food and Molecular Biosciences, Lincoln University, Canterbury, New Zealand
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3
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Wang N, Song X, Ye J, Zhang S, Cao Z, Zhu C, Hu J, Zhou Y, Huang Y, Cao S, Liu Z, Wu X, Chai L, Guo W, Xu Q, Gaut BS, Koltunow AMG, Zhou Y, Deng X. Structural variation and parallel evolution of apomixis in citrus during domestication and diversification. Natl Sci Rev 2022; 9:nwac114. [PMID: 36415319 PMCID: PMC9671666 DOI: 10.1093/nsr/nwac114] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 09/02/2023] Open
Abstract
Apomixis, or asexual seed formation, is prevalent in Citrinae via a mechanism termed nucellar or adventitious embryony. Here, multiple embryos of a maternal genotype form directly from nucellar cells in the ovule and can outcompete the developing zygotic embryo as they utilize the sexually derived endosperm for growth. Whilst nucellar embryony enables the propagation of clonal plants of maternal genetic constitution, it is also a barrier to effective breeding through hybridization. To address the genetics and evolution of apomixis in Citrinae, a chromosome-level genome of the Hongkong kumquat (Fortunella hindsii) was assembled following a genome-wide variation map including structural variants (SVs) based on 234 Citrinae accessions. This map revealed that hybrid citrus cultivars shelter genome-wide deleterious mutations and SVs into heterozygous states free from recessive selection, which may explain the capability of nucellar embryony in most cultivars during Citrinae diversification. Analyses revealed that parallel evolution may explain the repeated origin of apomixis in different genera of Citrinae. Within Fortunella, we found that apomixis of some varieties originated via introgression. In apomictic Fortunella, the locus associated with apomixis contains the FhRWP gene, encoding an RWP-RK domain-containing protein previously shown to be required for nucellar embryogenesis in Citrus. We found the heterozygous SV in the FhRWP and CitRWP promoters from apomictic Citrus and Fortunella, due to either two or three miniature inverted transposon element (MITE) insertions. A transcription factor, FhARID, encoding an AT-rich interaction domain-containing protein binds to the MITEs in the promoter of apomictic varieties, which facilitates induction of nucellar embryogenesis. This study provides evolutionary genomic and molecular insights into apomixis in Citrinae and has potential ramifications for citrus breeding.
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Affiliation(s)
- Nan Wang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Xietian Song
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Junli Ye
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Siqi Zhang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Zhen Cao
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Chenqiao Zhu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Jianbing Hu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Yin Zhou
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Yue Huang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Shuo Cao
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China
| | - Zhongjie Liu
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China
| | - Xiaomeng Wu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Lijun Chai
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Wenwu Guo
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Qiang Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA 92697, USA
| | - Anna M G Koltunow
- Queensland Alliance for Agriculture and Food Innovation, University of Queensland, Brisbane 4072, Australia
| | - Yongfeng Zhou
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China
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Mau M, Mandáková TM, Ma X, Ebersbach J, Zou L, Lysak MA, Sharbel TF. Evolution of an Apomixis-Specific Allele Class in Supernumerary Chromatin of Apomictic Boechera. FRONTIERS IN PLANT SCIENCE 2022; 13:890038. [PMID: 35720540 PMCID: PMC9198585 DOI: 10.3389/fpls.2022.890038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 05/03/2022] [Indexed: 06/06/2023]
Abstract
Asexual reproduction through seeds in plants (i.e., apomixis) is a heritable trait, and apomixis- linked loci have been identified in multiple species. However, direct identification of genomic elements is typically hindered as apomixis-linked loci and are commonly found in recombination-suppressed and repetitive regions. Heterochromatinized elements, such as B chromosomes and other supernumerary chromosomal DNA fragments have long been known to be associated with asexuality in both plants and animals and are prime candidate regions for the evolution of multiple apomixis factors controlling the individual elements of apomixis. Here, we examined molecular evolution, gene regulation, and chromosomal location of a male apomeiosis factor (UPG2), a long noncoding RNA gene, in sexual and apomictic Boechera with and without male apomeiosis (i.e., balanced and unbalanced apomicts). We revealed the origin of the gene in the apomixis genome on an apomixis-specific, supernumerary heterochromatic Boechera chromosome (Boe1). The UPG2 is active in the tapetum at male meiosis. We found allele classes specific to apomictic and sexual Boechera accessions and a third class that shares the features of both and points to a convergent transition state. Sex alleles are found only in some of the sexual accessions and have higher nucleotide divergence and lower transcriptional activity compared to apo alleles. These data demonstrate selective pressure to maintain the function of UPG2 for unreduced pollen formation in apomicts as the occasional transmission of the allele from unbalanced apomicts into sexual organisms that lead to pseudogenization and functional decay of copies in sexual organisms.
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Affiliation(s)
- Martin Mau
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
- Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada
| | | | - Xingliang Ma
- Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada
| | - Jana Ebersbach
- Saskatoon Research and Development Centre, Saskatoon, SK, Canada
| | - Lifang Zou
- Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada
| | - Martin A. Lysak
- Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Timothy F. Sharbel
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
- Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada
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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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Potente G, Léveillé-Bourret É, Yousefi N, Choudhury RR, Keller B, Diop SI, Duijsings D, Pirovano W, Lenhard M, Szövényi P, Conti E. Comparative Genomics Elucidates the Origin of a Supergene Controlling Floral Heteromorphism. Mol Biol Evol 2022; 39:msac035. [PMID: 35143659 PMCID: PMC8859637 DOI: 10.1093/molbev/msac035] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Supergenes are nonrecombining genomic regions ensuring the coinheritance of multiple, coadapted genes. Despite the importance of supergenes in adaptation, little is known on how they originate. A classic example of supergene is the S locus controlling heterostyly, a floral heteromorphism occurring in 28 angiosperm families. In Primula, heterostyly is characterized by the cooccurrence of two complementary, self-incompatible floral morphs and is controlled by five genes clustered in the hemizygous, ca. 300-kb S locus. Here, we present the first chromosome-scale genome assembly of any heterostylous species, that of Primula veris (cowslip). By leveraging the high contiguity of the P. veris assembly and comparative genomic analyses, we demonstrated that the S-locus evolved via multiple, asynchronous gene duplications and independent gene translocations. Furthermore, we discovered a new whole-genome duplication in Ericales that is specific to the Primula lineage. We also propose a mechanism for the origin of S-locus hemizygosity via nonhomologous recombination involving the newly discovered two pairs of CFB genes flanking the S locus. Finally, we detected only weak signatures of degeneration in the S locus, as predicted for hemizygous supergenes. The present study provides a useful resource for future research addressing key questions on the evolution of supergenes in general and the S locus in particular: How do supergenes arise? What is the role of genome architecture in the evolution of complex adaptations? Is the molecular architecture of heterostyly supergenes across angiosperms similar to that of Primula?
