Double Fertilization in Gnetum Gnemon: the Reationship Between the Cell Cycle and Sexual Reproduction

Total Page:16

File Type:pdf, Size:1020Kb

Double Fertilization in Gnetum Gnemon: the Reationship Between the Cell Cycle and Sexual Reproduction The Plant Cell, Vol. 7, 1975-1988, December 1995 O 1995 American Society of Plant Physiologists RESEARCH ARTICLE Double Fertilization in Gnetum gnemon: The Reationship between the Cell Cycle and Sexual Reproduction Jeffrey S. Carmichael 'I' and William E. Friedmanb a Department of Biology, University of North Dakota, Grand Forks, North Dakota 58202 Downloaded from https://academic.oup.com/plcell/article/7/12/1975/5985043 by guest on 27 September 2021 b Department of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, Colorado 80309 Gnetum gnemon, a nonflowering seed plant and member of the Gnetales, expresses a rudimentary pattern of double fertilization that results in the formation of two zygotes per pollen tube. The process of double fertilization in G. gnemon was examined with light and fluorescence micmscopy, and the DNA content of various nuclei involved in sexual reproduction was quantified with 4',6-diamidino9-phenylindole microspectrofluommetry. Male and female gamete nuclei pass through the synthesis phase of the cell cycle and increase their DNA content from 1C to 2C before fertilization. Each of the two zygotes found in association with a pollen tube is diploid and contains the 4C quantity of DNA at inception. Based on these results as well as previous studies of nuclear DNA content in plant sperm, eggs, and zygotes, three fundamental and distinct patterns of gamete karyogamy among seed plants can be circumscribed: (1) G1 karyogamy, in which male and female gametes contain the 1C quantity of DNA throughout karyogamy and the zygote undergoes DNA replication; (2) S-phase karyogamy, in which gamete nuclei initiate fusion at 1C but pass through the S phase of the cell cycle before completely fusing; and (3) G2 karyogamy, in which male and female gamete nuclei pass through the S phase of the cell cycle before the onset of fertilization. Our results show definitively a pattern of G2 karyogamy in G. gnemon. INTRODUCTION With the advent of in vitro fertilization techniques (Kranz et thought to be a unique feature of flowering plants. However, al., 1991; Kranz and Lorz, 1993, 1994; Faure et al., 1994a, a rudimentary process of double fertilization has been docu- 1994b) and regenerationof genetically engineered zygotes and mented recently in the nonflowering seed plants Gnefum embryos (Sangwan et al., 1991; Holm et al., 1994), there is gnemon (Carmichael and Friedman, 1996) and Ephedra renewed interest in the relationship between the cell cycle nevadensis and E. trifurca (Friedman, 1990a, 1990b, 1991, and sexual reproduction in higher plants (Friedman, 1991; 1992). The genera Gnetum and Ephedra, along with Welwit- Mogensen and Holm, 1995; Mogensen et al., 1995; Sherwood, schia mirabilis, compose the order Gnetales and are the closest 1995). Unfortunately, reproductive cell cycles have not been living relatives of angiosperms (Crane, 1985; Doyle and adequately investigated in most groups of seed plants, and, Donoghue, 1986, 1992; Doyle et al., 1994). Unlike flowering with one exception (Friedman, 1991), relationships between plants, in which a zygote and endosperm are formed, double cell cycle patterns and sexual reproduction have been derived fertilization in G. gnemon and Ephedra spp results in the exclusively from a small number of studies on angiosperms production of two zygotes per pollen tube, and the female (Taylor and McMaster, 1954; Woodard, 1956; DAmato et al., gametophyte serves as an embryo-nourishing tissue. Based 1965; Woodcock and Bell, 1968; Mericle and Mericle, 1970, on these discoveries, it has been proposed that double fertil- 1973; Hesemann, 1973; Bennett and Smith, 1976; Ermakov ization evolved before the origin of angiosperms and that the et al., 1980; Bino et al., 1990; Mogensen and Holm, 1995; original manifestationof double fertilization in seed plants likely Mogensen et al., 1995; Sherwood, 1995). resulted in the formation of two embryo products (Friedman, Sexual reproduction in flowering plants occurs by a process 1992, 1994, 1995). of double fertilization in which one sperm fuses with an egg Until recently, little was known about the nature and behavior cell to form a zygote and a second sperm nucleus fuses with of gametes during fertilization in Gnetum spp. Unlike all other two or more polar nuclei to produce endosperm, a polyploid land plants (except perhaps Mlwifschia), in which specific cells embryo-nourishing tissue. Previously, double fertilization was of the female gametophyte differentiate into eggs prior to fer- tilization, egg cells are not formed in G. gnemon and fertilization To whom correspondence