DOCSLIB.ORG

DNA Demethylation Is Initiated in the Central Cells of Arabidopsis and Rice

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
DNA Demethylation Is Initiated in the Central Cells of Arabidopsis and Rice DNA demethylation is initiated in the central cells of Arabidopsis and rice Kyunghyuk Parka,1, M. Yvonne Kimb,1, Martin Vickersc, Jin-Sup Parka, Youbong Hyuna, Takashi Okamotod,2, Daniel Zilbermanb,2, Robert L. Fischerb,2, Xiaoqi Fengc,2, Yeonhee Choia,2, and Stefan Scholtene,2 aDepartment of Biological Sciences, Seoul National University, 151-742 Seoul, South Korea; bDepartment of Plant and Microbial Biology, University of California, Berkeley, CA 94720; cDepartment of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom; dTokyo Metropolitan University, 192-0397 Tokyo, Japan; and eUniversity of Hamburg, 22609 Hamburg, Germany Contributed by Robert L. Fischer, November 17, 2016 (sent for review August 26, 2016; reviewed by Anna Koltunow and Nathan M. Springer) Cytosine methylation is a DNA modification with important regula- whereas overlaps with sequences that repress expression can en- tory functions in eukaryotes. In flowering plants, sexual reproduction hance gene activity (5, 6). CG methylation is also common within is accompanied by extensive DNA demethylation, which is required the transcribed regions of genes, where its function is presently for proper gene expression in the endosperm, a nutritive extraem- unclear (6). bryonic seed tissue. Endosperm arises from a fusion of a sperm cell In addition to methyltransferases, plants encode enzymes that carried in the pollen and a female central cell. Endosperm DNA can remove methylation from DNA (7). One of these, DEMETER demethylation is observed specifically on the chromosomes inherited (DME), is expressed in Arabidopsis thaliana male and female ga- from the central cell in Arabidopsis thaliana, rice, and maize, and metophytes, primarily in the vegetative and central cells, respec- requires the DEMETER DNA demethylase in Arabidopsis. DEMETER tively (8, 9). In the vegetative cell, DME catalyzes demethylation of is expressed in the central cell before fertilization, suggesting that thousands of discrete loci, most of which are relatively euchromatic endosperm demethylation patterns are inherited from the central TEs (10, 11). The maternal endosperm chromosomes inherited cell. Down-regulation of the MET1 DNA methyltransferase has also from the central cell are also extensively demethylated at simi- been proposed to contribute to central cell demethylation. However, lar sequences in Arabidopsis (10) as well as in the distantly re- with the exception of three maize genes, central cell DNA methyl- lated monocots rice (12) and maize (13). As in the vegetative cell, ation has not been directly measured, leaving the origin and mech- demethylation of maternal endosperm chromosomes requires anism of endosperm demethylation uncertain. Here, we report DME in Arabidopsis (10), and loss of DME function disrupts en- genome-wide analysis of DNA methylation in the central cells of dosperm gene expression, gene imprinting, and causes seeds to Arabidopsis and rice—species that diverged 150 million years ago— abort (8, 14). Several lines of evidence strongly argue that the as well as in rice egg cells. We find that DNA demethylation in both demethylation observed in the endosperm is inherited from the species is initiated in central cells, which requires DEMETER in Arabi- central cell: Only the central cell-derived chromosomes are deme- dopsis. However, we do not observe a global reduction of CG meth- thylated (10, 12, 13), DME is rapidly down-regulated following ylation that would be indicative of lowered MET1 activity; on the sperm fusion (8), and genes activated by demethylation are expressed contrary, CG methylation efficiency is elevated in female gametes in the central cell (15, 16). Down-regulation of MET1 in the central compared with nonsexual tissues. Our results demonstrate that cell has also been proposed to contribute to demethylation (2, 17). locus-specific, active DNA demethylation in the central cell is the origin of maternal chromosome hypomethylation in the endosperm. Significance DNA methylation | central cell | egg cell | epigenetics | gene imprinting Flowering plant reproduction involves two fertilization events: a sperm–egg fusion that forms the embryo, and a sperm–central cell lowering plant sexual reproduction is carried out by multicel- fusion that forms the nutritive extraembryonic endosperm. Flular gametophytes that arise through mitosis from haploid Chromosomes in the embryo, endosperm, and other plant tissues meiotic spores (1–3). The male gametophyte, pollen, consists of are modified by methylation, a covalent addition to cytosine in two sperm cells and a companion vegetative cell. The vegetative DNA that regulates gene expression. Maternal endosperm chro- cell forms the pollen tube that delivers the sperm into the female mosomes inherited from the central cell display a pattern of ex- gametophyte, where one of the sperm cells fuses with an egg to tensive demethylation, which is