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Affiliation(s)
- Giacomo Potente
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- BaseClear BV, Leiden, The Netherlands
- Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Étienne Léveillé-Bourret
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Département de Sciences Biologiques, Institut de Recherche en Biologie Végétale, Université de Montréal, Montréal, Canada
| | - Narjes Yousefi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Rimjhim Roy Choudhury
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Barbara Keller
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Seydina Issa Diop
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- BaseClear BV, Leiden, The Netherlands
- Zurich-Basel Plant Science Center, Zurich, Switzerland
| | | | | | - Michael Lenhard
- Institute for Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Péter Szövényi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Elena Conti
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Zurich-Basel Plant Science Center, Zurich, Switzerland
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Bakin E, Sezer F, Özbilen A, Kilic I, Uner B, Rayko M, Taskin KM, Brukhin V. Phylogenetic and Expression Analysis of CENH3 and APOLLO Genes in Sexual and Apomictic Boechera Species. PLANTS 2022; 11:plants11030387. [PMID: 35161368 PMCID: PMC8839901 DOI: 10.3390/plants11030387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/22/2022] [Accepted: 01/27/2022] [Indexed: 11/16/2022]
Abstract
Apomictic plants (reproducing via asexual seeds), unlike sexual individuals, avoid meiosis and egg cell fertilization. Consequently, apomixis is very important for fixing maternal genotypes in the next plant generations. Despite the progress in the study of apomixis, molecular and genetic regulation of the latter remains poorly understood. So far APOLLO gene encoding aspartate glutamate aspartate aspartate histidine exonuclease is one of the very few described genes associated with apomixis in Boechera species. The centromere-specific histone H3 variant encoded by CENH3 gene is essential for cell division. Mutations in CENH3 disrupt chromosome segregation during mitosis and meiosis since the attachment of spindle microtubules to a mutated form of the CENH3 histone fails. This paper presents in silico characteristic of APOLLO and CENH3 genes, which may affect apomixis. Furthermore, we characterize the structure of CENH3 by bioinformatic tools, study expression levels of APOLLO and CENH3 transcripts by Real-Time Polymerase Chain Reaction RT-PCR in gynoecium/siliques of the natural diploid apomictic and sexual Boechera species at the stages of meiosis and before and after fertilization. While CENH3 was a single copy gene in all Boechera species, the APOLLO gene have several polymorphic alleles associated with sexual and apomictic reproduction in the Boechera genera. Expression of the APOLLO apo-allele during meiosis was upregulated in gynoecium of apomict B. divaricarpa downregulating after meiosis until the 4th day after pollination (DAP). On the 5th DAP, expression in apomictic siliques increased again. In sexual B. stricta gynoecium and siliques APOLLO apo-allele did not express. Expression of the APOLLO sex-allele during and after meiosis in gynoecium of sexual plants was several times higher than that in apomictic gynoecium. However, after pollination the sex-allele was downregulated in sexual siliques to the level of apomicts and increased sharply on the 5th DAP, while in apomictic siliques it almost did not express. At the meiotic stage, the expression level of CENH3 in the gynoecium of apomicts was two times lower than that of the sexual Boechera, decreasing in both species after meiosis and keep remaining very low in siliques of both species for several days after artificial pollination until the 4th DAP, when the expression level raised in sexual B. stricta siliques exceeding 5 times the level in apomictic B. divaricarpa siliques. We also discuss polymorphism and phylogeny of the APOLLO and CENH3 genes. The results obtained may indicate to a role of the CENH3 and APOLLO genes in the development of apomixis in species of the genus Boechera.
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Affiliation(s)
- Evgeny Bakin
- Bioinformatics Institute, 197342 Saint-Petersburg, Russia;
| | - Fatih Sezer
- Department of Molecular Biology and Genetics, Çanakkale Onsekiz Mart University, Çanakkale 17100, Turkey; (F.S.); (B.U.)
| | - Aslıhan Özbilen
- Department of Biology, Çanakkale Onsekiz Mart University, Çanakkale 17100, Turkey; (A.Ö.); (I.K.)
| | - Irem Kilic
- Department of Biology, Çanakkale Onsekiz Mart University, Çanakkale 17100, Turkey; (A.Ö.); (I.K.)
| | - Buket Uner
- Department of Molecular Biology and Genetics, Çanakkale Onsekiz Mart University, Çanakkale 17100, Turkey; (F.S.); (B.U.)
| | - Mike Rayko
- Laboratory for Algorithmic Biology, Saint-Petersburg State University, 199004 Saint-Petersburg, Russia;
| | - Kemal Melih Taskin
- Department of Molecular Biology and Genetics, Çanakkale Onsekiz Mart University, Çanakkale 17100, Turkey; (F.S.); (B.U.)
- Correspondence: (K.M.T.); (V.B.)
| | - Vladimir Brukhin
- Plant Genomics Lab, ChemBio Cluster, ITMO University, 191002 Saint-Petersburg, Russia
- Department of Plant Embryology and Reproductive Biology, Komarov Botanical Institute Russian Academy of Sciences, 197376 Saint-Petersburg, Russia
- Correspondence: (K.M.T.); (V.B.)