should be addressed. occurs within a coenocytic female gametophyte (Carmichael 1976 The Plant Cell Friedmand an , 1996). Double fertilization results wheo ntw sperm nuclei are discharged from a pollen tube, and each sperm nucleus fuses wit hnearba y undifferentiated female nucleu foro st m zygotea zygoteo tw . Eace sth f associateho d wit polleha n tub viabls ei initiated ean s embryogenesis. An understanding of the relationship between the cell cycle ff sexuad an l reproductio gnemon. G n i allow clearea r sfo - rin terpretation of the unique process of double fertilization in this unusual and phylogenetically critical nonflowering seed plant. beeGives cellsg ha lace eg n t ni f ,th kunclea o r whethel al r Downloaded from https://academic.oup.com/plcell/article/7/12/1975/5985043 by guest on 27 September 2021 free nuclei within the coenocytic female gametophyte repre- sent potential female gametes and exhibit identical and synchronous cell cycles appropriat fertilizatioe th o et n process, or whether certain female nucle distinguishee ar i d from sur- rounding nuclei to participate in fertilization events. It was also unknown whethe zygoteo tw e srth formed from double fertil- ization in G. gnemon are similar with respect to DMA content and position within the cell cycle. To examine the relationship between the cell cycle and sex- l reproductioua gnemon,. G n i microspectrofluorometrn i f yo situ 4',6-diamidino-2-phenylindole (DAPI)-stained nuclei was used to quantify relative DNA levels of male and female gameto- phyte nuclei from inception, through sexual maturation, to ultimate formation of zygotes. This study of G. gnemon not only offers critical information regardin procese th w f dougsho o - fertilizatioe bl coordinatens i nonflowerina dn i g seed plant that lacks well-defined egg cells but also provides a framework for defining broade mord ran e fundamental relationships between cell cycle patterns and fertilization events among seed plants. This study conclusively demonstrates that in G. gnemon, male and female gamete nuclei pass through the S phase of the cell cycl increasd ean e contentheiA priorDN C 2 t ro frot C m1 to fertilization. We define this reproductive cell cycle pattern Figur . Spere1 m Formatio . gnemon.G n i as G2 karyogamy. ) Fluorescenc(A e vielongitudinaa f wo l section throug pollinateha d ovule showing a generative cell nucleus (GCN) and a tube nucleus RESULTS (TN) within a pollen tube. ) Generativ(B e cell nucleu prophasen si . ) Generativ(C e cell nucleu metaphasen si . Calibratio f Relativno LevelA e DN ValuesC s( ) spero Tw m ) nucle(D i (SN) forme mitotiy db c divisio generativa f no e cell nucleus within a pollen tube. Sperm nuclei remain within a single mas f cytoplasso constitutd man binucleatea e sperm cell. Relative fluorescence of DAPI-stained generative cell nuclei Bars = 10 urn. and sperm nuclei (Figure 1) was used to standardize C values l otheoal f r nuclei average Th . e relative fluorescenc pollef eo n tube generative cell nuclei during prophas metaphasd ean e tained for 2C generative cell nuclei (Figure 2B). Thus, it was (Figure reflects) con1C A s d definitiony 1-DN Bb , an C 2 e th , inferred from these average relative fluorescence values that tent because these nucle haploie ar i givd dmalean o ristw eeo t s equivalens wa leve C U wa 1 f DNA ~1o le U RF th 0 RF , 2 o t gamete nuclei by mitosis (Figure 1D). Relative fluorescence equivalenlineay levelb C 2 d r e ,interpolationan th o t U RF 0 4 , units (RFU) of generative cell nuclei in prophase and meta- reflecte complemenC 4 e dth f DNAo t . phase were 18.94 ± 0.59 (average ± SD, n = 7) (Figure 2A). average Th e relative fluorescenc f newleo y formed sperm nuclei, during telophase of inception, reflects the 1C DNA con- Male Gametophyte Development tent because these gamete nuclei are haploid and contain the 1C amount of DNA at this stage of development. The relative Pollen of G. gnemon is shed at the three-celled stage and fluorescence of telophase sperm nuclei was 9.77 ± 0.70 RFU consists of a prothallial cell, generative cell, and tube cell. Ap- (n = 14), which is almost exactly one-half of the readings ob- proximatel dayy3 s after pollination, pollen tube initiatee sar d A B 8, 1 - X=18.94 SD = 0.59 1 I I I I I Downloaded from https://academic.oup.com/plcell/article/7/12/1975/5985043 by guest on 27 September 2021 O 10 20 30 40 50 O 10 20 30 40 50 t t t t t t 1c 2c 4c 1c 2c 4c RELATIVE FLUORESCENCE UNITS RELATIVE FLUORESCENCE UNITS C D I I 'I n cl E= 19.38 w w 4- SD = 1.15 515- U 3 s 3 3- = 10- 2 3 7 2- 5- 5 Y 1- ò z z0 O 10 20 30 40 50 O 10 20 30 40 50 t t t t t t 1c 2c 4c 1c 2c 4c RELATIVE FLUORESCENCE UNITS RELATIVE FLUORESCENCE UNITS E Q "I I O 10 20 30 40 50 t t t 1c 2c 4c RELATIVE FLUORESCENCE UNITS Figure 2. Relative DNA Content of Male Nuclei within Pollen Tubes of G.
