Fungus Spores

9 Key excerpts on "Fungus Spores"

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  Fungal Biology

  • J. W. Deacon(Author)
  • 2009(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Chapter 10 Fungal spores, spore dormancy, and spore dispersal This chapter is divided into the following major sections: • general features of fungal spores • spore dormancy and germination • spore dispersal • dispersal and infection behavior of zoospores • zoospores as vectors of plant viruses • dispersal of airborne spores • spore sampling devices and human health Fungi are the supreme examples of spore-producing organisms. They produce millions of spores, with an astonishing variety of shapes, sizes, surface properties, and other features – all precisely matched to the specific requirements for dispersal and/or persistence in different environments. A small part of this diversity is illustrated in Fig. 10.1, for some of the more bizarrely shaped spores of the freshwater aquatic fungi that grow in fast-flowing streams. But even the common rounded spores of fungi have properties that determine whether they will be deposited on plant surfaces, or on soil, or in the human lungs, etc. In this chapter we discuss several examples of this fine-tuning, and we will see that the properties of a spore tell us much about the biology and ecology of a fungus. Fig. 10.1 Examples of tetraradiate, multiple-armed and sigmoid spores found in fast-flowing freshwater streams. Approximate spore lengths are shown in parentheses. (a) A single conidium of Dendrospora (150–200 mm); (b) conidium of Alatospora (30–40 mm); (c) conidium of Tetrachaetum (70–80 mm); (d) conidium of Heliscus (30 mm); (e) conidium of Clavariopsis (40 mm); (f) conidium of Lemonniera (60–70 mm); (g) conidium of Tetracladium (30–40 mm); (h) conidium of Anguillospora (150 mm). (a) General features of fungal spores Because of their extreme diversity we can define fungal spores in only a general way, as microscopic propagules that lack an embryo and are specialized for dispersal or dormant survival.

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  Fungi

  Experimental Methods In Biology, Second Edition

  • Ramesh Maheshwari(Author)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  47 CHAPTER 3 Spores Their Dormancy, Germination, and Uses If most of life were destroyed by a holocaust of natural or man-made origin, a residuum in the form of spores, cysts, or seeds might remain to serve as the raw material of further evolution. —P. Becquerel (1950) (in French, summary in Sussman and Halvorson, 1966) Fungal biology is inextricably linked with spores. Experiments on fungi almost always begin with spores and end when the culture has begun to produce spores. In the middle of the 17th century when fascination with looking at the microscopic-sized objects was developing, a French farmer named Mathieu Tillet (1714–1791) collected a black dusty mass from diseased grains of wheat and applied them to a plot sown with healthy wheat seed. He showed that the powdery mass caused the bunt of wheat, establishing that the disease is seed borne. The Italian botanist Micheli (1679–1737) collected spores of fungi, sowed them on organic substrate (pieces of melon), and put forth the view that fungi arose from their own spores. He described germination of powdery wheat bunt spores for the first time, and this was confirmed by Prevost (1755–1819). The Tulasne brothers, Louis (1815– 1885) and Charles (1817–1884), illustrated spores of several fungi. The German botanist Anton de Bary (1831–1888) traced the germination of spores, including those of the rust fungi (Figure 3.1), to mycelium inside the host plant tissue and its eventual external production of disseminative spores. It thus began to be understood that the vegetative mycelium of fungi is mostly hidden inside the substratum and that what is observed are only the externally produced colored spores. Most fungal spores are dark because of melanin pigment. Some fungi, however, produce colored spores. For example, Penicillium produces blue-green conidia, Fusarium puts forth pink conidia, and Puccinia forms pustules containing rust-colored urediospores, while the mushroom fungi discharge yellow-ish basidiospores.

