1
|
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.
Collapse
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
| |
Collapse
|
2
|
Niccolò T, Anderson AW, Emidio A. Apomixis: oh, what a tangled web we have! PLANTA 2023; 257:92. [PMID: 37000270 PMCID: PMC10066125 DOI: 10.1007/s00425-023-04124-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 03/21/2023] [Indexed: 06/19/2023]
Abstract
Apomixis is a complex evolutionary trait with many possible origins. Here we discuss various clues and causes, ultimately proposing a model harmonizing the three working hypotheses on the topic. Asexual reproduction through seeds, i.e., apomixis, is the holy grail of plant biology. Its implementation in modern breeding could be a game-changer for agriculture. It has the potential to generate clonal crops and maintain valuable complex genotypes and their associated heterotic traits without inbreeding depression. The genetic basis and origins of apomixis are still unclear. There are three central hypothesis for the development of apomixis that could be: i) a deviation from the sexual developmental program caused by an asynchronous development, ii) environmentally triggered through epigenetic regulations (a polyphenism of sex), iii) relying on one or more genes/alleles. Because of the ever-increasing complexity of the topic, the path toward a detailed understanding of the mechanisms underlying apomixis remains unclear. Here, we discuss the most recent advances in the evolution perspective of this multifaceted trait. We incorporated our understanding of the effect of endogenous effectors, such as small RNAs, epigenetic regulation, hormonal pathways, protein turnover, and cell wall modification in response to an upside stress. This can be either endogenous (hybridization or polyploidization) or exogenous environmental stress, mainly due to oxidative stress and the corresponding ROS (Reacting Oxygen Species) effectors. Finally, we graphically represented this tangled web.
Collapse
Affiliation(s)
- Terzaroli Niccolò
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy.
| | - Aaron W Anderson
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy
- Fulbright Scholar From Department of Plant Sciences, University of California, Davis, USA
| | - Albertini Emidio
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy
- Consorzio Interuniversitario per le Biotecnologie (CIB), Trieste, Italy
| |
Collapse
|
3
|
Paetzold C, Barke BH, Hörandl E. Evolution of Transcriptomes in Early-Generation Hybrids of the Apomictic Ranunculus auricomus Complex ( Ranunculaceae). Int J Mol Sci 2022; 23:ijms232213881. [PMID: 36430360 PMCID: PMC9697309 DOI: 10.3390/ijms232213881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/03/2022] [Accepted: 11/09/2022] [Indexed: 11/12/2022] Open
Abstract
Hybridisation in plants may cause a shift from sexual to asexual seed formation (apomixis). Indeed, natural apomictic plants are usually hybrids, but it is still unclear how hybridisation could trigger the shift to apomixis. The genome evolution of older apomictic lineages is influenced by diverse processes such as polyploidy, mutation accumulation, and allelic sequence divergence. To disentangle the effects of hybridisation from these other factors, we analysed the transcriptomes of flowering buds from artificially produced, diploid F2 hybrids of the Ranunculus auricomus complex. The hybrids exhibited unreduced embryo sac formation (apospory) as one important component of apomixis, whereas their parental species were sexual. We revealed 2915 annotated single-copy genes that were mostly under purifying selection according to dN/dS ratios. However, pairwise comparisons revealed, after rigorous filtering, 79 genes under diversifying selection between hybrids and parents, whereby gene annotation assigned ten of them to reproductive processes. Four genes belong to the meiosis-sporogenesis phase (ASY1, APC1, MSP1, and XRI1) and represent, according to literature records, candidate genes for apospory. We conclude that hybridisation could combine novel (or existing) mutations in key developmental genes in certain hybrid lineages, and establish (together with altered gene expression profiles, as observed in other studies) a heritable regulatory mechanism for aposporous development.
Collapse
Affiliation(s)
- Claudia Paetzold
- Department of Botany and Molecular Evolution, Senckenberg Research Institute, 60325 Frankfurt am Main, Germany
| | - Birthe H. Barke
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, 37073 Goettingen, Germany
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium), University of Goettingen, 37073 Goettingen, Germany
- Correspondence:
| |
Collapse
|
4
|
Noyes RD. Mendelian segregation for parthenogenetic embryo development at the diploid level in the flowering plant Erigeron. AMERICAN JOURNAL OF BOTANY 2022; 109:1641-1651. [PMID: 36112611 DOI: 10.1002/ajb2.16071] [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: 02/24/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 06/15/2023]
Abstract
PREMISE Parthenogenesis is the capacity of organisms to develop embryos from unfertilized eggs. When parthenogenesis is coupled with unreduced gamete formation (apomeiosis), genetically maternal progeny result. Genetic elucidation of this form of reproduction in plants, apomixis, has important agronomic implications. However, genetic characterization of apomeiosis and parthenogenesis has been problematic in part because the traits usually co-occur and are restricted to polyploids. In this work, the inheritance of parthenogenetic embryo development, by itself, was studied at the diploid level. METHODS Progeny resulting from a cross between a diploid (2n = 18), heterozygous, parthenogenetic pollen donor, and a diploid, wildtype, sexual seed parent were evaluated. Paternity was tested with conserved orthologous sequence (COS) markers, reproductive development of F1s was evaluated with microscopy of cleared ovules, and an amplified fragment length polymorphism (AFLP) marker (Eagc × Macg.615) co-segregating with parthenogenesis was characterized at the sequence level. RESULTS Of 102 diploid biparental progeny, 47 exhibited parthenogenetic embryo and endosperm development, and 55 lacked development of the egg and central cell. This result is consistent with Mendelian inheritance for a single locus (P = 0.43). Isolation and sequencing of the AFLP marker indicates that it is likely a portion of a Ty-Gypsy retrotransposon. Attempts to develop a sequence-characterized amplified region marker from the AFLP were unsuccessful. CONCLUSIONS This work shows that parthenogenesis can be transmitted simply at the diploid level. This advance is key in the development of a tractable system in Erigeron aimed at the identification of the parthenogenesis locus using genetic mapping strategies.
Collapse
Affiliation(s)
- Richard D Noyes
- Department of Biology, University of Central Arkansas, Conway, AR, US 72035
| |
Collapse
|
5
|
Chahal LS, Conner JA, Ozias-Akins P. Phylogenetically Distant BABY BOOM Genes From Setaria italica Induce Parthenogenesis in Rice. FRONTIERS IN PLANT SCIENCE 2022; 13:863908. [PMID: 35909735 PMCID: PMC9329937 DOI: 10.3389/fpls.2022.863908] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 06/13/2022] [Indexed: 06/02/2023]
Abstract
The combination of apomixis and hybrid production is hailed as the holy grail of agriculture for the ability of apomixis to fix heterosis of F1 hybrids in succeeding generations, thereby eliminating the need for repeated crosses to produce F1 hybrids. Apomixis, asexual reproduction through seed, achieves this feat by circumventing two processes that are fundamental to sexual reproduction (meiosis and fertilization) and replacing them with apomeiosis and parthenogenesis, resulting in seeds that are clonal to the maternal parent. Parthenogenesis, embryo development without fertilization, has been genetically engineered in rice, maize, and pearl millet using PsASGR-BABY BOOM-like (PsASGR-BBML) transgenes and in rice using the OsBABY BOOM1 (OsBBM1) cDNA sequence when expressed under the control of egg cell-specific promoters. A phylogenetic analysis revealed that BABY BOOM (BBM)/BBML genes from monocots cluster within three different clades. The BBM/BBML genes shown to induce parthenogenesis cluster within clade 1 (the ASGR-BBML clade) along with orthologs from other monocot species, such as Setaria italica. For this study, we tested the parthenogenetic potential of three BBM transgenes from S. italica, each a member of a different phylogenetic BBM clade. All transgenes were genomic constructs under the control of the AtDD45 egg cell-specific promoter. All SiBBM transgenes induced various levels of parthenogenetic embryo development, resulting in viable haploid T1 seedlings. Poor seed set and lower haploid seed production were characteristics of multiple transgenic lines. The results presented in this study illustrate that further functional characterization of BBMs in zygote/embryo development is warranted.
Collapse
Affiliation(s)
- Lovepreet Singh Chahal
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Tifton, GA, United States
| | - Joann A. Conner
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Tifton, GA, United States
- Department of Horticulture, University of Georgia, Tifton, GA, United States
| | - Peggy Ozias-Akins
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Tifton, GA, United States
- Department of Horticulture, University of Georgia, Tifton, GA, United States
| |
Collapse
|
6
|
Yu L, Ma X, Wadlington W, Ming R. Identification of structural variation and polymorphisms of a sex co-segregating scaffold in spinach. PLANT REPRODUCTION 2022; 35:19-30. [PMID: 34319458 DOI: 10.1007/s00497-021-00424-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Spinach is a common vegetable, and dioecy is maintained by a pair of XY sex chromosomes. Due to limited genomic resources and its highly repetitive genome, limited studies were conducted to investigate the genomic landscape of the region near sex-determining loci. In this study, we screened the structure variations (SVs) between Y-linked contigs and a 1.78-Mb X scaffold (Super_scaffold 66), which enabled the development of 12 sex co-segregating DNA markers. These markers were tested in one F1 mapping population and 40 spinach accessions, which comprised 692 individual plants with the strong sex linkage pattern. In addition, we found that Super_scaffold 66 was highly repetitive along with the enriched LTR-RTs insertions and decreased microsatellite distribution compared with the rest genome, which matches extremely low gene density featured by only nine annotated genes. Synteny analysis between Y contigs and Superscaffold_66 revealed a 340-Kb accumulative Y contig (non-continuous) and a 500-Kb X counterpart along with SVs and wide-spread tandem duplications. Among the nine genes, one ABC transporter gene revealed noticeable SVs between Y contig and X counterpart, as an approximate 5-Kb recent Gypsy LTR-RT insertion in the Y-linked allele, but not the X allele. The gene paucity, SVs, and sex-linked polymorphisms attributed to the recombination suppression. We proposed that Super_scaffold 66 is part of the non-recombining region containing the sex determination genes. The spread of 12 sex co-segregating markers from this 1.78 Mb genomic region indicated the existence and expansion of sex determination region during progression of the Y chromosome.