Recommended publications
  • Pollen Tube Guidance by Pistils Ensures Successful Double Fertilization Ravishankar Palanivelu∗ and Tatsuya Tsukamoto
    Advanced Review Pathfinding in angiosperm reproduction: pollen tube guidance by pistils ensures successful double fertilization Ravishankar Palanivelu∗ and Tatsuya Tsukamoto Sexual reproduction in flowering plants is unique in multiple ways. Distinct multicellular gametophytes contain either a pair of immotile, haploid male gametes (sperm cells) or a pair of female gametes (haploid egg cell and homodiploid central cell). After pollination, the pollen tube, a cellular extension of the male gametophyte, transports both male gametes at its growing tip and delivers them to the female gametes to affect double fertilization. The pollen tube travels a long path and sustains its growth over a considerable amount of time in the female reproductive organ (pistil) before it reaches the ovule, which houses the female gametophyte. The pistil facilitates the pollen tube’s journey by providing multiple, stage-specific, nutritional, and guidance cues along its path. The pollen tube interacts with seven different pistil cell types prior to completing its journey. Consequently, the pollen tube has a dynamic gene expression program allowing it to continuously reset and be receptive to multiple pistil signals as it migrates through the pistil. Here, we review the studies, including several significant recent advances, that led to a better understanding of the multitude of cues generated by the pistil tissues to assist the pollen tube in delivering the sperm cells to the female gametophyte. We also highlight the outstanding questions, draw attention to opportunities created by recent advances and point to approaches that could be undertaken to unravel the molecular mechanisms underlying pollen tube–pistil interactions. 2011 Wiley Periodicals, Inc.
    [Show full text]
  • Ap09 Biology Form B Q2
    AP® BIOLOGY 2009 SCORING GUIDELINES (Form B) Question 2 Discuss the patterns of sexual reproduction in plants. Compare and contrast reproduction in nonvascular plants with that in flowering plants. Include the following topics in your discussion: (a) alternation of generations (b) mechanisms that bring female and male gametes together (c) mechanisms that disperse offspring to new locations Four points per part. Student must write about all three parts for full credit. Within each part it is possible to get points for comparing and contrasting. Also, specific points are available from details provided about nonvascular and flowering plants. Discuss the patterns of sexual reproduction in plants (4 points maximum): (a) Alternation of generations (4 points maximum): Topic Description (1 point each) Alternating generations Haploid stage and diploid stage. Gametophyte Haploid-producing gametes. Dominant in nonvascular plants. Double fertilization in flowering plants. Gametangia; archegonia and antheridia in nonvascular plants. Sporophyte Diploid-producing spores. Heterosporous in flowering plants. Flowering plants produce seeds; nonvascular plants do not. Flowering plants produce flower structures. Sporangia (megasporangia and microsporangia). Dominant in flowering plants. (b) Mechanisms that bring female and male gametes together (4 points maximum): Nonvascular Plants (1 point each) Flowering Plants (1 point each) Aquatic—requires water for motile sperm Terrestrial—pollination by wind, water, or animal Micropyle in ovule for pollen tube to enter Pollen tube to carry sperm nuclei Self- or cross-pollination Antheridia produce sperm Gametophytes; no antheridia or archegonia Archegonia produce egg Ovules produce female gametophytes/gametes Pollen: male gametophyte that produces gametes © 2009 The College Board. All rights reserved. Visit the College Board on the Web: www.collegeboard.com.
