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Hörandl E. Apomixis and the paradox of sex in plants. ANNALS OF BOTANY 2024; 134:1-18. [PMID: 38497809 PMCID: PMC11161571 DOI: 10.1093/aob/mcae044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 03/15/2024] [Indexed: 03/19/2024]
Abstract
BACKGROUND The predominance of sex in eukaryotes, despite the high costs of meiosis and mating, remains an evolutionary enigma. Many theories have been proposed, none of them being conclusive on its own, and they are, in part, not well applicable to land plants. Sexual reproduction is obligate in embryophytes for the great majority of species. SCOPE This review compares the main forms of sexual and asexual reproduction in ferns and angiosperms, based on the generation cycling of sporophyte and gametophyte (leaving vegetative propagation aside). The benefits of sexual reproduction for maintenance of genomic integrity in comparison to asexuality are discussed in the light of developmental, evolutionary, genetic and phylogenetic studies. CONCLUSIONS Asexual reproduction represents modifications of the sexual pathway, with various forms of facultative sexuality. For sexual land plants, meiosis provides direct DNA repair mechanisms for oxidative damage in reproductive tissues. The ploidy alternations of meiosis-syngamy cycles and prolonged multicellular stages in the haploid phase in the gametophytes provide a high efficiency of purifying selection against recessive deleterious mutations. Asexual lineages might buffer effects of such mutations via polyploidy and can purge the mutational load via facultative sexuality. The role of organelle-nuclear genome compatibility for maintenance of genome integrity is not well understood. In plants in general, the costs of mating are low because of predominant hermaphroditism. Phylogenetic patterns in the archaeplastid clade suggest that high frequencies of sexuality in land plants are concomitant with a stepwise increase of intrinsic and extrinsic stress factors. Furthermore, expansion of genome size in land plants would increase the potential mutational load. Sexual reproduction appears to be essential for keeping long-term genomic integrity, and only rare combinations of extrinsic and intrinsic factors allow for shifts to asexuality.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with herbarium), University of Göttingen, Göttingen, Germany
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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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Lu L, Yang H, Xu Y, Zhang L, Wu J, Yi H. Laser capture microdissection-based spatiotemporal transcriptomes uncover regulatory networks during seed abortion in seedless Ponkan (Citrus reticulata). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:642-661. [PMID: 37077034 DOI: 10.1111/tpj.16251] [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: 11/09/2022] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 05/03/2023]
Abstract
Seed abortion is an important process in the formation of seedless characteristics in citrus fruits. However, the molecular regulatory mechanism underlying citrus seed abortion is poorly understood. Laser capture microdissection-based RNA-seq combined with Pacbio-seq was used to profile seed development in the Ponkan cultivars 'Huagan No. 4' (seedless Ponkan) (Citrus reticulata) and 'E'gan No. 1' (seeded Ponkan) (C. reticulata) in two types of seed tissue across three developmental stages. Through comparative transcriptome and dynamic phytohormone analyses, plant hormone signal, cell division and nutrient metabolism-related processes were revealed to play critical roles in the seed abortion of 'Huagan No. 4'. Moreover, several genes may play indispensable roles in seed abortion of 'Huagan No. 4', such as CrWRKY74, CrWRKY48 and CrMYB3R4. Overexpression of CrWRKY74 in Arabidopsis resulted in severe seed abortion. By analyzing the downstream regulatory network, we further determined that CrWRKY74 participated in seed abortion regulation by inducing abnormal programmed cell death. Of particular importance is that a preliminary model was proposed to depict the regulatory networks underlying seed abortion in citrus. The results of this study provide novel insights into the molecular mechanism across citrus seed development, and reveal the master role of CrWRKY74 in seed abortion of 'Huagan No. 4'.