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  Food Mycology

  A Multifaceted Approach to Fungi and Food

  • Jan Dijksterhuis, Robert A. Samson, Jan Dijksterhuis, Robert A. Samson(Authors)
  • 2007(Publication Date)
  • CRC Press

    (Publisher)

  Fungi are known for their capability to produce sexual and/or asex-ual spores as agents of reproduction, dispersal and survival. Some fungal species predomi-nantly form sexual spores as Talaromyces spe-cies even without the need of different mating types (homothallic) and ascospores are pro-duced in high numbers, while there is only restricted production of asexual spores. Alter-natively, many fungal species do not have a well recognised sexual stage and are desig-nated as the Deuteromycetes (mitosporic fungi). This group includes many members of genera as Aspergillus, Penicillium and Fusarium, 84 C HITARRA & D IJKSTERHUIS which are very relevant fungi for food situa-tions (Dijksterhuis and Samson, 2002). Spores play an important role in the life cycle of fungi acting as dispersal or survival spores. Dispersal spores are separated completely from the par-ent mycelium by different factors to facilitate migration to a new site. They have a moderate capacity for survival in a resting state (dor-mancy). They are also capable to germinate readily in the presence of nutrients or favour-able environmental conditions (Griffin, 1994). In case of Aspergillus and Penicillium , conidia are formed in chains on specialised spore-forming cells (phialides). Mature conidia have to survive in dry conditions during dispersion through the air current (Dijksterhuis and Sam-son, 2002). In contrast, survival spores are often produced in lower numbers and may not be separated from the parent mycelium (Carlisle et al ., 1994). As an example, thick-walled chla-mydospores are produced by, e.g., Mucor ra-cemosus , F. culmorum and Paecilomyces variotii and typically produced between hyphal cells. Besides, many ascospores are formed inside closed or open fruit bodies (ascomata) that reside within the mycelium and not on special-ised structures (conidiophores) that enable the spores to be distributed by air- or water cur-rents.

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  Fungi, Algae, and Protists

  • Britannica Educational Publishing, Kara Rogers(Authors)
  • 2010(Publication Date)
  • Britannica Educational Publishing

    (Publisher)

  CHAPTER 2Life Cycle and Ecology of Fungi and Lichens

  T he abundance and wide distribution of fungi in nature are a reflection of reproductive success and adaptation to various ecological niches. Reproduction may be either asexual or sexual. In asexual life cycles, fungi are haploid (containing one set of chromosomes), and they may use fragmentation, budding, fission, or spores to produce offspring. In sexually reproducing forms, a diploid stage occurs, in which the nuclei of the haploid sex cells fuse together, facilitating the recombination of genetic material. This provides an opportunity for the emergence of genetic variation between individuals of the same species, thereby improving species adaptation to the immediate environment. Certain species of fungi are very highly adapted to their habitats, requiring specific nutrients or temperature ranges for growth. Other species, however, are less tailored to their surroundings. These fungi often are able to assimilate a wide variety of organic substances and are relatively indifferent to other ecological factors such as temperature.

  REPRODUCTIVE PROCESSES OF FUNGI

  Following a period of intensive growth, fungi enter a reproductive phase by forming and releasing vast quantities of spores. Spores are usually single cells produced by fragmentation of the mycelium or within specialized structures (sporangia, gametangia, sporophores, etc.). Spores may be produced either directly by asexual methods or indirectly by sexual reproduction. Sexual reproduction in fungi, as in other living organisms, involves the fusion of two nuclei that are brought together when two sex cells (gametes) unite. Asexual reproduction, which is simpler and more direct, may be accomplished by various methods.

  Sir Alexander Fleming (b. Aug. 6, 1881, Lochfield Farm, Darvel, Ayrshire, Scot.—d. March 11,1955, London, Eng.)

  Scottish bacteriologist Sir Alexander Fleming was best known for his discovery of penicillin. Fleming had a genius for technical ingenuity and original observation. His work on wound infection and lysozyme, an antibacterial enzyme found in tears and saliva, guaranteed him a place in the history of bacteriology. But it was his discovery of penicillin in 1928, which started the antibiotic revolution, that sealed his lasting reputation. Fleming was recognized for this achievement in 1945, when he received the Nobel Prize for Physiology or Medicine, along with Australian pathologist Howard Walter Florey and British biochemist Ernst Boris Chain, both of whom isolated and purified penicillin.