Collapse
Affiliation(s)
- Li'ang Yu
- Department of Plant Biology, University of Illinois At Urbana-Champaign, 1201 West Gregory Drive, Urbana, IL, 61801-3838, USA
| | - Xiaokai Ma
- Center for Genomics and Biotechnology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - William Wadlington
- Department of Plant Biology, University of Illinois At Urbana-Champaign, 1201 West Gregory Drive, Urbana, IL, 61801-3838, USA
| | - Ray Ming
- Department of Plant Biology, University of Illinois At Urbana-Champaign, 1201 West Gregory Drive, Urbana, IL, 61801-3838, USA.
- Center for Genomics and Biotechnology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
| |
Collapse
|
7
|
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.
Collapse
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
| | | |
Collapse
|
8
|
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.
Collapse
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:
| |
Collapse
|
9
|
Carballo J, Zappacosta D, Selva JP, Caccamo M, Echenique V. Eragrostis curvula, a Model Species for Diplosporous Apomixis. PLANTS (BASEL, SWITZERLAND) 2021; 10:1818. [PMID: 34579351 PMCID: PMC8472828 DOI: 10.3390/plants10091818] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/16/2021] [Accepted: 08/26/2021] [Indexed: 11/16/2022]
Abstract
Eragrostis curvula (Schrad.) Ness is a grass with a particular apomictic embryo sac development called Eragrostis type. Apomixis is a type of asexual reproduction that produces seeds without fertilization in which the resulting progeny is genetically identical to the mother plant and with the potential to fix the hybrid vigour from more than one generation, among other advantages. The absence of meiosis and the occurrence of only two rounds of mitosis instead of three during embryo sac development make this model unique and suitable to be transferred to economically important crops. Throughout this review, we highlight the advances in the knowledge of apomixis in E. curvula using different techniques such as cytoembryology, DNA methylation analyses, small-RNA-seq, RNA-seq, genome assembly, and genotyping by sequencing. The main bulk of evidence points out that apomixis is inherited as a single Mendelian factor, and it is regulated by genetic and epigenetic mechanisms controlled by a complex network. With all this information, we propose a model of the mechanisms involved in diplosporous apomixis in this grass. All the genetic and epigenetic resources generated in E. curvula to study the reproductive mode changed its status from an orphan to a well-characterised species.
Collapse
Affiliation(s)
- Jose Carballo
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
| | - Diego Zappacosta
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, Bahía Blanca 8000, Argentina
| | - Juan Pablo Selva
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), San Juan 670, Bahía Blanca 8000, Argentina
| | - Mario Caccamo
- NIAB, 93 Lawrence Weaver Road, Cambridge CB3 0LE, UK;
| | - Viviana Echenique
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS–CCT–CONICET Bahía Blanca), Camino de la Carrindanga km 7, Bahía Blanca 8000, Argentina; (J.C.); (J.P.S.); (V.E.)
- Departamento de Agronomía, Universidad Nacional del Sur (UNS), San Andrés 800, Bahía Blanca 8000, Argentina
| |
Collapse
|
10
|
Ke Y, Podio M, Conner J, Ozias-Akins P. Single-cell transcriptome profiling of buffelgrass (Cenchrus ciliaris) eggs unveils apomictic parthenogenesis signatures. Sci Rep 2021; 11:9880. [PMID: 33972603 PMCID: PMC8110759 DOI: 10.1038/s41598-021-89170-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/15/2021] [Indexed: 12/04/2022] Open
Abstract
Apomixis, a type of asexual reproduction in angiosperms, results in progenies that are genetically identical to the mother plant. It is a highly desirable trait in agriculture due to its potential to preserve heterosis of F1 hybrids through subsequent generations. However, no major crops are apomictic. Deciphering mechanisms underlying apomixis becomes one of the alternatives to engineer self-reproducing capability into major crops. Parthenogenesis, a major component of apomixis, commonly described as the ability to initiate embryo formation from the egg cell without fertilization, also can be valuable in plant breeding for doubled haploid production. A deeper understanding of transcriptional differences between parthenogenetic and sexual or non-parthenogenetic eggs can assist with pathway engineering. By conducting laser capture microdissection-based RNA-seq on sexual and parthenogenetic egg cells on the day of anthesis, a de novo transcriptome for the Cenchrus ciliaris egg cells was created, transcriptional profiles that distinguish the parthenogenetic egg from its sexual counterpart were identified, and functional roles for a few transcription factors in promoting natural parthenogenesis were suggested. These transcriptome data expand upon previous gene expression studies and will be a resource for future research on the transcriptome of egg cells in parthenogenetic and sexual genotypes.
Collapse
Affiliation(s)
- Yuji Ke
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, GA, 31793, USA
| | - Maricel Podio
- Department of Horticulture, University of Georgia, Tifton, GA, 31793, USA
| | - Joann Conner
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, GA, 31793, USA.,Department of Horticulture, University of Georgia, Tifton, GA, 31793, USA
| | - Peggy Ozias-Akins
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, GA, 31793, USA. .,Department of Horticulture, University of Georgia, Tifton, GA, 31793, USA.
| |
Collapse
|
11
|
Soliman M, Podio M, Marconi G, Di Marsico M, Ortiz JPA, Albertini E, Delgado L. Differential Epigenetic Marks Are Associated with Apospory Expressivity in Diploid Hybrids of Paspalum rufum. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10040793. [PMID: 33920644 PMCID: PMC8072704 DOI: 10.3390/plants10040793] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
Apomixis seems to emerge from the deregulation of preexisting genes involved in sexuality by genetic and/or epigenetic mechanisms. The trait is associated with polyploidy, but diploid individuals of Paspalum rufum can form aposporous embryo sacs and develop clonal seeds. Moreover, diploid hybrid families presented a wide apospory expressivity variation. To locate methylation changes associated with apomixis expressivity, we compare relative DNA methylation levels, at CG, CHG, and CHH contexts, between full-sib P. rufum diploid genotypes presenting differential apospory expressivity. The survey was performed using a methylation content-sensitive enzyme ddRAD (MCSeEd) strategy on samples at premeiosis/meiosis and postmeiosis stages. Based on the relative methylation level, principal component analysis and heatmaps, clearly discriminate samples with contrasting apospory expressivity. Differential methylated contigs (DMCs) showed 14% of homology to known transcripts of Paspalum notatum reproductive transcriptome, and almost half of them were also differentially expressed between apomictic and sexual samples. DMCs showed homologies to genes involved in flower growth, development, and apomixis. Moreover, a high proportion of DMCs aligned on genomic regions associated with apomixis in Setaria italica. Several stage-specific differential methylated sequences were identified as associated with apospory expressivity, which could guide future functional gene characterization in relation to apomixis success at diploid and tetraploid levels.
Collapse
Affiliation(s)
- Mariano Soliman
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
| | - Maricel Podio
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
| | - Gianpiero Marconi
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Marco Di Marsico
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Juan Pablo A. Ortiz
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
| | - Emidio Albertini
- Department Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy; (G.M.); (M.D.M.)
| | - Luciana Delgado
- CONICET-UNR/Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR), Universidad Nacional de Rosario, Zavalla S2123, Argentina; (M.S.); (M.P.); (J.P.A.O.)
| |
Collapse
|
12
|
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.
Collapse
Affiliation(s)
- Sam W. Henderson
- Correspondence: (S.W.H.); (A.M.G.K.); Tel.: +61-407-323-260 (A.M.G.K.)
| | | | | | | |
Collapse
|
13
|
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.
Collapse
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,
| |
Collapse
|
14
|
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]
|
15
|
Colono C, Ortiz JPA, Permingeat HR, Souza Canada ED, Siena LA, Spoto N, Galdeano F, Espinoza F, Leblanc O, Pessino SC. A Plant-Specific TGS1 Homolog Influences Gametophyte Development in Sexual Tetraploid Paspalum notatum Ovules. FRONTIERS IN PLANT SCIENCE 2019; 10:1566. [PMID: 31850040 PMCID: PMC6895069 DOI: 10.3389/fpls.2019.01566] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 11/08/2019] [Indexed: 05/04/2023]
Abstract
Aposporous apomictic plants form clonal maternal seeds by inducing the emergence of non-reduced (2n) embryo sacs in the ovule nucellus and the development of embryos by parthenogenesis. In previous work, we reported a plant-specific TRIMETHYLGUANOSINE SYNTHASE 1 (TGS1) gene (PN_TGS1-like) showing expression levels positively correlated with sexuality rates in facultative apomictic Paspalum notatum. PN_ TGS1-like displayed contrasting in situ hybridization patterns in apomictic and sexual plant ovules from premeiosis to anthesis. Here we transformed sexual P. notatum with a TGS1-like antisense construction under a constitutive promoter, in order to produce lines with reduced transcript representation. Antisense plants developed prominent trichomes on the adaxial leaf surface, a trait absent from control genotypes. Reproductive development analysis revealed occasional formation of twin ovules. While control individuals typically displayed a single meiotic embryo sac per ovule, antisense lines showed 12.93-15.79% of ovules bearing extra nuclei, which can be assigned to aposporous-like embryo sacs (AES-like) or, alternatively, to gametophytes with a misguided cell fate development. Moreover, around 8.42-9.52% of ovules showed what looked like a combination of meiotic and aposporous-like sacs. Besides, 32.5% of ovules at early developmental stages displayed nucellar cells with prominent nuclei resembling apospory initials (AIs), which surrounded the megaspore mother cell (MMC) or the MMC-derived meiotic products. Two or more concurrent meiosis events were never detected, which suggest a non-reduced nature for the extra nuclei observed in the mature ovules, unless they were generated by proliferation and misguided differentiation of the legitimate meiotic products. The antisense lines produced a similar amount of viable even-sized pollen with respect to control genotypes, and formed an equivalent full seed set (∼9% of total seeds) after self-pollination. Flow cytometry analyses of caryopses derived from antisense lines revealed that all full seeds had originated from meiotic embryo sacs (i.e. by sexuality). A reduction of 25.55% in the germination percentage was detected when comparing antisense lines with controls. Our results indicate that PN_ TGS1-like influences ovule, gametophyte and possibly embryo development.
