DOCSLIB.ORG

Pilobolus: the Shotgun Fungus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Pilobolus: the Shotgun Fungus Pilobolus. the Shotgun Fungus CHARLES R. COBLE CHARLES E. BLAND Downloaded from http://online.ucpress.edu/abt/article-pdf/36/4/221/369026/4444751.pdf by guest on 24 September 2021 T HE STUDY OF FUNGI in high-school biology is a rather unexciting phase of the course for most ~~~~~WI students (and teachers). Classroom and laboratory work with fungi, when it is undertaken, usually is limited to a study of the comparative morphology of the Ascomycetes and the Basidiomycetes-the higher fungi. This is understandable (and even com- mendable), because the larger varieties, such as Morchella, bracket fungi, puffballs, and mushrooms, and the more "glamorous" Penicillium, yeasts, and rusts belong to these classes. Laboratory or field experiments using fungi are X_.~ even less frequent in high-school biology. Granted, a few standard laboratory activities make use of fungi; for example, mating the plus and minus strains of the common bread mold, Rhizopus, to ob- serve zygote formation. However, from the stand- Fig. 1. Living young fruit-body of Pilobolus. Note the nu- point of exciting student interest, teachers often find merous droplets present on the subsporangial swelling and that the standard "canned" laboratory activities in- stipe. S, sporangium; SS, subsporangial swelling; ST, stipe; WD, "water droplets." Photo, by C. E. Bland. reproduced by volving fungi often fall short of their mark. permission of Mycologia. There are, however, some relatively little-known fungi that display rather interesting features and that lend themselves quite well to some open-ended experimentation by high-school students. One such fungus is Pilobolus, which is equipped with a "shot- gun." ' Charles R. Coble (left) is assistant professor of science Pilobolus is a member of the same class as Rhizo- education, and Charles E. pus: the Zygomycetes. Like many other members of Bland (right) is assistant its class, Pilobolus is a saprobe and a common in- professor of biology, at East habitant of horse and cow dung. Of particular in- Carolina University, Green- ville, N.C. 27834. Coble has terest is the mechanism of spore dispersal developed _4 his A.B., M.A.T., and Ed.D. by Pilobolus, in which the entire sporangium (spore degrees from the University case) is violently shot off the sporangiophore and of North Carolina, where he taught before joining the ECU adheres to the first solid object it strikes. The spor- faculty, in 1972; earlier he taught in Charlotte, N.C., schools, angiophores are specializing in planetarium and television instruction. Bland positively phototropic; that is, they has his A.B. and Ph.D. degrees from the University of North eject their sporangia in the direction of light. Carolina, where he taught botany and plant anatomy, 1967- 69, before accepting his position at ECU. He has published Structure and Asexual nearly 20 papers in mycology and has recently prepared Reproduction (with J. N. Couch) a section on the family Actinoplanaceae for the next edition of Bergey's Manual of Determinative The fruit body (asexual reproductive structure) Bacteriology. of Pilobolus (fig. 1) consists of two main parts: the 221 Downloaded from http://online.ucpress.edu/abt/article-pdf/36/4/221/369026/4444751.pdf by guest on 24 September 2021 IH Fig. 2. Schematic drawing of Pilobolus, illustrating development of asexual reproductive structures. For explanation see text. sporangium and the sporangiophore. The terminally stick to any object it strikes. In nature this frequent- located, black sporangium contains numerous ly is a nearby blade of grass. Being so deposited, the spores, which under suitable conditions may germi- sporangia are in a good position to be eaten, along nate (sprout) to give rise to new plants. The highly with the grass, by a horse, cow, or other grazing specialized sporangiophore, which supports the spor- animal. The sporangia and spores pass unharmed angium, consists of the enlarged subsporangial swell- through the digestive system of the animal and are ing and the stalk, or stipe (fig. 1 and A in fig. 2). excreted. In the fresh, moist dung the spores within Usually, droplets of "water" are visible over both the subsporangial swelling and the stipe. During de- velopment, the subsporangial swelling, acting as a primitive lens, and the stipe function together in the orientation of the sporangium toward light. This is brought about by a growth response, which is trig- gered whenever light entering the subsporangial swelling is brought to focus at any point other than the orange-pigmented area at the top of the stipe. Therefore, through light-triggered directional growth of the stipe, the sporangium is very accu- 1k' rately aimed at the light source. On reaching maturi- ty, the sporangium is violently discharged ("shot") from the sporangiophore (B in fig. 