Vývoj samčího a samičího gametofytu, opylení, oplodnění, embryogeneze u nahosemenných Mgr. Hana Cempírková, Ph.D., Rostlinná embryologie, podzimní semestr 2022 Pěstování ve stromovém kmene Gymnosperm life cycle Z vřetena šišky vyrůstají šupiny. Šištice (strobilus) – místo vývoje gamatofytů a embrya What are female cones and male cones? — Trees Pacific Northwest Composite of pine cones : 1. whole 5-month female cone; 2. longitudinal section through a female cone; 3. longitudinal section through a male cone; 4. whole male cone - UWDC - UW-Madison Libraries Ginkgo biloba | Gymnosperms | Introduction to Botany | Botany | Biocyclopedia.com Většina jehličnatých nese na jednom stromu oba typy šištic. Jinan je ale dvoudomá rostlina (oblíbené jsou samčí stromy, protože neprodukují plody s páchnoucí a jedovatou dužinou. Samčí gametofyt Part a shows a cross section of a male cone, which is oval with a flattened bottom. A stem-like structure runs up the middle, and oblong microsporophylls radiate from either side. Migrograph b shows a blowup of a microsphorphyll, which is filled with round pollen grains. Micrograph C shows a blowup of a pollen grain, which is oval with two lobes and resembles Mickey Mouse. Mikrosporocyty v mikrosporangiu à mikrospory à pylové zrno (samčí gametofyt) A male cone has a central axis on which bracts, a type of modified leaf, are attached. The bracts are known as microsporophylls (Figure 2) and are the sites where microspores will develop. The microspores develop inside the mikrosporangium (2 or more, on the microsporophyll). Within the microsporangium, cells known as microsporocytes divide by meiosis to produce four haploid microspores. Further mitosis of the microspore produces two nuclei: the generative nucleus, and the tube nucleus. Upon maturity, the male gametophyte (pollen) is released from the male cones and is carried by the wind to land on the female cone. Vývoj pylového zrna nahosemenných Department of Botany Pollen Germination in Gymnosperms | Encyclopedia MDPI Mikrospora à prothalliové (proklové) buňky (degenerují) a antheridiová buňka Antheridiová buňka à vegetativní a generativní buňka Generativní buňka (po opylení) à dvě spermatické buňky 4 až 5 mitóz v různých stádiích (před a po opylení) Proklové buňky Generativní b. Vegetativní b. The male gametophyte of gymnosperms is generally more complex than that of flowering plants; it develops and germinates more slowly; and it is formed through three to five mitoses, which in different groups taxa occur at different stages—before or after pollination. In this regard, pollen released from microsporangia consists of different number of cells : four cells in pine and ginkgo (two prothallial cells, generative cell and tube cell), two in sequoia, and one in juniper. Male gametes in all cases are formed after pollination. U primitivních nahosemenných jsou pohyblivé spermatické buňky (ale pylová zrna jako taková klíčí a až před oplodněním dojde k uvolnění obrvených pohyblivých spermatic. buněk). Vývoj pylového zrna borovice (Pinus) Podrobnosti na: http://adpcollege.ac.in/online/attendence/classnotes/files/1624597770.pdf Samičí gametofyt Part A shows a cross section of a female cone, which is similar in shape to the male cone but with a wider central structure. Megasporophylls radiate from either side of this structure. At the base the megasprophylls are narrow, and the widen out into a roughly diamond shape. Part B shows a blowup of the megasprophyll, which has an oval ovule at its base. Part C shows a blowup of the ovule. The megaspore mother cell is at the center. An opening called a micropyle allows entry of the pollen tube from the base. The female cone also has a central axis on which bracts known as megasporophylls (Figure 3) are present. In the female cone, megaspore mother cells are present in the megasporangium. The megaspore mother cell divides by meiosis to produce four haploid megaspores. One of the megaspores divides to form the multicellular female gametophyte, while the others divide to form the rest of the structure. The female gametophyte is contained within a structure called the archegonium. Zralé vajíčko borovice How can one explain sporophyte and gametophyte in bryophyte, gymnosperm, and angiosperm? - Quora Opylení u nahosemenných Integration and macroevolutionary patterns in the pollination biology of conifers - Leslie - 2015 - Evolution - Wiley Online Library Polinační kapky plant development - Preparatory events | Britannica Different pollination strategies are found in conifers. Saccate pollen of Pinus and Picea floats on the surface of the pollination drop and with it is transferred to the nucellus, where it germinates. In Abies, an analogue of a pollination drop is formed from moisture collected after rain or dew. Pollen often germinates in the micropilar canal and the tube grows towards the nucellus. In Larix, the pollination drop is absent, but the micropilar canal is filled with ovular secretion. Surrounded by this secretion, pollen hydrates, swells, and sheds exine. In this form, it floats to the nucellus, where forms a pollen tube. This usually happens a few weeks after pollination. In some Tsuga species and all Araucariaceae species, there is no pollination drop—pollen lands on the conical surface next to the ovule and may remain there for several weeks. It then germinates and forms a long tube that grows through the micropyle into the ovule and reaches the nucellus. 