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  Indoor Environmental Quality

  • Thad Godish(Author)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  These include thick-walled, dor- mant clamydospores and hardened mycelial masses called sclerotia. A number of species of fungi grow as single cells during all or part of their life history. Most notable of these are yeasts, which reproduce asexually by budding and sexually by producing sac-like ascospores. In genera such as Candida , under certain environmental conditions the organism develops yeast-like growth, while under others, it develops a typical mycelium. B. Dispersal Most fungal species produce sexual and/or asexual spores which serve to both reproduce the organism and disperse it to new substrates. As a conse- Figure 6.1 Fungal colonies. Chapter six: Biological contaminants — mold 169 quence of evolutionary processes, fungal spores have size and aerodynamic properties that enhance airborne dispersal. Spores vary in size (2 to 100 μ m), with the smallest being single cells and the largest being multicellular. Spores of Alternaria and Cladosporium, which illustrate different spore shapes and sizes, can be seen in Figures 6.4 and 6.5. Spore dispersal may occur by passive or active release mechanisms, with subsequent entrainment and movement by horizontal or convective air cur- rents. Once airborne, spores may be carried varying distances, depending on their aerodynamic properties as well as existing atmospheric conditions. In still air (such as may occur in houses) they settle out relatively rapidly. Based on Stokes Law, the largest and heaviest spores would settle out more quickly, with smaller spores being suspended for longer periods of time. Figure 6.2 Asexual spores and spore bearing structures of Penicillium . (Courtesy of University of Minnesota.) Figure 6.3 Asexual spores and spore-bearing structures of Aspergillus . (Courtesy of University of Minnesota.)

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  Mushrooms

  Cultivation, Nutritional Value, Medicinal Effect, and Environmental Impact

  • Philip G. Miles, Shu-Ting Chang(Authors)
  • 2004(Publication Date)
  • CRC Press

    (Publisher)

  Plant pathologists have long been concerned with studies of spore germination because of their interest in prevention of the spread of fungal diseases by spores. Thus, many of the techniques that have been developed for testing the effectiveness of various treatments to prevent spore germination have been developed by workers in the field of plant pathology, and certain standard procedures have been established. Of greatest interest from the standpoint of edible mushrooms, however, is the germination of basidiospores. Although the basidiospore commonly takes in water and swells as a first stage in germination, it is the emergence of the germination tube that is commonly accepted as the criterion of germination. Thus, microscopic examinations are made at intervals of time to determine the percentage of spores that have formed germ tubes, and these structures are called germlings. Besides the effects of nutritional and environmental factors on germination, the age of the fruiting body in reference to the time of discharge of the spores may also influence results, as will the density of spores in the germination chamber. Genetic factors also have an effect on spore germination.

  X. RELATIONSHIP OF FUNGI WITH OTHER ORGANISMS — SYMBIOSIS

  Whether in the water, soil, or other terrestrial habitats, the fungi carry on their existence in the presence of other living organisms. Only when we take the fungi into the laboratory and establish pure cultures are the fungi truly separated during their growth from other organisms. This living together, which is the normal situation in nature for all living things, is referred to as symbiosis. Symbiosis is commonly studied by taking a particular organism, or group of organisms, and examining any special relationships that species of a different taxon may have with it. For example, the relationship of insects with pollination of flowering plants or the role of bacteria of the genus Rhizobium

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  Fungi

  Biology and Applications

  • Kevin Kavanagh(Author)
  • 2005(Publication Date)
  • Wiley

    (Publisher)

  Hyphae are predominantly multinucleated, with cross-walls called septa dividing the 38 FUNGAL GENETICS budding yeast asexual reproduction sexual reproduction schmoo cells zygote budding zygote diploids ascus formation meiosis sporogenesis Figure 2.1 Life cycles of Saccharomyces cerevisiae hypha into compartments. The compartments are connected through pores in the septa, and therefore display cytoplasmic continuity. The function of the hypha is primarily in nutrient acquisition, exploration of the environment and secretion of enzymes to assist in both processes. In pathogenic fungi, the hyphal growth form can also be important for virulence. In filamentous fungi, vegeta- tive hyphal growth initiates from a spore. Spores are products of either sexual (ascospores, basidiospores) or asexual (conidia) reproduction. Conidia are typ- ically produced from a differentiated structure called a conidiophore, whereas ascospores and basidiospores are produced within an ascus or basidium, respec- tively, contained with the fruiting body called an ascocarp or basidiocarp. During asexual reproduction in the ascomycetes, such as Aspergillus nidulans (Figures 2.2, 2.6), a spore containing a single nucleus (monokaryotic) germi- nates into a mutinucleate, homokaryotic hypha. The hypha grows and devel- ops branches for a period of time, then initiates a specialized branch called the conidiophore. Development of the conidiophore involves numerous differ- ent cell types, and is investigated as a model developmental process. The nucleus divides mitotically within the conidiophore, allowing the ultimate produc- tion of asexual, haploid conidia. Upon release, conidia germinate into vegeta- tively growing hyphae, and the cycle continues. The factors that trigger initial conidiophore development in Aspergillus are not clear, but involve the supply of carbon and nitrogen.