2). This is ac- complished by means of a "water-squirt" mechan- ism, which is capable of projecting the sporangium to a distance of 1.8 m. On discharge, the sporangiophore is thrust against the substrate where, being no longer functional, it disintegrates (C in fig. 2). However, the sporangi- Fig. 3. Collecting dish containing freshly collected horse um, by means of a ring of mucilage at its base, will dung. 222 THE AMERICANBIOLOGY TEACHER, APRIL 1974 A z Downloaded from http://online.ucpress.edu/abt/article-pdf/36/4/221/369026/4444751.pdf by guest on 24 September 2021 t~~~~~~~~~~~~~~~~~~~~~,- ft B Fig. 4. Collecting dishes arranged to maintain moist condi- tions necessary for growth of Pilobolus. -r . the sporangia germinate (D in fig. 2) to give rise to rapidly growing, vegetative filaments, called hyphae. The hyphae grow throughout the dung (E in fig. 2). After two or three days' growth, asexual repro- duction is initiated when enlarged, orange-colored -'6- -% structures, called trophocysts, are formed along the hyphae (F in fig. 2). It is from the trophocysts that the sporangiophore and sporangium develop. This C~~~~~~~~~~~~~~~~~~~~~~~~~ Fig. Reslts o ligh expeiment wit ilobous. Fr ex plnto e et developmental process, which is illustrated by G-K in fig. 2, requires about 12 hours for completion and results in synchronized maturation of the sporangia at approximately noon of the day of discharge. Fol- Fig. 5. Light experiments with Pilobolus. For explanation see lowing the first "crop" of sporangia, new but smaller text. numbers develop daily for two or three days. PILOBOLUS 223 Downloaded from http://online.ucpress.edu/abt/article-pdf/36/4/221/369026/4444751.pdf by guest on 24 September 2021 F'ig. 7. Growth response of fruit bodies of Pilobolus. Experimenting with Pilobolus gle, centrally located opening, 4 mm in diameter, is made in the cover. Clear tape is placed over the Pilobolus can be easily obtained for observation opening, in order to catch any sporangia that make a and experimentation in the classroom or laboratory. "bull's-eye." After a sufficient number of days (2-3) For this, simply collect fresh horse or cow dung (fig. have elapsed to allow for sporangial discharge, the 3) and keep it under moist conditions (fig. 4). After covering is removed, to reveal the pattern shown in three or four days the clear mycelia, sporangio- fig. 6, A. Under these conditions the sporangia are phores, and black sporangia should have developed discharged very directly at the light source, and the and be plainly visible. A good hand magnifying glass high accuracy of the phototropic-response mechan- or dissecting microscope will reveal most of the ism can be plainly seen. If concentric lines are external anatomy of Pilobolus. drawn at regular intervals around the hole, students After examining the gross features of Pilobolus, can make some mathematical estimates of the ac- the students can undertake a number of interesting curacy of sporangial discharge. experiments with this remarkable organism. The fol- Effect of light intensity. For this experiment a lowing are suggested subjects for investigation; they collecting dish is wrapped in aluminum foil and then should serve only as guides for the development of covered with semiopaque paper in which two holes other types of experiments. of different sizes have been made (B in fig. 5). Clear Effect of a diffuse light source. In a room with tape is placed over the holes-again, to catch any diffuse lighting, the sporangia will be discharged in sporangia that make a bull's-eye. The pattern a random fashion and will adhere to the first object formed by the discharged sporangia is seen in fig. they touch. This can be observed by simply covering 6, B. Unquestionably, the brighter (larger) light a transparent collecting dish with another, similar source is shown to be more effective in bringing dish. about a phototropic response. The growth response Effect of a light source. To test the effect of a of the fruit bodies is seen in fig. 7. single-point light source on the phototropic response Effect of colors of light. To test the effect of colors of Pilobolus, a collecting dish is covered with paper and wrapped in aluminum foil (A in fig. 5). A sin- (Concluded on p. 242) 224 THE AMERICANBIOLOGY TEACHER, APRIL 1974 Today he went to see his family physician, for he troversial issues have been disregarded in education. has not been feeling too well lately. Suddenly, it Recently, educators such as Merrill Harmin, seems that everything has fallen out from under Howard Kirschenbaum, and Sid Simon (1973: him. He was told that he has incurable cancer and Clarifying Values through Subject Matter, Winston has only two years to live. Press, Inc., Minneapolis) have advocated the presen- If you were told by your doctor that you had an tation not only of facts and concepts but also of incurable disease, with only a few years to live, clarifying values.