Collapse
Affiliation(s)
- Carolina Colono
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Juan Pablo A. Ortiz
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Hugo R. Permingeat
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | | | - Lorena A. Siena
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Nicolás Spoto
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
| | - Florencia Galdeano
- Genetics Laboratory, IBONE, CONICET, Universidad Nacional del Nordeste, Corrientes, Argentina
| | - Francisco Espinoza
- Genetics Laboratory, IBONE, CONICET, Universidad Nacional del Nordeste, Corrientes, Argentina
| | | | - Silvina C. Pessino
- Molecular Biology Laboratory, IICAR, CONICET, Universidad Nacional de Rosario, Rosario, Argentina
- *Correspondence: Silvina C. Pessino,
| |
Collapse
|
16
|
Vijverberg K, Ozias-Akins P, Schranz ME. Identifying and Engineering Genes for Parthenogenesis in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:128. [PMID: 30838007 PMCID: PMC6389702 DOI: 10.3389/fpls.2019.00128] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/24/2019] [Indexed: 05/16/2023]
Abstract
Parthenogenesis is the spontaneous development of an embryo from an unfertilized egg cell. It naturally occurs in a variety of plant and animal species. In plants, parthenogenesis usually is found in combination with apomeiosis (the omission of meiosis) and pseudogamous or autonomous (with or without central cell fertilization) endosperm formation, together known as apomixis (clonal seed production). The initiation of embryogenesis in vivo and in vitro has high potential in plant breeding methods, particularly for the instant production of homozygous lines from haploid gametes [doubled haploids (DHs)], the maintenance of vigorous F1-hybrids through clonal seed production after combining it with apomeiosis, reverse breeding approaches, and for linking diploid and polyploid gene pools. Because of this large interest, efforts to identify gene(s) for parthenogenesis from natural apomicts have been undertaken by using map-based cloning strategies and comparative gene expression studies. In addition, engineering parthenogenesis in sexual model species has been investigated via mutagenesis and gain-of-function strategies. These efforts have started to pay off, particularly by the isolation of the PsASGR-BabyBoom-Like from apomictic Pennisetum, a gene proven to be transferable to and functional in sexual pearl millet, rice, and maize. This review aims to summarize the current knowledge on parthenogenesis, the possible gene candidates also outside the grasses, and the use of these genes in plant breeding protocols. It shows that parthenogenesis is able to inherit and function independently from apomeiosis and endosperm formation, is expressed and active in the egg cell, and can induce embryogenesis in polyploid, diploid as well as haploid egg cells in plants. It also shows the importance of genes involved in the suppression of transcription and modifications thereof at one hand, and in embryogenesis for which transcription is allowed or artificially overexpressed on the other, in parthenogenetic reproduction. Finally, it emphasizes the importance of functional endosperm to allow for successful embryo growth and viable seed production.
Collapse
Affiliation(s)
- Kitty Vijverberg
- Biosystematics Group, Experimental Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
- *Correspondence: Kitty Vijverberg,
| | - Peggy Ozias-Akins
- Department of Horticulture, Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton Campus, Tifton, GA, United States
| | - M. Eric Schranz
- Biosystematics Group, Experimental Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
| |
Collapse
|
17
|
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.
Collapse
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.
| |
Collapse
|
18
|
Hand ML, de Vries S, Koltunow AMG. A Comparison of In Vitro and In Vivo Asexual Embryogenesis. Methods Mol Biol 2016; 1359:3-23. [PMID: 26619856 DOI: 10.1007/978-1-4939-3061-6_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In plants, embryogenesis generally occurs through the sexual process of double fertilization, which involves a haploid sperm cell fusing with a haploid egg cell to ultimately give rise to a diploid embryo. Embryogenesis can also occur asexually in the absence of fertilization, both in vitro and in vivo. Somatic or gametic cells are able to differentiate into embryos in vitro following the application of plant growth regulators or stress treatments. Asexual embryogenesis also occurs naturally in some plant species in vivo, from either ovule cells as part of a process defined as apomixis, or from somatic leaf tissue in other species. In both in vitro and in vivo asexual embryogenesis, the embryo precursor cells must attain an embryogenic fate without the act of fertilization. This review compares the processes of in vitro and in vivo asexual embryogenesis including what is known regarding the genetic and epigenetic regulation of each process, and considers how the precursor cells are able to change fate and adopt an embryogenic pathway.
Collapse
Affiliation(s)
- Melanie L Hand
- Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture, Waite Campus, Urrbrae, South Australia
| | - Sacco de Vries
- Department of Biochemistry, University of Wageningen, Wageningen, 6703 HA, The Netherlands
| | - Anna M G Koltunow
- Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture, Waite Campus, Urrbrae, South Australia.
| |
Collapse
|
19
|
Sapkota S, Conner JA, Hanna WW, Simon B, Fengler K, Deschamps S, Cigan M, Ozias-Akins P. In Silico and Fluorescence In Situ Hybridization Mapping Reveals Collinearity between the Pennisetum squamulatum Apomixis Carrier-Chromosome and Chromosome 2 of Sorghum and Foxtail Millet. PLoS One 2016; 11:e0152411. [PMID: 27031857 PMCID: PMC4816547 DOI: 10.1371/journal.pone.0152411] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/14/2016] [Indexed: 12/22/2022] Open
Abstract
Apomixis, or clonal propagation through seed, is a trait identified within multiple species of the grass family (Poaceae). The genetic locus controlling apomixis in Pennisetum squamulatum (syn Cenchrus squamulatus) and Cenchrus ciliaris (syn Pennisetum ciliare, buffelgrass) is the apospory-specific genomic region (ASGR). Previously, the ASGR was shown to be highly conserved but inverted in marker order between P. squamulatum and C. ciliaris based on fluorescence in situ hybridization (FISH) and varied in both karyotype and position of the ASGR on the ASGR-carrier chromosome among other apomictic Cenchrus/Pennisetum species. Using in silico transcript mapping and verification of physical positions of some of the transcripts via FISH, we discovered that the ASGR-carrier chromosome from P. squamulatum is collinear with chromosome 2 of foxtail millet and sorghum outside of the ASGR. The in silico ordering of the ASGR-carrier chromosome markers, previously unmapped in P. squamulatum, allowed for the identification of a backcross line with structural changes to the P. squamulatum ASGR-carrier chromosome derived from gamma irradiated pollen.
Collapse
Affiliation(s)
- Sirjan Sapkota
- Department of Horticulture, University of Georgia-Tifton Campus, Tifton, Georgia, 31793, United States of America
| | - Joann A Conner
- Department of Horticulture, University of Georgia-Tifton Campus, Tifton, Georgia, 31793, United States of America
| | - Wayne W Hanna
- Department of Crop and Soil Sciences, University of Georgia-Tifton Campus, Tifton, Georgia, 31793, United States of America
| | - Bindu Simon
- Department of Horticulture, University of Georgia-Tifton Campus, Tifton, Georgia, 31793, United States of America
| | - Kevin Fengler
- DuPont Pioneer, DuPont Pioneer, Johnston, Iowa, 50131, United States of America
| | - Stéphane Deschamps
- DuPont Experimental Station, Wilmington, Delaware, 19803, United States of America
| | - Mark Cigan
- DuPont Pioneer, DuPont Pioneer, Johnston, Iowa, 50131, United States of America
| | - Peggy Ozias-Akins
- Department of Horticulture, University of Georgia-Tifton Campus, Tifton, Georgia, 31793, United States of America
| |
Collapse
|
20
|
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.
Collapse
|
21
|
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.
Collapse
Affiliation(s)
- Radim J Vašut
- Laboratory of Genetics, Wageningen University and Research Centre, P.O. Box 309, NL-6700 AH Wageningen, the Netherlands
| | | | | | | |
Collapse
|
22
|
Simon B, Conner JA, Ozias-Akins P. Selection and validation of reference genes for gene expression analysis in apomictic and sexual Cenchrus ciliaris. BMC Res Notes 2013; 6:397. [PMID: 24083672 PMCID: PMC3854615 DOI: 10.1186/1756-0500-6-397] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 09/25/2013] [Indexed: 11/24/2022] Open
Abstract
Background Apomixis is a naturally occurring asexual mode of seed reproduction resulting in offspring genetically identical to the maternal plant. Identifying differential gene expression patterns between apomictic and sexual plants is valuable to help deconstruct the trait. Quantitative RT-PCR (qRT-PCR) is a popular method for analyzing gene expression. Normalizing gene expression data using proper reference genes which show stable expression under investigated conditions is critical in qRT-PCR analysis. We used qRT-PCR to validate expression and stability of six potential reference genes (EF1alpha, EIF4A, UBCE, GAPDH, ACT2 and TUBA) in vegetative and reproductive tissues of B-2S and B-12-9 accessions of C. ciliaris. Findings Among tissue types evaluated, EF1alpha showed the highest level of expression while TUBA showed the lowest. When all tissue types were evaluated and compared between genotypes, EIF4A was the most stable reference gene. Gene expression stability for specific ovary stages of B-2S and B-12-9 was also determined. Except for TUBA, all other tested reference genes could be used for any stage-specific ovary tissue normalization, irrespective of the mode of reproduction. Conclusion Our gene expression stability assay using six reference genes, in sexual and apomictic accessions of C. ciliaris, suggests that EIF4A is the most stable gene across all tissue types analyzed. All other tested reference genes, with the exception of TUBA, could be used for gene expression comparison studies between sexual and apomictic ovaries over multiple developmental stages. This reference gene validation data in C. ciliaris will serve as an important base for future apomixis-related transcriptome data validation.
