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Woudenberg S, Hadid F, Weijers D, Borassi C. The maternal embrace: the protection of plant embryos. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:4210-4218. [PMID: 38400751 DOI: 10.1093/jxb/erae071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 02/21/2024] [Indexed: 02/26/2024]
Abstract
All land plants-the embryophytes-produce multicellular embryos, as do other multicellular organisms, such as brown algae and animals. A unique characteristic of plant embryos is their immobile and confined nature. Their embedding in maternal tissues may offer protection from the environment, but also physically constrains development. Across the different land plants, a huge discrepancy is present between their reproductive structures whilst leading to similarly complex embryos. Therefore, we review the roles that maternal tissues play in the control of embryogenesis across land plants. These nurturing, constraining, and protective roles include both direct and indirect effects. In this review, we explore how the maternal surroundings affect embryogenesis and which chemical and mechanical barriers are in place. We regard these questions through the lens of evolution, and identify key questions for future research.
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Affiliation(s)
- Sjoerd Woudenberg
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
| | - Feras Hadid
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
| | - Cecilia Borassi
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
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Zhao S, Rong J. Single-cell RNA-seq reveals a link of ovule abortion and sugar transport in Camellia oleifera. FRONTIERS IN PLANT SCIENCE 2024; 15:1274013. [PMID: 38371413 PMCID: PMC10869455 DOI: 10.3389/fpls.2024.1274013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/15/2024] [Indexed: 02/20/2024]
Abstract
Camellia oleifera is the most important woody oil crop in China. Seed number per fruit is an important yield trait in C. oleifera. Ovule abortion is generally observed in C. oleifera and significantly decreases the seed number per fruit. However, the mechanisms of ovule abortion remain poorly understood at present. Single-cell RNA sequencing (scRNA-seq) was performed using mature ovaries of two C. oleifera varieties with different ovule abortion rates (OARs). In total, 20,526 high-quality cells were obtained, and 18 putative cell clusters were identified. Six cell types including female gametophyte, protoxylem, protophloem, procambium, epidermis, and parenchyma cells were identified from three main tissue types of ovule, placenta, and pericarp inner layer. A comparative analysis on scRNA-seq data between high- and low-OAR varieties demonstrated that the overall expression of CoSWEET and CoCWINV in procambium cells, and CoSTP in the integument was significantly upregulated in the low-OAR variety. Both the infertile ovule before pollination and the abortion ovule producing after compatible pollination might be attributed to selective abortion caused by low sugar levels in the apoplast around procambium cells and a low capability of hexose uptake in the integument. Here, the first single-cell transcriptional landscape is reported in woody crop ovaries. Our investigation demonstrates that ovule abortion may be related to sugar transport in placenta and ovules and sheds light on further deciphering the mechanism of regulating sugar transport and the improvement of seed yield in C. oleifera.
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Affiliation(s)
- Songzi Zhao
- Jiangxi Province Key Laboratory of Camellia Germplasm Conservation and Utilization, Jiangxi Academy of Forestry, Nanchang, China
| | - Jun Rong
- Jiangxi Province Key Laboratory of Watershed Ecosystem Change and Biodiversity, Center for Watershed Ecology, Institute of Life Science and School of Life Sciences, Nanchang University, Nanchang, China
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3
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Bjerkan KN, Alling RM, Myking IV, Brysting AK, Grini PE. Genetic and environmental manipulation of Arabidopsis hybridization barriers uncovers antagonistic functions in endosperm cellularization. FRONTIERS IN PLANT SCIENCE 2023; 14:1229060. [PMID: 37600172 PMCID: PMC10433385 DOI: 10.3389/fpls.2023.1229060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/12/2023] [Indexed: 08/22/2023]
Abstract
Speciation involves reproductive isolation, which can occur by hybridization barriers acting in the endosperm of the developing seed. The nuclear endosperm is a nutrient sink, accumulating sugars from surrounding tissues, and undergoes coordinated cellularization, switching to serve as a nutrient source for the developing embryo. Tight regulation of cellularization is therefore vital for seed and embryonic development. Here we show that hybrid seeds from crosses between Arabidopsis thaliana as maternal contributor and A. arenosa or A. lyrata as pollen donors result in an endosperm based post-zygotic hybridization barrier that gives rise to a reduced seed germination rate. Hybrid seeds display opposite endosperm cellularization phenotypes, with late cellularization in crosses with A. arenosa and early cellularization in crosses with A. lyrata. Stage specific endosperm reporters display temporally ectopic expression in developing hybrid endosperm, in accordance with the early and late cellularization phenotypes, confirming a disturbance of the source-sink endosperm phase change. We demonstrate that the hybrid barrier is under the influence of abiotic factors, and show that a temperature gradient leads to diametrically opposed cellularization phenotype responses in hybrid endosperm with A. arenosa or A. lyrata as pollen donors. Furthermore, different A. thaliana accession genotypes also enhance or diminish seed viability in the two hybrid cross-types, emphasizing that both genetic and environmental cues control the hybridization barrier. We have identified an A. thaliana MADS-BOX type I family single locus that is required for diametrically opposed cellularization phenotype responses in hybrid endosperm. Loss of AGAMOUS-LIKE 35 significantly affects the germination rate of hybrid seeds in opposite directions when transmitted through the A. thaliana endosperm, and is suggested to be a locus that promotes cellularization as part of an endosperm based mechanism involved in post-zygotic hybrid barriers. The role of temperature in hybrid speciation and the identification of distinct loci in control of hybrid failure have great potential to aid the introduction of advantageous traits in breeding research and to support models to predict hybrid admixture in a changing global climate.
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Affiliation(s)
- Katrine N. Bjerkan
- Section for Genetics and Evolutionary Biology (EVOGENE), Department of Biosciences, University of Oslo, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Renate M. Alling
- Section for Genetics and Evolutionary Biology (EVOGENE), Department of Biosciences, University of Oslo, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Ida V. Myking
- Section for Genetics and Evolutionary Biology (EVOGENE), Department of Biosciences, University of Oslo, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Anne K. Brysting
- Section for Genetics and Evolutionary Biology (EVOGENE), Department of Biosciences, University of Oslo, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Paul E. Grini
- Section for Genetics and Evolutionary Biology (EVOGENE), Department of Biosciences, University of Oslo, Oslo, Norway
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van Ekelenburg YS, Hornslien KS, Van Hautegem T, Fendrych M, Van Isterdael G, Bjerkan KN, Miller JR, Nowack MK, Grini PE. Spatial and temporal regulation of parent-of-origin allelic expression in the endosperm. PLANT PHYSIOLOGY 2023; 191:986-1001. [PMID: 36437711 PMCID: PMC9922421 DOI: 10.1093/plphys/kiac520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Genomic imprinting promotes differential expression of parental alleles in the endosperm of flowering plants and is regulated by epigenetic modification such as DNA methylation and histone tail modifications in chromatin. After fertilization, the endosperm develops through a syncytial stage before it cellularizes and becomes a nutrient source for the growing embryo. Regional compartmentalization has been shown both in early and late endosperm development, and different transcriptional domains suggest divergent spatial and temporal regional functions. The analysis of the role of parent-of-origin allelic expression in the endosperm as a whole and the investigation of domain-specific functions have been hampered by the inaccessibility of the tissue for high-throughput transcriptome analyses and contamination from surrounding tissue. Here, we used fluorescence-activated nuclear sorting (FANS) of nuclear targeted GFP fluorescent genetic markers to capture parental-specific allelic expression from different developmental stages and specific endosperm domains. This approach allowed us to successfully identify differential genomic imprinting with temporal and spatial resolution. We used a systematic approach to report temporal regulation of imprinted genes in the endosperm, as well as region-specific imprinting in endosperm domains. Analysis of our data identified loci that are spatially differentially imprinted in one domain of the endosperm, while biparentally expressed in other domains. These findings suggest that the regulation of genomic imprinting is dynamic and challenge the canonical mechanisms for genomic imprinting.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Paul E Grini
- Authors for correspondence: E-mail: (P.E.G.), (K.S.H.)
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5
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Pereira PA, Boavida LC, Santos MR, Becker JD. AtNOT1 is required for gametophyte development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1289-1303. [PMID: 32369648 DOI: 10.1111/tpj.14801] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 04/15/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
In flowering plants, pollen development is under a dynamic and well-orchestrated transcriptional control, characterized by an early phase with high transcript diversity and a late post-mitotic phase skewed to a cell-type-specific transcriptome. Such transcriptional changes require a balance between synthesis and degradation of mRNA transcripts, the latter being initiated by deadenylation. The CCR4-NOT complex is the main evolutionary conserved deadenylase complex in eukaryotes, and its function is essential during germline specification in animals. We hypothesized that the CCR4-NOT complex might play a central role in mRNA turnover during microgametogenesis in Arabidopsis. Disruption of NOT1 gene, which encodes the scaffold protein of the CCR4-NOT complex, showed abnormal seed set. Genetic analysis failed to recover homozygous progeny, and reciprocal crosses confirmed reduced transmission through the male and female gametophytes. Concordantly, not1 embryo sacs showed delayed development and defects in embryogenesis. not1 pollen grains exhibited abnormal male germ unit configurations and failed to germinate. Transcriptome analysis of pollen from not1/+ mutants revealed that lack of NOT1 leads to an extensive transcriptional deregulation during microgametogenesis. Therefore, our work establishes NOT1 as an important player during gametophyte development in Arabidopsis.
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Affiliation(s)
- Patrícia A Pereira
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
| | - Leonor C Boavida
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
| | - Mário R Santos
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
| | - Jörg D Becker
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
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6
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Kwiatkowska M, Kadłuczka D, Wędzony M, Dedicova B, Grzebelus E. Refinement of a clearing protocol to study crassinucellate ovules of the sugar beet ( Beta vulgaris L., Amaranthaceae). PLANT METHODS 2019; 15:71. [PMID: 31316582 PMCID: PMC6613245 DOI: 10.1186/s13007-019-0452-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 06/26/2019] [Indexed: 05/24/2023]
Abstract
BACKGROUND Clearing methods allow relatively quick processing of plant material and examination of cellular structures by rendering tissues and organs translucent. They have been adapted for plant embryology, primarily to study ovule development, megasporogenesis, megagametogenesis and embryogenesis. Such clearing methods overcome several disadvantages of the conventional embedding-sectioning techniques that are arduous and time-consuming. Although numerous protocols with different clearing solutions have been described, there have been no reports to date proposing a reliable method to clear the crassinucellate ovules of the sugar beet (Beta vulgaris L.), an economically important crop. Therefore, this study aims to find a suitable approach to improve the tissue transparency of sugar beet ovules at different developmental stages. RESULTS We established a methyl salicylate-based protocol that significantly improved the transparency of the B. vulgaris ovule structures, which allowed us to observe the megagameto- and embryogenesis of that species. This was achieved by (1) chemical softening of the tissues; (2) vacuum pump-assisted infiltration step; (3) shaking-assisted incubation with clearing mixtures; and (4) manual removal of the chemically softened seed coat. CONCLUSIONS The effectiveness of our method is due to the strategy combining various approaches at different stages of the procedure aiming at increasing the accessibility of the internal ovule structures to the clearing solution. The results of this study may be applied in sugar beet breeding programs, and it will provide a basis for further investigation of numerous aspects of the species' embryology. Moreover, that unique approach may be easily adapted to other species developing crassinucellate ovules.