Load more

Recommended publications
  • 1 5 Chapter 1 Introduction I. LIFE CYCLES and DIVERSITY of VASCULAR PLANTS the Subjects of This Thesis Are the Pteri
    Chapter 1-15 Chapter 1 Introduction I. LIFE CYCLES AND DIVERSITY OF VASCULAR PLANTS The subjects of this thesis are the pteridophytes and seed plants that are conventionally classified as the vascular plants or tracheophytes. Vascular plants were traditionally defined by the possession of specialized conducting tissues, called phloem and xylem. Mosses are now believed to have inherited their conducting tissues from a common ancestor with the tracheophytes (Mishler & Churchill 1984) but are not considered in this thesis. Vascular plants can be divided into four groups with respect to life cycle. These groups are homosporous pteridophytes, heterosporous pteridophytes, gymnosperms and angiosperms. This is not intended to be a phylogenetic classification. There are about a quarter of a million species of vascular plant alive today. The vast majority are angiosperms and most of the remainder are homosporous pteridophytes. Heterosporous pteridophytes and gymnosperms contribute only a small number of species (Table 1.1). TABLE 1.1 Estimated number of extant species in each of the major groups of vascular plants (data from Parker 1982). Homosporous pteridophytes 12,000 species Heterosporous pteridophytes <1,000 species Gymnosperms <1,000 species Angiosperms >200,000 species A. Homosporous pteridophytes Homosporous pteridophytes produce a single type of spore. Spores are dispersed and develop into photosynthetic or mycoparasitic gametophytes. A gametophyte's gender is indeterminate at the time of spore dispersal, and a single gametophyte may produce eggs and/or sperm. Sperm are motile, and require free water to fertilize eggs. The young sporophyte is nourished by the maternal gametophyte during early development but later becomes Chapter 1-16 nutritionally independent.
    [Show full text]
  • Reproduction in Plants Which But, She Has Never Seen the Seeds We Shall Learn in This Chapter
    Reproduction in 12 Plants o produce its kind is a reproduction, new plants are obtained characteristic of all living from seeds. Torganisms. You have already learnt this in Class VI. The production of new individuals from their parents is known as reproduction. But, how do Paheli thought that new plants reproduce? There are different plants always grow from seeds. modes of reproduction in plants which But, she has never seen the seeds we shall learn in this chapter. of sugarcane, potato and rose. She wants to know how these plants 12.1 MODES OF REPRODUCTION reproduce. In Class VI you learnt about different parts of a flowering plant. Try to list the various parts of a plant and write the Asexual reproduction functions of each. Most plants have In asexual reproduction new plants are roots, stems and leaves. These are called obtained without production of seeds. the vegetative parts of a plant. After a certain period of growth, most plants Vegetative propagation bear flowers. You may have seen the It is a type of asexual reproduction in mango trees flowering in spring. It is which new plants are produced from these flowers that give rise to juicy roots, stems, leaves and buds. Since mango fruit we enjoy in summer. We eat reproduction is through the vegetative the fruits and usually discard the seeds. parts of the plant, it is known as Seeds germinate and form new plants. vegetative propagation. So, what is the function of flowers in plants? Flowers perform the function of Activity 12.1 reproduction in plants. Flowers are the Cut a branch of rose or champa with a reproductive parts.