essential for seed development in form the zygote and the other sperm fuses with the homodiploid Arabidopsis thaliana. Demethylation is presumed to occur in the central cell to form the triploid endosperm (1–3). The endosperm central cell, but direct evidence for this is very limited. Here, we is an extraembryonic, placenta-like tissue that nourishes the em- provide a genome-wide DNA methylation analysis of Arabidopsis bryo and—particularly in monocots like rice and maize—the and rice central cells, which demonstrates that the demethylation seedling after germination (4). Monocot endosperm also consti- observed in the endosperm is indeed initiated in the central cell. tutes the bulk of human nutrition (4). Proper gene expression in the endosperm requires extensive Author contributions: T.O., D.Z., R.L.F., and Y.C. designed research; K.P., M.Y.K., J.-S.P., Y.H., reprogramming of DNA methylation (5). Methylation is a covalent X.F., and S.S. performed research; M.V., D.Z., X.F., and Y.C. analyzed data; and D.Z. and X.F. wrote the paper. modification of cytosine that is accurately copied after DNA rep- Reviewers: A.K., CSIRO, Australia; and N.M.S., University of Minnesota. lication, thereby passing epigenetic information during cell division (6). Plant methylation is categorized into three contexts: CG, CHG The authors declare no conflict of interest. (H = A,T,orG),andCHH(6).CGmethylation,themost Freely available online through the PNAS open access option. abundant and widespread of the three, is maintained by the MET1 Data deposition: The data reported in this paper have been deposited in the Gene Ex- pression Omnibus (GEO) database, www.ncbi.nlm.nih.gov/geo (accession no. GSE89789). DNA methyltransferase (6). All three types of methylation are 1 found in transposable elements (TEs), which are transcriptionally K.P. and M.Y.K. contributed equally to this work. 2 repressed and heritably silenced by methylation (6). TE and To whom correspondence may be addressed. Email: [email protected], [email protected], [email protected], [email protected], [email protected], or TE-like methylated sequences that overlap gene regulatory regions [email protected]. — influence gene expression overlaps with transcriptional start sites This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. and other regions that promote expression cause gene silencing, 1073/pnas.1619047114/-/DCSupplemental. 15138–15143 | PNAS | December 27, 2016 | vol. 113 | no. 52 www.pnas.org/cgi/doi/10.1073/pnas.1619047114 Downloaded by guest on September 25, 2021 However, with the exception of three maize genes (16, 18), DNA AB0.54 Sperm 1 1 Sperm methylation has not been analyzed in the central cell, leaving the 0.54 Genes CC Rep2 1 TEs CC Rep2 Embryo Embryo dme/+ n origin of endosperm demethylation uncertain. noita CC oitalyhtemGC ddme/+m Here, we report genome-wide analysis of DNA methylation in CC Rep1 l CC Rep1 VC CCC yhtemGC Endosperm VC the central cells of Arabidopsis and rice as well as in rice egg cells. Endosperm We find that DNA demethylation in both species is initiated in central cells, which requires DME in Arabidopsis. However, we do 0 0 0 0 0 not find evidence for a global reduction of CG methylation that -2 10-1 2-3 4 3210-11 2-2 10-1 2-3 4 3210-12 CDkb kb would be indicative of reduced MET1 activity. Instead, we find 0.7 .22 0.22 0.7 TEs CC Rep1 CC Rep22 0.22 TEs Embryo that CG methylation is efficiently maintained in the central cells dme/+ n noitalyhtemG Sperm CC o Embryo VC it Endosperm of both species and in rice eggs. Our results support locus- a lyhtemHH VC specific, active demethylation in the central cell as the cause of dme/+ Endosperm endosperm hypomethylation. CC Rep2 CC H CC Rep1 C C Sperm Results 0 0 0 0 0 -2 10-1 2-3 4 3210-10 1 2 -2 10-1 2-3 4 3210-12 Isolation of Arabidopsis Central Cells. We used the INTACT (Iso- kb kb lation of Nuclei Tagged in specific Cell Types) approach (19, 20) to Fig. 2. DNA methylation in Arabidopsis central cells in comparison with isolate central cell nuclei from wild-type Arabidopsis plants. A re- other cell types. Genes (A) and TEs (B–D) were aligned at the 5′ and 3′ ends. porter protein (Nuclear Targeting Fusion, NTF) consisting of a Methylation within each 100-bp interval was averaged and plotted from nuclear envelope localization domain fused to GFP was expressed 2 kb away from the annotated gene or TE (negative numbers) to 4 kb into from the DD7 central cell-specific promoter (Fig. 1) (21). Nuclei the annotated region (positive numbers). The dashed lines represent the were released from ovule tissue protoplasts and captured using points of alignment. Previously published data are from ref. 10. anti-GFP antibodies; purity was calculated as the fraction of GFP+ nuclei in the obtained sample (Fig. S1). For DNA methylation confined to sequences that show demethylation of maternal chro- analysis, we used two biological replicates, one with 85% purity (87 mosomes in the endosperm (10), nearly the entire distribution is on + + GFP nuclei; replicate 1) and one with 90% purity (75 GFP the right side of the graph for both replicates (red traces in Fig.