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Affiliation(s)
- Monika Kwiatkowska
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland
| | - Dariusz Kadłuczka
- Institute of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, 29 Listopada 54, 31-425 Kraków, Poland
| | - Maria Wędzony
- Institute of Biology, Pedagogical University of Cracow, Podchorążych 2, 30-084 Kraków, Poland
| | - Beata Dedicova
- MariboHilleshög Research AB, Säbyholmsvägen 24, 261 91 Landskrona, Sweden
| | - Ewa Grzebelus
- Institute of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, 29 Listopada 54, 31-425 Kraków, Poland
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Hornslien KS, Miller JR, Grini PE. Regulation of Parent-of-Origin Allelic Expression in the Endosperm. PLANT PHYSIOLOGY 2019; 180:1498-1519. [PMID: 31064812 PMCID: PMC6752901 DOI: 10.1104/pp.19.00320] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 04/29/2019] [Indexed: 05/22/2023]
Abstract
Genomic imprinting is an epigenetic phenomenon established in the gametes prior to fertilization that causes differential expression of parental alleles, mainly in the endosperm of flowering plants. The overlap between previously identified panels of imprinted genes is limited. To investigate imprinting, we used high-resolution sequencing data acquired with sequence-capture technology. We present a bioinformatics pipeline to assay parent-of-origin allele-specific expression and report more than 300 loci with parental expression bias in Arabidopsis (Arabidopsis thaliana). In most cases, the level of expression from maternal and paternal alleles was not binary, instead supporting a differential dosage hypothesis for the evolution of imprinting in plants. To address imprinting regulation, we systematically employed mutations in regulative epigenetic pathways suggested to be major players in the process. We established the mechanistic mode of imprinting for more than 50 loci regulated by DNA methylation and Polycomb-dependent histone methylation. However, the imprinting patterns of most genes were not affected by these mechanisms. To this end, we also demonstrated that the RNA-directed DNA methylation pathway alone does not substantially influence imprinting patterns, suggesting that more complex epigenetic pathways regulate most of the identified imprinted genes.
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Affiliation(s)
- Karina S Hornslien
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Jason R Miller
- College of Natural Sciences and Mathematics, Shepherd University, Shepherdstown, West Virginia 25443-5000
- J. Craig Venter Institute, Rockville, Maryland 20850
| | - Paul E Grini
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway
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Glöckle B, Urban WJ, Nagahara S, Andersen ED, Higashiyama T, Grini PE, Schnittger A. Pollen differentiation as well as pollen tube guidance and discharge are independent of the presence of gametes. Development 2018; 145:dev.152645. [PMID: 29217755 PMCID: PMC5825867 DOI: 10.1242/dev.152645] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 11/27/2017] [Indexed: 12/16/2022]
Abstract
After meiosis, an unequal cell division generates the male gamete lineage in flowering plants. The generative cell will undergo a second division, giving rise to the two gametes, i.e. the sperm cells. The other cell will develop into the vegetative cell that plays a crucial role in pollen tube formation and sperm delivery. Recently, the vegetative cell has been suggested to be important for programming of the chromatin state in sperm cells and/or the resulting fertilization products. Blocking the initial unequal division genetically, we first highlight that the default differentiation state after male meiosis is a vegetative fate, which is consistent with earlier work. We find that uni-nucleated mutant microspores differentiated as wild-type vegetative cells, including chromatin remodeling and the transcriptional activation of transposable elements. Moreover, live-cell imaging revealed that this vegetative cell is sufficient for the correct guidance of the pollen tube to the female gametes. Hence, we conclude that vegetative cell differentiation and function does not depend on the formation or presence of the actual gametes but rather on external signals or a cell-autonomous pace keeper. Summary: Cell biological analyses in Arabidopsis show that the vegetative cell differentiates without the presence of the actual gametes, and is solely sufficient for pollen tube germination, guidance, ovule penetration and pollen tube discharge.
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Affiliation(s)
- Barbara Glöckle
- Department of Molecular Mechanisms of Phenotypic Plasticity, Institut de Biologie Moléculaire des Plantes du CNRS, IBMP-CNRS - UPR2357, Université de Strasbourg, 12 Rue du Général Zimmer, 67084 Strasbourg Cedex, France.,Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Wojciech J Urban
- University of Hamburg, Biozentrum Klein Flottbek, Department of Developmental Biology, 22609 Hamburg, Germany
| | - Shiori Nagahara
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Ellen D Andersen
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Tetsuya Higashiyama
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.,JST ERATO Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Paul E Grini
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Arp Schnittger
- Department of Molecular Mechanisms of Phenotypic Plasticity, Institut de Biologie Moléculaire des Plantes du CNRS, IBMP-CNRS - UPR2357, Université de Strasbourg, 12 Rue du Général Zimmer, 67084 Strasbourg Cedex, France .,University of Hamburg, Biozentrum Klein Flottbek, Department of Developmental Biology, 22609 Hamburg, Germany
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Pratibha P, Singh SK, Srinivasan R, Bhat SR, Sreenivasulu Y. Gametophyte Development Needs Mitochondrial Coproporphyrinogen III Oxidase Function. PLANT PHYSIOLOGY 2017; 174:258-275. [PMID: 28270625 PMCID: PMC5411134 DOI: 10.1104/pp.16.01482] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 02/28/2017] [Indexed: 05/03/2023]
Abstract
Tetrapyrrole biosynthesis is one of the most essential metabolic pathways in almost all organisms. Coproporphyrinogen III oxidase (CPO) catalyzes the conversion of coproporphyrinogen III into protoporphyrinogen IX in this pathway. Here, we report that mutation in the Arabidopsis (Arabidopsis thaliana) CPO-coding gene At5g63290 (AtHEMN1) adversely affects silique length, ovule number, and seed set. Athemn1 mutant alleles were transmitted via both male and female gametes, but homozygous mutants were never recovered. Plants carrying Athemn1 mutant alleles showed defects in gametophyte development, including nonviable pollen and embryo sacs with unfused polar nuclei. Improper differentiation of the central cell led to defects in endosperm development. Consequently, embryo development was arrested at the globular stage. The mutant phenotype was completely rescued by transgenic expression of AtHEMN1 Promoter and transcript analyses indicated that AtHEMN1 is expressed mainly in floral tissues and developing seeds. AtHEMN1-green fluorescent protein fusion protein was found targeted to mitochondria. Loss of AtHEMN1 function increased coproporphyrinogen III level and reduced protoporphyrinogen IX level, suggesting the impairment of tetrapyrrole biosynthesis. Blockage of tetrapyrrole biosynthesis in the AtHEMN1 mutant led to increased reactive oxygen species (ROS) accumulation in anthers and embryo sacs, as evidenced by nitroblue tetrazolium staining. Our results suggest that the accumulated ROS disrupts mitochondrial function by altering their membrane polarity in floral tissues. This study highlights the role of mitochondrial ROS homeostasis in gametophyte and seed development and sheds new light on tetrapyrrole/heme biosynthesis in plant mitochondria.
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Affiliation(s)
- Pritu Pratibha
- Biotechnology Division, Council of Scientific and Industrial Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., S.K.S., Y.S.)
- Academy of Scientific and Innovative Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., Y.S.); and
- Indian Council of Agricultural Research-National Research Centre on Plant Biotechnology, New Delhi 110012, India (R.S., S.R.B.)
| | - Sunil Kumar Singh
- Biotechnology Division, Council of Scientific and Industrial Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., S.K.S., Y.S.)
- Academy of Scientific and Innovative Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., Y.S.); and
- Indian Council of Agricultural Research-National Research Centre on Plant Biotechnology, New Delhi 110012, India (R.S., S.R.B.)
| | - Ramamurthy Srinivasan
- Biotechnology Division, Council of Scientific and Industrial Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., S.K.S., Y.S.)
- Academy of Scientific and Innovative Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., Y.S.); and
- Indian Council of Agricultural Research-National Research Centre on Plant Biotechnology, New Delhi 110012, India (R.S., S.R.B.)
| | - Shripad Ramachandra Bhat
- Biotechnology Division, Council of Scientific and Industrial Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., S.K.S., Y.S.);
- Academy of Scientific and Innovative Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., Y.S.); and
- Indian Council of Agricultural Research-National Research Centre on Plant Biotechnology, New Delhi 110012, India (R.S., S.R.B.)
| | - Yelam Sreenivasulu
- Biotechnology Division, Council of Scientific and Industrial Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., S.K.S., Y.S.);
- Academy of Scientific and Innovative Research-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India (P.P., Y.S.); and
- Indian Council of Agricultural Research-National Research Centre on Plant Biotechnology, New Delhi 110012, India (R.S., S.R.B.)
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Endosperm-based hybridization barriers explain the pattern of gene flow between Arabidopsis lyrata and Arabidopsis arenosa in Central Europe. Proc Natl Acad Sci U S A 2017; 114:E1027-E1035. [PMID: 28115687 DOI: 10.1073/pnas.1615123114] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Based on the biological species concept, two species are considered distinct if reproductive barriers prevent gene flow between them. In Central Europe, the diploid species Arabidopsis lyrata and Arabidopsis arenosa are genetically isolated, thus fitting this concept as "good species." Nonetheless, interspecific gene flow involving their tetraploid forms has been described. The reasons for this ploidy-dependent reproductive isolation remain unknown. Here, we show that hybridization between diploid A. lyrata and A. arenosa causes mainly inviable seed formation, revealing a strong postzygotic reproductive barrier separating these two species. Although viability of hybrid seeds was impaired in both directions of hybridization, the cause for seed arrest differed. Hybridization of A. lyrata seed parents with A. arenosa pollen donors resulted in failure of endosperm cellularization, whereas the endosperm of reciprocal hybrids cellularized precociously. Endosperm cellularization failure in both hybridization directions is likely causal for the embryo arrest. Importantly, natural tetraploid A. lyrata was able to form viable hybrid seeds with diploid and tetraploid A. arenosa, associated with the reestablishment of normal endosperm cellularization. Conversely, the defects of hybrid seeds between tetraploid A. arenosa and diploid A. lyrata were aggravated. According to these results, we hypothesize that a tetraploidization event in A. lyrata allowed the production of viable hybrid seeds with A. arenosa, enabling gene flow between the two species.