4 funkce polinační kapky: zachycení pylu, doprava mikropylárním kanálem, klíčení a ochrana vajíčka. Později během evoluce další fce: odměna hmyzu = vývoj nektaru. Opylení a oplodnění • krátká vzdálenost mezi opylením a oplozením • dlouhá doba mezi opylením a oplozením • • [Schema van de gametofyten en bevruchting bij gymnospermen][Scheme of the gametophytes and fertilization in Gymnosperms) A Megasporangium with megaspore mother cell (2n), B After meiosis of the megasporocyte: only one of the four haploid cells persists. The pollen grain is germinated, C The megagametophyt develops within the megaspore. D The megagametophyt contains two (or three) archegonia, each with one egg cell. The pollen tube is grown allowing the sperm cell to reach the archegonium . The nucleus of the sperm cell fuses with that of the egg cell: fertilization! E An embryo develops, surrounded by rests of the megasporophyte and there around nucellus tissue F The seed is nearly ripe. For different plant groups, the time from pollination to fertilization varies from several weeks (most species of Cupressaceae and Pinaceae) to a year (Pinus and some Araucariaceae) Oplození • • I = integument •N = nucellus •M = megagametofyt •f, u = oplodněné (fert.) a neoplodněné (unfert.) archegonium •ac = archegoniální komůrka •p = pylová láčka • Embryogenesis in plants. Embryology. EMBRYOGENESIS IN GYMNOSPERMS 179 with the upper and lower regions of the zygote. Division of nuclei of the lower group is always accompanied by division in the Schematic of ovule tip at time of fertilization, showing layers of integument (I), nucellus (N), megagametophyte (M), with two archegonia (in white), of which one is fertilized (f), the other unfertilized (u). Pollen tubes (p) have grown into the nucellus; the sulcus end of the tube hangs over the archegonial chamber (ac). The archegonial chamber may be filled with fluid (blue) that originates either from ruptured pollen tubes (asterisk), from cells of the megagametophyte that line the chamber, and/or from archegonia. Vývoj embrya Developmental stages during embryogenesis in conifers. The course of embryo development can be divided into four phases: proembryogenesis; early and late embryogenesis; and maturation. During proembryogenesis, a polar structure characterized by dividing cells on one pole of the embryo (embryonal mass) and large vacuolated cells on the opposite pole appears. The vacuolated cells give rise to the suspensor, which disappears as maturation progresses. Early embryogenesis is characterized by elongation of the suspensor. Subsequently, the embryonic mass is converted into the embryo proper, which separates from the suspensor by gymnosperm-specific tube cells. This stage (late embryogenesis) culminates with the specification of the protoderm (the outermost layer of the embryo proper) and the presence of cells in the proximal region of the embryo proper that divide periclinally to become the precursors for the root cap. As the embryo matures, shoot and root meristem is established. Snímek 1 Vývoj embrya velmi dlouhý – od opylení po zralá semena to může trvat i 3 roky! (od opylení k oplození to může trvat jeden rok). V borovici: four independent embryos are formed . This phenomenon is known as polyembryony, because more than one embryo is formed from a zygote . As the polyembryony occurs due to the splitting of a zygote, it is called cleavage (=štěpení) polyembryony. Only a single deep-seated proembryo develops into an embryo and the growth of other embryos is arrested at different stages of development Dozrávání semen v šiškách Pine cones found at different life stages : r/mildlyinteresting Šiška – Wikipedie Semena All the Health Benefits of Pine Nuts, Recipes, Cautions, and More Piniové oříšky Venkovní bonsai - Jinan dvoulaločný - Ginkgo biloba - e-Bonsai Ginkgo biloba Forest Seeds Tvorba a sbírky Smrk Araucarie SEMENA | ARAUCARIA HETEROPHYLLA ( syn. EXCELSA) /10 SEMEN/ | Prodej semen exotických rostlin,zeleniny,chilli papriček Jedle Herbář Wendys - Herbář Wendys Tis Asi dvacet druhů borovice pinie (Pinus pinea) s velkými semeny vhodnými ke sklízení: nejčastější borovice mexická, Colorado, italská a čínská. Sarkotesta kolem semene jinanu obsahuje butyric acid – smrdí. Syrové plody obsahují 4-methoxypyridoxine, což je látka, která v těle ničí vitamín B6 (spolehlivě ji likvidujeme tepelnou úpravou). Semena zbavená dužiny se dají jíst (v Číně po opražení). Oplození je oddálené, dochází k němu až po opadu plodu na zem. Epimatium (dužnatý nepravý míšek) je jediný z rostliny tisu nejedovatý. Stavba semene Conifer seed histology. Generalized diagram of a resin vesicle... | Download Scientific Diagram Shrnutí Figure 19-13