    [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]
  • Regulatory Mechanisms of Double Fertilization
    REVIEW ARTICLE published: 11 September 2014 doi: 10.3389/fpls.2014.00452 The beginning of a seed: regulatory mechanisms of double fertilization Andrea Bleckmann 1, Svenja Alter 2 and Thomas Dresselhaus 1* 1 Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Regensburg, Germany 2 Plant Breeding, Center of Life and Food Sciences Weihenstephan, Technische Universität München, Freising, Germany Edited by: The launch of seed development in flowering plants (angiosperms) is initiated by the Paolo Sabelli, University of Arizona, process of double fertilization: two male gametes (sperm cells) fuse with two female USA gametes (egg and central cell) to form the precursor cells of the two major seed Reviewed by: components, the embryo and endosperm, respectively. The immobile sperm cells are Yanhai Yin, Iowa State University, USA delivered by the pollen tube toward the ovule harboring the female gametophyte by Meng-Xiang Sun, Wuhan University, species-specific pollen tube guidance and attraction mechanisms. After pollen tube burst China inside the female gametophyte, the two sperm cells fuse with the egg and central cell *Correspondence: initiating seed development. The fertilized central cell forms the endosperm while the Thomas Dresselhaus, Cell Biology fertilized egg cell, the zygote, will form the actual embryo and suspensor. The latter and Plant Biochemistry, Biochemie-Zentrum Regensburg, structure connects the embryo with the sporophytic maternal tissues of the developing University of Regensburg, seed.
    [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]
  • BY 124 SI WORKSHEET 2 Terms Double Fertilization Two Sperm Cells E
    BY 124 SI WORKSHEET 2 Terms Double Fertilization Two sperm cells enter the female gametophyte, one fertilizes the egg (diploid zygote) and the other fuses with the two nuclei in the large central cell of the female gametophyte, producing a triploid cell. Taproot Root system consisting of a main vertical taproot which develops from the embryonic root. Gives rise to lateral roots or branch roots. Can penetrate deeper into the ground and adapt to deeper sources of water. Nodes The points on a stem where leaves are attached. Internodes are the spaces between nodes Ground tissue system (2 types) Tissue that is neither vascular nor dermal. Main role is nutrient storage and photosynthesis. (parenchyma cells). 2 types: pith – ground tissue that is internal to the vascular tissue. Cortex – ground tissue that is external to the vascular tissue. Apical dominance the inhibition of axillary buds by apical buds. Proximity of axillary buds to apical buds is responsible for their dormancy. If an animal eats the end of a shoot or the sun doesn’t reach the top but reaches the sides, axillary buds break their dormancy (example: pruning trees) Parenchyma cells Primary cell walls are thin and flexible, lack secondary cell wall. Large central vacuole. Least specialized of all plant cells. Perform most of the metabolic functions of the plant, synthesizing and storing organic products. Fleshy tissue of many fruits are parenchyma cells. Most retain the ability to divide and differentiate into other cell types. Alive at maturity. Sieve tube elements long narrow tubes that transport nutrients. ST elements lack a nucleus, ribosomes, a vacuole, and a cytoskeleton enabling nutrients to pass more easily through the cell.
    [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]
  • Fertilization-Independent Seed Development in Arabidopsis Thaliana (Ovule͞apomixis)
    Proc. Natl. Acad. Sci. USA Vol. 94, pp. 4223–4228, April 1997 Plant Biology Fertilization-independent seed development in Arabidopsis thaliana (ovuleyapomixis) ABDUL M. CHAUDHURY*, LUO MING,CELIA MILLER,STUART CRAIG,ELIZABETH S. DENNIS, AND W. JAMES PEACOCK* Commonwealth Scientific and Industrial Research Organization, Plant Industry, GPO Box 1600, Canberra ACT 2601, Australia Contributed by W. James Peacock, January 28, 1997 ABSTRACT We report mutants in Arabidopsis thaliana mutational approach in Arabidopsis might detect mutants (fertilization-independent seed: fis) in which certain processes displaying some components of apomixis. of seed development are uncoupled from the double fertiliza- For the isolation of these mutants, we used stamenless tion event that occurs after pollination. These mutants were pistillata (pi) (4). If pi plants are not pollinated, the siliques isolated as ethyl methanesulfonate-induced pseudo-revertants remain short; they only elongate when seed is formed. We of the pistillata phenotype. Although the pistillata (pi) mutant identified mutants in which the siliques elongated without has short siliques devoid of seed, the fis mutants in the pi pollination (5), and recently Ohad et al (6) described a mutant background have long siliques containing developing seeds, that forms endosperm without fertilization. even though the flowers remain free of pollen. The three fis In the present paper, we describe fis1 (fertilization- mutations map to loci on three different chromosomes. In fis1 independent seed), fis2, and fis3, whose developmental and and fis2 seeds, the autonomous endosperm nuclei are diploid genetic characterization indicates that these genes normally and the endosperm develops to the point of cellularization; the have a controlling role in seed development after pollination partially developed seeds then atrophy.