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Xu Y, Jia H, Tan C, Wu X, Deng X, Xu Q. Apomixis: genetic basis and controlling genes. HORTICULTURE RESEARCH 2022; 9:uhac150. [PMID: 36072837 PMCID: PMC9437720 DOI: 10.1093/hr/uhac150] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/27/2022] [Indexed: 05/12/2023]
Abstract
Apomixis is the phenomenon of clonal reproduction by seed. As apomixis can produce clonal progeny with exactly the same genotype as the maternal plant, it has an important application in genotype fixation and accelerating agricultural breeding strategies. The introduction of apomixis to major crops would bring many benefits to agriculture, including permanent fixation of superior genotypes and simplifying the procedures of hybrid seed production, as well as purification and rejuvenation of crops propagated vegetatively. Although apomixis naturally occurs in more than 400 plant species, it is rare among the major crops. Currently, with better understanding of apomixis, some achievements have been made in synthetic apomixis. However, due to prevailing limitations, there is still a long way to go to achieve large-scale application of apomixis to crop breeding. Here, we compare the developmental features of apomixis and sexual plant reproduction and review the recent identification of apomixis genes, transposons, epigenetic regulation, and genetic events leading to apomixis. We also summarize the possible strategies and potential genes for engineering apomixis into crop plants.
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Affiliation(s)
- Yuantao Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Huihui Jia
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Chunming Tan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Xiaomeng Wu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
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Soliman M, Bocchini M, Stein J, Ortiz JPA, Albertini E, Delgado L. Environmental and Genetic Factors Affecting Apospory Expressivity in Diploid Paspalum rufum. PLANTS 2021; 10:plants10102100. [PMID: 34685909 PMCID: PMC8537111 DOI: 10.3390/plants10102100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/22/2021] [Accepted: 09/27/2021] [Indexed: 11/30/2022]
Abstract
In angiosperms, gametophytic apomixis (clonal reproduction through seeds) is strongly associated with polyploidy and hybridization. The trait is facultative and its expressivity is highly variable between genotypes. Here, we used an F1 progeny derived from diploid apomictic (aposporic) genotypes of Paspalum rufum and two F2 families, derived from F1 hybrids with different apospory expressivity (%AES), to analyze the influence of the environment and the transgenerational transmission of the trait. In addition, AFLP markers were developed in the F1 population to identify genomic regions associated with the %AES. Cytoembryological analyses showed that the %AES was significantly influenced by different environments, but remained stable across the years. F1 and F2 progenies showed a wide range of %AES variation, but most hybrids were not significantly different from the parental genotypes. Maternal and paternal genetic linkage maps were built covering the ten expected linkage groups (LG). A single-marker analysis detected at least one region of 5.7 cM on LG3 that was significantly associated with apospory expressivity. Our results underline the importance of environmental influence in modulating apospory expressivity and identified a genomic region associated with apospory expressivity at the diploid level.
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Affiliation(s)
- Mariano Soliman
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Rosario S2125ZAA, Zavalla, Argentina; (M.S.); (J.S.); (J.P.A.O.)
| | - Marika Bocchini
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (M.B.); (E.A.)
| | - Juliana Stein
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Rosario S2125ZAA, Zavalla, Argentina; (M.S.); (J.S.); (J.P.A.O.)
| | - Juan Pablo A. Ortiz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Rosario S2125ZAA, Zavalla, Argentina; (M.S.); (J.S.); (J.P.A.O.)
| | - Emidio Albertini
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (M.B.); (E.A.)
| | - Luciana Delgado
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Rosario S2125ZAA, Zavalla, Argentina; (M.S.); (J.S.); (J.P.A.O.)
- Correspondence:
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Fehrer J, Slavíková R, Paštová L, Josefiová J, Mráz P, Chrtek J, Bertrand YJK. Molecular Evolution and Organization of Ribosomal DNA in the Hawkweed Tribe Hieraciinae (Cichorieae, Asteraceae). FRONTIERS IN PLANT SCIENCE 2021; 12:647375. [PMID: 33777082 PMCID: PMC7994888 DOI: 10.3389/fpls.2021.647375] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/19/2021] [Indexed: 05/14/2023]
Abstract
Molecular evolution of ribosomal DNA can be highly dynamic. Hundreds to thousands of copies in the genome are subject to concerted evolution, which homogenizes sequence variants to different degrees. If well homogenized, sequences are suitable for phylogeny reconstruction; if not, sequence polymorphism has to be handled appropriately. Here we investigate non-coding rDNA sequences (ITS/ETS, 5S-NTS) along with the chromosomal organization of their respective loci (45S and 5S rDNA) in diploids of the Hieraciinae. The subtribe consists of genera Hieracium, Pilosella, Andryala, and Hispidella and has a complex evolutionary history characterized by ancient intergeneric hybridization, allele sharing among species, and incomplete lineage sorting. Direct or cloned Sanger sequences and phased alleles derived from Illumina genome sequencing were subjected to phylogenetic analyses. Patterns of homogenization and tree topologies based on the three regions were compared. In contrast to most other plant groups, 5S-NTS sequences were generally better homogenized than ITS and ETS sequences. A novel case of ancient intergeneric hybridization between Hispidella and Hieracium was inferred, and some further incongruences between the trees were found, suggesting independent evolution of these regions. In some species, homogenization of ITS/ETS and 5S-NTS sequences proceeded in different directions although the 5S rDNA locus always occurred on the same chromosome with one 45S rDNA locus. The ancestral rDNA organization in the Hieraciinae comprised 4 loci of 45S rDNA in terminal positions and 2 loci of 5S rDNA in interstitial positions per diploid genome. In Hieracium, some deviations from this general pattern were found (3, 6, or 7 loci of 45S rDNA; three loci of 5S rDNA). Some of these deviations concerned intraspecific variation, and most of them occurred at the tips of the tree or independently in different lineages. This indicates that the organization of rDNA loci is more dynamic than the evolution of sequences contained in them and that locus number is therefore largely unsuitable to inform about species relationships in Hieracium. No consistent differences in the degree of sequence homogenization and the number of 45S rDNA loci were found, suggesting interlocus concerted evolution.