Collapse
Affiliation(s)
- Bindu Simon
- Department of Horticulture, The University of Georgia Tifton Campus, Tifton, GA 31793, USA.
| | | | | |
Collapse
|
23
|
Aliyu OM, Seifert M, Corral JM, Fuchs J, Sharbel TF. Copy number variation in transcriptionally active regions of sexual and apomictic Boechera demonstrates independently derived apomictic lineages. THE PLANT CELL 2013; 25:3808-23. [PMID: 24170129 PMCID: PMC3877827 DOI: 10.1105/tpc.113.113860] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 09/11/2013] [Accepted: 10/15/2013] [Indexed: 05/19/2023]
Abstract
In asexual (apomictic) plants, the absence of meiosis and sex is expected to lead to mutation accumulation. To compare mutation accumulation in the transcribed genomic regions of sexual and apomictic plants, we performed a double-validated analysis of copy number variation (CNV) on 10 biological replicates each of diploid sexual and diploid apomictic Boechera, using a high-density (>700 K) custom microarray. The Boechera genome demonstrated higher levels of depleted CNV, compared with enriched CNV, irrespective of reproductive mode. Genome-wide patterns of CNV revealed four divergent lineages, three of which contain both sexual and apomictic genotypes. Hence genome-wide CNV reflects at least three independent origins (i.e., expression) of apomixis from different sexual genetic backgrounds. CNV distributions for different families of transposable elements were lineage specific, and the enrichment of LINE/L1 and long term repeat/Copia elements in lineage 3 apomicts is consistent with sex and meiosis being mechanisms for purging genomic parasites. We hypothesize that significant overrepresentation of specific gene ontology classes (e.g., pollen-pistil interaction) in apomicts implies that gene enrichment could be an adaptive mechanism for genome stability in diploid apomicts by providing a polyploid-like system for buffering the effects of deleterious mutations.
Collapse
Affiliation(s)
- Olawale M. Aliyu
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany
| | - Michael Seifert
- Data Inspection Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany
- Cellular Networks and Systems Biology, Biotechnology Center of the Technical University Dresden, D-01307 Dresden, Germany
- Innovative Methods of Computing, Center for Information Services and High Performance Computing, Technical University Dresden, D-01187 Dresden, Germany
| | - José M. Corral
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany
| | - Joerg Fuchs
- Karyotype Evolution Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany
| | - Timothy F. Sharbel
- Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany
- Address correspondence to
| |
Collapse
|
24
|
Barcaccia G, Albertini E. Apomixis in plant reproduction: a novel perspective on an old dilemma. PLANT REPRODUCTION 2013; 26:159-79. [PMID: 23852378 PMCID: PMC3747320 DOI: 10.1007/s00497-013-0222-y] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 06/23/2013] [Indexed: 05/19/2023]
Abstract
Seed is one of the key factors of crop productivity. Therefore, a comprehension of the mechanisms underlying seed formation in cultivated plants is crucial for the quantitative and qualitative progress of agricultural production. In angiosperms, two pathways of reproduction through seed exist: sexual or amphimictic, and asexual or apomictic; the former is largely exploited by seed companies for breeding new varieties, whereas the latter is receiving continuously increasing attention from both scientific and industrial sectors in basic research projects. If apomixis is engineered into sexual crops in a controlled manner, its impact on agriculture will be broad and profound. In fact, apomixis will allow clonal seed production and thus enable efficient and consistent yields of high-quality seeds, fruits, and vegetables at lower costs. The development of apomixis technology is expected to have a revolutionary impact on agricultural and food production by reducing cost and breeding time, and avoiding the complications that are typical of sexual reproduction (e.g., incompatibility barriers) and vegetative propagation (e.g., viral transfer). However, the development of apomixis technology in agriculture requires a deeper knowledge of the mechanisms that regulate reproductive development in plants. This knowledge is a necessary prerequisite to understanding the genetic control of the apomictic process and its deviations from the sexual process. Our molecular understanding of apomixis will be greatly advanced when genes that are specifically or differentially expressed during embryo and embryo sac formation are discovered. In our review, we report the main findings on this subject by examining two approaches: i) analysis of the apomictic process in natural apomictic species to search for genes controlling apomixis and ii) analysis of gene mutations resembling apomixis or its components in species that normally reproduce sexually. In fact, our opinion is that a novel perspective on this old dilemma pertaining to the molecular control of apomixis can emerge from a cross-check among candidate genes in natural apomicts and a high-throughput analysis of sexual mutants.
Collapse
Affiliation(s)
- Gianni Barcaccia
- Laboratory of Genetics and Genomics, DAFNAE, University of Padova, Campus of Agripolis, Viale dell’Università 16, 35020 Legnaro, Italy
| | - Emidio Albertini
- Department of Applied Biology, University of Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy
| |
Collapse
|
25
|
Conner JA, Gunawan G, Ozias-Akins P. Recombination within the apospory specific genomic region leads to the uncoupling of apomixis components in Cenchrus ciliaris. PLANTA 2013; 238:51-63. [PMID: 23553451 DOI: 10.1007/s00425-013-1873-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 03/11/2013] [Indexed: 05/07/2023]
Abstract
Apomixis enables the clonal propagation of maternal genotypes through seed. If apomixis could be harnessed via genetic engineering or introgression, it would have a major economic impact for agricultural crops. In the grass species Pennisetum squamulatum and Cenchrus ciliaris (syn. P. ciliare), apomixis is controlled by a single dominant "locus", the apospory-specific genomic region (ASGR). For P. squamulatum, 18 published sequenced characterized amplified region (SCAR) markers have been identified which always co-segregate with apospory. Six of these markers are conserved SCARs in the closely related species, C. ciliaris and co-segregate with the trait. A screen of progeny from a cross of sexual × apomictic C. ciliaris genotypes identified a plant, A8, retaining two of the six ASGR-linked SCAR markers. Additional and newly identified ASGR-linked markers were generated to help identify the extent of recombination within the ASGR. Based on analysis of missing markers, the A8 recombinant plant has lost a significant portion of the ASGR but continues to form aposporous embryo sacs. Seedlings produced from aposporous embryo sacs are 6× in ploidy level and hence the A8 recombinant does not express parthenogenesis. The recombinant A8 plant represents a step forward in reducing the complexity of the ASGR locus to determine the factor(s) required for aposporous embryo sac formation and documents the separation of expression of the two components of apomixis in C. ciliaris.
Collapse
Affiliation(s)
- Joann A Conner
- Department of Horticulture, University of Georgia Tifton Campus, Tifton, GA, 31973, USA.
| | | | | |
Collapse
|
26
|
Podio M, Rodríguez MP, Felitti S, Stein J, Martínez EJ, Siena LA, Quarin CL, Pessino SC, Ortiz JPA. Sequence characterization, in silico mapping and cytosine methylation analysis of markers linked to apospory in Paspalum notatum. Genet Mol Biol 2012; 35:827-37. [PMID: 23271945 PMCID: PMC3526092 DOI: 10.1590/s1415-47572012005000070] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 07/01/2012] [Indexed: 12/20/2022] Open
Abstract
In previous studies we reported the identification of several AFLP, RAPD and RFLP molecular markers linked to apospory in Paspalum notatum. The objective of this work was to sequence these markers, obtain their flanking regions by chromosome walking and perform an in silico mapping analysis in rice and maize. The methylation status of two apospory-related sequences was also assessed using methylation-sensitive RFLP experiments. Fourteen molecular markers were analyzed and several protein-coding sequences were identified. Copy number estimates and RFLP linkage analysis showed that the sequence PnMAI3 displayed 2–4 copies per genome and linkage to apospory. Extension of this marker by chromosome walking revealed an additional protein-coding sequence mapping in silico in the apospory-syntenic regions of rice and maize. Approximately 5 kb corresponding to different markers were characterized through the global sequencing procedure. A more refined analysis based on sequence information indicated synteny with segments of chromosomes 2 and 12 of rice and chromosomes 3 and 5 of maize. Two loci associated with apomixis locus were tested in methylation-sensitive RFLP experiments using genomic DNA extracted from leaves. Although both target sequences were methylated no methylation polymorphisms associated with the mode of reproduction were detected.
Collapse
Affiliation(s)
- Maricel Podio
- Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Santa Fe, Argentina. ; Instituto de Botánica del Nordeste, Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Corrientes, Argentina
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Nkongolo K, Mehes-Smith M. Karyotype evolution in the Pinaceae: implication with molecular phylogeny. Genome 2012. [DOI: 10.1139/g2012-061] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The family Pinaceae is made up mostly of diploid species (2n = 24). Systematization of karyotype analysis was developed to make comparison of intra- and interspecific karyotypes among the Pinaceae more accurate and reliable. Considering all parameters, the genera Pseudotsuga and Pseudolarix have the “most derived” (or advanced) and asymmetric karyotypes in the Pinaceae, followed by Larix, Picea, Abies, and Cedrus. The genus Pinus was the “least derived” (or ancestral) of all the genera of the Pinaceae analyzed. Differences in karyotype formulae and asymmetry indices were found among species within the same genera, suggesting that structural changes may have contributed to the diversification of the genus. This review is a detailed analysis of comparative karyotyping based on similar parameters, including numeric data and cytogenetic information. Telomeric sequence repeats and rDNA distribution in the Pinaceae were surveyed. The role of transposition in rDNA chromosome distribution is analyzed. Cytogenetic implications of hybridization between related species are reported. Likewise, the relationships between molecular phylogenetic and karyotype evolution is discussed in light of several reports. Within many genera, chromosomal organization was conserved despite independent molecular divergence and adaptation through the evolutionary history of the species of the Pinaceae.