Load more

Recommended publications
  • Starch Biosynthesis in the Developing Endosperms of Grasses and Cereals
    Review Starch Biosynthesis in the Developing Endosperms of Grasses and Cereals Ian J. Tetlow * and Michael J. Emes Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, ON N1G 2W1, Canada; [email protected] * Correspondence: [email protected]; Tel.: +1-519-824-4120 Received: 31 October 2017; Accepted: 27 November 2017; Published: 1 December 2017 Abstract: The starch-rich endosperms of the Poaceae, which includes wild grasses and their domesticated descendents the cereals, have provided humankind and their livestock with the bulk of their daily calories since the dawn of civilization up to the present day. There are currently unprecedented pressures on global food supplies, largely resulting from population growth, loss of agricultural land that is linked to increased urbanization, and climate change. Since cereal yields essentially underpin world food and feed supply, it is critical that we understand the biological factors contributing to crop yields. In particular, it is important to understand the biochemical pathway that is involved in starch biosynthesis, since this pathway is the major yield determinant in the seeds of six out of the top seven crops grown worldwide. This review outlines the critical stages of growth and development of the endosperm tissue in the Poaceae, including discussion of carbon provision to the growing sink tissue. The main body of the review presents a current view of our understanding of storage starch biosynthesis, which occurs inside the amyloplasts of developing endosperms. Keywords: amylopectin; amylose; cereals; debranching enzymes; endosperm; forage grasses; Poaceae; starch; starch synthase; starch branching enzyme 1. Introduction The grasses can rightly be regarded as a cornerstone of human civilization.
    [Show full text]
  • Molecular Control of Oil Metabolism in the Endosperm of Seeds
    International Journal of Molecular Sciences Review Molecular Control of Oil Metabolism in the Endosperm of Seeds Romane Miray †, Sami Kazaz † , Alexandra To and Sébastien Baud * Institut Jean-Pierre Bourgin, INRAE, CNRS, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France; [email protected] (R.M.); [email protected] (S.K.); [email protected] (A.T.) * Correspondence: [email protected] † These authors contributed equally to this work. Abstract: In angiosperm seeds, the endosperm develops to varying degrees and accumulates different types of storage compounds remobilized by the seedling during early post-germinative growth. Whereas the molecular mechanisms controlling the metabolism of starch and seed-storage proteins in the endosperm of cereal grains are relatively well characterized, the regulation of oil metabolism in the endosperm of developing and germinating oilseeds has received particular attention only more recently, thanks to the emergence and continuous improvement of analytical techniques allowing the evaluation, within a spatial context, of gene activity on one side, and lipid metabolism on the other side. These studies represent a fundamental step toward the elucidation of the molecular mechanisms governing oil metabolism in this particular tissue. In particular, they highlight the importance of endosperm-specific transcriptional controls for determining original oil compositions usually observed in this tissue. In the light of this research, the biological functions of oils stored in the endosperm of seeds then appear to be more diverse than simply constituting a source of carbon made available for the germinating seedling. Keywords: seed; endosperm; oil; fatty acid; metabolism Citation: Miray, R.; Kazaz, S.; To, A.; Baud, S.