    [Show full text]
  • Heterospory: the Most Iterative Key Innovation in the Evolutionary History of the Plant Kingdom
    Biol. Rej\ (1994). 69, l>p. 345-417 345 Printeii in GrenI Britain HETEROSPORY: THE MOST ITERATIVE KEY INNOVATION IN THE EVOLUTIONARY HISTORY OF THE PLANT KINGDOM BY RICHARD M. BATEMAN' AND WILLIAM A. DiMlCHELE' ' Departments of Earth and Plant Sciences, Oxford University, Parks Road, Oxford OXi 3P/?, U.K. {Present addresses: Royal Botanic Garden Edinburiih, Inverleith Rojv, Edinburgh, EIIT, SLR ; Department of Geology, Royal Museum of Scotland, Chambers Street, Edinburgh EHi ijfF) '" Department of Paleohiology, National Museum of Natural History, Smithsonian Institution, Washington, DC^zo^bo, U.S.A. CONTENTS I. Introduction: the nature of hf^terospon' ......... 345 U. Generalized life history of a homosporous polysporangiophyle: the basis for evolutionary excursions into hetcrospory ............ 348 III, Detection of hcterospory in fossils. .......... 352 (1) The need to extrapolate from sporophyte to gametophyte ..... 352 (2) Spatial criteria and the physiological control of heterospory ..... 351; IV. Iterative evolution of heterospory ........... ^dj V. Inter-cladc comparison of levels of heterospory 374 (1) Zosterophyllopsida 374 (2) Lycopsida 374 (3) Sphenopsida . 377 (4) PtiTopsida 378 (5) f^rogymnospermopsida ............ 380 (6) Gymnospermopsida (including Angiospermales) . 384 (7) Summary: patterns of character acquisition ....... 386 VI. Physiological control of hetcrosporic phenomena ........ 390 VII. How the sporophyte progressively gained control over the gametophyte: a 'just-so' story 391 (1) Introduction: evolutionary antagonism between sporophyte and gametophyte 391 (2) Homosporous systems ............ 394 (3) Heterosporous systems ............ 39(1 (4) Total sporophytic control: seed habit 401 VIII. Summary .... ... 404 IX. .•Acknowledgements 407 X. References 407 I. I.NIRODUCTION: THE NATURE OF HETEROSPORY 'Heterospory' sensu lato has long been one of the most popular re\ie\v topics in organismal botany.
    [Show full text]
  • Gametophyte Morphology and Development of Six Species of Pteris (Pteridaceae) from Java Island Indonesia
    THE JOURNAL OF TROPICAL LIFE SCIENCE OPEN ACCESS Freely available online VOL. 5, NO. 2, pp. 98-104, May, 2015 Gametophyte Morphology and Development of Six Species of Pteris (Pteridaceae) from Java Island Indonesia Dwi Sunarti Puspitasari1, Tatik Chikmawati2*, Titien Ngatinem Praptosuwiryo3 1Plant Biology Graduate Program, Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Darmaga Campus, Bogor, Indonesia 2Department of Biology, Faculty of Mathematics and Natural Sciences Bogor Agricultural University, Darmaga Campus, Bogor, Indonesia 3Center for Plant Conservation- Bogor Botanical Gardens, Indonesian Institute of Sciences, Bogor, West Java, Indonesia ABSTRACT The morphology of sporophyte, the type of reproduction, and cytology of Pteris had been reported, while the gametophyte morphology of Pteris in Java island has not been studied yet. The objective of this study was to describe the gametophyte morphology and development of P. biaurita, P. ensiformis, P. exelsa, P. longipinnula, P. tripartita, and P. vittata in Java island. Spores were obtained from fertile leaves of Pteris plants originated from several locations in Java island. The number of spores per sporangium was counted from fresh fertile leaves with mature sporangia. As much as 0.002 g spores was sown in a transparent box with sterile medium contain of ver- miculite, sphagnum moss, and perlite with ratio 2:2:1. The gametophyte development of each species was observed under a microscope every 7 days. The spores of P. ensiformis were germinated faster, ten days after sowing, while the spores of P. longipinnula were germinated slower, 18 days after sowing. The pattern of spore germination is Vittaria-type.