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Affiliation(s)
- Judith Fehrer
- Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia
- *Correspondence: Judith Fehrer,
| | - Renáta Slavíková
- Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia
| | | | - Jiřina Josefiová
- Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia
| | - Patrik Mráz
- Department of Botany, Charles University, Prague, Czechia
| | - Jindřich Chrtek
- Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia
- Department of Botany, Charles University, Prague, Czechia
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Fiaz S, Wang X, Younas A, Alharthi B, Riaz A, Ali H. Apomixis and strategies to induce apomixis to preserve hybrid vigor for multiple generations. GM CROPS & FOOD 2021; 12:57-70. [PMID: 32877304 PMCID: PMC7553744 DOI: 10.1080/21645698.2020.1808423] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/06/2020] [Indexed: 11/16/2022]
Abstract
Hybrid seeds of several important crops with supreme qualities including yield, biotic and abiotic stress tolerance have been cultivated for decades. Thus far, a major challenge with hybrid seeds is that they do not have the ability to produce plants with the same qualities over subsequent generations. Apomixis, an asexual mode of reproduction by avoiding meiosis, exists naturally in flowering plants, and ultimately leads to seed production. Apomixis has the potential to preserve hybrid vigor for multiple generations in economically important plant genotypes. The evolution and genetics of asexual seed production are unclear, and much more effort will be required to determine the genetic architecture of this phenomenon. To fix hybrid vigor, synthetic apomixis has been suggested. The development of MiMe (mitosis instead of meiosis) genotypes has been utilized for clonal gamete production. However, the identification and parental origin of genes responsible for synthetic apomixis are little known and need further clarification. Genome modifications utilizing genome editing technologies (GETs), such as clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (cas), a reverse genetics tool, have paved the way toward the utilization of emerging technologies in plant molecular biology. Over the last decade, several genes in important crops have been successfully edited. The vast availability of GETs has made functional genomics studies easy to conduct in crops important for food security. Disruption in the expression of genes specific to egg cell MATRILINEAL (MTL) through the CRISPR/Cas genome editing system promotes the induction of haploid seed, whereas triple knockout of the Baby Boom (BBM) genes BBM1, BBM2, and BBM3 cause embryo arrest and abortion, which can be fully rescued by male-transmitted BBM1. The establishment of synthetic apomixis by engineering the MiMe genotype by genome editing of BBM1 expression or disruption of MTL leads to clonal seed production and heritability for multiple generations. In the present review, we discuss current developments related to the use of CRISPR/Cas technology in plants and the possibility of promoting apomixis in crops to preserve hybrid vigor. In addition, genetics, evolution, epigenetic modifications, and strategies for MiMe genotype development are discussed in detail.
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Affiliation(s)
- Sajid Fiaz
- Department of Plant Breeding and Genetics, The University of Haripur 22620 , Khyber Pakhtunkhwa, Pakistan
| | - Xiukang Wang
- College of Life Sciences, Yan'an University , Yan'an, Shaanxi, China
| | - Afifa Younas
- Department of Botany, Lahore College for Women University , Lahore, Pakistan
| | - Badr Alharthi
- College of Science and Engineering, Flinders University , Adelaide, Australia
- University College of Khurma, Taif University , Taif, Saudi Arabia
| | - Adeel Riaz
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences , Beijing, China
| | - Habib Ali
- Department of Agricultural Engineering, Khawaja Fareed University of Engineering and Information Technology , Rahim Yar Khan, Pakistan
- Department of Entomology, Sub-Campus Depalpur, University of Agriculture Faisalabad , Faisalabad, Pakistan
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Henderson SW, Henderson ST, Goetz M, Koltunow AMG. Efficient CRISPR/Cas9-Mediated Knockout of an Endogenous PHYTOENE DESATURASE Gene in T1 Progeny of Apomictic Hieracium Enables New Strategies for Apomixis Gene Identification. Genes (Basel) 2020; 11:E1064. [PMID: 32927657 PMCID: PMC7563859 DOI: 10.3390/genes11091064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/06/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022] Open
Abstract
Most Hieracium subgenus Pilosella species are self-incompatible. Some undergo facultative apomixis where most seeds form asexually with a maternal genotype. Most embryo sacs develop by mitosis, without meiosis and seeds form without fertilization. Apomixis is controlled by dominant loci where recombination is suppressed. Loci deletion by γ-irradiation results in reversion to sexual reproduction. Targeted mutagenesis of genes at identified loci would facilitate causal gene identification. In this study, the efficacy of CRISPR/Cas9 editing was examined in apomictic Hieracium by targeting mutations in the endogenous PHYTOENE DESATURASE (PDS) gene using Agrobacterium-mediated leaf disk transformation. In three experiments, the expected albino dwarf-lethal phenotype, characteristic of PDS knockout, was evident in 11% of T0 plants, 31.4% were sectorial albino chimeras, and the remainder were green. The chimeric plants flowered. Germinated T1 seeds derived from apomictic reproduction in two chimeric plants were phenotyped and sequenced to identify PDS gene edits. Up to 86% of seeds produced albino seedlings with complete PDS knockout. This was attributed to continuing Cas9-mediated editing in chimeric plants during apomictic seed formation preventing Cas9 segregation from the PDS target. This successful demonstration of efficient CRISPR/Cas9 gene editing in apomictic Hieracium, enabled development of the discussed strategies for future identification of causal apomixis genes.
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Affiliation(s)
- Sam W. Henderson
- Correspondence: (S.W.H.); (A.M.G.K.); Tel.: +61-407-323-260 (A.M.G.K.)