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11
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Abstract
Flowering plants, like placental mammals, have an extensive maternal contribution toward progeny development. Plants are distinguished from animals by a genetically active haploid phase of growth and development between meiosis and fertilization, called the gametophyte. Flowering plants are further distinguished by the process of double fertilization that produces sister progeny, the endosperm and the embryo, of the seed. Because of this, there is substantial gene expression in the female gametophyte that contributes to the regulation of growth and development of the seed. A primary function of the endosperm is to provide growth support to its sister embryo. Several mutations in Zea mays subsp. mays have been identified that affect the contribution of the mother gametophyte to the seed. The majority affect both the endosperm and the embryo, although some embryo-specific effects have been observed. Many alter the pattern of expression of a marker for the basal endosperm transfer layer, a tissue that transports nutrients from the mother plant to the developing seed. Many of them cause abnormal development of the female gametophyte prior to fertilization, revealing potential cellular mechanisms of maternal control of seed development. These effects include reduced central cell size, abnormal architecture of the central cell, abnormal numbers and morphology of the antipodal cells, and abnormal egg cell morphology. These mutants provide insight into the logic of seed development, including necessary features of the gametes and supporting cells prior to fertilization, and set up future studies on the mechanisms regulating maternal contributions to the seed.
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12
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Wang F, Muto A, Van de Velde J, Neyt P, Himanen K, Vandepoele K, Van Lijsebettens M. Functional Analysis of the Arabidopsis TETRASPANIN Gene Family in Plant Growth and Development. PLANT PHYSIOLOGY 2015; 169:2200-14. [PMID: 26417009 PMCID: PMC4634101 DOI: 10.1104/pp.15.01310] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/26/2015] [Indexed: 05/05/2023]
Abstract
TETRASPANIN (TET) genes encode conserved integral membrane proteins that are known in animals to function in cellular communication during gamete fusion, immunity reaction, and pathogen recognition. In plants, functional information is limited to one of the 17 members of the Arabidopsis (Arabidopsis thaliana) TET gene family and to expression data in reproductive stages. Here, the promoter activity of all 17 Arabidopsis TET genes was investigated by pAtTET::NUCLEAR LOCALIZATION SIGNAL-GREEN FLUORESCENT PROTEIN/β-GLUCURONIDASE reporter lines throughout the life cycle, which predicted functional divergence in the paralogous genes per clade. However, partial overlap was observed for many TET genes across the clades, correlating with few phenotypes in single mutants and, therefore, requiring double mutant combinations for functional investigation. Mutational analysis showed a role for TET13 in primary root growth and lateral root development and redundant roles for TET5 and TET6 in leaf and root growth through negative regulation of cell proliferation. Strikingly, a number of TET genes were expressed in embryonic and seedling progenitor cells and remained expressed until the differentiation state in the mature plant, suggesting a dynamic function over developmental stages. The cis-regulatory elements together with transcription factor-binding data provided molecular insight into the sites, conditions, and perturbations that affect TET gene expression and positioned the TET genes in different molecular pathways; the data represent a hypothesis-generating resource for further functional analyses.
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Affiliation(s)
- Feng Wang
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.);Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.); andDepartment of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Arcavacata of Rende, Italy (A.M.)
| | - Antonella Muto
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.);Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.); andDepartment of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Arcavacata of Rende, Italy (A.M.)
| | - Jan Van de Velde
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.);Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.); andDepartment of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Arcavacata of Rende, Italy (A.M.)
| | - Pia Neyt
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.);Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.); andDepartment of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Arcavacata of Rende, Italy (A.M.)
| | - Kristiina Himanen
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.);Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.); andDepartment of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Arcavacata of Rende, Italy (A.M.)
| | - Klaas Vandepoele
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.);Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.); andDepartment of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Arcavacata of Rende, Italy (A.M.)
| | - Mieke Van Lijsebettens
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.);Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (F.W, A.M., J.V.d.V., P.N., K.H., K.V., M.V.L.); andDepartment of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Arcavacata of Rende, Italy (A.M.)
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Liu B, Butenko MA, Shi CL, Bolivar JL, Winge P, Stenvik GE, Vie AK, Leslie ME, Brembu T, Kristiansen W, Bones AM, Patterson SE, Liljegren SJ, Aalen RB. NEVERSHED and INFLORESCENCE DEFICIENT IN ABSCISSION are differentially required for cell expansion and cell separation during floral organ abscission in Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:5345-57. [PMID: 23963677 DOI: 10.1093/jxb/ert232] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Bin Liu
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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Zhang B, Carrie C, Ivanova A, Narsai R, Murcha MW, Duncan O, Wang Y, Law SR, Albrecht V, Pogson B, Giraud E, Van Aken O, Whelan J. LETM proteins play a role in the accumulation of mitochondrially encoded proteins in Arabidopsis thaliana and AtLETM2 displays parent of origin effects. J Biol Chem 2012; 287:41757-73. [PMID: 23043101 PMCID: PMC3516725 DOI: 10.1074/jbc.m112.383836] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 10/01/2012] [Indexed: 11/06/2022] Open
Abstract
The Arabidopsis thaliana genome contains two genes with homology to the mitochondrial protein LETM1 (leucine zipper-EF-hand-containing transmembrane protein). Inactivation of both genes, Atletm1 and Atletm2, together is lethal. Plants that are hemizygous for AtLETM2 and homozygous for Atletm1 (letm1(-/-) LETM2(+/-)) displayed a mild retarded growth phenotype during early seedling growth. It was shown that accumulation of mitochondrial proteins was reduced in hemizygous (letm1(-/-) LETM2(+/-)) plants. Examination of respiratory chain proteins by Western blotting, blue native PAGE, and enzymatic activity assays revealed that the steady state level of ATP synthase was reduced in abundance, whereas the steady state levels of other respiratory chain proteins remained unchanged. The absence of a functional maternal AtLETM2 allele in an Atletm1 mutant background resulted in early seed abortion. Reciprocal crosses revealed that maternally, but not paternally, derived AtLETM2 was absolutely required for seed development. This requirement for a functional maternal allele of AtLETM2 was confirmed using direct sequencing of reciprocal crosses of Col-0 and Ler accessions. Furthermore, AtLETM2 promoter β-glucuronidase constructs displayed exclusive maternal expression patterns.
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Affiliation(s)
- Botao Zhang
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Chris Carrie
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Aneta Ivanova
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Reena Narsai
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
- Centre for Computational Systems Biology, Bayliss Building M316 University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia and
| | - Monika W. Murcha
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Owen Duncan
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Yan Wang
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Simon R. Law
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Verónica Albrecht
- the Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Acton 2601, Australian Capital Territory, Australia
| | - Barry Pogson
- the Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Acton 2601, Australian Capital Territory, Australia
| | - Estelle Giraud
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - Olivier Van Aken
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
| | - James Whelan
- From the Australian Research Council Centre of Excellence in Plant Energy Biology and
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Ngo QA, Baroux C, Guthörl D, Mozerov P, Collinge MA, Sundaresan V, Grossniklaus U. The Armadillo repeat gene ZAK IXIK promotes Arabidopsis early embryo and endosperm development through a distinctive gametophytic maternal effect. THE PLANT CELL 2012; 24:4026-43. [PMID: 23064319 PMCID: PMC3517234 DOI: 10.1105/tpc.112.102384] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The proper balance of parental genomic contributions to the fertilized embryo and endosperm is essential for their normal growth and development. The characterization of many gametophytic maternal effect (GME) mutants affecting seed development indicates that there are certain classes of genes with a predominant maternal contribution. We present a detailed analysis of the GME mutant zak ixik (zix), which displays delayed and arrested growth at the earliest stages of embryo and endosperm development. ZIX encodes an Armadillo repeat (Arm) protein highly conserved across eukaryotes. Expression studies revealed that ZIX manifests a GME through preferential maternal expression in the early embryo and endosperm. This parent-of-origin-dependent expression is regulated by neither the histone and DNA methylation nor the DNA demethylation pathways known to regulate some other GME mutants. The ZIX protein is localized in the cytoplasm and nucleus of cells in reproductive tissues and actively dividing root zones. The maternal ZIX allele is required for the maternal expression of miniseed3. Collectively, our results reveal a reproductive function of plant Arm proteins in promoting early seed growth, which is achieved through a distinct GME of ZIX that involves mechanisms for maternal allele-specific expression that are independent of the well-established pathways.
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Affiliation(s)
- Quy A. Ngo
- Institute of Plant Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
- Section of Plant Biology, University of California, Davis, California 95616
- Address correspondence to
| | - Celia Baroux
- Institute of Plant Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
| | - Daniela Guthörl
- Institute of Plant Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
| | - Peter Mozerov
- Institute of Plant Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
| | - Margaret A. Collinge
- Institute of Plant Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
| | - Venkatesan Sundaresan
- Section of Plant Biology, University of California, Davis, California 95616
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Ueli Grossniklaus
- Institute of Plant Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
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16
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Meza TJ, Moen MN, Vågbø CB, Krokan HE, Klungland A, Grini PE, Falnes PØ. The DNA dioxygenase ALKBH2 protects Arabidopsis thaliana against methylation damage. Nucleic Acids Res 2012; 40:6620-31. [PMID: 22532610 PMCID: PMC3413135 DOI: 10.1093/nar/gks327] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The Escherichia coli AlkB protein (EcAlkB) is a DNA repair enzyme which reverses methylation damage such as 1-methyladenine (1-meA) and 3-methylcytosine (3-meC). The mammalian AlkB homologues ALKBH2 and ALKBH3 display EcAlkB-like repair activity in vitro, but their substrate specificities are different, and ALKBH2 is the main DNA repair enzyme for 1-meA in vivo. The genome of the model plant Arabidopsis thaliana encodes several AlkB homologues, including the yet uncharacterized protein AT2G22260, which displays sequence similarity to both ALKBH2 and ALKBH3. We have here characterized protein AT2G22260, by us denoted ALKBH2, as both our functional studies and bioinformatics analysis suggest it to be an orthologue of mammalian ALKBH2. The Arabidopsis ALKBH2 protein displayed in vitro repair activities towards methyl and etheno adducts in DNA, and was able to complement corresponding repair deficiencies of the E. coli alkB mutant. Interestingly, alkbh2 knock-out plants were sensitive to the methylating agent methylmethanesulphonate (MMS), and seedlings from these plants developed abnormally when grown in the presence of MMS. The present study establishes ALKBH2 as an important enzyme for protecting Arabidopsis against methylation damage in DNA, and suggests its homologues in other plants to have a similar function.