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Affiliation(s)
- Liqing Lu
- National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, P.R. China
| | - Haijian Yang
- Fruit Tree Research Institute of Chongqing Academy of Agricultural Sciences, Chongqing, 401329, P.R. China
| | - Yanhui Xu
- National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, P.R. China
| | - Li Zhang
- National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, P.R. China
| | - Juxun Wu
- National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, P.R. China
| | - Hualin Yi
- National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, P.R. China
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Cornaro L, Banfi C, Cucinotta M, Colombo L, van Dijk PJ. Asexual reproduction through seeds: the complex case of diplosporous apomixis. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:2462-2478. [PMID: 36794770 DOI: 10.1093/jxb/erad054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 02/07/2023] [Indexed: 06/06/2023]
Abstract
Apomixis is considered a potentially revolutionary tool to generate high-quality food at a lower cost and shorter developmental time due to clonal seed production through apomeiosis and parthenogenesis. In the diplosporous type of apomixis, meiotic recombination and reduction are circumvented either by avoiding or failing meiosis or by a mitotic-like division. Here, we review the literature on diplospory, from early cytological studies dating back to the late 19th century to recent genetic findings. We discuss diplosporous developmental mechanisms, including their inheritance. Furthermore, we compare the strategies adopted to isolate the genes controlling diplospory with those to produce mutants forming unreduced gametes. Nowadays, the dramatically improved technologies of long-read sequencing and targeted CRISPR/Cas mutagenesis justify the expectation that natural diplospory genes will soon be identified. Their identification will answer questions such as how the apomictic phenotype can be superimposed upon the sexual pathway and how diplospory genes have evolved. This knowledge will contribute to the application of apomixis in agriculture.
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Affiliation(s)
- Letizia Cornaro
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Camilla Banfi
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Mara Cucinotta
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Lucia Colombo
- Department of Biosciences, University of Milan, Via Giovanni Celoria 26, 20133, Milano, Italy
| | - Peter J van Dijk
- KeyGene N.V., Agro Business Park 90, 6708 PW Wageningen, The Netherlands
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Montalt R, Cuenca J, Vives MC, Mournet P, Navarro L, Ollitrault P, Aleza P. Genotyping by Sequencing for SNP-Based Linkage Analysis and the Development of KASPar Markers for Male Sterility and Polyembryony in Citrus. PLANTS (BASEL, SWITZERLAND) 2023; 12:1567. [PMID: 37050193 PMCID: PMC10096700 DOI: 10.3390/plants12071567] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/29/2023] [Accepted: 04/03/2023] [Indexed: 06/19/2023]
Abstract
Polyembryony and male sterility (MS) are essential characters for citrus breeding. MS, coupled with parthenocarpy, allows for addressing the diversification of diploid seedless mandarin varieties, and nucleocytoplasmic MS is the most prevalent system. Polyembryony limits the use of seed parents in scion breeding programs, and the recovery of monoembryonic hybrids to be used as female parents is a crucial pre-breeding component. The objectives of this work were the identification of SNPs closely linked with the genes implied in these traits for marker-assisted selection. Genotyping by sequencing was used to genotype 61 diploid hybrids from an F1 progeny recovered from crossing 'Kiyomi' and 'Murcott' tangors. A total of 6444 segregating markers were identified and used to establish the two parental genetic maps. They consisted of 1374 and 697 markers encompassing 1416.287 and 1339.735 cM for 'Kiyomi' and 'Murcott', respectively. Phenotyping for MS and polyembryony was performed. The genotype-trait association study identified a genomic region on LG8 which was significantly associated with MS, and a genomic region on LG1 which was significantly associated with polyembryony. Annotation of the identified region for MS revealed 19 candidate genes. One SNP KASPar marker was developed and fully validated for each trait.