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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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Fei X, Shi J, Liu Y, Niu J, Wei A. The steps from sexual reproduction to apomixis. PLANTA 2019; 249:1715-1730. [PMID: 30963237 DOI: 10.1007/s00425-019-03113-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 02/18/2019] [Indexed: 05/03/2023]
Abstract
In this paper, an interaction model of apomixis-related genes was constructed to analyze the emergence of apomictic types. It is speculated that apomixis technology will be first implemented in gramineous plants. Apomixis (asexual seed formation) is a phenomenon in which a plant bypasses the most fundamental aspects of sexual reproduction-meiosis and fertilization-to form a viable seed. Plants can form seeds without fertilization, and the seed genotype is consistent with the female parent. The development of apomictic technology would be revolutionary for agriculture and for food production as it would reduce costs and breeding times and also avoid many complications typical of sexual reproduction (e.g. incompatibility barriers) and of vegetative propagation (e.g. viral transfer). The application of apomictic reproductive technology has the potential to revolutionize crop breeding. This article reviews recent advances in apomixis in cytology and molecular biology. The general idea of identifying apomixis was proposed and the process of the emergence of non-fusion types was discussed. To better understand the apomixis mechanism, an apomixis regulatory model was established. At the same time, the realization of apomixis technology is proposed, which provides reference for the research and application of apomixis.
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Affiliation(s)
- Xitong Fei
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Jingwei Shi
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Yulin Liu
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Jinshuang Niu
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Anzhi Wei
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China.
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Brukhin V, Osadtchiy JV, Florez-Rueda AM, Smetanin D, Bakin E, Nobre MS, Grossniklaus U. The Boechera Genus as a Resource for Apomixis Research. FRONTIERS IN PLANT SCIENCE 2019; 10:392. [PMID: 31001306 PMCID: PMC6454215 DOI: 10.3389/fpls.2019.00392] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/14/2019] [Indexed: 05/03/2023]
Abstract
The genera Boechera (A. Löve et D. Löve) and Arabidopsis, the latter containing the model plant Arabidopsis thaliana, belong to the same clade within the Brassicaceae family. Boechera is the only among the more than 370 genera in the Brassicaceae where apomixis is well documented. Apomixis refers to the asexual reproduction through seed, and a better understanding of the underlying mechanisms has great potential for applications in agriculture. The Boechera genus currently includes 110 species (of which 38 are reported to be triploid and thus apomictic), which are distributed mostly in the North America. The apomictic lineages of Boechera occur at both the diploid and triploid level and show signs of a hybridogenic origin, resulting in a modification of their chromosome structure, as reflected by alloploidy, aneuploidy, substitutions of homeologous chromosomes, and the presence of aberrant chromosomes. In this review, we discuss the advantages of the Boechera genus to study apomixis, consider its modes of reproduction as well as the inheritance and possible mechanisms controlling apomixis. We also consider population genetic aspects and a possible role of hybridization at the origin of apomixis in Boechera. The molecular tools available to study Boechera, such as transformation techniques, laser capture microdissection, analysis of transcriptomes etc. are also discussed. We survey available genome assemblies of Boechera spp. and point out the challenges to assemble the highly heterozygous genomes of apomictic species. Due to these challenges, we argue for the application of an alternative reference-free method for the comparative analysis of such genomes, provide an overview of genomic sequencing data in the genus Boechera suitable for such analysis, and provide examples of its application.
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Affiliation(s)
- Vladimir Brukhin
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, Saint Petersburg, Russia
- Department of Plant Embryology and Reproductive Biology, Komarov Botanical Institute RAS, Saint Petersburg, Russia
| | - Jaroslaw V. Osadtchiy
- Department of Plant Embryology and Reproductive Biology, Komarov Botanical Institute RAS, Saint Petersburg, Russia
| | - Ana Marcela Florez-Rueda
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Dmitry Smetanin
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Evgeny Bakin
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, Saint Petersburg, Russia
- Bioinformatics Institute, Saint Petersburg, Russia
| | - Margarida Sofia Nobre
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Ueli Grossniklaus
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
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Galla G, Siena LA, Ortiz JPA, Baumlein H, Barcaccia G, Pessino SC, Bellucci M, Pupilli F. A Portion of the Apomixis Locus of Paspalum Simplex is Microsyntenic with an Unstable Chromosome Segment Highly Conserved Among Poaceae. Sci Rep 2019; 9:3271. [PMID: 30824748 PMCID: PMC6397161 DOI: 10.1038/s41598-019-39649-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 01/16/2019] [Indexed: 01/04/2023] Open
Abstract
The introgression of apomixis in major seed crops, would guarantee self-seeding of superior heterotic seeds over generations. In the grass species Paspalum simplex, apomixis is controlled by a single locus in which recombination is blocked. In the perspective of isolating the genetic determinants of apomixis, we report data on sequencing, in silico mapping and expression analysis of some of the genes contained in two cloned genomic regions of the apomixis locus of P. simplex. In silico mapping allowed us to identify a conserved synteny group homoeologous to the apomixis locus, located on a telomeric position of chromosomes 12, 8, 3 and 4 of rice, Sorghum bicolor, Setaria italica and Brachypodium distachyum, respectively, and on a more centromeric position of maize chromosome 1. Selected genes of the apomixis locus expressed sense and antisense transcripts in reproductively committed cells of sexual and apomictic ovules. Some of the genes considered here expressed apomixis-specific allelic variants which showed partial non-overlapping expression patterns with alleles shared by sexual and apomictic reproductive phenotypes. Our findings open new routes for the isolation of the genetic determinants of apomixis and, in perspective, for its introgression in crop grasses.
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Affiliation(s)
- Giulio Galla
- Department of Agriculture Food Natural resources Animals and Environment (DAFNAE), University of Padova, 35020, Legnaro (PD), Italy
| | - Lorena A Siena
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET-UNR, Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Juan Pablo A Ortiz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET-UNR, Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Helmut Baumlein
- The Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466, Gatersleben, Germany
| | - Gianni Barcaccia
- Department of Agriculture Food Natural resources Animals and Environment (DAFNAE), University of Padova, 35020, Legnaro (PD), Italy
| | - Silvina C Pessino
- Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), CONICET-UNR, Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Michele Bellucci
- Institute of Biosciences and Bioresources (IBBR), National Research Council (CNR), 06128, Perugia, Italy
| | - Fulvio Pupilli
- Institute of Biosciences and Bioresources (IBBR), National Research Council (CNR), 06128, Perugia, Italy.