    [Show full text]
  • Spore Reproduction of Japanese Climbing Fern in Florida As a Function of Management Timing
    Spore Reproduction of Japanese Climbing Fern in Florida as a Function of Management Timing Candice M. Prince1, Dr. Gregory E. MacDonald1, Dr. Kimberly Bohn2, Ashlynn Smith1, and Dr. Mack Thetford1 1University of Florida, 2Pennsylvania State University Photo Credit: Chris Evans, University of Illinois, Bugwood.org Exotic climbing ferns in Florida Old world climbing fern Japanese climbing fern (Lygodium microphyllum) (Lygodium japonicum) Keith Bradley, Atlas of Florida Vascular Plants Chris Evans, University of Illinois, Bugwood.org Japanese climbing fern (Lygodium japonicum) • Native to temperate and tropical Asia • Climbing habit • Early 1900s: introduced as an ornamental1 • Long-distance dispersal via wind, pine straw bales2,3 Chris Evans, University of Illinois, Bugwood.org Dennis Teague, U.S. Air Force, Bugwood.org Distribution • Established in 9 southeastern states • In FL: present throughout the state, USDA NRCS National Plant Data Team, 2016 but most invasive in northern areas • Winter dieback, re-sprouts from rhizomes1 • Occurs in mesic and temporally hydric areas1 Atlas of Florida Vascular Plants, Institute of Systemic Botany, 2016 Impacts Chris Evans, University of Illinois, Bugwood.org • Smothers and displaces vegetation, fire ladders • Florida Exotic Pest Plant Council: Category I species Chuck Bargeron, University of Georgia, Bugwood.org • Florida Noxious Weed List • Alabama Noxious Weed List (Class B) Japanese climbing fern: life cycle John Tiftickjian, Sigel Lab, University of Delta State University Louisiana at Lafayette
    [Show full text]
  • Educator Guide
    Educator Guide Presented by The Field Museum Education Department INSIDE: s )NTRODUCTION TO "OTANY s 0LANT $IVISIONS AND 2ELATED 2ESEARCH s #URRICULUM #ONNECTIONS s &OCUSED &IELD 4RIP !CTIVITIES s +EY 4ERMS Introduction to Botany Botany is the scientific study of plants and fungi. Botanists (plant scientists) in The Field Museum’s Science and Education Department are interested in learning why there are so many different plants and fungi in the world, how this diversity is distributed across the globe, how best to classify it, and what important roles these organisms play in the environment and in human cultures. The Field Museum acquired its first botanical collections from the World’s Columbian Exposition of 1893 when Charles F. Millspaugh, a physician and avid botanist, began soliciting donations of exhibited collections for the Museum. In 1894, the Museum’s herbarium was established with Millspaugh as the Museum’s first Curator of Botany. He helped to expand the herbarium to 50,000 specimens by 1898, and his early work set the stage for the Museum’s long history of botanical exploration. Today, over 70 major botanical expeditions have established The Field’s herbarium as one of the world’s preeminent repositories of plants and fungi with more than 2.7 million specimens. These collections are used to study biodiversity, evolution, conservation, and ecology, and also serves as a depository for important specimens and material used for drug screening. While flowering plants have been a major focus during much of the department’s history, more recently several staff have distinguished themselves in the areas of economic botany, evolutionary biology and mycology.
    [Show full text]
  • Queendom Fungi Worksheet
    www.mush.bio The basic structural features of fungi are not cells but hyphae. Hyphae are microscopic branching filaments filled with cytoplasm and nuclei. Each thread consists of a tube formed from a wall enclosing cytoplasm and a vacuole. The hyphal walls are not made of cellulose but of a substance called chitin, also found in the exoskeletons of arthropods, an organic nitrogenous compound. The hyphae contain many nuclei distributed throughout the cytoplasm. Sometimes the hyphae are divided into compartments by cross walls called septa. Fungi with cross walls are called septate fungi, while fungi without cross walls are called coenocytic fungi. 1. What are hyphae? 2. Describe the inside of hyphae. 3. What surrounds the hyphae and what compound is it made of? 4. What are hyphal cross walls called? Are they always present? Fungi do not have chlorophyll so they cannot make their food in the way that plants do. Fungi, like animals, are heterotrophs. However, fungi are absorptive, not ingestive heterotrophs (digest food after they eat it) like animals. They feed on dead or decaying organic matter and are classified as saprophytes. Their hyphae penetrate the dead material and form a branching network called a mycelium. The tips of the growing hyphae produce enzymes which digest the organic material. The soluble products are absorbed into the hyphae. Because fungi digest food first and then absorb it, they are absorptive heterotrophs. When bread mold fungi, such as Rhizopus stolonifer, grow on stale bread or rotting fruit, the mycelium can be seen as gray colored “fuzz”. Rhizopus reproduces asexually by sending up vertical hyphae called sporangiophores.