Collapse
Affiliation(s)
- K.K. Nkongolo
- Department of Biology and Biomolecular Science Program, Laurentian University, Sudbury, ON P3E 2C6, Canada
| | - M. Mehes-Smith
- Department of Biology and Biomolecular Science Program, Laurentian University, Sudbury, ON P3E 2C6, Canada
| |
Collapse
|
28
|
Contreras RN, Ruter JM, Conner J, Zeng Y, Ozias-Akins P. Confirmation of hybridity using GISH and determination of 18S rDNA copy number using FISH in interspecific F(1) hybrids of Tecoma (Bignoniaceae). Genome 2012; 55:437-45. [PMID: 22663256 DOI: 10.1139/g2012-030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interspecific hybridization in Tecoma Juss. was conducted to develop novel forms for the nursery industry. We report fertile hybrids from the cross T. garrocha Hieron. (pistillate parent) × T. stans (L.) Juss. ex Kunth. Leaf morphology of the F(1) hybrids of T. garrocha × T. stans was intermediate between the parents. GISH also confirmed hybridity. The F(1) hybrids were successfully backcrossed to both parents and self-pollinated to produce BC and F(2) progeny. Tecoma garrocha , T. stans, and T. guarume A. DC. 'Tangelo' were self-fertile. The F(1) hybrids also were crossed with T. capensis (Thunb.) Lindl. and T. guarume 'Tangelo', resulting in three-species hybrids. FISH conducted on F(1) hybrids identified four copies of the 18S internal transcribed spacer region. Further analysis using FISH has the potential to provide information on the evolution of Bignoniaceae and the potential role of polyploidy.
Collapse
Affiliation(s)
- Ryan N Contreras
- Department of Horticulture, Oregon State University, 4017 Agricultural and Life Sciences Building, Corvallis, OR 97331-7304, USA.
| | | | | | | | | |
Collapse
|
29
|
Yamashita KI, Nakazawa Y, Namai K, Amagai M, Tsukazaki H, Wako T, Kojima A. Modes of inheritance of two apomixis components, diplospory and parthenogenesis, in Chinese chive (Allium ramosum) revealed by analysis of the segregating population generated by back-crossing between amphimictic and apomictic diploids. BREEDING SCIENCE 2012; 62:160-9. [PMID: 23136527 PMCID: PMC3405961 DOI: 10.1270/jsbbs.62.160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 03/25/2012] [Indexed: 05/07/2023]
Abstract
To investigate the mode of inheritance of apomixis in Chinese chive, the degrees of diplospory and parthenogenesis were evaluated in F(1) and BC(1) progenies derived from crosses between amphimictic and apomictic diploids (2n = 16, 2x). The F(1) population was generated by crossing three amphimictic diploids 94Mo13, 94Mo49 and 94Mo50 with an apomictic diploid KaD2 and comprised 110 diploids and 773 triploids. All the diploid F(1) plants examined were completely or highly eusporous and completely syngamic. All the triploid F(1) plants examined were highly diplosporous and highly parthenogenetic. KaD2 could not transmit its high level of apomixis via monoploid pollen grains. The BC(1) population, generated by crossing 94Mo49 with apomictic triploids found in the F(1) offspring, exhibited heteroploidy; it comprised haploid, diploid, triploid, tetraploid and various aneuploid individuals. In this generation, clear segregation was observed between diplospory and parthenogenesis. Analysis of the BC(1) population suggests that diplospory and parthenogenesis are each controlled by single dominant genes, D and P, respectively. However, all the BC(1) plants characterized as parthenogenetic were diplosporous. The absence of phenotypically eusporous parthenogenetic plants can be explained by assuming that the presence of diplospory gene is a prerequisite for the parthenogenesis gene expression in Chinese chive.
Collapse
Affiliation(s)
- Ken-ichiro Yamashita
- Institute of Vegetable and Tea Science, National Agriculture and Food Research Organization, 360 Kusawa, Tsu, Mie 514-2392, Japan
- Corresponding author (e-mail: )
| | - Yoshiko Nakazawa
- Tochigi Prefectural Agricultural Experiment Station, Utsunomiya, 1080 Utsunomiya, Tochigi 320-0002, Japan
| | - Kiyoshi Namai
- Tochigi Prefectural Agricultural Experiment Station, Utsunomiya, 1080 Utsunomiya, Tochigi 320-0002, Japan
| | - Masayuki Amagai
- Tochigi Prefectural Agricultural Experiment Station, Utsunomiya, 1080 Utsunomiya, Tochigi 320-0002, Japan
| | - Hikaru Tsukazaki
- Institute of Vegetable and Tea Science, National Agriculture and Food Research Organization, 360 Kusawa, Tsu, Mie 514-2392, Japan
| | - Tadayuki Wako
- Institute of Vegetable and Tea Science, National Agriculture and Food Research Organization, 360 Kusawa, Tsu, Mie 514-2392, Japan
| | - Akio Kojima
- Institute of Vegetable and Tea Science, National Agriculture and Food Research Organization, 360 Kusawa, Tsu, Mie 514-2392, Japan
| |
Collapse
|
30
|
Nakano M, Shimada T, Endo T, Fujii H, Nesumi H, Kita M, Ebina M, Shimizu T, Omura M. Characterization of genomic sequence showing strong association with polyembryony among diverse Citrus species and cultivars, and its synteny with Vitis and Populus. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 183:131-142. [PMID: 22195586 DOI: 10.1016/j.plantsci.2011.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 07/14/2011] [Accepted: 08/09/2011] [Indexed: 05/27/2023]
Abstract
Polyembryony, in which multiple somatic nucellar cell-derived embryos develop in addition to the zygotic embryo in a seed, is common in the genus Citrus. Previous genetic studies indicated polyembryony is mainly determined by a single locus, but the underlying molecular mechanism is still unclear. As a step towards identification and characterization of the gene or genes responsible for nucellar embryogenesis in Citrus, haplotype-specific physical maps around the polyembryony locus were constructed. By sequencing three BAC clones aligned on the polyembryony haplotype, a single contiguous draft sequence consisting of 380 kb containing 70 predicted open reading frames (ORFs) was reconstructed. Single nucleotide polymorphism genotypes detected in the sequenced genomic region showed strong association with embryo type in Citrus, indicating a common polyembryony locus is shared among widely diverse Citrus cultivars and species. The arrangement of the predicted ORFs in the characterized genomic region showed high collinearity to the genomic sequence of chromosome 4 of Vitis vinifera and linkage group VI of Populus trichocarpa, suggesting that the syntenic relationship among these species is conserved even though V. vinifera and P. trichocarpa are non-apomictic species. This is the first study to characterize in detail the genomic structure of an apomixis locus determining adventitious embryony.
Collapse
Affiliation(s)
- Michiharu Nakano
- Department of Citrus Research, National Institute of Fruit Tree Science, Shizuoka 424-0292, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Okada T, Ito K, Johnson SD, Oelkers K, Suzuki G, Houben A, Mukai Y, Koltunow AM. Chromosomes carrying meiotic avoidance loci in three apomictic eudicot Hieracium subgenus Pilosella species share structural features with two monocot apomicts. PLANT PHYSIOLOGY 2011. [PMID: 21896890 DOI: 10.1104/fpp.111.181164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The LOSS OF APOMEIOSIS (LOA) locus is one of two dominant loci known to control apomixis in the eudicot Hieracium praealtum. LOA stimulates the differentiation of somatic aposporous initial cells after the initiation of meiosis in ovules. Aposporous initial cells undergo nuclear proliferation close to sexual megaspores, forming unreduced aposporous embryo sacs, and the sexual program ceases. LOA-linked genetic markers were used to isolate 1.2 Mb of LOA-associated DNAs from H. praealtum. Physical mapping defined the genomic region essential for LOA function between two markers, flanking 400 kb of identified sequence and central unknown sequences. Cytogenetic and sequence analyses revealed that the LOA locus is located on a single chromosome near the tip of the long arm and surrounded by extensive, abundant complex repeat and transposon sequences. Chromosomal features and LOA-linked markers are conserved in aposporous Hieracium caespitosum and Hieracium piloselloides but absent in sexual Hieracium pilosella. Their absence in apomictic Hieracium aurantiacum suggests that meiotic avoidance may have evolved independently in aposporous subgenus Pilosella species. The structure of the hemizygous chromosomal region containing the LOA locus in the three Hieracium subgenus Pilosella species resembles that of the hemizygous apospory-specific genomic regions in monocot Pennisetum squamulatum and Cenchrus ciliaris. Analyses of partial DNA sequences at these loci show no obvious conservation, indicating that they are unlikely to share a common ancestral origin. This suggests convergent evolution of repeat-rich hemizygous chromosomal regions containing apospory loci in these monocot and eudicot species, which may be required for the function and maintenance of the trait.