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  Mechanisms of Adaptation

  • J.R. Spkatch(Author)
  • 2014(Publication Date)
  • Academic Press

    (Publisher)

  The spore is formed within the parent vegetative cell and is a round to ovoid, optically refractile , resistant , metabolically quiescent cell. It can remain in a dormant or crytobiotic state essentially indefinitely until environmenta l circumstances are appropriat e for its germination . Under these conditions it gives rise to the vegetative cell capable of growth and division. There are sound reasons why the bacteria l endospore continues to occupy the attention of biologists and biochemists, (a) The dramati c resistance of endospores is of practica l concern to those seeking to achieve sterility, whether in food, laboratory media, or space ships. Further , the biochemical basis of this resistance has continued to elude investigators , (b) The condition of cryptobiosis or metabolic dormancy is one extreme form of a widespread biological phenomenon that allows organisms to cope with broadly fluctu-ating environmenta l circumstances , (c) The occurrence of a well-defined cellular morphogenesi s in a prokaryot e offers an attractive model system for investigating the biochemical and regulatory features of a developmenta l process. While endospores are formed by a number of genera (Bacillus, Thermo-actinomyces, Clostridium, Sporosarcina, Desulfatomaculum and Sporolacto-bacillus) (Buchanan and Gibbons, 1974), the available evidence suggests that the events are essentially similar. Thus, this section shall be exclusively concerned with the genus Bacillus. A. ENDOSPORE MORPHOLOGY Figure 1 is a phase-contras t micrograph of B. fastidiosus illustrating the intracellular and optically refractil e nature of the endospore. Figure 2 is an electron micrograph of a thin section of a B. megaterium endospore. The 4 MARTIN DWORKIN FIG. 1. Phase-contrast photomicrograph of spores and vegetative cells of Bacillus fastidiosus.

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  Plant Pathology: Fundamentals and Applications

  • Srinivasulu, B(Authors)
  • 2018(Publication Date)
  • Daya Publishing House

    (Publisher)

  Cannot be resold/distributed. 5. Fungi belong to Mastigomycotina Fungi belong to Ascomycotina 6. Sexual spores - Oospores Ascospores in cleistothecia 7. Motile spores - Present (zoospores) Motile spores – Absent 8. Antheridium and Oogonium Antheridium and Ascogonium 9. Common during high humid weather Common during dry season 10. Endophytic Ectophytic or Endophytic Division: Eumycota Sub-Division-4: BASIDIOMYCOTINA This sub-division comprises of a large number of higher fungi. The true Basidiomycotina consists of forms like mushroom, toadstool, puffballs and stink horns. The so-called shell or Bracket fungi and Bird’s nest fungi also belong to this group. The smuts, the rusts and the jelly fungi also belong to Basidiomycotina. This sub-division differs from others in that they produce the spores called basidiospores externally on the specialised spore-bearing structure called basidium. A typical basidium produces four one-celled haploid uninucleate spores. The hyphae of the mycelium are highly septate and penetrate into the substratum to absorb nourishment. It is usually white, light yellow or orange in colour. In some forms they produce thick strands called rhizomorphs. The mycelium passes through three distinct stages of development before the fungus completes its life cycle; primary mycelium, secondary mycelium and tertiary mycelium. The primary mycelium develops from germination of basidiospore. The secondary mycelium originates from the primary mycelium. Its cells are typically binucleate. Clamp connections are present. The tertiary mycelium is represented by specialised tissues which compose the sporophores. The cells of this mycelium are binucleate. Thus the basidium, the presence of dikaryotic mycelium and the formation of clamp connections are the typical characteristics of this sub-division. The basidia are typically formed in defnite layers called hymeneal layer.

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