    [Show full text]
  • Plant Propagation Lab Exercise Module 2
    Plant Propagation Lab Exercise Module 2 PROPAGATION OF SPORE BEARING PLANTS FERNS An introduction to plant propagation laboratory exercises by: Gabriel Campbell-Martinez and Dr. Mack Thetford Plant Propagation Lab Exercise Module 2 PROPAGATION OF SPORE BEARING PLANTS FERNS An introduction to plant propagation laboratory exercises by: Gabriel Campbell-Martinez and Dr. Mack Thetford LAB OBJECTIVES • Introduce students to the life cycle of ferns. • Demonstrate the appropriate use of terms to describe the morphological characteristics for describing the stages of fern development. • Demonstrate techniques for collection, cleaning, and sowing of fern spores. • Provide alternative systems for fern spore germination in home or commercial settings. Fern spore germination Fern relationship to other vascular plants Ferns • Many are rhizomatous and have circinate vernation • Reproduce sexually by spores • Eusporangiate ferns • ~250 species of horsetails, whisk ferns moonworts • Leptosporangiate • ~10,250 species Sporophyte Generation Spores are produced on the mature leaves (fronds) of the sporophyte generation of ferns. The spores are arranged in sporangia which are often inside a structure called a sorus. The sori often have a protective covering of living leaf tissue over them that is called an indusium. As the spores begin to mature the indusium may also go through physical changes such as a change in color or desiccating and becoming smaller as it dries to allow an opening for dispersal. The spores (1n) may be wind dispersed or they may require rain (water) to aid in dispersal. Gametophyte Generation The gametophyte generation is initiated with the germination of the spore (1n). The germinated spore begins to grow and form a heart-shaped structure called a prothallus.
    [Show full text]
  • The Development of the Sporangium of Equisetum Hyemale.* Lon a Hawkins
    122 The Ohio Naturalist. [Vol. VII, No. 6, THE DEVELOPMENT OF THE SPORANGIUM OF EQUISETUM HYEMALE.* LON A HAWKINS. The sporangium of Equisetum has been the subject of con- siderable study. The first work of importance was by Hof- meister who seems to refer the whole of the sporangium to a single cell. Later Russow while verifying many of Hofmeister's statements did not agree to this, but considered it to be of the eusporangiate type, the sporogenous tissue as arising from the division of a single cell but part of the walls and tapetum coming from the surrounding tissue. This is now the generally accepted view. Goebel (1) gives an account of the development of the sporangium of E. palustre or E. limosum which he illustrates with two figures. According to this description it seems that the first division of the sporangial initial is periclinal and separates the primary sporogenous cell from the primary wall cell. In sub- sequent development the primary sporogenous cell divides much more rapidly than the other and we have a large mass of sporogenous tissue formed while a segment of the rather thin wall of the sporangium is all that comes from the primary wall cell. This is one of the points where Bower (2) disagrees with Goebel. In his study of E. arevense and E. limosum he came to the conclusion that Equisetum is eusporangiate; that the contents of the sporangium are ultimately referable to a single initial; that the first division is periclinal, the inner cell and part of the outer going to form spores; and that the sporo- genous tissue cannot be referred to a single cell as Goebel holds.
    [Show full text]
  • Plant Reproduction
    AccessScience from McGraw-Hill Education Page 1 of 10 www.accessscience.com Plant reproduction Contributed by: Scott D. Russell Publication year: 2014 The formation of a new plant that is either an exact copy or recombination of the genetic makeup of its parents. There are three types of plant reproduction considered here: (1) vegetative reproduction, in which a vegetative organ forms a clone of the parent; (2) asexual reproduction, in which reproductive components undergo a nonsexual form of production of offspring without genetic rearrangement, also known as apomixis; and (3) sexual reproduction, in which meiosis (reduction division) leads to formation of male and female gametes that combine through syngamy (union of gametes) to produce offspring. See also: PLANT; PLANT PHYSIOLOGY. Vegetative reproduction Unlike animals, plants may be readily stimulated to produce identical copies of themselves through cloning. In animals, only a few cells, which are regarded as stem cells, are capable of generating cell lineages, organs, or new organisms. In contrast, plants generate or produce stem cells from many plant cells of the root, stem, or leaf that are not part of an obvious generative lineage—a characteristic that has been known as totipotency, or the general ability of a single cell to regenerate a whole new plant. This ability to establish new plants from one or more cells is the foundation of plant biotechnology. In biotechnology, a single cell may be used to regenerate new organisms that may or may not genetically differ from the original organism. If it is identical to the parent, it is a clone; however, if this plant has been altered through molecular biology, it is known as a genetically modified organism (GMO).