Collapse
Affiliation(s)
- Takashi Okada
- Commonwealth Scientific and Industrial Research Organization Plant Industry, Glen Osmond, South Australia 5064, Australia
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Okada T, Ito K, Johnson SD, Oelkers K, Suzuki G, Houben A, Mukai Y, Koltunow AM. Chromosomes carrying meiotic avoidance loci in three apomictic eudicot Hieracium subgenus Pilosella species share structural features with two monocot apomicts. PLANT PHYSIOLOGY 2011; 157:1327-41. [PMID: 21896890 PMCID: PMC3252177 DOI: 10.1104/pp.111.181164] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 09/03/2011] [Indexed: 05/02/2023]
Abstract
The LOSS OF APOMEIOSIS (LOA) locus is one of two dominant loci known to control apomixis in the eudicot Hieracium praealtum. LOA stimulates the differentiation of somatic aposporous initial cells after the initiation of meiosis in ovules. Aposporous initial cells undergo nuclear proliferation close to sexual megaspores, forming unreduced aposporous embryo sacs, and the sexual program ceases. LOA-linked genetic markers were used to isolate 1.2 Mb of LOA-associated DNAs from H. praealtum. Physical mapping defined the genomic region essential for LOA function between two markers, flanking 400 kb of identified sequence and central unknown sequences. Cytogenetic and sequence analyses revealed that the LOA locus is located on a single chromosome near the tip of the long arm and surrounded by extensive, abundant complex repeat and transposon sequences. Chromosomal features and LOA-linked markers are conserved in aposporous Hieracium caespitosum and Hieracium piloselloides but absent in sexual Hieracium pilosella. Their absence in apomictic Hieracium aurantiacum suggests that meiotic avoidance may have evolved independently in aposporous subgenus Pilosella species. The structure of the hemizygous chromosomal region containing the LOA locus in the three Hieracium subgenus Pilosella species resembles that of the hemizygous apospory-specific genomic regions in monocot Pennisetum squamulatum and Cenchrus ciliaris. Analyses of partial DNA sequences at these loci show no obvious conservation, indicating that they are unlikely to share a common ancestral origin. This suggests convergent evolution of repeat-rich hemizygous chromosomal regions containing apospory loci in these monocot and eudicot species, which may be required for the function and maintenance of the trait.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Anna M. Koltunow
- Commonwealth Scientific and Industrial Research Organization Plant Industry, Glen Osmond, South Australia 5064, Australia (T.O., S.D.J., K.O., A.M.K.); Laboratory of Plant Molecular Genetics, Division of Natural Science, Osaka Kyoiku University, Kashiwara, Osaka 582–8582, Japan (K.I., G.S., Y.M.); Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.H.)
| |
Collapse
|
33
|
Akiyama Y, Goel S, Conner JA, Hanna WW, Yamada-Akiyama H, Ozias-Akins P. Evolution of the apomixis transmitting chromosome in Pennisetum. BMC Evol Biol 2011; 11:289. [PMID: 21975191 PMCID: PMC3198970 DOI: 10.1186/1471-2148-11-289] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 10/05/2011] [Indexed: 11/28/2022] Open
Abstract
Background Apomixis is an intriguing trait in plants that results in maternal clones through seed reproduction. Apomixis is an elusive, but potentially revolutionary, trait for plant breeding and hybrid seed production. Recent studies arguing that apomicts are not evolutionary dead ends have generated further interest in the evolution of asexual flowering plants. Results In the present study, we investigate karyotypic variation in a single chromosome responsible for transmitting apomixis, the Apospory-Specific Genomic Region carrier chromosome, in relation to species phylogeny in the genera Pennisetum and Cenchrus. A 1 kb region from the 3' end of the ndhF gene and a 900 bp region from trnL-F were sequenced from 12 apomictic and eight sexual species in the genus Pennisetum and allied genus Cenchrus. An 800 bp region from the Apospory-Specific Genomic Region also was sequenced from the 12 apomicts. Molecular cytological analysis was conducted in sixteen Pennisetum and two Cenchrus species. Our results indicate that the Apospory-Specific Genomic Region is shared by all apomictic species while it is absent from all sexual species or cytotypes. Contrary to our previous observations in Pennisetum squamulatum and Cenchrus ciliaris, retrotransposon sequences of the Opie-2-like family were not closely associated with the Apospory-Specific Genomic Region in all apomictic species, suggesting that they may have been accumulated after the Apospory-Specific Genomic Region originated. Conclusions Given that phylogenetic analysis merged Cenchrus and newly investigated Pennisetum species into a single clade containing a terminal cluster of Cenchrus apomicts, the presumed monophyletic origin of Cenchrus is supported. The Apospory-Specific Genomic Region likely preceded speciation in Cenchrus and its lateral transfer through hybridization and subsequent chromosome repatterning may have contributed to further speciation in the two genera.
Collapse
Affiliation(s)
- Yukio Akiyama
- Department of Horticulture, The University of Georgia, 2360 Rainwater Rd,, Tifton, GA 31793-5766, USA
| | | | | | | | | | | |
Collapse
|
34
|
Cloning plants by seeds: Inheritance models and candidate genes to increase fundamental knowledge for engineering apomixis in sexual crops. J Biotechnol 2011; 159:291-311. [PMID: 21906637 DOI: 10.1016/j.jbiotec.2011.08.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 08/16/2011] [Accepted: 08/17/2011] [Indexed: 01/02/2023]
Abstract
Apomixis is desirable in agriculture as a reproductive strategy for cloning plants by seeds. Because embryos derive from the parthenogenic development of apomeiotic egg cells, apomixis excludes fertilization in addition to meiotic segregation and recombination, resulting in offspring that are exact replicas of the parent. Introgression of apomixis from wild relatives to crop species and transformation of sexual genotypes into apomictically reproducing ones are long-held goals of plant breeding. In fact, it is generally accepted that the introduction of apomixis into agronomically important crops will have revolutionary implications for agriculture. This review deals with the current genetic and molecular findings that have been collected from model species to elucidate the mechanisms of apomeiosis, parthenogenesis and apomixis as a whole. Our goal is to critically determine whether biotechnology can combine key genes known to control the expression of the processes miming the main components of apomixis in plants. Two natural apomicts, as the eudicot Hypericum perforatum L. (St. John's wort) and the monocot Paspalum spp. (crowngrass), and the sexual model species Arabidopsis thaliana are ideally suited for such investigations at the genomic and biotechnological levels. Some novel views and original concepts have been faced on this review, including (i) the parallel between Y-chromosome and apomixis-bearing chromosome (e.g., comparative genomic analyses revealed common features as repression of recombination events, accumulation of transposable elements and degeneration of genes) from the most primitive (Hypericum-type) to the most advanced (Paspalum-type) in evolutionary terms, and (ii) the link between apomixis and gene-specific silencing mechanisms (i.e., likely based on chromatin remodelling factors), with merging lines of evidence regarding the role of auxin in cell fate specification of embryo sac and egg cell development in Arabidopsis. The production of engineered plants exhibiting apomictic-like phenotypes is critically reviewed and discussed.
Collapse
|
35
|
Zeng Y, Conner J, Ozias-Akins P. Identification of ovule transcripts from the Apospory-Specific Genomic Region (ASGR)-carrier chromosome. BMC Genomics 2011; 12:206. [PMID: 21521529 PMCID: PMC3111391 DOI: 10.1186/1471-2164-12-206] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 04/26/2011] [Indexed: 01/10/2023] Open
Abstract
Background Apomixis, asexual seed production in plants, holds great potential for agriculture as a means to fix hybrid vigor. Apospory is a form of apomixis where the embryo develops from an unreduced egg that is derived from a somatic nucellar cell, the aposporous initial, via mitosis. Understanding the molecular mechanism regulating aposporous initial specification will be a critical step toward elucidation of apomixis and also provide insight into developmental regulation and downstream signaling that results in apomixis. To discover candidate transcripts for regulating aposporous initial specification in P. squamulatum, we compared two transcriptomes derived from microdissected ovules at the stage of aposporous initial formation between the apomictic donor parent, P. squamulatum (accession PS26), and an apomictic derived backcross 8 (BC8) line containing only the Apospory-Specific Genomic Region (ASGR)-carrier chromosome from P. squamulatum. Toward this end, two transcriptomes derived from ovules of an apomictic donor parent and its apomictic backcross derivative at the stage of apospory initiation, were sequenced using 454-FLX technology. Results Using 454-FLX technology, we generated 332,567 reads with an average read length of 147 base pairs (bp) for the PS26 ovule transcriptome library and 363,637 reads with an average read length of 142 bp for the BC8 ovule transcriptome library. A total of 33,977 contigs from the PS26 ovule transcriptome library and 26,576 contigs from the BC8 ovule transcriptome library were assembled using the Multifunctional Inertial Reference Assembly program. Using stringent in silico parameters, 61 transcripts were predicted to map to the ASGR-carrier chromosome, of which 49 transcripts were verified as ASGR-carrier chromosome specific. One of the alien expressed genes could be assigned as tightly linked to the ASGR by screening of apomictic and sexual F1s. Only one transcript, which did not map to the ASGR, showed expression primarily in reproductive tissue. Conclusions Our results suggest that a strategy of comparative sequencing of transcriptomes between donor parent and backcross lines containing an alien chromosome of interest can be an efficient method of identifying transcripts derived from an alien chromosome in a chromosome addition line.
Collapse
Affiliation(s)
- Yajuan Zeng
- Department of Horticulture, The University of Georgia Tifton Campus, Tifton, GA 31973, USA
| | | | | |
Collapse
|
36
|
Abstract
Sex chromosomes in land plants can evolve as a consequence of close linkage between the two sex determination genes with complementary dominance required to establish stable dioecious populations, and they are found in at least 48 species across 20 families. The sex chromosomes in hepatics, mosses, and gymnosperms are morphologically heteromorphic. In angiosperms, heteromorphic sex chromosomes are found in at least 19 species from 4 families, while homomorphic sex chromosomes occur in 20 species from 13 families. The prevalence of the XY system found in 44 out of 48 species may reflect the predominance of the evolutionary pathway from gynodioecy towards dioecy. All dioecious species have the potential to evolve sex chromosomes, and reversions back from dioecy to various forms of monoecy, gynodioecy, or androdioecy have also occurred. Such reversals may occur especially during the early stages of sex chromosome evolution before the lethality of the YY (or WW) genotype is established.