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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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León-Martínez G, Vielle-Calzada JP. Apomixis in flowering plants: Developmental and evolutionary considerations. Curr Top Dev Biol 2019; 131:565-604. [DOI: 10.1016/bs.ctdb.2018.11.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Henderson ST, Johnson SD, Eichmann J, Koltunow AMG. Genetic analyses of the inheritance and expressivity of autonomous endosperm formation in Hieracium with different modes of embryo sac and seed formation. ANNALS OF BOTANY 2017; 119:1001-1010. [PMID: 28130222 PMCID: PMC5604576 DOI: 10.1093/aob/mcw262] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/18/2016] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS Apomixis, or asexual seed formation, in polyploid Hieracium subgenus Pilosella species results in clonal progeny with a maternal genotype. An aposporous embryo sac forms mitotically from a somatic cell, without prior meiosis, while embryo and endosperm formation is fertilization independent (autonomous). The latter two developmental components are tightly linked in Hieracium . Recently, two plants, AutE196 and AutE24, were identified from two different crosses. Both form embryo sacs via the sexual route by undergoing meiosis, and embryo development requires fertilization; however, 18 % of embryo sacs can undergo autonomous endosperm (AutE) formation. This study investigated the qualitative and quantitative inheritance of the AutE trait and factors influencing phenotype expressivity. An additional focus was to identify the linkage group bearing the AutE locus in AutE196. METHODS Crosses and cytology were used to examine the inheritance of AutE from AutE24 and AutE196, and to reintroduce apomictic components into AutE plants, thereby changing the ploidy of developing embryo sacs and increasing the dosage of AutE loci. Markers from a Hieracium apomict linkage map were examined within a backcrossed AutE196 mapping population to identify the linkage group containing the AutE196 locus. KEY RESULTS Qualitative autonomous endosperm in the AutE24 line was conferred by a single dominant locus, and the trait was transmitted through male and female gametes in AutE196 and AutE24. Expressivity of the trait did not significantly increase when AutE loci from AutE196 and AutE24 were both present in the progeny, within embryo sacs formed via apospory, or sexually derived embryo sacs with increased ploidy. It remains unclear if these are identical loci. CONCLUSIONS The qualitative trait of autonomous endosperm formation is conferred by single dominant loci in AutE196 and AutE24. High expressivity of autonomous endosperm formation observed in apomicts requires additional genetic factors. Potential candidates may be signals arising from fertilization-independent embryo formation.
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Keçeli BN, De Storme N, Geelen D. In Vivo Ploidy Determination of Arabidopsis thaliana Male and Female Gametophytes. Methods Mol Biol 2017; 1669:77-85. [PMID: 28936651 DOI: 10.1007/978-1-4939-7286-9_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Organ- or tissue-specific ploidy level determination is often used for answering biological, molecular, genetic, or evolutionary questions in plant sciences. However, current techniques for ploidy determination either cannot provide information on single cell level, require destructive sample preparation, or are laborious and time-consuming. Here, we present a new approach developed in Arabidopsis thaliana, which is not only less labor intensive but also allows in vivo ploidy determination on single cell level. The technique is based on the incorporation of a transgenic construct, consisting of the centromere-specific protein CENH3 fused to the fluorescent reporter GFP that specifically labels centromeric regions and hence allows for an accurate visual determination of the cell's chromosome number. Moreover, by combining the construct with a gametophyte-specific promoter, the technique enables accurate chromosome quantification in all individual gametophytic cell types formed during micro- and mega-gametogenesis. As such, CENH3-based centromere visualization provides an easy and straightforward method to monitor meiotic cell division integrity, gametophytic chromosome dynamics, and reproductive ploidy stability.
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Affiliation(s)
- Burcu Nur Keçeli
- In Vitro Biology and Horticulture, Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, Coupure Links 653, B-9000, Ghent, Belgium
| | - Nico De Storme
- In Vitro Biology and Horticulture, Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, Coupure Links 653, B-9000, Ghent, Belgium
| | - Danny Geelen
- In Vitro Biology and Horticulture, Department of Plant Production, Faculty of Bioscience Engineering, University of Ghent, Coupure Links 653, B-9000, Ghent, Belgium.