    [Show full text]
  • Plant Reproduction Asexual Reproduction
    Plant Reproduction Asexual Reproduction • Asexual reproduction is natural “cloning.” Parts of the plant, such as leaves or stems, produce roots and become an independent plant. Sexual Reproduction • Sexual reproduction requires fusion of male cells in the pollen grain with female cells in the ovule. Terms to know: • Haploid: having a single set of chromosomes in each cell. • Diploid: having two sets of chromosomes in each cell, one set from each parent. • Mitosis: cell division, which produces two genetically identical diploid cells. • Meiosis: reduction division, which produces four haploid reproductive cells. Terms to know: • Spore: haploid reproductive cell that leads to a gametophyte in plant alternation of generations. • Gamete: mature haploid male or female germ cell able to unite with another of the opposite sex in sexual reproduction to form a zygote. • Zygote: diploid, eukaryotic cell formed during fertilization event between two gametes, combining DNA of each gamete, containing the genetic information to form a new individual. Terms to know: • Sporophyte: diploid, multicellular stage which develops from zygote, produced when a haploid female cell is fertilized by a haploid male cell, produces haploid spores by meiosis. • Gametophyte: haploid, multicellular stage, develops from a spore by mitosis, produces haploid gametes by mitosis. Plant Life Cycle Animals vs. Plants Plant Reproduction Animal Reproduction Alternation of No alternation of Life cycle generations generations Gametes Haploid gametes Haploid gametes Spores Haploid spores N/A (no spores) Gametes made Haploid gametophyte, Diploid organism, by by by mitosis meiosis Diploid sporophyte, by Spores made by N/A (no spores) meiosis Alternation of Generations • Plants have a double life cycle with two forms: • Sporophyte • Gametophyte Non-flowering plants • Mosses, ferns, and related plants have motile, swimming sperm.
    [Show full text]
  • Double Fertilization Embryo and Endosperm Development in Flowering Plants
    V. Raghavan Double Fertilization Embryo and Endosperm Development in Flowering Plants ▶ Written by Professor Val Raghavan, an acknowledged expert in plant developmental biology ▶ With excellent illustrations, including 16 color plates ▶ Comprehensive overview of flowering plant development "Double Fertilization" provides a comprehensive overview of all aspects of this central event in the reproduction and development of flowering plants. Written by Val Raghavan, The Ohio State University, an acknowledged expert in plant developmental biology, the book vividly describes the molecular and cellular steps of the unique and complex fertilization process that culminates in the formation of embryo and endosperm, focusing on the latest results from the model plant Arabidopsis. The text is complemented by excellent illustrations, including 16 color plates. 2006, XX, 237 p. 75 illus., 27 illus. in color. Since embryo and endosperm constitute the edible parts of many seeds and grains widely used in human and animal nutrition, an understanding of the fertilization process has Printed book great relevance for genetic engineering aimed at improving the nutritional quality of crop Hardcover plants. This book is ideally suited to researchers and graduate students seeking a coherent view of current perspectives on embryogenesis and endosperm development in flowering ▶ 199,99 € | £179.99 | $249.99 plants. ▶ *213,99 € (D) | 219,99 € (A) | CHF 236.00 eBook Available from your bookstore or ▶ springer.com/shop MyCopy Printed eBook for just ▶ € | $ 24.99 ▶ springer.com/mycopy Order online at springer.com ▶ or for the Americas call (toll free) 1-800-SPRINGER ▶ or email us at: [email protected]. ▶ For outside the Americas call +49 (0) 6221-345-4301 ▶ or email us at: [email protected].