Collapse
Affiliation(s)
- Ray Ming
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana-Champaign, Illinois 61801, USA.
| | | | | |
Collapse
|
37
|
|
38
|
Huo H, Conner JA, Ozias-Akins P. Genetic mapping of the apospory-specific genomic region in Pennisetum squamulatum using retrotransposon-based molecular markers. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2009; 119:199-212. [PMID: 19370319 DOI: 10.1007/s00122-009-1029-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 03/25/2009] [Indexed: 05/21/2023]
Abstract
Pennisetum squamulatum reproduces by apomixis, a type of asexual reproduction through seeds. Apomixis in P. squamulatum is transmitted as a dominant Mendelian trait, and a genomic region, the apospory-specific genomic region (ASGR), is sufficient for inheritance of the trait. The ASGR is physically large (>50 Mb), highly heterochromatic, hemizygous, and recombinationally suppressed. These characteristics have hindered high-resolution genetic mapping and map-based cloning of apomixis genes. In this study, the long terminal repeat (LTR) regions of ASGR-abundant retrotransposons in the genome of P. squamulatum and ASGR-linked bacterial artificial chromosome clones were identified and sequenced for designing LTR-specific primers. Two hundred and ninety single-dose sequence specific amplified polymorphism (SSAP) markers were generated from 38 primer combinations. The SSAP markers combined with two previous ASGR-mapped markers were used for genetic linkage analysis and construction of a genetic map resulting in the formation of 27 linkage groups at LOD 10, one of which contained >60% of the SSAP markers. After removing identical markers (identical band scoring) on the largest linkage group, 46 markers were finally used for genetic mapping at LOD 10. The markers distributed across 10 different loci covering 19 cM; however, 45 markers were distributed within 9 cM. Six markers were recovered and sequenced. Five markers were successfully converted into sequence characterized amplified regions (SCARs). Segregation of SCAR markers was not always consistent with the SSAP markers of origin suggesting a greater level of error in the SSAP map resulting in an inflated map distance for the ASGR. One SCAR marker (Pst 56-1205-400) detected expression of an ASGR retrotransposon in root, anther, leaf and ovary of P. squamulatum, although sequencing of the RT-PCR product failed to find a functional open reading frame for the transcript.
Collapse
Affiliation(s)
- Heqiang Huo
- Department of Horticulture, University of Georgia Tifton Campus, Tifton, GA 31793, USA
| | | | | |
Collapse
|
39
|
Yamada-Akiyama H, Akiyama Y, Ebina M, Xu Q, Tsuruta SI, Yazaki J, Kishimoto N, Kikuchi S, Takahara M, Takamizo T, Sugita SI, Nakagawa H. Analysis of expressed sequence tags in apomictic guineagrass (Panicum maximum). JOURNAL OF PLANT PHYSIOLOGY 2009; 166:750-61. [PMID: 19046615 DOI: 10.1016/j.jplph.2008.10.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 10/06/2008] [Accepted: 10/06/2008] [Indexed: 05/20/2023]
Abstract
Apomixis is an intriguing asexual mode of reproduction, because it produces maternal clones that permit vegetative reproduction through seeds. Guineagrass (Panicum maximum) has both facultative aposporous apomixis and obligate sexual modes of reproduction. Despite the importance of apomixis in guineagrass, expressed sequence tags (ESTs) for this condition have not been studied in this species. We constructed a guineagrass cDNA library from two aposporous strains, Ku5954 and GM64-3A, and utilized them as microarray probes. To find genes uniquely expressed in the immature pistils of apomicts, we performed a microarray analysis using target RNA from another apomict, OKI64. Of the 4608 probes in the microarray, only 394 showed clear gene expression in the immature pistils. Of the 394 expressed probes, 196 were successfully sequenced. Of these, 181 had significant homology with other species, including 10 ESTs with matches in a pistil cDNA library from another aposporous species, Cenchrus ciliaris. Of the remaining ESTs, three showed significant homology only with animal database sequences and the other 12 ESTs showed no homology with any previously registered sequence. In reverse-transcriptase PCR and real-time quantitative PCR, nine ESTs reliably detected ovary-specific gene expression. Of these, three revealed aposporous ovary-specific genes expressed in the early developmental stage, suggesting that these could be apomixis-related genes.
Collapse
Affiliation(s)
- Hitomi Yamada-Akiyama
- National Institute of Livestock and Grassland Science, Nasushiobara, Tochigi 329-2793, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Wada N, Kajiyama S, Akiyama Y, Kawakami S, No D, Uchiyama S, Otani M, Shimada T, Nose N, Suzuki G, Mukai Y, Fukui K. Bioactive beads-mediated transformation of rice with large DNA fragments containing Aegilops tauschii genes. PLANT CELL REPORTS 2009; 28:759-768. [PMID: 19214515 DOI: 10.1007/s00299-009-0678-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 01/05/2009] [Accepted: 01/25/2009] [Indexed: 05/27/2023]
Abstract
Transformation with large DNA molecules enables multiple genes to be introduced into plants simultaneously to produce transgenic plants with complex phenotypes. In this study, a large DNA fragment (ca. 100 kb) containing a set of Aegilops tauschii hardness genes was introduced into rice plants using a novel transformation method, called bioactive beads-mediated transformation. Nine transgenic rice plants were obtained and the presence of transgenes in the rice genome was confirmed by PCR and FISH analyses. The results suggested that multiple transgenes were successfully integrated in all transgenic plants. The expression of one of the transgenes, puroindoline b, was confirmed at the mRNA and protein levels in the T(2) generation. Our study clearly demonstrates that the bioactive bead method is capable of producing transgenic rice plants carrying large DNA fragments. This method will facilitate the production of useful transgenic plants by introducing multiple genes simultaneously.
Collapse
Affiliation(s)
- Naoki Wada
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
There are a growing number of examples where naturally occurring mutations disrupt an established physiological or developmental pathway to yield a new condition that is evolutionary favored. Asexual reproduction by seed in plants, or apomixis, occurs in a diversity of taxa and has evolved from sexual ancestors. One form of apomixis, diplospory, is a multi-step development process that is initiated when meiosis is altered to produce an unreduced rather than a reduced egg cell. Subsequent parthenogenetic development of the unreduced egg yields genetically maternal progeny. While it has long been apparent from cytological data that meiosis in apomicts was malfunctional or completely bypassed, the genetic basis of the phenomenon has been a long-standing mystery. New data from genetic analysis of Arabidopsis mutants in combination with more sophisticated molecular understanding of meiosis in plants indicate that a weak mutation of the gene SWI, called DYAD, interferes with sister chromatid cohesion in meiosis I, causes synapsis to fail in female meiosis and yields two unreduced cells. The new work shows that a low percentage of DYAD ovules produce functional unreduced egg cells (2n) that can be fertilized by haploid pollen (1n) to give rise to triploid (3n) progeny. While the DYAD mutants differ in some aspects from naturally occurring apomicts, the work establishes that mutation to a single gene can effectively initiate apomictic development and, furthermore, focuses efforts to isolate apomixis genes on a narrowed set of developmental events. Profitable manipulation of meiosis and recombination in agronomically important crops may be on the horizon.
Collapse
Affiliation(s)
- Richard D Noyes
- Department of Biology, University of Central Arkansas, 180 Lewis Science Center, Conway, AR 72035, USA.
| |
Collapse
|
42
|
Conner JA, Goel S, Gunawan G, Cordonnier-Pratt MM, Johnson VE, Liang C, Wang H, Pratt LH, Mullet JE, DeBarry J, Yang L, Bennetzen JL, Klein PE, Ozias-Akins P. Sequence analysis of bacterial artificial chromosome clones from the apospory-specific genomic region of Pennisetum and Cenchrus. PLANT PHYSIOLOGY 2008; 147:1396-411. [PMID: 18508959 PMCID: PMC2442526 DOI: 10.1104/pp.108.119081] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 05/25/2008] [Indexed: 05/18/2023]
Abstract
Apomixis, asexual reproduction through seed, is widespread among angiosperm families. Gametophytic apomixis in Pennisetum squamulatum and Cenchrus ciliaris is controlled by the apospory-specific genomic region (ASGR), which is highly conserved and macrosyntenic between these species. Thirty-two ASGR bacterial artificial chromosomes (BACs) isolated from both species and one ASGR-recombining BAC from P. squamulatum, which together cover approximately 2.7 Mb of DNA, were used to investigate the genomic structure of this region. Phrap assembly of 4,521 high-quality reads generated 1,341 contiguous sequences (contigs; 730 from the ASGR and 30 from the ASGR-recombining BAC in P. squamulatum, plus 580 from the C. ciliaris ASGR). Contigs containing putative protein-coding regions unrelated to transposable elements were identified based on protein similarity after Basic Local Alignment Search Tool X analysis. These putative coding regions were further analyzed in silico with reference to the rice (Oryza sativa) and sorghum (Sorghum bicolor) genomes using the resources at Gramene (www.gramene.org) and Phytozome (www.phytozome.net) and by hybridization against sorghum BAC filters. The ASGR sequences reveal that the ASGR (1) contains both gene-rich and gene-poor segments, (2) contains several genes that may play a role in apomictic development, (3) has many classes of transposable elements, and (4) does not exhibit large-scale synteny with either rice or sorghum genomes but does contain multiple regions of microsynteny with these species.