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Affiliation(s)
- Rafael Montalt
- Centro de Citricultura y Producción Vegetal, Instituto Valenciano de Investigaciones Agrarias (IVIA), 46113 Valencia, Spain
| | - José Cuenca
- Agrupación de Viveristas de Agrios (AVASA), 12570 Castellón, Spain
| | - María Carmen Vives
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), 46113 Valencia, Spain
| | - Pierre Mournet
- UMR AGAP, CIRAD, 34398 Montpellier, France
- UMR AGAP, Institut Agro, CIRAD, INRAE, Université Montpellier, 34060 Montpellier, France
| | - Luis Navarro
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), 46113 Valencia, Spain
| | - Patrick Ollitrault
- UMR AGAP, CIRAD, 34398 Montpellier, France
- UMR AGAP, Institut Agro, CIRAD, INRAE, Université Montpellier, 34060 Montpellier, France
| | - Pablo Aleza
- Centro de Citricultura y Producción Vegetal, Instituto Valenciano de Investigaciones Agrarias (IVIA), 46113 Valencia, Spain
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Murugan T, Awasthi OP, Singh SK, Chawla G, Solanke AU, Kumar S, Jha GK. Molecular and histological validation of modified in ovulo nucellus culture based high-competency direct somatic embryogenesis and amplitude true-to-the-type plantlet recovery in Kinnow mandarin. FRONTIERS IN PLANT SCIENCE 2023; 14:1116151. [PMID: 36968388 PMCID: PMC10031028 DOI: 10.3389/fpls.2023.1116151] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 02/15/2023] [Indexed: 06/18/2023]
Abstract
Kinnow (Citrus nobilis Lour. × Citrus deliciosa Ten.) needs to be genetically improved for traits such as seedlessness using biotechnological tools. Indirect somatic embryogenesis (ISE) protocols have been reported for citrus improvement. However, its use is restricted due to frequent occurrences of somaclonal variation and low recovery of plantlets. Direct somatic embryogenesis (DSE) using nucellus culture has played a significant role in apomictic fruit crops. However, its application in citrus is limited due to the injury caused to tissues during isolation. Optimization of the explant developmental stage, explant preparation method, and modification in the in vitro culture techniques can play a vital role in overcoming the limitation. The present investigation deals with a modified in ovulo nucellus culture technique after the concurrent exclusion of preexisting embryos. The ovule developmental events were examined in immature fruits at different stages of fruit growth (stages I-VII). The ovules of stage III fruits (>21-25 mm in diameter) were found appropriate for in ovulo nucellus culture. Optimized ovule size induced somatic embryos at the micropylar cut end on induction medium containing Driver and Kuniyuki Walnut (DKW) basal medium with kinetin (KIN) 5.0 mg L-1 and malt extract (ME) 1,000 mg L-1. Simultaneously, the same medium supported the maturation of somatic embryos. The matured embryos from the above medium gave robust germination with bipolar conversion on Murashige and Tucker (MT) medium + gibberellic acid (GA3) 2.0 mg L-1 + ά-naphthaleneacetic acid (NAA) 0.5 mg L-1 + spermidine 100 mg L-1 + coconut water (CW) 10% (v/v). The bipolar germinated seedlings established well upon preconditioning in a plant bio regulator (PBR)-free liquid medium under the light. Consequently, a cent percent survival of emblings was achieved on a potting medium containing cocopeat:vermiculite:perlite (2:1:1). Histological studies confirmed the single nucellus cell origin of somatic embryos by undergoing normal developmental events. Eight polymorphic Inter Simple Sequence Repeats (ISSR) markers confirmed the genetic stability of acclimatized emblings. Since the protocol can induce rapid single-cell origin of genetically stable in vitro regenerants in high frequency, it has potential for the induction of solid mutants, besides crop improvement, mass multiplication, gene editing, and virus elimination in Kinnow mandarin.
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Affiliation(s)
- Theivanai Murugan
- Division of Fruits and Horticultural Technology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Om Prakash Awasthi
- Division of Fruits and Horticultural Technology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Sanjay Kumar Singh
- Division of Fruits and Horticultural Technology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Gautam Chawla
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Amolkumar U. Solanke
- Division of Molecular Biology and Biotechnology, ICAR-National Institute for Plant Biotechnology, New Delhi, India
| | - Sunil Kumar
- Division of Fruits and Horticultural Technology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Girish Kumar Jha
- Discipline of Agricultural Statistics, Division of Agricultural Economics, ICAR-Indian Agricultural Research Institute, New Delhi, India
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Pan-mitogenomics reveals the genetic basis of cytonuclear conflicts in citrus hybridization, domestication, and diversification. Proc Natl Acad Sci U S A 2022; 119:e2206076119. [PMID: 36260744 PMCID: PMC9618123 DOI: 10.1073/pnas.2206076119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Although interactions between the cytoplasmic and nuclear genomes occurred during diversification of many plants, the evolutionary conflicts due to cytonuclear interactions are poorly understood in crop breeding. Here, we constructed a pan-mitogenome and identified chimeric open reading frames (ORFs) generated by extensive structural variations (SVs). Meanwhile, short reads from 184 accessions of citrus species were combined to construct three variation maps for the nuclear, mitochondrial, and chloroplast genomes. The population genomic data showed discordant topologies between the cytoplasmic and nuclear genomes because of differences in mutation rates and levels of heteroplasmy from paternal leakage. An analysis of species-specific SVs indicated that mitochondrial heteroplasmy was common and that chloroplast heteroplasmy was undetectable. Interestingly, we found a prominent divergence in the mitogenomes and the highest genetic load in the, which may provide the basis for cytoplasmic male sterility (CMS) and thus influence the reshuffling of the cytoplasmic and nuclear genomes during hybridization. Using cytoplasmic replacement experiments, we identified a type of species-specific CMS in mandarin related to two chimeric mitochondrial genes. Our analyses indicate that cytoplasmic genomes from mandarin have rarely been maintained in hybrids and that paternal leakage produced very low levels of mitochondrial heteroplasmy in mandarin. A genome-wide association study (GWAS) provided evidence for three nuclear genes that encode pentatricopeptide repeat (PPR) proteins contributing to the cytonuclear interactions in the Citrus genus. Our study demonstrates the occurrence of evolutionary conflicts between cytoplasmic and nuclear genomes in citrus and has important implications for genetics and breeding.