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Affiliation(s)
- Trine J Meza
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway
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17
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Cloning plants by seeds: Inheritance models and candidate genes to increase fundamental knowledge for engineering apomixis in sexual crops. J Biotechnol 2011; 159:291-311. [PMID: 21906637 DOI: 10.1016/j.jbiotec.2011.08.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 08/16/2011] [Accepted: 08/17/2011] [Indexed: 01/02/2023]
Abstract
Apomixis is desirable in agriculture as a reproductive strategy for cloning plants by seeds. Because embryos derive from the parthenogenic development of apomeiotic egg cells, apomixis excludes fertilization in addition to meiotic segregation and recombination, resulting in offspring that are exact replicas of the parent. Introgression of apomixis from wild relatives to crop species and transformation of sexual genotypes into apomictically reproducing ones are long-held goals of plant breeding. In fact, it is generally accepted that the introduction of apomixis into agronomically important crops will have revolutionary implications for agriculture. This review deals with the current genetic and molecular findings that have been collected from model species to elucidate the mechanisms of apomeiosis, parthenogenesis and apomixis as a whole. Our goal is to critically determine whether biotechnology can combine key genes known to control the expression of the processes miming the main components of apomixis in plants. Two natural apomicts, as the eudicot Hypericum perforatum L. (St. John's wort) and the monocot Paspalum spp. (crowngrass), and the sexual model species Arabidopsis thaliana are ideally suited for such investigations at the genomic and biotechnological levels. Some novel views and original concepts have been faced on this review, including (i) the parallel between Y-chromosome and apomixis-bearing chromosome (e.g., comparative genomic analyses revealed common features as repression of recombination events, accumulation of transposable elements and degeneration of genes) from the most primitive (Hypericum-type) to the most advanced (Paspalum-type) in evolutionary terms, and (ii) the link between apomixis and gene-specific silencing mechanisms (i.e., likely based on chromatin remodelling factors), with merging lines of evidence regarding the role of auxin in cell fate specification of embryo sac and egg cell development in Arabidopsis. The production of engineered plants exhibiting apomictic-like phenotypes is critically reviewed and discussed.
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18
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Shi CL, Stenvik GE, Vie AK, Bones AM, Pautot V, Proveniers M, Aalen RB, Butenko MA. Arabidopsis class I KNOTTED-like homeobox proteins act downstream in the IDA-HAE/HSL2 floral abscission signaling pathway. THE PLANT CELL 2011; 23:2553-67. [PMID: 21742991 PMCID: PMC3226213 DOI: 10.1105/tpc.111.084608] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 06/01/2011] [Accepted: 06/19/2011] [Indexed: 11/08/2022]
Abstract
Floral organ abscission in Arabidopsis thaliana is regulated by the putative ligand-receptor system comprising the signaling peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) and the two receptor-like kinases HAESA and HAESA-LIKE2. The IDA signaling pathway presumably activates a MITOGEN-ACTIVATED PROTEIN KINASE (MAPK) cascade to induce separation between abscission zone (AZ) cells. Misexpression of IDA effectuates precocious floral abscission and ectopic cell separation in latent AZ cell regions, which suggests that negative regulators are in place to prevent unrestricted and untimely AZ cell separation. Through a screen for mutations that restore floral organ abscission in ida mutants, we identified three new mutant alleles of the KNOTTED-LIKE HOMEOBOX gene BREVIPEDICELLUS (BP)/KNOTTED-LIKE FROM ARABIDOPSIS THALIANA1 (KNAT1). Here, we show that bp mutants, in addition to shedding their floral organs prematurely, have phenotypic commonalities with plants misexpressing IDA, such as enlarged AZ cells. We propose that BP/KNAT1 inhibits floral organ cell separation by restricting AZ cell size and number and put forward a model whereby IDA signaling suppresses BP/KNAT1, which in turn allows KNAT2 and KNAT6 to induce floral organ abscission.
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Affiliation(s)
- Chun-Lin Shi
- Department of Molecular Biosciences, University of Oslo, N-0316 Oslo, Norway
| | | | - Ane Kjersti Vie
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Atle M. Bones
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Véronique Pautot
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318 Institut National de la Recherche Agronomique-Agro Paris Tech, Bâtiment 2, Institut National de la Recherche Agronomique Centre de Versailles-Grignon, 78026 Versailles Cedex, France
| | - Marcel Proveniers
- Molecular Plant Physiology, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Reidunn B. Aalen
- Department of Molecular Biosciences, University of Oslo, N-0316 Oslo, Norway
| | - Melinka A. Butenko
- Department of Molecular Biosciences, University of Oslo, N-0316 Oslo, Norway
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Drews GN, Wang D, Steffen JG, Schumaker KS, Yadegari R. Identification of genes expressed in the angiosperm female gametophyte. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:1593-9. [PMID: 21118822 DOI: 10.1093/jxb/erq385] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Until recently, identification of gene regulatory networks controlling the development of the angiosperm female gametophyte has presented a significant challenge to the plant biology community. The angiosperm female gametophyte is fairly inaccessible because it is a highly reduced structure relative to the sporophyte and is embedded within multiple layers of the sporophytic tissue of the ovule. Moreover, although mutations affecting the female gametophyte can be readily isolated, their analysis can be difficult because most affect genes involved in basic cellular processes that are also required in the diploid sporophyte. In recent years, expression-based approaches in multiple species have begun to uncover gene sets expressed in specific female gametophyte cells as a means of identifying regulatory networks controlling cell differentiation in the female gametophyte. Here, recent efforts to identify and analyse gene expression programmes in the Arabidopsis female gametophyte are reviewed.
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Affiliation(s)
- Gary N Drews
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
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20
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The Arabidopsis CUL4-DDB1 complex interacts with MSI1 and is required to maintain MEDEA parental imprinting. EMBO J 2011; 30:731-43. [PMID: 21240189 DOI: 10.1038/emboj.2010.359] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Accepted: 12/13/2010] [Indexed: 11/08/2022] Open
Abstract
Protein ubiquitylation regulates a broad variety of biological processes in all eukaryotes. Recent work identified a novel class of cullin-containing ubiquitin ligases (E3s) composed of CUL4, DDB1, and one WD40 protein, believed to act as a substrate receptor. Strikingly, CUL4-based E3 ligases (CRL4s) have important functions at the chromatin level, including responses to DNA damage in metazoans and plants and, in fission yeast, in heterochromatin silencing. Among putative CRL4 receptors we identified MULTICOPY SUPPRESSOR OF IRA1 (MSI1), which belongs to an evolutionary conserved protein family. MSI1-like proteins contribute to different protein complexes, including the epigenetic regulatory Polycomb repressive complex 2 (PRC2). Here, we provide evidence that Arabidopsis MSI1 physically interacts with DDB1A and is part of a multimeric protein complex including CUL4. CUL4 and DDB1 loss-of-function lead to embryo lethality. Interestingly, as in fis class mutants, cul4 mutants exhibit autonomous endosperm initiation and loss of parental imprinting of MEDEA, a target gene of the Arabidopsis PRC2 complex. In addition, after pollination both MEDEA transcript and protein accumulate in a cul4 mutant background. Overall, our work provides the first evidence of a physical and functional link between a CRL4 E3 ligase and a PRC2 complex, thus indicating a novel role of ubiquitylation in the repression of gene expression.
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Abstract
The angiosperm female gametophyte is critical for plant reproduction. It contains the egg cell and central cell that become fertilized and give rise to the embryo and endosperm of the seed, respectively. Female gametophyte development begins early in ovule development with the formation of a diploid megaspore mother cell that undergoes meiosis. One resulting haploid megaspore then develops into the female gametophyte. Genetic and epigenetic processes mediate specification of megaspore mother cell identity and limit megaspore mother cell formation to a single cell per ovule. Auxin gradients influence female gametophyte polarity and a battery of transcription factors mediate female gametophyte cell specification and differentiation. The mature female gametophyte secretes peptides that guide the pollen tube to the embryo sac and contains protein complexes that prevent seed development before fertilization. Post-fertilization, the female gametophyte influences seed development through maternal-effect genes and by regulating parental contributions. Female gametophytes can form by an asexual process called gametophytic apomixis, which involves formation of a diploid female gametophyte and fertilization-independent development of the egg into the embryo. These functions collectively underscore the important role of the female gametophyte in seed and food production.
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Affiliation(s)
- Gary N. Drews
- Department of Biology, University of Utah, Salt Lake City, UT 84112
- Address correspondence to
| | - Anna M.G Koltunow
- Commonwealth Scientific and Industrial Research Organization Plant Industry, Waite Campus, South Australia 5064, Australia
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22
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Tsukamoto T, Palanivelu R. Loss of LORELEI function in the pistil delays initiation but does not affect embryo development in Arabidopsis thaliana. PLANT SIGNALING & BEHAVIOR 2010; 5:1487-1490. [PMID: 21051955 PMCID: PMC3115263 DOI: 10.4161/psb.5.11.13598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 09/11/2010] [Indexed: 05/29/2023]
Abstract
Double fertilization, uniquely observed in plants, requires successful sperm cell delivery by the pollen tube to the female gametophyte, followed by migration, recognition and fusion of the two sperm cells with two female gametic cells. The female gametophyte not only regulates these steps but also controls the subsequent initiation of seed development. Previously, we reported that loss of LORELEI, which encodes a putative glycosylphosphatidylinositol (GPI)-anchored protein, in the female reproductive tissues causes a delay in initiation of seed development. From these studies, however, it was unclear if embryos derived from fertilization of lre-5 gametophytes continued to lag behind wild type during seed development. Additionally, it was not determined if the delay in initiation of seed development had any lingering effects during seed germination. Finally, it was not known if loss of LORELEI function affects seedling development given that LORELEI is expressed in eight-day-old seedlings. Here, we showed that despite a delay in initiation, lre-5/lre-5 embryos recover, becoming equivalent to the developing wild-type embryos beginning at 72 hours after pollination. Additionally, lre-5/lre-5 seed germination, and seedling and root development are indistinguishable from wild type indicating that loss of LORELEI is tolerated, at least under standard growth conditions, in vegetative tissues.
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Tsukamoto T, Palanivelu R. Loss of LORELEI function in the pistil delays initiation but does not affect embryo development in Arabidopsis thaliana. PLANT SIGNALING & BEHAVIOR 2010; 5:1487-1490. [PMID: 21051955 PMCID: PMC3115263 DOI: 10.1111/j.1365-313x.2010.04177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 09/11/2010] [Indexed: 05/30/2023]
Abstract
Double fertilization, uniquely observed in plants, requires successful sperm cell delivery by the pollen tube to the female gametophyte, followed by migration, recognition and fusion of the two sperm cells with two female gametic cells. The female gametophyte not only regulates these steps but also controls the subsequent initiation of seed development. Previously, we reported that loss of LORELEI, which encodes a putative glycosylphosphatidylinositol (GPI)-anchored protein, in the female reproductive tissues causes a delay in initiation of seed development. From these studies, however, it was unclear if embryos derived from fertilization of lre-5 gametophytes continued to lag behind wild type during seed development. Additionally, it was not determined if the delay in initiation of seed development had any lingering effects during seed germination. Finally, it was not known if loss of LORELEI function affects seedling development given that LORELEI is expressed in eight-day-old seedlings. Here, we showed that despite a delay in initiation, lre-5/lre-5 embryos recover, becoming equivalent to the developing wild-type embryos beginning at 72 hours after pollination. Additionally, lre-5/lre-5 seed germination, and seedling and root development are indistinguishable from wild type indicating that loss of LORELEI is tolerated, at least under standard growth conditions, in vegetative tissues.
