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Kingdom Fungi Chapter 21.

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1 Kingdom Fungi Chapter 21

2 LEARNING OBJECTIVE 1 Describe the distinguishing characteristics of the kingdom Fungi

3 Fungi Eukaryotes that lack chlorophyll and are heterotrophic
Absorb predigested food through the cell wall and plasma membrane

Cause food spoilage Make food products better Provides a food source Provide medicine Cause plant disease Damage property Cause disease

5 Examples of foods made possible by fungi
Yeast Beer and Wine Bread Mushrooms White button, crimini,portabella Truffles, chanterelles Mycoprotein (food additive like tofu) Cheese Rennin, blue cheese Soy sauce Tempeh Citric acid (soft drinks)

6 Evolutionary History of Fungi
Fungi appeared around 1.5 billion years ago. Earliest fungi were aquatic. Fungi are more closely related to animals than plants. Fungi probably evolved from a flagellated protist.

7 KEY TERMS CHITIN A nitrogen-containing polysaccharide that forms cell walls of many fungi HYPHA One of the threadlike filaments composing the mycelium of a fungus

8 KEY TERMS MYCELIUM Other fungi (yeasts) are unicellular
Vegetative (nonreproductive) body of most fungi, consisting of a branched network of hyphae Other fungi (yeasts) are unicellular

9 Filamentous Fungi

10 growing on agar in a culture dish. In nature, fungal
Hyphae (c) (d) (e) (a) A fungal mycelium growing on agar in a culture dish. In nature, fungal mycelia are rarely so symmetrical. (b) Electron micrograph of a mycelium. (c) A hypha divided into cells by septa; each cell is monokaryotic. In some fungi the septa are perforated (as shown). (d) A septate hypha in which each cell is dikaryotic (has two nuclei). (e) A coenocytic hypha. Figure 21.1: Filamentous fungi. Fig. 21-1, p. 407

11 LEARNING OBJECTIVE 2 Explain the fate of a fungal spore that lands on an appropriate food source

12 KEY TERMS SPORE A reproductive cell that gives rise to individual offspring in fungi and certain other organisms

13 Spores Fungi reproduce by spores
May be produced sexually or asexually When a fungal spore comes into contact with an appropriate food source, the spore germinates and begins to grow a mycelium

14 Germination: Spore to Mycelium

15 Spore Hypha Mycelium Fig. 21-2, p. 407
Figure 21.2: Germination of a spore to form a mycelium. Mycelium Fig. 21-2, p. 407

16 LEARNING OBJECTIVE 3 List distinguishing characteristics and give examples of each of the following fungal groups: chytridiomycetes, zygomycetes, glomeromycetes, ascomycetes, and basidiomycetes

17 Major Phyla of Fungi

18 Evolution of ascospores Common flagellated ancestor
Zygomycetes Glomeromycetes Basidiomycetes Ascomycetes Chytrids Evolution of ascospores Evolution of basidiospores Evolution of dikaryotic stage Figure 21.3: Major phyla of fungi. This cladogram shows evolutionary relationships among the fungi, based on comparisons of DNA sequence data for many species. The chytrids branched off first during fungal evolution. Loss of flagellum Common flagellated ancestor Fig. 21-3, p. 408

19 KEY TERMS CHYTRID (chytridiomycetes)
A fungus characterized by production of flagellated cells at some stage in its life history A parasitic chytrid is partly responsible for declining amphibian populations

20 A Chytrid

21 KEY TERMS ZYGOMYCETE A fungus characterized by production of nonmotile, asexual spores and sexual zygospores Black bread mold is a zygomycete

22 A Zygomycete

23 Life Cycle: Black Bread Mold

24 In asexual reproduction, certain hyphae form
Spore germinates 1a In asexual reproduction, certain hyphae form sporangia in which clusters of black, asexual, haploid spores develop. When released, they give rise to new hyphae. ASEXUAL REPRODUCTION (by spores) Haploid (n) 7 Spores germinate and produce haploid mycelia. Sporangia Spores + - Sporangium containing spores produced by mitosis SEXUAL REPRODUCTION HAPLOID (n) STAGE 1b Hyphae of (+) and (-) mating types grow toward one another. + - 6 Meiosis occurs and zygospore germinates; hypha develops sporangium at its tip. Figure 21.6: The life cycle of the black bread mold. (Top) Asexual reproduction involves the formation of haploid spores. (Bottom) Sexual reproduction in the black bread mold (Rhizopus nigricans) takes place only between genetically distinct mating types, which are designated + and −. Germination of zygospore DIPLOID (2n) STAGE + Mature zygospore within zygosporangium Gametangia - When (+) and (-) hyphae meet, they form gametangia. 2 Meiosis Plasmogamy 5 Zygospore develops from zygote; it is encased by thick-walled, black zygosporangium. Plasmogamy occurs as gametangia fuse. Karyogamy 3 4 Karyogamy occurs with nuclei fusing to form diploid zygote. Fig. 21-6, p. 410

25 Microsporidium Infection

26 Microsporidian cell Polar tube Host cell 1 Spore of microsporidium
Figure 21.7: Infection by a microsporidium. 1 Spore of microsporidium has coiled polar tube. 2 Spore ejects its polar tube and penetrates host cell. 3 Infective cytoplasm is injected into host cell. Fig. 21-7, p. 411

27 1. Spore of microsporidium has coiled
Microsporidian cell Polar tube 1. Spore of microsporidium has coiled polar tube. 2. Spore ejects its polar tube and penetrates host cell. 3. Infective cytoplasm is injected into host cell. Host cell Figure 26.10: Infection by microsporidium. Stepped Art Fig. 21-7, p. 411