    [Show full text]
  • The Genetics and Morphology of Some Endosperm Characters in Maize
    The Genetics and Morphology of Some Endosperm Characters in Maize . - P. C. MANGELSDORF The Genetics and Morphology of Some Endosperm Characters in Maize P. C. MANGELSDORF The Bulletins of this Station are mailed free to citizens of Connecticut who apply for them, and to other applicants as far as the editions permit. CONNECTICUT AGRICULTURAL EXPERIMENT STATION OFFICERS AND STAFF as of June, 1926 BOARD OF CONTROL His Excellency, John H. Trumbull, ex-oficio, President. Charles R. Treat, Vice President ................................Orange George A. Hopson, Secretary ............................Mount Carmel Wm. L. Slate, Jr., Treasurer ...............................New Haven Joseph W. Alsop .................................................Avon Elijah Rogers ............................................. Southington Edward C. Schneider ......................................Middletown Francis F. Lincoln ............................................Cheshire STAFF. E. H. JENKINS,PII.D., Director Emeritus. Administration. WM. L. SLATE,JR., B.Sc., Director and Treasurer. MISS L. M. BRAUTLECHT,Bookkeeper and Librarian. V. BERCER,Stenographer and Bookkeeper. E;:: Li ARY E. BRADLEY,Secretary. C. E. GRAHAM,In charge of Buildings and Grounds. Chemistry: E. M. BAILEY,PH.D.. Chemist in Charge. Analvtical C. E. SHEPARD > ~aboratory. OWEN L.J. NOLANFISHER, A,B. W. T. MATHIS FRANKC. SHELDON,Laboratory Assirtant. V. L. CHURCHILL,Sampling Agent. MISS MABELBACON, Stenographer. Biochemical T. B. OSRORNE,PH.D., Chemist in Charge. Laboratory. H. 13. VICKERY,PH.D., Biochemist. MISS HELENC. CANNON.B.S., Dietitian. Botany. G. P. CLINTON,Sc.D., Botanist in Charge. E. M. STODDARD,B.S., Pomologist. MISSFLORENCEA. MCCORMICK, PH.D., Pathologist. WILLISR. HUNTPH.D., Assistant in Botany. A. D. MCDONNELL, General Assistant. MRS. W. W. KELSEY,Secretary. Entomology. W. E. BRITTON,PH.D., Entomologist in Charge; State Entomologist. B. H. WALDEN,B.AGR.
    [Show full text]
  • Seed Fertilization, Development, and Germination in Hydatellaceae (Nymphaeales): Implications for Endosperm Evolution in Early A
    American Journal of Botany 96(9): 1581–1593. 2009. S EED FERTILIZATION, DEVELOPMENT, AND GERMINATION IN HYDATELLACEAE (NYMPHAEALES): IMPLICATIONS FOR ENDOSPERM EVOLUTION IN EARLY ANGIOSPERMS 1 Paula J. Rudall, 2,6 Tilly Eldridge, 2 Julia Tratt, 2 Margaret M. Ramsay, 2 Renee E. Tuckett, 3 Selena Y. Smith, 4,7 Margaret E. Collinson, 4 Margarita V. Remizowa, 5 and Dmitry D. Sokoloff 5 2 Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK; 3 The University of Western Australia, Crawley, WA 6009, Australia; 4 Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK; and 5 Department of Higher Plants, Biological Faculty, Moscow State University 119991, Moscow, Russia New data on endosperm development in the early-divergent angiosperm Trithuria (Hydatellaceae) indicate that double fertiliza- tion results in formation of cellularized micropylar and unicellular chalazal domains with contrasting ontogenetic trajectories, as in waterlilies. The micropylar domain ultimately forms the cellular endosperm in the dispersed seed. The chalazal domain forms a single-celled haustorium with a large nucleus; this haustorium ultimately degenerates to form a space in the dispersed seed, simi- lar to the chalazal endosperm haustorium of waterlilies. The endosperm condition in Trithuria and waterlilies resembles the helo- bial condition that characterizes some monocots, but contrasts with Amborella and Illicium , in which most of the mature endosperm is formed from the chalazal domain. The precise location of the primary endosperm nucleus governs the relative sizes of the cha- lazal and micropylar domains, but not their subsequent developmental trajectories. The unusual tissue layer surrounding the bi- lobed cotyledonary sheath in seedlings of some species of Trithuria is a belt of persistent endosperm, comparable with that of some other early-divergent angiosperms with a well-developed perisperm, such as Saururaceae and Piperaceae.