    [Show full text]
  • General Characters of Pteridophytes.Pdf
    Pteridophytes: General Characters 1. Meaning of Pteridophytes: Pteridophyta (Gr, Pteron = feather, phyton = plant), the name was originally given to those groups of plants which have well developed pinnate or frond like leaves. Pteridophytes are cryptogams (Gr. kruptos = hidden, and Gamos = wedded) which have well developed vascular tissue. Therefore, these plants are also known as vascular cryptogams or snakes of plant kingdom. They are represented by about 400 living and fossil genera and some 10,500 species. Palaeobotanical studies reveal that these plants were dominant on the earth during the Devonian period and they were originated about 400 million years ago in the Silurian period of the Palaeozoic era. Earliest known Pteridophyte is Cooksonia. 2. General Characters of Pteridophytes: (i) Majority of the living Pteridophytes are terrestrial and prefer to grow in cool, moist and shady places e.g., ferns. Some members are aquatic (e.g., Marsilea, Azolla), xerophytic (e.g., Selaginella rupestris, Equisetum) or epiphytic (e.g., Lycopodium squarrosum) (Fig. 1). (ii) Majority of the Pteridophytes are herbaceous but a few are perennial and tree like (e.g., Angiopteris). Smallest Pteridophyte is Azolla (an aquatic fern) and largest is Cyathea (tree fern). (iii) Plant body is sporophytic and can be differentiated into root, stem and leaves. (iv) Roots are adventitious in nature with monopodial or dichotomous branching. Internally usually they are diarch. (v) Stem is usually branched. Branching is monopodial or dichotomous. Branches do not arise in the axil of the leaves. In many Pteridophytes stem is represented by rhizome. (vi) Leaves may be small, thin, scaly (microphyllous e.g., Equisetum), simple and sessile (e.g., Selaginella) or large and pinnately compound (megaphyllous e.g., Dryopteris, Adiantum).
    [Show full text]
  • Histochemistry of Spore Mucilage and Inhibition of Spore Adhesion in Champia Parvula, a Marine Alga
    University of Rhode Island DigitalCommons@URI Open Access Dissertations 1994 Histochemistry of Spore Mucilage and Inhibition of Spore Adhesion in Champia parvula, A Marine Alga Martha E. Apple University of Rhode Island Follow this and additional works at: https://digitalcommons.uri.edu/oa_diss Recommended Citation Apple, Martha E., "Histochemistry of Spore Mucilage and Inhibition of Spore Adhesion in Champia parvula, A Marine Alga" (1994). Open Access Dissertations. Paper 783. https://digitalcommons.uri.edu/oa_diss/783 This Dissertation is brought to you for free and open access by DigitalCommons@URI. It has been accepted for inclusion in Open Access Dissertations by an authorized administrator of DigitalCommons@URI. For more information, please contact [email protected]. HISTOCHEMISTRY OF SPORE MUCILAGE AND INHIBITION OF SPORE ADHESION IN CHAMPIA PARVULA, A MARINE RED ALGA. BY MARTHA E. APPLE A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN BIOLOGICAL SCIENCES UNIVERSITY OF RHODE ISLAND 1994 DOCTOR OF PHILOSOPHY DISSERTATION OF MARTHA E. APPLE APPROVED: Dissertation Committee Major Professor DEAN OF THE GRADUATE SCHOOL UNIVERSITY OF RHODE ISLAND 1994 Abstract Spores of the marine red alga, Champja parvu!a, attached initially to plastic or glass cover slips by extracellular mucilage. Adhesive rhizoids emerged from germinating spores, provided a further basis of attachment and rhizoidal division formed the holdfast. Mucilage of holdfasts and attached spores stained for sulfated and carboxylated polysaccharides. Rhizoids and holdfast cells but not mucilage stained for protein. Removal of holdfasts with HCI revealed protein anchors in holdfast cell remnants. Spores detached when incubated in the following enzymes: 13-galactosidase, protease, ce!!u!ase, a-amylase, hya!uronidase, sulfatase, and mannosidase.
    [Show full text]