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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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Rabiger DS, Taylor JM, Spriggs A, Hand ML, Henderson ST, Johnson SD, Oelkers K, Hrmova M, Saito K, Suzuki G, Mukai Y, Carroll BJ, Koltunow AMG. Generation of an integrated Hieracium genomic and transcriptomic resource enables exploration of small RNA pathways during apomixis initiation. BMC Biol 2016; 14:86. [PMID: 27716180 PMCID: PMC5054587 DOI: 10.1186/s12915-016-0311-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/21/2016] [Indexed: 11/23/2022] Open
Abstract
Background Application of apomixis, or asexual seed formation, in crop breeding would allow rapid fixation of complex traits, economizing improved crop delivery. Identification of apomixis genes is confounded by the polyploid nature, high genome complexity and lack of genomic sequence integration with reproductive tissue transcriptomes in most apomicts. Results A genomic and transcriptomic resource was developed for Hieracium subgenus Pilosella (Asteraceae) which incorporates characterized sexual, apomictic and mutant apomict plants exhibiting reversion to sexual reproduction. Apomicts develop additional female gametogenic cells that suppress the sexual pathway in ovules. Disrupting small RNA pathways in sexual Arabidopsis also induces extra female gametogenic cells; therefore, the resource was used to examine if changes in small RNA pathways correlate with apomixis initiation. An initial characterization of small RNA pathway genes within Hieracium was undertaken, and ovary-expressed ARGONAUTE genes were identified and cloned. Comparisons of whole ovary transcriptomes from mutant apomicts, relative to the parental apomict, revealed that differentially expressed genes were enriched for processes involved in small RNA biogenesis and chromatin silencing. Small RNA profiles within mutant ovaries did not reveal large-scale alterations in composition or length distributions; however, a small number of differentially expressed, putative small RNA targets were identified. Conclusions The established Hieracium resource represents a substantial contribution towards the investigation of early sexual and apomictic female gamete development, and the generation of new candidate genes and markers. Observed changes in small RNA targets and biogenesis pathways within sexual and apomictic ovaries will underlie future functional research into apomixis initiation in Hieracium. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0311-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- David S Rabiger
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Private Bag 2, Glen Osmond, South Australia, 5064, Australia
| | - Jennifer M Taylor
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Bellenden Street, Crace, Australian Capital Territory, 2911, Australia
| | - Andrew Spriggs
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Bellenden Street, Crace, Australian Capital Territory, 2911, Australia
| | - Melanie L Hand
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Private Bag 2, Glen Osmond, South Australia, 5064, Australia
| | - Steven T Henderson
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Private Bag 2, Glen Osmond, South Australia, 5064, Australia
| | - Susan D Johnson
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Private Bag 2, Glen Osmond, South Australia, 5064, Australia
| | - Karsten Oelkers
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Private Bag 2, Glen Osmond, South Australia, 5064, Australia
| | - Maria Hrmova
- Australian Centre for Plant Functional Genomics, University of Adelaide PMB 1, Glen Osmond, South Australia, 5064, Australia
| | - Keisuke Saito
- Division of Natural Science, Osaka Kyoiku University, Osaka, 582-8582, Japan
| | - Go Suzuki
- Division of Natural Science, Osaka Kyoiku University, Osaka, 582-8582, Japan
| | - Yasuhiko Mukai
- Division of Natural Science, Osaka Kyoiku University, Osaka, 582-8582, Japan
| | - Bernard J Carroll
- School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Queensland, 4072, Australia
| | - Anna M G Koltunow
- Commonwealth Scientific and Industrial Research Organisation Agriculture and Food, Private Bag 2, Glen Osmond, South Australia, 5064, Australia.
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Abstract
Apomixis (asexual seed formation) is the result of a plant gaining the ability to bypass the most fundamental aspects of sexual reproduction: meiosis and fertilization. Without the need for male fertilization, the resulting seed germinates a plant that develops as a maternal clone. This dramatic shift in reproductive process has been documented in many flowering plant species, although no major seed crops have been shown to be capable of apomixis. The ability to generate maternal clones and therefore rapidly fix desirable genotypes in crop species could accelerate agricultural breeding strategies. The potential of apomixis as a next-generation breeding technology has contributed to increasing interest in the mechanisms controlling apomixis. In this review, we discuss the progress made toward understanding the genetic and molecular control of apomixis. Research is currently focused on two fronts. One aims to identify and characterize genes causing apomixis in apomictic species that have been developed as model species. The other aims to engineer or switch the sexual seed formation pathway in non-apomictic species, to one that mimics apomixis. Here we describe the major apomictic mechanisms and update knowledge concerning the loci that control them, in addition to presenting candidate genes that may be used as tools for switching the sexual pathway to an apomictic mode of reproduction in crops.
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Shirasawa K, Hand ML, Henderson ST, Okada T, Johnson SD, Taylor JM, Spriggs A, Siddons H, Hirakawa H, Isobe S, Tabata S, Koltunow AMG. A reference genetic linkage map of apomictic Hieracium species based on expressed markers derived from developing ovule transcripts. ANNALS OF BOTANY 2015; 115:567-80. [PMID: 25538115 PMCID: PMC4343286 DOI: 10.1093/aob/mcu249] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
BACKGROUND AND AIMS Apomixis in plants generates clonal progeny with a maternal genotype through asexual seed formation. Hieracium subgenus Pilosella (Asteraceae) contains polyploid, highly heterozygous apomictic and sexual species. Within apomictic Hieracium, dominant genetic loci independently regulate the qualitative developmental components of apomixis. In H. praealtum, LOSS OF APOMEIOSIS (LOA) enables formation of embryo sacs without meiosis and LOSS OF PARTHENOGENESIS (LOP) enables fertilization-independent seed formation. A locus required for fertilization-independent endosperm formation (AutE) has been identified in H. piloselloides. Additional quantitative loci appear to influence the penetrance of the qualitative loci, although the controlling genes remain unknown. This study aimed to develop the first genetic linkage maps for sexual and apomictic Hieracium species using simple sequence repeat (SSR) markers derived from expressed transcripts within the developing ovaries. METHODS RNA from microdissected Hieracium ovule cell types and ovaries was sequenced and SSRs were identified. Two different F1 mapping populations were created to overcome difficulties associated with genome complexity and asexual reproduction. SSR markers were analysed within each mapping population to generate draft linkage maps for apomictic and sexual Hieracium species. KEY RESULTS A collection of 14 684 Hieracium expressed SSR markers were developed and linkage maps were constructed for Hieracium species using a subset of the SSR markers. Both the LOA and LOP loci were successfully assigned to linkage groups; however, AutE could not be mapped using the current populations. Comparisons with lettuce (Lactuca sativa) revealed partial macrosynteny between the two Asteraceae species. CONCLUSIONS A collection of SSR markers and draft linkage maps were developed for two apomictic and one sexual Hieracium species. These maps will support cloning of controlling genes at LOA and LOP loci in Hieracium and should also assist with identification of quantitative loci that affect the expressivity of apomixis. Future work will focus on mapping AutE using alternative populations.