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Wang D, Zhang C, Hearn DJ, Kang IH, Punwani JA, Skaggs MI, Drews GN, Schumaker KS, Yadegari R. Identification of transcription-factor genes expressed in the Arabidopsis female gametophyte. BMC PLANT BIOLOGY 2010; 10:110. [PMID: 20550711 PMCID: PMC3236301 DOI: 10.1186/1471-2229-10-110] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 06/16/2010] [Indexed: 05/04/2023]
Abstract
BACKGROUND In flowering plants, the female gametophyte is typically a seven-celled structure with four cell types: the egg cell, the central cell, the synergid cells, and the antipodal cells. These cells perform essential functions required for double fertilization and early seed development. Differentiation of these distinct cell types likely involves coordinated changes in gene expression regulated by transcription factors. Therefore, understanding female gametophyte cell differentiation and function will require dissection of the gene regulatory networks operating in each of the cell types. These efforts have been hampered because few transcription factor genes expressed in the female gametophyte have been identified. To identify such genes, we undertook a large-scale differential expression screen followed by promoter-fusion analysis to detect transcription-factor genes transcribed in the Arabidopsis female gametophyte. RESULTS Using quantitative reverse-transcriptase PCR, we analyzed 1,482 Arabidopsis transcription-factor genes and identified 26 genes exhibiting reduced mRNA levels in determinate infertile 1 mutant ovaries, which lack female gametophytes, relative to ovaries containing female gametophytes. Spatial patterns of gene transcription within the mature female gametophyte were identified for 17 transcription-factor genes using promoter-fusion analysis. Of these, ten genes were predominantly expressed in a single cell type of the female gametophyte including the egg cell, central cell and the antipodal cells whereas the remaining seven genes were expressed in two or more cell types. After fertilization, 12 genes were transcriptionally active in the developing embryo and/or endosperm. CONCLUSIONS We have shown that our quantitative reverse-transcriptase PCR differential-expression screen is sufficiently sensitive to detect transcription-factor genes transcribed in the female gametophyte. Most of the genes identified in this study have not been reported previously as being expressed in the female gametophyte. Therefore, they might represent novel regulators and provide entry points for reverse genetic and molecular approaches to uncover the gene regulatory networks underlying female gametophyte development.
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Affiliation(s)
- Dongfang Wang
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA
| | - Changqing Zhang
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA
- Current Address: The Section of Molecular, Cell and Developmental Biology, University of Texas at Austin, Austin, Texas 78712-0159, USA
| | - David J Hearn
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA
- Current Address: Department of Biological Sciences, Towson University, Towson, Maryland 21252-0001, USA
| | - Il-Ho Kang
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA
- Current Address: Department of Horticulture, Iowa State University, Ames, Iowa 50011-1100, USA
| | - Jayson A Punwani
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA
- Current Address: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3280, USA
| | - Megan I Skaggs
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA
| | - Gary N Drews
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA
| | - Karen S Schumaker
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA
| | - Ramin Yadegari
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA
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Abstract
Flowering plants have evolved to be a predominant life form on earth. A common principle of flowering plants and probably one of the main reasons for their evolutionary success is the rapid development of an embryo next to a supporting tissue called the endosperm. The embryo and the endosperm are protected by surrounding maternal tissues, the integuments, and the trinity of integuments, embryo and endosperm comprise the plant seed. For proper seed development, these three structures have to develop in a highly controlled and co-ordinated manner, representing a paradigm for cell-cell communication during development. Communication pathways between the endosperm and the seed coat are now beginning to be unravelled. Moreover, recently isolated mutants affecting plant reproduction have allowed a genetic dissection of seed development, and revealed that the embryo plays a previously unrecognized yet important role in co-ordinating seed development.
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Tsukamoto T, Qin Y, Huang Y, Dunatunga D, Palanivelu R. A role for LORELEI, a putative glycosylphosphatidylinositol-anchored protein, in Arabidopsis thaliana double fertilization and early seed development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:571-88. [PMID: 20163554 DOI: 10.1111/j.1365-313x.2010.04177.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In plants, double fertilization requires successful sperm cell delivery into the female gametophyte followed by migration, recognition and fusion of the two sperm cells with two female gametes. We isolated a null allele (lre-5) of LORELEI, which encodes a putative glycosylphosphatidylinositol (GPI)-anchored protein implicated in reception of the pollen tube by the female gametophyte. Although most lre-5 female gametophytes do not allow pollen tube reception, in those that do, early seed development is delayed. A fraction of lre-5/lre-5 seeds underwent abortion due to defect(s) in the female gametophyte. The aborted seeds contained endosperm but no zygote/embryo, reminiscent of autonomous endosperm development in the pollen tube reception mutants scylla and sirene. However, unpollinated lre-5/lre-5 ovules did not initiate autonomous endosperm development and endosperm development in aborted seeds began after central cell fertilization. Thus, the egg cell probably remained unfertilized in aborted lre-5/lre-5 seeds. The lre-5/lre-5 ovules that remain undeveloped due to defective pollen tube reception did not induce synergid degeneration and repulsion of supernumerary pollen tubes. In ovules, LORELEI is expressed during pollen tube reception, double fertilization and early seed development. Null mutants of LORELEI-like-GPI-anchored protein 1 (LLG1), the closest relative of LORELEI among three Arabidopsis LLG genes, are fully fertile and did not enhance reproductive defects in lre-5/lre-5 pistils, suggesting that LLG1 function is not redundant with that of LORELEI in the female gametophyte. Our results show that, besides pollen tube reception, LORELEI also functions during double fertilization and early seed development.
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Affiliation(s)
- Tatsuya Tsukamoto
- School of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA
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27
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Andreuzza S, Li J, Guitton AE, Faure JE, Casanova S, Park JS, Choi Y, Chen Z, Berger F. DNA LIGASE I exerts a maternal effect on seed development in Arabidopsis thaliana. Development 2010; 137:73-81. [PMID: 20023162 DOI: 10.1242/dev.041020] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Maternal effects are defined by mutations that affect the next generation when they are maternally inherited. To date, most indepth studies of maternal effects in plants have attributed their origin to genomic imprinting that restricts expression to the maternal allele. The DNA glycosylase DEMETER (DME) removes methylated cytosine residues, causing transcriptional activation of the maternal allele of imprinted genes. In this study, we show that loss-of-function of the major DNA LIGASE I (AtLIG1) in Arabidopsis thaliana causes maternal effects in the endosperm, which is the seed tissue that nurtures embryo development. AtLIG1 expression is not imprinted and has a limited impact on imprinted gene expression. Genetic interaction analyses further indicate that AtLIG1 acts downstream of DME. The removal of methylated cytosine residues by DME involves the creation of DNA single-strand breaks and our results suggest that AtLIG1 repairs these breaks.
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Affiliation(s)
- Sebastien Andreuzza
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore
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28
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Grini PE, Thorstensen T, Alm V, Vizcay-Barrena G, Windju SS, Jørstad TS, Wilson ZA, Aalen RB. The ASH1 HOMOLOG 2 (ASHH2) histone H3 methyltransferase is required for ovule and anther development in Arabidopsis. PLoS One 2009; 4:e7817. [PMID: 19915673 PMCID: PMC2772814 DOI: 10.1371/journal.pone.0007817] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Accepted: 10/20/2009] [Indexed: 01/05/2023] Open
Abstract
Background SET-domain proteins are histone lysine (K) methyltransferases (HMTase) implicated in defining transcriptionally permissive or repressive chromatin. The Arabidopsis ASH1 HOMOLOG 2 (ASHH2) protein (also called SDG8, EFS and CCR1) has been suggested to methylate H3K4 and/or H3K36 and is similar to Drosophila ASH1, a positive maintainer of gene expression, and yeast Set2, a H3K36 HMTase. Mutation of the ASHH2 gene has pleiotropic developmental effects. Here we focus on the role of ASHH2 in plant reproduction. Methodology/Principal Findings A slightly reduced transmission of the ashh2 allele in reciprocal crosses implied involvement in gametogenesis or gamete function. However, the main requirement of ASHH2 is sporophytic. On the female side, close to 80% of mature ovules lack embryo sac. On the male side, anthers frequently develop without pollen sacs or with specific defects in the tapetum layer, resulting in reduction in the number of functional pollen per anther by up to ∼90%. In consistence with the phenotypic findings, an ASHH2 promoter-reporter gene was expressed at the site of megaspore mother cell formation as well as tapetum layers and pollen. ashh2 mutations also result in homeotic changes in floral organ identity. Transcriptional profiling identified more than 300 up-regulated and 600 down-regulated genes in ashh2 mutant inflorescences, whereof the latter included genes involved in determination of floral organ identity, embryo sac and anther/pollen development. This was confirmed by real-time PCR. In the chromatin of such genes (AP1, AtDMC1 and MYB99) we observed a reduction of H3K36 trimethylation (me3), but not H3K4me3 or H3K36me2. Conclusions/Significance The severe distortion of reproductive organ development in ashh2 mutants, argues that ASHH2 is required for the correct expression of genes essential to reproductive development. The reduction in the ashh2 mutant of H3K36me3 on down-regulated genes relevant to the observed defects, implicates ASHH2 in regulation of gene expression via H3K36 trimethylation in chromatin of Arabidopsis inflorescences.
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Affiliation(s)
- Paul E. Grini
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | - Tage Thorstensen
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | - Vibeke Alm
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | | | - Susanne S. Windju
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | - Tommy S. Jørstad
- Department of Biology, Norwegian University of Sciences and Technology, Trondheim, Norway
| | - Zoe A. Wilson
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Reidunn B. Aalen
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
- * E-mail:
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29
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The contribution of cell cycle regulation to endosperm development. ACTA ACUST UNITED AC 2009; 22:207-19. [DOI: 10.1007/s00497-009-0105-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 07/05/2009] [Indexed: 01/08/2023]
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Wang X, Xu C, Wu R, Larkins BA. Genetic dissection of complex endosperm traits. TRENDS IN PLANT SCIENCE 2009; 14:391-398. [PMID: 19546022 DOI: 10.1016/j.tplants.2009.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Revised: 04/23/2009] [Accepted: 04/23/2009] [Indexed: 05/28/2023]
Abstract
The endosperm of plants is a major source of food, feed and industrial raw materials. The genetic analysis of endosperm traits poses numerous challenges due to the endosperm's complex genetic composition and unique physical and developmental properties. Modern molecular techniques and statistical methods have greatly improved the mapping of quantitative trait loci underlying endosperm traits and have led to revolutionary insights regarding epistatic and epigenetic effects. This article describes the current state of the methodologies used in the genetic dissection of endosperm traits and highlights practical issues and statistical concepts and procedures.