    [Show full text]
  • Plant Diversity Plant Diversity
    Plant Diversity (Freeman Ch 30 & 40) 25 February 2010 ECOL 182R UofA K. E. Bonine •From • Origins, Relationships,Plant Diversity Diversity 28-3, 28-5, 39-3 Videos 18 Feb KB – • Shared Derived Traits Lecture Schedule Sea to Land 23 Feb KB – ( 25 Feb KB – •NonvascularSynapomorphies 2 Mar KB – Fungi •Seedless 4 Mar KB – Prokaryotes, Ch31 & Protists Plant Diversity, Form, Function 1 9 Mar KB – 11 Mar KB – Plant Form and Function Plant Function 13-21 Mar Spring Break (middle third) Plant Ecology to Seedsto 23 Mar KB – ) Ecology Vascular 25 Mar KB - Part 2. Discussion and Review. , Ch38&39 , Ch28&29 30 Mar KB - , Ch50,52,53 Biology of the Galapagos, Ch50,52,53 , Ch36&37 Wikelski 2000 and http://livinggalapagos.org/ Plants , Ch30&40 EXAM 2 The Evolution of Land Plants Figure 29-8 Bacteria (from the edge of the swamp…) Archaea Eukaryotic Eukarya Excavata Alveolata Stramenopila Rhizaria Green stuff Discicristata Bacteria Archaea Chromalveolata 3 Diplomonads Parabasalids Euglenids Ciliates Dinoflagellates 2 Apicomplexa Oomycetes Diatoms Brown algae Plantae Opisthokonta Amoebozoa Foraminifera Chlorarachniophytes Glaucophyte algae Red algae Unikonta Green algae Land plants Fungi Choanoflagellates Green Original Land Plants Related to Algae plants Animals Land plants retain derived features they Lobose amoebae Eight major lineages Cellular slime molds of eukaryotes (protist branches are in color) Plasmodial • Chlorophyllshare with a slime molds •Starch • Cellulose 5 as a storage product a green algae ( in cell walls.and 4 b . See Figure 30.9 Charales . ): 6 1 Land Plants are Monophyletic Land Plants Comprise ~Ten Clades Nonvascular (3 clades) Land plants are monophyletic, all -paraphyletic group descendants from a single common ancestor.
    [Show full text]
  • Three Cell Fusions During Double Fertilization
    Le´ veillard, T., and Sahel, J.-A. (2010). Sci. Transl. Mohand-Said, S., Deudon-Combe, A., Hicks, D., Venkatesh, A., Ma, S., Le, Y.Z., Hall, M.N., Ru¨ egg, Med. 2, 26ps16. Simonutti, M., Forster, V., Fintz, A.C., Le´ veillard, M.A., and Punzo, C. (2015). J. Clin. Invest. 125, T., Dreyfus, H., and Sahel, J.A. (1998). Proc. Natl. 1446–1458. Le´ veillard, T., Mohand-Saı¨d, S., Lorentz, O., Hicks, Acad. Sci. USA 95, 8357–8362. D., Fintz, A.-C., Cle´ rin, E., Simonutti, M., Forster, Xiong, W., MacColl Garfinkel, A.E., Li, Y., Beno- V., Cavusoglu, N., Chalmel, F., et al. (2004). Nat. Punzo, C., Kornacker, K., and Cepko, C.L. (2009). witz, L.I., and Cepko, C.L. (2015). J. Clin. Invest. Genet. 36, 755–759. Nat. Neurosci. 12, 44–52. 125, 1433–1445. Three Cell Fusions during Double Fertilization Stefanie Sprunck1 and Thomas Dresselhaus1,* 1Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany *Correspondence: [email protected] http://dx.doi.org/10.1016/j.cell.2015.04.032 Fertilization of both egg and central cell is a major distinguishing feature of flowering plants. Now, Maruyama et al. report a third cell fusion event between the persistent synergid and the fertilized central cell shortly after double fertilization in Arabidopsis. This causes rapid dilution of pollen tube attractant(s), preventing polytubey. Almost 120 years ago, Sergei Gavrilovich Arabidopsis, usually only one pollen tube phenomenon was named as synergid- Navashin (1898) and Le´ on Guignard arrives at the embryo sac and communi- endosperm fusion (SE fusion; Figure 1).
    [Show full text]