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Affiliation(s)
- Kenta Shirasawa
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Melanie L Hand
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Steven T Henderson
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Takashi Okada
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Susan D Johnson
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Jennifer M Taylor
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Andrew Spriggs
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Hayley Siddons
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Hideki Hirakawa
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Sachiko Isobe
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Satoshi Tabata
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
| | - Anna M G Koltunow
- Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia
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Vašut RJ, Vijverberg K, van Dijk PJ, de Jong H. Fluorescent in situ hybridization shows DIPLOSPOROUS located on one of the NOR chromosomes in apomictic dandelions (Taraxacum) in the absence of a large hemizygous chromosomal region. Genome 2015; 57:609-20. [PMID: 25760668 DOI: 10.1139/gen-2014-0143] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Apomixis in dandelions (Taraxacum: Asteraceae) is encoded by two unlinked dominant loci and a third yet undefined genetic factor: diplosporous omission of meiosis (DIPLOSPOROUS, DIP), parthenogenetic embryo development (PARTHENOGENESIS, PAR), and autonomous endosperm formation, respectively. In this study, we determined the chromosomal position of the DIP locus in Taraxacum by using fluorescent in situ hybridization (FISH) with bacterial artificial chromosomes (BACs) that genetically map within 1.2-0.2 cM of DIP. The BACs showed dispersed fluorescent signals, except for S4-BAC 83 that displayed strong unique signals as well. Under stringent blocking of repeats by C0t-DNA fragments, only a few fluorescent foci restricted to defined chromosome regions remained, including one on the nucleolus organizer region (NOR) chromosomes that contains the 45S rDNAs. FISH with S4-BAC 83 alone and optimal blocking showed discrete foci in the middle of the long arm of one of the NOR chromosomes only in triploid and tetraploid diplosporous dandelions, while signals in sexual diploids were lacking. This agrees with the genetic model of a single dose, dominant DIP allele, absent in sexuals. The length of the DIP region is estimated to cover a region of 1-10 Mb. FISH in various accessions of Taraxacum and the apomictic sister species Chondrilla juncea, confirmed the chromosomal position of DIP within Taraxacum but not outside the genus. Our results endorse that, compared to other model apomictic species, expressing either diplospory or apospory, the genome of Taraxacum shows a more similar and less diverged chromosome structure at the DIP locus. The different levels of allele sequence divergence at apomeiosis loci may reflect different terms of asexual reproduction. The association of apomeiosis loci with repetitiveness, dispersed repeats, and retrotransposons commonly observed in apomictic species may imply a functional role of these shared features in apomictic reproduction, as is discussed.
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Affiliation(s)
- Radim J Vašut
- Laboratory of Genetics, Wageningen University and Research Centre, P.O. Box 309, NL-6700 AH Wageningen, the Netherlands
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28
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Hand ML, Vít P, Krahulcová A, Johnson SD, Oelkers K, Siddons H, Chrtek J, Fehrer J, Koltunow AMG. Evolution of apomixis loci in Pilosella and Hieracium (Asteraceae) inferred from the conservation of apomixis-linked markers in natural and experimental populations. Heredity (Edinb) 2015; 114:17-26. [PMID: 25026970 PMCID: PMC4815591 DOI: 10.1038/hdy.2014.61] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 05/30/2014] [Accepted: 06/03/2014] [Indexed: 11/09/2022] Open
Abstract
The Hieracium and Pilosella (Lactuceae, Asteraceae) genera of closely related hawkweeds contain species with two different modes of gametophytic apomixis (asexual seed formation). Both genera contain polyploid species, and in wild populations, sexual and apomictic species co-exist. Apomixis is known to co-exist with sexuality in apomictic Pilosella individuals, however, apomictic Hieracium have been regarded as obligate apomicts. Here, a developmental analysis of apomixis within 16 Hieracium species revealed meiosis and megaspore tetrad formation in 1 to 7% of ovules, for the first time indicating residual sexuality in this genus. Molecular markers linked to the two independent, dominant loci LOSS OF APOMEIOSIS (LOA) and LOSS OF PARTHENOGENESIS (LOP) controlling apomixis in Pilosella piloselloides subsp. praealta were screened across 20 phenotyped Hieracium individuals from natural populations, and 65 phenotyped Pilosella individuals from natural and experimental cross populations, to examine their conservation, inheritance and association with reproductive modes. All of the tested LOA and LOP-linked markers were absent in the 20 Hieracium samples irrespective of their reproductive mode. Within Pilosella, LOA and LOP-linked markers were essentially absent within the sexual plants, although they were not conserved in all apomictic individuals. Both loci appeared to be inherited independently, and evidence for additional genetic factors influencing quantitative expression of LOA and LOP was obtained. Collectively, these data suggest independent evolution of apomixis in Hieracium and Pilosella and are discussed with respect to current knowledge of the evolution of apomixis.
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Affiliation(s)
- M L Hand
- Commonwealth Scientific and Industrial Research Organization (CSIRO) Plant Industry, Waite Campus, Glen Osmond, SA, Australia
| | - P Vít
- Institute of Botany, Academy of Sciences of the Czech Republic, Zámek 1, Průhonice, Czech Republic
| | - A Krahulcová
- Institute of Botany, Academy of Sciences of the Czech Republic, Zámek 1, Průhonice, Czech Republic
| | - S D Johnson
- Commonwealth Scientific and Industrial Research Organization (CSIRO) Plant Industry, Waite Campus, Glen Osmond, SA, Australia
| | - K Oelkers
- Commonwealth Scientific and Industrial Research Organization (CSIRO) Plant Industry, Waite Campus, Glen Osmond, SA, Australia
| | - H Siddons
- Commonwealth Scientific and Industrial Research Organization (CSIRO) Plant Industry, Waite Campus, Glen Osmond, SA, Australia
| | - J Chrtek
- Institute of Botany, Academy of Sciences of the Czech Republic, Zámek 1, Průhonice, Czech Republic
- Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, Prague, Czech Republic
| | - J Fehrer
- Institute of Botany, Academy of Sciences of the Czech Republic, Zámek 1, Průhonice, Czech Republic
| | - A M G Koltunow
- Commonwealth Scientific and Industrial Research Organization (CSIRO) Plant Industry, Waite Campus, Glen Osmond, SA, Australia
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