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Affiliation(s)
- Xuefeng Wang
- Jiangsu Provincial Key Laboratory of Crop Genetics and Physiology; Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou, China
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31
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Stangeland B, Rosenhave EM, Winge P, Berg A, Amundsen SS, Karabeg M, Mandal A, Bones AM, Grini PE, Aalen RB. AtMBD8 is involved in control of flowering time in the C24 ecotype of Arabidopsis thaliana. PHYSIOLOGIA PLANTARUM 2009; 136:110-26. [PMID: 19374717 DOI: 10.1111/j.1399-3054.2009.01218.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Arabidopsis thaliana accession C24 is a vernalization-responsive, moderately late flowering ecotype. We report that a mutation in AtMBD8, which encodes a protein with a putative Methyl-CpG-Binding Domain (MBD), in C24 background, results in a delay in flowering time during both long and short days. The atmbd8-1 mutant responded to vernalization as wild type (wt) plants. Consistent with a role in modulation of flowering time, an AtMBD8::GUS-reporter construct was expressed in the shoot meristem region and developing leaves. Full-genome transcriptional profiling revealed very few changes in gene expression between atmbd8-1 and wt plants. The expression level of FLC, the major repressor of transition to flowering, was unchanged in atmbd8-1, and in accordance with that, genes upstream of FLC were unaffected by the mutation. The expression level of CONSTANS, involved in photoperiodic control of flowering, was very similar in atmbd8-1 and wt plants. In contrast, the major promoters of flowering, FT and SOC1, were both downregulated. As FT is a regulator of SOC1, we conclude that AtMBD8 is a novel promoter of flowering that acts upstream of FT in the C24 accession. In contrast to atmbd8-1, the Colombia (Col) SALK T-DNA insertion line, atmbd8-2, did not display a delayed transition to flowering. Transcriptional profiling revealed that a substantial number of genes were differentially expressed between C24 and Col wt seedlings. Several of these genes are also differentially expressed in late flowering mutants. We suggest that these differences contribute to the contrasting effect of a mutation in AtMBD8 in the two ecotypes.
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Affiliation(s)
- Biljana Stangeland
- Department of Molecular Biosciences, University of Oslo, Blindern, N-0316 Oslo, Norway
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32
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Gusti A, Baumberger N, Nowack M, Pusch S, Eisler H, Potuschak T, De Veylder L, Schnittger A, Genschik P. The Arabidopsis thaliana F-box protein FBL17 is essential for progression through the second mitosis during pollen development. PLoS One 2009; 4:e4780. [PMID: 19277118 PMCID: PMC2651519 DOI: 10.1371/journal.pone.0004780] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 01/22/2009] [Indexed: 01/24/2023] Open
Abstract
In fungi and metazoans, the SCF-type Ubiquitin protein ligases (E3s) play a critical role in cell cycle regulation by degrading negative regulators, such as cell cycle-dependent kinase inhibitors (CKIs) at the G1-to-S-phase checkpoint. Here we report that FBL17, an Arabidopsis thaliana F-box protein, is involved in cell cycle regulation during male gametogenesis. FBL17 expression is strongly enhanced in plants co-expressing E2Fa and DPa, transcription factors that promote S-phase entry. FBL17 loss-of-function mutants fail to undergo pollen mitosis II, which generates the two sperm cells in mature A. thaliana pollen. Nonetheless, the single sperm cell-like cell in fbl17 mutants is functional but will exclusively fertilize the egg cell of the female gametophyte, giving rise to an embryo that will later abort, most likely due to the lack of functional endosperm. Seed abortion can, however, be overcome by mutations in FIE, a component of the Polycomb group complex, overall resembling loss-of-function mutations in the A. thaliana cyclin-dependent kinase CDKA;1. Finally we identified ASK11, as an SKP1-like partner protein of FBL17 and discuss a possible mechanism how SCF(FBL17) may regulate cell division during male gametogenesis.
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Affiliation(s)
- Andi Gusti
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
| | - Nicolas Baumberger
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
| | - Moritz Nowack
- Unigruppe am Max-Planck-Institut für Züchtungsforschung, Max-Delbrück-Laboratorium, Lehrstuhl für Botanik III, Universität Köln, Köln, Germany
| | - Stefan Pusch
- Unigruppe am Max-Planck-Institut für Züchtungsforschung, Max-Delbrück-Laboratorium, Lehrstuhl für Botanik III, Universität Köln, Köln, Germany
| | - Herfried Eisler
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
| | - Thomas Potuschak
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
| | - Lieven De Veylder
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), Gent, Belgium
- Department of Molecular Genetics, Ghent University, Gent, Belgium
| | - Arp Schnittger
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
- Unigruppe am Max-Planck-Institut für Züchtungsforschung, Max-Delbrück-Laboratorium, Lehrstuhl für Botanik III, Universität Köln, Köln, Germany
| | - Pascal Genschik
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
- * E-mail:
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The EPIP peptide of INFLORESCENCE DEFICIENT IN ABSCISSION is sufficient to induce abscission in arabidopsis through the receptor-like kinases HAESA and HAESA-LIKE2. THE PLANT CELL 2008; 20:1805-17. [PMID: 18660431 DOI: 10.1105/tpc.108.059139] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In Arabidopsis thaliana, the final step of floral organ abscission is regulated by INFLORESCENCE DEFICIENT IN ABSCISSION (IDA): ida mutants fail to abscise floral organs, and plants overexpressing IDA display earlier abscission. We show that five IDA-LIKE (IDL) genes are expressed in different tissues, but plants overexpressing these genes have phenotypes similar to IDA-overexpressing plants, suggesting functional redundancy. IDA/IDL proteins have N-terminal signal peptides and a C-terminal conserved motif (extended PIP [EPIP]) at the C terminus (EPIP-C). IDA can, similar to CLAVATA3, be processed by an activity from cauliflower meristems. The EPIP-C of IDA and IDL1 replaced IDA function in vivo, when the signal peptide was present. In addition, synthetic IDA and IDL1 EPIP peptides rescued ida and induced early floral abscission in wild-type flowers. The EPIP-C of the other IDL proteins could partially substitute for IDA function. Similarly to ida, a double mutant between the receptor-like kinases (RLKs) HAESA (HAE) and HAESA-LIKE2 (HSL2) displays nonabscising flowers. Neither overexpression of IDA nor synthetic EPIP or EPIP-C peptides could rescue the hae hsl2 abscission deficiency. We propose that IDA and the IDL proteins constitute a family of putative ligands that act through RLKs to regulate different events during plant development.
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RNAi of met1 reduces DNA methylation and induces genome-specific changes in gene expression and centromeric small RNA accumulation in Arabidopsis allopolyploids. Genetics 2008; 178:1845-58. [PMID: 18430920 DOI: 10.1534/genetics.107.086272] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Changes in genome structure and gene expression have been documented in both resynthesized and natural allopolyploids that contain two or more divergent genomes. The underlying mechanisms for rapid and stochastic changes in gene expression are unknown. Arabidopsis suecica is a natural allotetraploid derived from the extant A. thaliana and A. arenosa genomes that are homeologous in the allotetraploid. Here we report that RNAi of met1 reduced DNA methylation and altered the expression of approximately 200 genes, many of which encode transposons, predicted proteins, and centromeric and heterochromatic RNAs. Reduced DNA methylation occurred frequently in promoter regions of the upregulated genes, and an En/Spm-like transposon was reactivated in met1-RNAi A. suecica lines. Derepression of transposons, heterochromatic repeats, and centromeric small RNAs was primarily derived from the A. thaliana genome, and A. arenosa homeologous loci were less affected by methylation defects. A high level of A. thaliana centromeric small RNA accumulation was correlated with hypermethylation of A. thaliana centromeres. The greater effects of reduced DNA methylation on transposons and centromeric repeats in A. thaliana than in A. arenosa are consistent with the repression of many genes that are expressed at higher levels in A. thaliana than in A. arenosa in the resynthesized allotetraploids. Moreover, non-CG (CC) methylation in the promoter region of A. thaliana At2g23810 remained in the resynthesized allotetraploids, and the methylation spread within the promoter region in natural A. suecica, leading to silencing of At2g23810. At2g23810 was demethylated and reactivated in met1-RNAi A. suecica lines. We suggest that many A. thaliana genes are transcriptionally repressed in resynthesized allotetraploids, and a subset of A. thaliana loci including transposons and centromeric repeats are heavily methylated and subjected to homeologous genome-specific RNA-mediated DNA methylation in natural allopolyploids.
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Natural variation in the degree of autonomous endosperm formation reveals independence and constraints of embryo growth during seed development in Arabidopsis thaliana. Genetics 2008; 179:829-41. [PMID: 18505878 DOI: 10.1534/genetics.107.084889] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Seed development in flowering plants is a paradigm for the coordination of different tissues during organ growth. It requires a tight interplay between the two typically sexually produced structures: the embryo, developing from the fertilized egg cell, and the endosperm, originating from a fertilized central cell, along with the surrounding maternal tissues. Little is known about the presumptive signal transduction pathways administering and coordinating these different tissues during seed growth and development. Recently, a new signal has been identified emanating from the fertilization of the egg cell that triggers central cell proliferation without prior fertilization. Here, we demonstrate that there exists a large natural genetic variation with respect to the outcome of this signaling process in the model plant Arabidopsis thaliana. By using a recombinant inbred line population between the two Arabidopsis accessions Bayreuth-0 and Shahdara, we have identified two genetic components that influence the development of unfertilized endosperm. Exploiting this natural variation, we could further dissect the interdependence of embryo and endosperm growth during early seed development. Our data show an unexpectedly large degree of independence in embryo growth, but also reveal the embryo's developmental restrictions with respect to endosperm size. This work provides a genetic framework for dissection of the interplay between embryo and endosperm during seed growth in plants.
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36
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Ngo QA, Moore JM, Baskar R, Grossniklaus U, Sundaresan V. Arabidopsis GLAUCEpromotes fertilization-independent endosperm development and expression of paternally inherited alleles. Development 2007; 134:4107-17. [DOI: 10.1242/dev.007310] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Early seed development of sexually reproducing plants requires both maternal and paternal genomes but is prominently maternally influenced. A novel gametophytic maternal-effect mutant defective in early embryo and endosperm development, glauce (glc), has been isolated from a population of Arabidopsis Ds transposon insertion lines. The glc mutation results from a deletion at the Ds insertion site, and the molecular identity of GLC is not known. glcembryos can develop up to the globular stage in the absence of endosperm and glc central cells appear to be unfertilized. glc suppresses autonomous endosperm development observed in the fertilization-independent seed (fis) class mutants. glc is also epistatic to mea, one of the fis class mutants, in fertilized seeds, and is essential for the biparental embryonic expression of PHE1, a repressed downstream target of MEA. In addition, maternal GLC function is required for the paternal embryonic expression of the ribosome protein gene RPS5a and the AMP deaminase gene FAC1,both of which are essential for early embryo and endosperm development. These results indicate that factors derived from the female gametophyte activate a subset of the paternal genome of fertilized seeds.