    [Show full text]
  • AS Flower Reproduction
    2/11/19 AMOEBA SISTERS: VIDEO RECAP ANGIOSPERM REPRODUCTION Amoeba Sisters Video Recap of Plant Reproduction in Angiosperms 1. What characteristics are common in angiosperms? 2. A topic emphasized in this clip is that not all fruits are sweet. Or even edible! Every plant that forms a flower must have a fruit. How would you define a “fruit?” How can fruits be • Flowering plants helpful in seed dispersal? • Bear fruit Fruit is something that has flesh AMOEBA SISTERS: VIDEO RECAP around ANGIOSPERMseeds. REPRODUCTION Amoeba Sisters Video Recap of Plant ReproductionWhen animals in Angiosperms eat them, seeds move away from parent plant. 1. What characteristics are common in angiosperms? 2. A topic emphasized in this clip is that not all fruits are sweet. Or even edible! Every plant that forms a flower must have a fruit. How would you define a “fruit?” How can fruits be helpful in seed dispersal? 3. Flowers can contain one or both genders of flower parts. 4. Flowers can contain one or both genders of flower parts. Label A, B, and C. Label D, E, F, and G. A is the ____________________________________________. D is the ____________________________________________. B is the ____________________________________________. E is the ____________________________________________. C is the ____________________________________________. F is the ____________________________________________. All of these3. Flowers are can contain one or ?both _________________________ genders of flower parts. 4. FlowersG is cathen co ____________________________________________.ntain
    [Show full text]
  • Mechanical Properties of Starch, Protein and Endosperm and Their Relationship to Hardness in Wheat
    Food Structure Volume 11 Number 3 Article 1 1992 Mechanical Properties of Starch, Protein and Endosperm and Their Relationship to Hardness in Wheat Gregory M. Glenn Agricultural Research Service Ruth K. Johnston Agricultural Research Service Follow this and additional works at: https://digitalcommons.usu.edu/foodmicrostructure Recommended Citation Glenn, Gregory M. and Johnston, Ruth K. (1992) "Mechanical Properties of Starch, Protein and Endosperm and Their Relationship to Hardness in Wheat," Food Structure: Vol. 11 : No. 3 , Article 1. Available at: https://digitalcommons.usu.edu/foodmicrostructure/vol11/iss3/1 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Food Structure by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. FOOD STRUCTURE, Vol. 11 (1992), pp. 187-199 1046-705X/92$3. 00 +.00 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA MECHANICAL PROPERTIES OF STARCH, PROTEIN AND ENDOSPERM AND THEIR RELATIONSHIP TO HARDNESS IN WHEAT Gregory M. Glenn and Ruth K. Johnston United States Department of Agriculture, Agricultural Research Service Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710 Abstract Introduction Various mechanical properties of whole endo­ The characterization of the mechanical properties sperm, starch granules, and storage protein deposits of materials is important in gaining a better under­ were compared to determine whether the findings were standing of their functional properties (Benham and consistent with the current theories on wheat hardness. Crawford, 1987). One commonly measured mechanical All mechanical measurements were performed in situ property is hardness.
    [Show full text]
  • Evolution of Endosperm Developmental Patterns Among Basal Flowering Plants
    Int. J. Plant Sci. 161(6 Suppl.):S57–S81. 2000. ᭧ 2000 by The University of Chicago. All rights reserved. 1058-5893/2000/16106S-0005$03.00 EVOLUTION OF ENDOSPERM DEVELOPMENTAL PATTERNS AMONG BASAL FLOWERING PLANTS Sandra K. Floyd1 and William E. Friedman Department of Environmental, Population, and Organismic Biology, CB 334, University of Colorado, Boulder, Colorado 80309, U.S.A. A phylogenetically based comparative investigation of endosperm development was undertaken in a sample of 13 basal angiosperm taxa. The specific goals were to (1) provide a full developmental analysis of all aspects of endosperm in each species, (2) compare patterns among taxa to determine phylogenetic character distri- bution, (3) reconstruct the ancestral developmental pattern for angiosperms, and (4) explore scenarios of ontogenetic evolution that occurred during the early radiation of flowering plants. Five taxa, Acorus calamus, Cabomba caroliniana, Ceratophyllum demersum, Drimys winteri, and Platanus racemosa, are described in detail. Data from an additional eight taxa were analyzed and compared with these five. Endosperm ontogeny can be conceived of as a series of stages (characters) during which differential patterns of development occur among taxa (character states). We discovered that differential developmental fate of chalazal and micropylar domains is a common pattern among the endosperms of all basal angiosperm taxa and suggest that this may be a feature of endosperm development in all angiosperms. Differential development of chalazal and micropylar domains in endosperm in basal angiosperms also bears a marked similarity to what occurs in angiosperm embryos. This may have implications for understanding the evolutionary origin of endosperm. Basal angio- sperms also exhibit variable endosperm developmental characters, indicating that significant ontogenetic trans- formation occurred during the early radiation of the clade, although magnoliid taxa exhibit a high degree of conservation in endosperm characters.