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8
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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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Xu Y, Jia H, Tan C, Wu X, Deng X, Xu Q. Apomixis: genetic basis and controlling genes. HORTICULTURE RESEARCH 2022; 9:uhac150. [PMID: 36072837 PMCID: PMC9437720 DOI: 10.1093/hr/uhac150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/27/2022] [Indexed: 05/12/2023]
Abstract
Apomixis is the phenomenon of clonal reproduction by seed. As apomixis can produce clonal progeny with exactly the same genotype as the maternal plant, it has an important application in genotype fixation and accelerating agricultural breeding strategies. The introduction of apomixis to major crops would bring many benefits to agriculture, including permanent fixation of superior genotypes and simplifying the procedures of hybrid seed production, as well as purification and rejuvenation of crops propagated vegetatively. Although apomixis naturally occurs in more than 400 plant species, it is rare among the major crops. Currently, with better understanding of apomixis, some achievements have been made in synthetic apomixis. However, due to prevailing limitations, there is still a long way to go to achieve large-scale application of apomixis to crop breeding. Here, we compare the developmental features of apomixis and sexual plant reproduction and review the recent identification of apomixis genes, transposons, epigenetic regulation, and genetic events leading to apomixis. We also summarize the possible strategies and potential genes for engineering apomixis into crop plants.
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Affiliation(s)
- Yuantao Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Huihui Jia
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Chunming Tan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Xiaomeng Wu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, China
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Jia HH, Xu YT, Yin ZP, Wu XM, Qing M, Fan YJ, Song X, Xie KD, Xie ZZ, Xu Q, Deng XX, Guo WW. Transcriptomes and DNA methylomes in apomictic cells delineate nucellar embryogenesis initiation in citrus. DNA Res 2021; 28:6356518. [PMID: 34424285 PMCID: PMC8476932 DOI: 10.1093/dnares/dsab014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/20/2021] [Indexed: 12/13/2022] Open
Abstract
Citrus nucellar poly-embryony (NPE) is a mode of sporophytic apomixis that asexual embryos formed in the seed through adventitious embryogenesis from the somatic nucellar cells. NPE allows clonal propagation of rootstocks, but it impedes citrus cross breeding. To understand the cellular processes involved in NPE initiation, we profiled the transcriptomes and DNA methylomes in laser microdissection captured citrus apomictic cells. In apomictic cells, ribosome biogenesis and protein degradation were activated, whereas auxin polar transport was repressed. Reactive oxygen species (ROS) accumulated in the poly-embryonic ovules, and response to oxidative stress was provoked. The global DNA methylation level, especially that of CHH context, was decreased, whereas the methylation level of the NPE-controlling key gene CitRWP was increased. A C2H2 domain-containing transcription factor gene and CitRWP co-expressed specifically in apomictic cells may coordinate to initiate NPE. The activated embryogenic development and callose deposition processes indicated embryogenic fate of nucellar embryo initial (NEI) cells. In our working model for citrus NPE initiation, DNA hyper-methylation may activate transcription of CitRWP, which increases C2H2 expression and ROS accumulation, triggers epigenetic regulation and regulates cell fate transition and NEI cell identity in the apomictic cells.
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Affiliation(s)
- Hui-Hui Jia
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuan-Tao Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhao-Ping Yin
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiao-Meng Wu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Mei Qing
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yan-Jie Fan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xin Song
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Kai-Dong Xie
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zong-Zhou Xie
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qiang Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiu-Xin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wen-Wu Guo
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
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