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Affiliation(s)
- Quy A. Ngo
- Section of Plant Biology, University of California, One Shields Avenue, Davis,CA 95616, USA
| | - James M. Moore
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724,USA
- Institute of Plant Biology and Zürich-Basel Plant Science Center,University of Zürich, Zollikerstrasse 107, CH-8008 Zürich,Switzerland
| | - Ramamurthy Baskar
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724,USA
- Institute of Plant Biology and Zürich-Basel Plant Science Center,University of Zürich, Zollikerstrasse 107, CH-8008 Zürich,Switzerland
| | - Ueli Grossniklaus
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724,USA
- Institute of Plant Biology and Zürich-Basel Plant Science Center,University of Zürich, Zollikerstrasse 107, CH-8008 Zürich,Switzerland
| | - Venkatesan Sundaresan
- Section of Plant Biology, University of California, One Shields Avenue, Davis,CA 95616, USA
- Department of Plant Sciences, University of California, One Shields Avenue,Davis, CA 95616, USA
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The Arabidopsis SET-domain protein ASHR3 is involved in stamen development and interacts with the bHLH transcription factor ABORTED MICROSPORES (AMS). PLANT MOLECULAR BIOLOGY 2007; 66:47-59. [PMID: 17978851 DOI: 10.1007/s11103-007-9251-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 10/04/2007] [Indexed: 12/24/2022]
Abstract
The Arabidopsis thaliana genome contains more than 30 genes encoding SET-domain proteins that are thought to be epigenetic regulators of gene expression and chromatin structure. SET-domain proteins can be divided into subgroups, and members of the Polycomb group (PcG) and trithorax group (trxG) have been shown to be important regulators of development. Both in animals and plants some of these proteins are components of multimeric protein complexes. Here, we have analyzed the Arabidopsis trxG protein ASHR3 which has a SET domain and pre- and post-SET domains similar to that of Ash1 in Drosophila. In addition to the SET domain, a divergent PHD finger is found in the N-terminus of the ASHR3 protein. As expected from SET-domain proteins involved in transcriptional activation, ASHR3 (coupled to GFP) localizes to euchromatin. A yeast two-hybrid screening revealed that the ASHR3 protein interacts with the putative basic helix-loop-helix (bHLH) transcription factor ABORTED MICROSPORES (AMS), which is involved in anther and stamen development in Arabidopsis. Deletion mapping indicated that both the PHD finger and the SET domain mediate the interaction between the two proteins. Overexpression of ASHR3 led in general to growth arrest, and specifically to degenerated anthers and male sterility. Expression analyses demonstrated that ASHR3 like AMS is expressed in the anther and in stamen filaments. We therefore propose that AMS can target ASHR3 to chromatin and regulate genes involved in stamen development and function.
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Steffen JG, Kang IH, Macfarlane J, Drews GN. Identification of genes expressed in the Arabidopsis female gametophyte. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 51:281-92. [PMID: 17559508 DOI: 10.1111/j.1365-313x.2007.03137.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The angiosperm female gametophyte typically consists of one egg cell, two synergid cells, one central cell, and three antipodal cells. Each of these four cell types has unique structural features and performs unique functions that are essential for the reproductive process. The gene regulatory networks conferring these four phenotypic states are largely uncharacterized. As a first step towards dissecting the gene regulatory networks of the female gametophyte, we have identified a large collection of genes expressed in specific cells of the Arabidopsis thaliana female gametophyte. We identified these genes using a differential expression screen based on reduced expression in determinant infertile1 (dif1) ovules, which lack female gametophytes. We hybridized ovule RNA probes with Affymetrix ATH1 genome arrays and validated the identified genes using real-time RT-PCR. These assays identified 71 genes exhibiting reduced expression in dif1 ovules. We further validated 45 of these genes using promoter::GFP fusions and 43 were expressed in the female gametophyte. In the context of the ovule, 11 genes were expressed exclusively in the antipodal cells, 11 genes were expressed exclusively or predominantly in the central cell, 17 genes were expressed exclusively or predominantly in the synergid cells, one gene was expressed exclusively in the egg cell, and three genes were expressed strongly in multiple cells of the female gametophyte. These genes provide insights into the molecular processes functioning in the female gametophyte and can be used as starting points to dissect the gene regulatory networks functioning during differentiation of the four female gametophyte cell types.
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Affiliation(s)
- Joshua G Steffen
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
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Nowack MK, Shirzadi R, Dissmeyer N, Dolf A, Endl E, Grini PE, Schnittger A. Bypassing genomic imprinting allows seed development. Nature 2007; 447:312-5. [PMID: 17468744 DOI: 10.1038/nature05770] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 03/23/2007] [Indexed: 11/08/2022]
Abstract
In developing progeny of mammals the two parental genomes are differentially expressed according to imprinting marks, and embryos with only a uniparental genetic contribution die. Gene expression that is dependent on the parent of origin has also been observed in the offspring of flowering plants, and mutations in the imprinting machinery lead to embryonic lethality, primarily affecting the development of the endosperm-a structure in the seed that nourishes the embryo, analogous to the function of the mammalian placenta. Here we have generated Arabidopsis thaliana seeds in which the endosperm is of uniparental, that is, maternal, origin. We demonstrate that imprinting in developing seeds can be bypassed and viable albeit smaller seedlings can develop from seeds lacking a paternal contribution to the endosperm. Bypassing is only possible if the mother is mutant for any of the FIS-class genes, which encode Polycomb group chromatin-modifying factors. Thus, these data provide functional evidence that the action of the FIS complex balances the contribution of the paternal genome. As flowering plants have evolved a special reproduction system with a parallel fusion of two female with two male gametes, our findings support the hypothesis that only with the evolution of double fertilization did the action of the FIS genes become a requirement for seed development. Furthermore, our data argue for a gametophytic origin of endosperm in flowering plants, thereby supporting a hypothesis raised in 1900 by Eduard Strasburger.
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Affiliation(s)
- Moritz K Nowack
- University group at the Max Planck Institute for Plant Breeding Research, Max-Delbrück-Laboratorium, Department of Botany III, University of Cologne, Carl-von-Linné-Weg 10, D-50829 Cologne, Germany
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Berger F, Grini PE, Schnittger A. Endosperm: an integrator of seed growth and development. CURRENT OPINION IN PLANT BIOLOGY 2006; 9:664-70. [PMID: 17011228 DOI: 10.1016/j.pbi.2006.09.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 09/20/2006] [Indexed: 05/08/2023]
Abstract
Plant reproduction relies on interactions between parental and zygotic components. Elaborate reciprocal signaling pathways enable coordination of the genetic programs between these components. A first and important step in this communication is the tight control of cell cycle events in the gametes prior to fertilization. This prepares for coordinated fertilization and the initiation of seed development. The dialog between the various actors of reproduction extends after fertilization, with the endosperm taking a central role. Importantly, the endosperm mediates a maternal input that is based on memory of the transcriptional states of imprinted genes, which is crucial for harmonious seed growth. Our current knowledge suggests that the endosperm is an integrator of the different components and genetic programs that are involved in seed development.
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Affiliation(s)
- Frédéric Berger
- Temasek Lifescience Laboratory, 1 Research Link, National University of Singapore, 117604, Singapore.
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41
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Butenko MA, Stenvik GE, Alm V, Saether B, Patterson SE, Aalen RB. Ethylene-dependent and -independent pathways controlling floral abscission are revealed to converge using promoter::reporter gene constructs in the ida abscission mutant. JOURNAL OF EXPERIMENTAL BOTANY 2006; 57:3627-37. [PMID: 16990374 DOI: 10.1093/jxb/erl130] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The process of floral organ abscission in Arabidopsis thaliana can be modulated by ethylene and involves numerous genes contributing to cell separation. One gene that is absolutely required for abscission is INFLORESCENCE DEFICIENT IN ABSCISSION, IDA, as the ida mutant is completely blocked in abscission. To elucidate the genetic pathways regulating floral abscission, molecular markers expressed in the floral abscission zone have been studied in an ida mutant background. Using plants with promoter-reporter gene constructs including promoters of a novel FLORAL ABSCISSION ASSOCIATED gene (FAA) encoding a putative single-stranded binding protein (BASIL), chitinase (CHIT::GUS) and cellulase (BAC::GUS), it is shown that IDA acts in the last steps of the abscission process. These markers, as well as HAESA, encoding a receptor-like kinase, were unaffected in their temporal expression patterns in ida compared with wild-type plants; thus showing that different regulatory pathways are active in the abscission process. In contrast to BASIL, CHIT::GUS and BAC::GUS showed, however, much weaker induction of expression in an ida background, consistent with a reduction in pathogen-associated responses and a lack of total dissolution of cell walls in the mutant. IDA, encoding a putative secreted peptide ligand, and HAESA appeared to have identical patterns of expression in floral abscission zones. Lastly, to address the role of ethylene, IDA::GUS expression in the wild type and the ethylene-insensitive mutant etr1-1 was compared. Similar temporal patterns, yet restricted spatial expression patterns were observed in etr1-1, suggesting that the pathways regulated by IDA and by ethylene act in parallel, but are, to some degree, interdependent.
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Affiliation(s)
- Melinka A Butenko
- Department of Molecular Biosciences, University of Oslo, PO Box 1041 Blindern, N-0316 Oslo, Norway
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42
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Gutiérrez-Marcos JF, Costa LM, Evans MMS. Maternal gametophytic baseless1 is required for development of the central cell and early endosperm patterning in maize (Zea mays). Genetics 2006; 174:317-29. [PMID: 16849604 PMCID: PMC1569813 DOI: 10.1534/genetics.106.059709] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In angiosperms, double fertilization of an egg cell and a central cell with two sperm cells results in the formation of a seed containing a diploid embryo and a triploid endosperm. The extent to which the embryo sac controls postfertilization events in the seed is unknown. The novel gametophytic maternal-effect maize mutation, baseless1 (bsl1) affects central cell development within the embryo sac, frequently by altering the position of the two polar nuclei. Despite this irregularity, fertilization is as efficient as in wild type. The spatial expression of basal endosperm-specific transcripts is altered in free-nuclear and cellular mutant endosperms. At later stages of seed development, bsl1 predominantly affects development of the basal endosperm transfer layer (BETL). When bsl1/+ diploid plants were pollinated by wild-type tetraploid plants, the BETL abnormalities observed in bsl1/bsl1/+/+ tetraploid endosperms were diverse and of variable severity. Moreover, the frequency of kernels with severely perturbed BETL development correlated with the percentage of severely affected bsl1 central cells. Therefore, BSL1 is likely required in the central cell before fertilization for correct BETL patterning to occur. These findings provide new genetic evidence that a maternal gametophytic component is necessary for correct endosperm patterning.