    [Show full text]
  • Endosperm: Types and Function
    ENDOSPERM: TYPES AND FUNCTION Durgeshwer Singh Department of Botany Mahatma Gandhi Central University ENDOSPERM Two Male Gametes Most important plant product on the Polar or Secondary earth for human being. Egg Cell Nuclei Two third of all human calories come from endosperm Endosperm Zygote (Syngamy) (Triple Fusion) Cereals – Wheat, rice, maize, barley, millets Oils – Coconut, Corn oil, Palm, Caster, Double Fertilization TYPES OF ENDOSPERMS On the basis of their development, the following three types of endosperm have been recognised: • Nuclear Endosperm • Cellular Endosperm • Helobial Endosperm Nuclear Endosperm • Most common, found in about 56% families. • No cell wall formation during initial few divisions of the primary endosperm nucleus and nuclei are remain free in the cytoplasm of the embryo sac • The number of divisions depends on the size of embryo sac, larger size more division. • The size of endospermic nuclei are not same. Usually the nuclei at the chalazal end are larger and at micropylar end are smaller. • The wall formation occurs subsequently as in Glycine max and Arachis hypogea OR nuclei remains free indefinitely as in Limanthes douglasii, Acer pseudoplantanus and Myricaria germanica etc. • Hundreds of free nuclei are found along the periphery in the embryo sac of Primula, Malva, Mangifera, Citrus, Arachis; indicating that wall formation takes place at later stage. • Wall formation takes place only at 8 or 16 nucleate stage as in Calotropis, Rafflesia and Xeranthenum. • The wall formation is usually centripetal. i.e. it begins at the periphery of the embryo sac and cell plates gradually extended inwards. • In Cocus nucifera the milky or watery liquid endosperm, which fills the large embryo sac, contains numerous free nuclei.
    [Show full text]
  • Biol 211 (2) Chapter 31 October 9Th Lecture
    S.I. Biol 211 Biology 211 (2) Week 7! Chapter 31! ! VOCABULARY! Practice: http://www.superteachertools.us/speedmatch/speedmatch.php? gamefile=4106#.VhqUYGRVhBc ! Alternation of Angiosperm: A Antheridia: The Archegonia: The generations: A life cycle flowering vascular sperm producing egg-producing involving alternation of a plant that produces structure in most structure in most multicellular haploid seed within mature land plants except land plants except ovaries (fruits). The angiosperms angiosperms stage (gametophyte) with angiosperms form a a multicellular diploid single lineage stage (sporophyte). Occurs in most plants and some protists. Artificial selection: Bisexual Carpel: The female Diploid: Having two Deliberate manipulation gametophyte: One reproductive organ sets of by humans, as in animal gametophyte that in a flower, chromosomes (2n) and plant breeding, of produces both eggs contains the ovary, the genetic composition and sperm which contains of a population by ovules, which allowing only individuals contain the with desirable traits to megasporangia reproduce Double fertilization: An Endosperm: A Fruit: In Gametangia: The unusual form of triploid (3n) tissue angiosperms, a gamete-forming reproduction seen in in the seed of a mature, ripened structure found in flowering plants, in which flowering plant plant ovary, along all land plants one sperm cell fuses with an (angiosperm) that with the seeds it except angiosperms. egg to form a zygote and the serves as food for contains and Contains an other sperm cell fuses with two polar nuclei to form the the plant embryo. adjacent fused antheridium and triploid endosperm Functionally parts, often archegonium. analogous to the functions in seed yolk of an egg dispersal Gametophyte: In Gymnosperm: A Haploid: Having Heterospory: In organisms undergoing vascular plant that one set of seed plants, the alternation of makes seeds but chromosomes production of two generations, the does not produce distinct types of multicellular haploid form flowers.