Collapse
Affiliation(s)
- Joann A Conner
- Department of Horticulture, University of Georgia, Tifton, Georgia 31793-0748, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Nakano M, Shimizu T, Kuniga T, Nesumi H, Omura M. Mapping and Haplotyping of the Flanking Region of the Polyembryony Locus in Citrus unshiu Marcow. ACTA ACUST UNITED AC 2008. [DOI: 10.2503/jjshs1.77.109] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
44
|
Affiliation(s)
- Peggy Ozias-Akins
- Department of Horticulture, University of Georgia Tifton Campus, Tifton, Georgia;
| | | |
Collapse
|
45
|
Kantama L, Sharbel TF, Schranz ME, Mitchell-Olds T, de Vries S, de Jong H. Diploid apomicts of the Boechera holboellii complex display large-scale chromosome substitutions and aberrant chromosomes. Proc Natl Acad Sci U S A 2007. [PMID: 17704257 DOI: 10.1073/pnas.070664710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023] Open
Abstract
We conducted a cytogenetic study of sexual lines of Boechera stricta and Boechera holboellii (2n = 14) and seven diploid apomictic accessions of their interspecific hybrid Boechera divaricarpa and B. holboellii (2n = 14 or 15). By studying chromosome morphology, rDNA repeats, genome painting, male meiosis, pollen morphology, and flow-cytometry seed screens, we revealed an unexpected plethora of chromosome forms, pairing behavior, and hybrid composition in all apomictic lines. Genome painting demonstrated that the apomicts are alloploid with variable numbers of B. stricta and B. holboellii-like chromosomes. We assume that large-scale homeologous chromosome substitutions took place in the apomictic hybrids that resulted from recurrent diploid-polyploid transitions through restitutional meiosis and polyploidy-diploid transitions through reductional meiosis. A second peculiarity was the presence of a largely heterochromatic chromosome (Het) in all apomictic accessions (2n = 14 and 15) and an additional smaller chromosome (Del) in the aneuploids (2n = 15). Both chromosomes share repetitive pericentromere repeats with those from the sexual B. stricta, suggesting that they originated from this species. Pairing and behavior at meiosis I of the Het share features with both Y and B chromosomes and suggest that the Del arose from a translocation event or homeologous recombination between a B. holboellii (or related taxon) and a B. stricta chromosome. Based on its presence exclusively in apomictic accessions, we propose that the Het chromosome plays a role in the genetic control of apomixis.
Collapse
Affiliation(s)
- Laksana Kantama
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, NL-6703 HA, Wageningen, The Netherlands
| | | | | | | | | | | |
Collapse
|
46
|
Kantama L, Sharbel TF, Schranz ME, Mitchell-Olds T, de Vries S, de Jong H. Diploid apomicts of the Boechera holboellii complex display large-scale chromosome substitutions and aberrant chromosomes. Proc Natl Acad Sci U S A 2007; 104:14026-31. [PMID: 17704257 PMCID: PMC1955788 DOI: 10.1073/pnas.0706647104] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We conducted a cytogenetic study of sexual lines of Boechera stricta and Boechera holboellii (2n = 14) and seven diploid apomictic accessions of their interspecific hybrid Boechera divaricarpa and B. holboellii (2n = 14 or 15). By studying chromosome morphology, rDNA repeats, genome painting, male meiosis, pollen morphology, and flow-cytometry seed screens, we revealed an unexpected plethora of chromosome forms, pairing behavior, and hybrid composition in all apomictic lines. Genome painting demonstrated that the apomicts are alloploid with variable numbers of B. stricta and B. holboellii-like chromosomes. We assume that large-scale homeologous chromosome substitutions took place in the apomictic hybrids that resulted from recurrent diploid-polyploid transitions through restitutional meiosis and polyploidy-diploid transitions through reductional meiosis. A second peculiarity was the presence of a largely heterochromatic chromosome (Het) in all apomictic accessions (2n = 14 and 15) and an additional smaller chromosome (Del) in the aneuploids (2n = 15). Both chromosomes share repetitive pericentromere repeats with those from the sexual B. stricta, suggesting that they originated from this species. Pairing and behavior at meiosis I of the Het share features with both Y and B chromosomes and suggest that the Del arose from a translocation event or homeologous recombination between a B. holboellii (or related taxon) and a B. stricta chromosome. Based on its presence exclusively in apomictic accessions, we propose that the Het chromosome plays a role in the genetic control of apomixis.
Collapse
Affiliation(s)
- Laksana Kantama
- *Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, NL-6703 HA, Wageningen, The Netherlands
| | - Timothy F. Sharbel
- Apomixis Research Group, Department of Cytogenetics and Genome Analysis, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany
| | - M. Eric Schranz
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Kruislaan 318, NL-1098 MS, Amsterdam, The Netherlands
| | | | - Sacco de Vries
- *Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, NL-6703 HA, Wageningen, The Netherlands
| | - Hans de Jong
- Laboratory of Genetics, Wageningen University, Arboretumlaan 4, NL-6703 BD, Wageningen, The Netherlands
- **To whom correspondence should be addressed. E-mail:
| |
Collapse
|
47
|
Kaushal P, Roy AK, Khare A, Malaviya DR, Zadoo SN, Choubey RN. Crossability and Characterization of Interspecific Hybrids between Sexual Pennisetum glaucum (Pearl Millet) and a New Cytotype (2n=56) of Apomictic P. squamulatum. CYTOLOGIA 2007. [DOI: 10.1508/cytologia.72.111] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Pankaj Kaushal
- Crop Improvement Division, Indian Grassland and Fodder Research Institute
| | - Ajoy Kumar Roy
- Crop Improvement Division, Indian Grassland and Fodder Research Institute
| | - Aarti Khare
- Crop Improvement Division, Indian Grassland and Fodder Research Institute
| | | | | | - Rang Nath Choubey
- Crop Improvement Division, Indian Grassland and Fodder Research Institute
| |
Collapse
|
48
|
Jiang J, Gill BS. Current status and the future of fluorescence in situ hybridization (FISH) in plant genome research. Genome 2006; 49:1057-68. [PMID: 17110986 DOI: 10.1139/g06-076] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fluorescence in situ hybridization (FISH), which allows direct mapping of DNA sequences on chromosomes, has become the most important technique in plant molecular cytogenetics research. Repetitive DNA sequence can generate unique FISH patterns on individual chromosomes for karyotyping and phylogenetic analysis. FISH on meiotic pachytene chromosomes coupled with digital imaging systems has become an efficient method to develop physical maps in plant species. FISH on extended DNA fibers provides a high-resolution mapping approach to analyze large DNA molecules and to characterize large genomic loci. FISH-based physical mapping provides a valuable complementary approach in genome sequencing and map-based cloning research. We expect that FISH will continue to play an important role in relating DNA sequence information to chromosome biology. FISH coupled with immunoassays will be increasingly used to study features of chromatin at the cytological level that control expression and regulation of genes.
Collapse
Affiliation(s)
- Jiming Jiang
- Department of Horticulture, University of Wisconsin, Madison, WI 53706, USA.
| | | |
Collapse
|
49
|
Akiyama Y, Goel S, Chen Z, Hanna WW, Ozias-Akins P. Pennisetum squamulatum: is the predominant cytotype hexaploid or octaploid? ACTA ACUST UNITED AC 2006; 97:521-4. [PMID: 16793863 DOI: 10.1093/jhered/esl005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Apomixis is a mode of asexual reproduction where maternal clones are produced through seeds. Consequently, genetic segregation is prevented in hybrid progenies. Pennisetum squamulatum has been used to transfer apomixis into the related sexual species Pennisetum glaucum by the introgression of an apospory-specific genomic region (ASGR)-carrier chromosome. Crosses between P. glaucum and P. squamulatum or Pennisetum purpureum have been relatively easy to make even though P. squamulatum has been reported to have a different basic chromosome number than the other 2 species (9 vs. 7) and to be hexaploid (2n = 6x = 54). Our extensive examination of one accession had shown a chromosome number of 2n = 56. In order to determine if there was a variation among accessions, we counted the number of chromosomes in 5 accessions of P. squamulatum using centromeric and 18S-5.8S-26S rDNA probes as molecular cytological markers. Our results showed that P. squamulatum is most likely octaploid with a basic chromosome number of 7 (2n = 8x = 56) and may belong to the secondary gene pool of Pennisetum. Moreover, a morphologically similar ASGR-carrier chromosome that confers apomixis was observed in all accessions.
Collapse
Affiliation(s)
- Yukio Akiyama
- Department of Horticulture, University of Georgia Tifton Campus, Tifton, GA 31793-0748, USA
| | | | | | | | | |
Collapse
|
50
|
Fujimoto R, Okazaki K, Fukai E, Kusaba M, Nishio T. Comparison of the genome structure of the self-incompatibility (S) locus in interspecific pairs of S haplotypes. Genetics 2006; 173:1157-67. [PMID: 16624926 PMCID: PMC1526501 DOI: 10.1534/genetics.104.037267] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Accepted: 04/01/2006] [Indexed: 11/18/2022] Open
Abstract
The determinants of recognition specificity of self-incompatibility in Brassica are SRK in the stigma and SP11/SCR in the pollen, both of which are encoded in the S locus. The nucleotide sequence analyses of many SRK and SP11/SCR alleles have identified several interspecific pairs of S haplotypes having highly similar sequences between B. oleracea and B. rapa. These interspecific pairs of S haplotypes are considered to be derived from common ancestors and to have maintained the same recognition specificity after speciation. In this study, the genome structures of three interspecific pairs of S haplotypes were compared by sequencing SRK, SP11/SCR, and their flanking regions. Regions between SRK and SP11/SCR in B. oleracea were demonstrated to be much longer than those of B. rapa and several retrotransposon-like sequences were identified in the S locus in B. oleracea. Among the seven retrotransposon-like sequences, six sequences were found to belong to the ty3 gypsy group. The gag sequences of the retrotransposon-like sequences were phylogenetically different from each other. In Southern blot analysis using retrotransposon-like sequences as probes, the B. oleracea genome showed more signals than the B. rapa genome did. These findings suggest a role for the S locus and genome evolution in self-incompatible plant species.
Collapse
Affiliation(s)
- Ryo Fujimoto
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | | | | | | | | |
Collapse
|