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43
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Iwakawa H, Shinmyo A, Sekine M. Arabidopsis CDKA;1, a cdc2 homologue, controls proliferation of generative cells in male gametogenesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 45:819-31. [PMID: 16460514 DOI: 10.1111/j.1365-313x.2005.02643.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The protein kinase cdc2 is conserved throughout eukaryotes and acts as a key regulator of the cell cycle. In plants, A-type cyclin-dependent kinase (CDKA), a homologue of cdc2, has a role throughout the cell cycle. Here we show that a loss-of-function mutation in CDKA;1, encoding the only Arabidopsis CDKA, results in lethality of the male gametophyte. Heterozygous plants produced mature siliques containing about 50% aborted seeds, and segregation distortion was observed in paternal inheritance. Microspores normally undergo an asymmetric cell division, pollen mitosis I (PMI), to produce bicellular pollen grains. The larger vegetative cell does not divide, but the smaller generative cell undergoes mitosis, PMII, to form the two sperm cells, thereby generating tricellular pollen grains. The cdka-1 mutant, however, produces mature bicellular pollen grains, consisting of a single sperm-like cell and a vegetative cell, due to failure of PMII. The mutant sperm-like cell is fertile, and preferentially fuses with the egg cell to initiate embryogenesis. As the central cell nucleus remains unfertilized, however, double fertilization does not occur. In heterozygous plants, the embryo is arrested at the globular stage, most likely because of loss of endosperm development, whereas it is arrested at the one- or two-cell stage in presumptive homozygous plants. Thus, CDKA;1 is essential for cell division of the generative cell in male gametogenesis.
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Affiliation(s)
- Hidekazu Iwakawa
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0101, Japan
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44
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Nowack MK, Grini PE, Jakoby MJ, Lafos M, Koncz C, Schnittger A. A positive signal from the fertilization of the egg cell sets off endosperm proliferation in angiosperm embryogenesis. Nat Genet 2005; 38:63-7. [PMID: 16311592 DOI: 10.1038/ng1694] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Accepted: 10/14/2005] [Indexed: 11/08/2022]
Abstract
Double fertilization of the egg cell and the central cell by one sperm cell each produces the diploid embryo and the typically triploid endosperm and is one of the defining characteristics of flowering plants (angiosperms). Endosperm and embryo develop in parallel to form the mature seed, but little is known about the coordination between these two organisms. We characterized a mutation of the Arabidopsis thaliana Cdc2 homolog CDC2A (also called CDKA;1), which has a paternal effect. In cdc2a mutant pollen, only one sperm cell, instead of two, is produced. Mutant pollen is viable but can fertilize only one cell in the embryo sac, allowing for a genetic dissection of the double fertilization process. We observed exclusive fertilization of the egg cell by cdc2a sperm cells. Moreover, we found that unfertilized endosperm developed, suggesting that a previously unrecognized positive signal from the fertilization of the egg cell initiates proliferation of the central cell.
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Affiliation(s)
- Moritz K Nowack
- Unigruppe am Max-Planck-Institut für Züchtungsforschung, Max-Delbrück-Laboratorium, Lehrstuhl für Botanik III, Universität Köln, Carl-von-Linné-Weg 10, D-50829 Köln, Germany
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45
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Grimanelli D, Perotti E, Ramirez J, Leblanc O. Timing of the maternal-to-zygotic transition during early seed development in maize. THE PLANT CELL 2005; 17:1061-72. [PMID: 15749756 PMCID: PMC1087986 DOI: 10.1105/tpc.104.029819] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Accepted: 02/09/2005] [Indexed: 05/18/2023]
Abstract
In animals, early embryonic development is largely dependent on maternal transcripts synthesized during gametogenesis. Recent data in plants also suggest maternal control over early seed development, but the actual timing of zygotic genome activation is unclear. Here, we analyzed the timing of the maternal-to-zygotic transition during early Zea mays seed development. We show that for 16 genes expressed during early seed development, only maternally inherited alleles are detected during 3 d after fertilization in both the embryo and the endosperm. Microarray analyses of precocious embryonic development in apomictic hybrids between maize and its wild relative, Tripsacum, demonstrate that early embryo development occurs without significant quantitative changes to the transcript population in the ovule before fertilization. Precocious embryo development is also correlated with a higher proportion of polyadenylated mRNA in the ovules. Our data suggest that the maternal-to-zygotic transition occurs several days after fertilization. By contrast, novel transcription accompanies early endosperm development, indicating that different mechanisms are involved in the initiation of endosperm and embryo development.
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Affiliation(s)
- Daniel Grimanelli
- Institut de Recherche pour le Développement, Unité Mixte de Recherche 5096, 34394 Montpellier, France.
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46
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Pagnussat GC, Yu HJ, Ngo QA, Rajani S, Mayalagu S, Johnson CS, Capron A, Xie LF, Ye D, Sundaresan V. Genetic and molecular identification of genes required for female gametophyte development and function in Arabidopsis. Development 2005; 132:603-14. [PMID: 15634699 DOI: 10.1242/dev.01595] [Citation(s) in RCA: 394] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The plant life cycle involves an alternation of generations between sporophyte and gametophyte. Currently, the genes and pathways involved in gametophytic development and function in flowering plants remain largely unknown. A large-scale mutant screen of Ds transposon insertion lines was employed to identify 130 mutants of Arabidopsis thaliana with defects in female gametophyte development and function. A wide variety of mutant phenotypes were observed, ranging from defects in different stages of early embryo sac development to mutants with apparently normal embryo sacs, but exhibiting defects in processes such as pollen tube guidance, fertilization or early embryo development. Unexpectedly, nearly half of the mutants isolated in this study were found to be primarily defective in post-fertilization processes dependent on the maternal allele, suggesting that genes expressed from the female gametophyte or the maternal genome play a major role in the early development of plant embryos. Sequence identification of the genes disrupted in the mutants revealed genes involved in protein degradation, cell death, signal transduction and transcriptional regulation required for embryo sac development, fertilization and early embryogenesis. These results provide a first comprehensive overview of the genes and gene products involved in female gametophyte development and function within a flowering plant.
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Affiliation(s)
- Gabriela C Pagnussat
- Section of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
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47
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Costa LM, Gutièrrez-Marcos JF, Dickinson HG. More than a yolk: the short life and complex times of the plant endosperm. TRENDS IN PLANT SCIENCE 2004; 9:507-14. [PMID: 15465686 DOI: 10.1016/j.tplants.2004.08.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- Liliana M Costa
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
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48
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Sorensen AM, Kroeber S, Saedler H. The ABNORMAL GAMETOPHYTES (AGM) Gene Product of Arabidopsis Demonstrates a Role in Mitosis During Gamete Development. ACTA ACUST UNITED AC 2004; 45:905-13. [PMID: 15295074 DOI: 10.1093/pcp/pch106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Screening a T-DNA mutagenized population of Arabidopsis thaliana for reduced seed set and segregation distortion led to the isolation of the ABNORMAL GAMETOPHYTES (AGM) mutant. Homozygous plants were never recovered, but heterozygous plants showed mitotic defects during gametogenesis resulting in approximately 50% abortion of both the male and female gametes. Isolation of the genomic sequence flanking the co-segregating T-DNA element led to the identification of a gene located on chromosome 5, predicted to encode a transmembrane protein. BLAST homology searches identified two homologous proteins that are not redundant, as is clear from the existence of the agm mutant. Unexpectedly, expression studies using the beta-glucuronidase reporter gene suggest that AGM and its closest Arabidopsis homolog are mostly expressed in cells undergoing mitosis. Thus, AGM is not a gametophytic gene as originally speculated on the basis of segregation distortion, but rather classified as an essential gene crucial to the process of mitosis in plants.
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Affiliation(s)
- Anna-Marie Sorensen
- Max Planck Institute for Plant Breeding Research, Department of Molecular Plant Genetics, Carl-von-Linné Weg 10, D-50829-Cologne, Germany.
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Gutiérrez-Marcos JF, Costa LM, Biderre-Petit C, Khbaya B, O'Sullivan DM, Wormald M, Perez P, Dickinson HG. maternally expressed gene1 Is a novel maize endosperm transfer cell-specific gene with a maternal parent-of-origin pattern of expression. THE PLANT CELL 2004; 16:1288-301. [PMID: 15105441 PMCID: PMC423216 DOI: 10.1105/tpc.019778] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2003] [Accepted: 02/04/2004] [Indexed: 05/18/2023]
Abstract
Growth of the maize (Zea mays) endosperm is tightly regulated by maternal zygotic and sporophytic genes, some of which are subject to a parent-of-origin effect. We report here a novel gene, maternally expressed gene1 (meg1), which shows a maternal parent-of-origin expression pattern during early stages of endosperm development but biallelic expression at later stages. Interestingly, a stable reporter fusion containing the meg1 promoter exhibits a similar pattern of expression. meg1 is exclusively expressed in the basal transfer region of the endosperm. Further, we show that the putatively processed MEG1 protein is glycosylated and subsequently localized to the labyrinthine ingrowths of the transfer cell walls. Hence, the discovery of a parent-of-origin gene expressed solely in the basal transfer region opens the door to epigenetic mechanisms operating in the endosperm to regulate certain aspects of nutrient trafficking from the maternal tissue into the developing seed.
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50
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Haslekås C, Grini PE, Nordgard SH, Thorstensen T, Viken MK, Nygaard V, Aalen RB. ABI3 mediates expression of the peroxiredoxin antioxidant AtPER1 gene and induction by oxidative stress. PLANT MOLECULAR BIOLOGY 2004; 53:313-26. [PMID: 14750521 DOI: 10.1023/b:plan.0000006937.21343.2a] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The peroxiredoxin antioxidant gene AtPER1 has been considered to be specifically expressed in the embryo and aleurone layer during maturation and desiccation stages of development, and in the mature seed, typically for late embryogenesis-abundant (lea) transcripts. In the abscisic acid-insensitive abi3-1 mutant, the AtPER1 transcript level is strongly reduced, suggesting ABI3 to be a prime regulator of AtPER1. We have studied the expression pattern and regulation of AtPER1 with a series of nine promoter::GUS constructs with deletions and/or mutations in putative regulatory elements. Arabidopsis lines harbouring these constructs revealed AtPER1 promoter activity in the endosperm, especially the chalazal cyst, already when the embryo is in the late globular stage, in the embryo from the late torpedo stage, and in distinct cells of unfertilized and fertilized ovules. Early expression seems to be dependent on a putative antioxidant-responsive promoter element (ARE), while from the bent cotyledon stage endosperm and embryo expression is dependent on an ABA-responsive element (ABRE) likely to bind ABI5. The shortest promoter fragment (113 bp), devoid of ARE, ABRE and without an intact RY/Sph element thought to bind ABI3 did not drive GUS expression. The AtPER1::GUS construct also revealed expression in cotyledons, meristems and stem branching points. In general, seed and vegetative expression coincided with the expression pattern of ABI3. In plants ectopically expressing ABI3, AtPER1::GUS expression was found in true leaves, and AtPER1 could be induced by exogenous ABA and oxidative stress (H2O2 and hydroquinone). ABI3-mediated oxidative stress induction was dependent on the presence of an intact ARE element.
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Affiliation(s)
- Camilla Haslekås
- Division of Cell and Molecular Biology, Department of Biology, University of Oslo, P.O. Box 1031, Blindern, 0315 Oslo, Norway
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