    [Show full text]
  • Endosperm of Angiosperms and Genomic Imprinting
    life Review Endosperm of Angiosperms and Genomic Imprinting Elizabeth L. Kordyum * and Sergei L. Mosyakin Institute of Botany, National Academy of Sciences of Ukraine, 01004 Kyiv, Ukraine; [email protected] or [email protected] * Correspondence: [email protected] Received: 29 April 2020; Accepted: 29 June 2020; Published: 3 July 2020 Abstract: Modern ideas about the role of epigenetic systems in the regulation of gene expression allow us to understand the mechanisms of vital activities in plants, such as genomic imprinting. It is important that genomic imprinting is known first and foremost for the endosperm, which not only provides an embryo with necessary nutrients, but also plays a special biological role in the formation of seeds and fruits. Available data on genomic imprinting in the endosperm have been obtained only for the triploid endosperm in model plants, which develops after double fertilization in a Polygonum-type embryo sac, the most common type among angiosperms. Here we provide a brief overview of a wide diversity of embryo sacs and endosperm types and ploidy levels, as well as their distribution in the angiosperm families, positioned according to the Angiosperm Phylogeny Group IV (APG IV) phylogenetic classification. Addition of the new, non-model taxa to study gene imprinting in seed development will extend our knowledge about the epigenetic mechanisms underlying angiosperm fertility. Keywords: embryo sack; endosperm; genomic imprinting; phylogeny; ploidy 1. Introduction The history of science convinces us that scientific thought and discoveries usually develop in a spiral pattern: at new turns, old problems acquire new levels of understanding in the light of new ideas and methodological approaches, as well as new achievements in technology, chemistry, and bioinformatics.
    [Show full text]
  • Endosperm Development Is an Autonomously Programmed Process 5 Independent of Embryogenesis 6
    bioRxiv preprint doi: https://doi.org/10.1101/2020.08.31.275354; this version posted August 31, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 2 BREAKTHROUGH REPORT 3 4 Endosperm development is an autonomously programmed process 5 independent of embryogenesis 6 7 Authors: 8 Hanxian Xiong,a* Wei Wanga* and Meng-Xiang Suna,1 9 10 Affiliations: 11 aState Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, 12 Wuhan 430072, China. 13 14 *equal contribution in this work 15 1Address correspondence to [email protected]. 16 17 The author responsible for distribution of materials integral to the findings presented in 18 this article in accordance with the policy described in the Instructions for Authors 19 (www.plantcell.org) is: Meng-Xiang Sun ([email protected]). 20 21 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.08.31.275354; this version posted August 31, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 22 Abstract 23 The seeds of land plants contain three genetically distinct structures: the embryo, 24 endosperm, and seed coat. The embryo and endosperm need to interact and exchange 25 signals to ensure coordinated growth.
    [Show full text]
  • Parts of the Seed
    Parts of the Seed F ALL the facets of nature, the plant seed must be one of the mostO wondrous. When a plant creates new life through sexual reproduction, it encases the new life in a tiny protective package, along with a supply of food. This is the seed. Objective: þ Identify the parts of a seed. Key Terms: Ñ cotyledon dicotyledon embryo endosperm epicotyl hilum hypocotyl micropyle monocotyledon plumule radicle seed coat suspensor E-unit: Parts of the Seed u Page 1 u AgEdLibrary.com Copyright © 2006 by CAERT, Inc. — Reproduction by subscription only. 070026 Seed Parts The seeds for new life are found inside fruit. They contain everything necessary for the growth and development of a new plant. The three primary parts of a seed are the embryo, endosperm, and seed coat. The embryo is the young multicellular organism before it emerges from the seed. The endosperm is a source of stored food, consisting primarily of starches. The seed coat consists of one or more protective layers that encase the seed. Seed coat Epicotyl Endosperm Hypocotyl Cotyledons Epicotyl Cotyledon Seed coat Radicle Dicotyledon Monocotyledon FIGURE 1. The seeds of monocotyledons differ from the seeds of dicotyledons. A seed begins to form an embryo following fertilization and the start of a zygote. The initial division of the zygote results in two cells. The bottom cell develops into a multicellular struc- ture, called the suspensor. It is involved in nutrient uptake from the endosperm and anchors the embryo. The top cell develops into the embryo. The first cell divisions from this top cell create a chain of cells called the proembryo.
    [Show full text]