28 Animation: Zygomycete Life Cycle

A fungus that forms a distinctive branching form (arbuscular mycorrhizae) of endomycorrhizae with roots of most trees and herbaceous plants

30 Glomeromycetes

31 Cells of root cortex Root epidermis Soil Vesicle Root hair Arbuscule
Spore Figure 21.8: Glomeromycetes. These fungi form arbuscular mycorrhizae. Note how the mycelium has grown into the root, and its hyphae branch between the cells of the root. Hyphae have penetrated through the cell walls of two root cells and have branched extensively to form arbuscules. The tip of one hypha between root cells has enlarged and serves as a vesicle that stores food. The tip of a hypha in the soil has enlarged, forming a spore. The spaces between the root cells have been magnified. Cortex cell Hyphae of fungus Fig. 21-8, p. 412

32 KEY TERMS ASCOMYCETE A fungus characterized by production of nonmotile, asexual conidia and sexual ascospores Ascomycetes include yeasts, cup fungi, morels, truffles, pink and green molds

33 Conidia

34 Conidia Fig. 21-9, p. 412 Figure 21.9: Conidia.
Conidia are asexual reproductive cells produced by ascomycetes and a few basidiomycetes. Shown is an electron micrograph of Penicillium conidiophores, which resemble paintbrushes. Note the conidia pinching off the tips of the “brushes.” Fig. 21-9, p. 412

35 Life Cycle: Ascomycetes

36 In asexual reproduction, hyphae produce haploid conidia. Germinating
conidium 9 When released, ascospores germinate and form new haploid mycelia. ASEXUAL REPRODUCTION (by spores) Conidiophore Haploid (n) 1 Haploid mycelia of opposite mating types both produce coenocytic sexual hyphae. (–) mating type 8 Each nucleus becomes incorporated into an ascospore. (–) mating type Plasmogamy 2 Plasmogamy occurs as hyphae of the two mating types fuse and nuclei are exchanged. Nuclei migrate. Mature ascus has eight haploid ascospores. SEXUAL REPRODUCTION HAPLOID (n) STAGE 3 Dikaryotic hyphae form and produce asci. Second meiotic division DIKARYOTIC STAGE (n + n) Mitosis produces eight haploid nuclei. 7 Figure 21.10: The life cycle of an ascomycete. (Top) Asexual reproduction involves the formation of haploid conidia. (Bottom) Sexual reproduction involves the fusion of two haploid hyphae to form a dikaryotic (n + n) structure. Asci form from this structure; in each ascus the n + n nuclei fuse, followed by meiosis and mitosis to produce eight ascospores. The asci form the inner layer of a fruiting body known as an ascocarp. First meiotic division DIPLOID (2n) STAGE Developing ascus with n + n nuclei 6 Meiosis occurs, forming four haploid nuclei. Zygote Hyphae form an ascocarp. Nuclei fuse 4 Meiosis Ascocarp Karyogamy occurs in each ascus. Two haploid nuclei fuse, forming a diploid zygote nucleus. 5 Karyogamy Mycelium Fig , p. 414

37 Sexual Reproduction in Ascomycetes

38 Penicillium. The mold Penicillium produces penicillin, which inhibits the growth of Gram-positive bacteria.

39 Penicillium WWI, bacterial infections killed more soldiers than bullets did directly. 1928 Dr. Fleming working at St. Mary’s Hospital in London noticed that mold growing on staph bacterial culture plates had killed the pathogen zone of dead bacteria The action of penicillin is seen in Figure A. This shows an 'overlay plate', in which a central colony of the fungus Penicillium notatum was allowed to grow on agar for 5-6 days, then the plate was overlaid with a thin film of molten agar containing cells of the yellow bacterium, Micrococcus luteus. The production of penicillin by the fungus has created a zone of growth inhibition of the bacterium. This demonstration parallels what Alexander Fleming would have observed originally, although he saw inhibition and cellular lysis of the bacterium Staphylococcus aureus. Figure B shows the typical asexual sporing structures of a species of Penicillium. The spores are produced in chains from flask-shaped cells (phialides) which are found at the tips of a brush-like aerial structure. B&W is an actual photograph of Fleming’s dish (note clear lysed bacterial cells in zone around mold)

40 Penicillin kills bacteria by interfering with their ability to synthesize cell wall.
In this sequence, Escherichia coli were incubated in penicillin for 30 minutes. The bacteria lengthen, but cannot divide. Eventually the weak cell wall ruptures (last panel). In this sequence, Escherichia coli were incubated in penicillin for 30 minutes. The bacteria lengthen, but cannot divide. Eventually the weak cell wall ruptures (last panel).

41 Animations Mode of action of Pennicillin:
Development of Antibiotic resistance:

A fungus characterized by production of sexual basidiospores Basidiomycetes include mushrooms, puffballs, rusts, smuts

43 Basidiomycete Fruiting Bodies


45 Sexual Reproduction in Basidiomycetes

46 Cap Gill, bearing basidia Basidiospore Basidium Gills Button stage
Fruiting body (Basidiocarp) Stalk Base Figure 21.13: Sexual reproduction in the basidiomycetes. Mycelium (a) Compacted hyphae form the basidiocarp commonly called a mushroom. Numerous basidia are borne on the gills. (b) Each basidium produces four basidiospores, which are attached to the basidium. Fig , p. 417

47 Life Cycle: Basidiomycetes

1 Basidiospores germinate and form primary mycelia. Basidiospores released 2 Plasmogamy occurs with the fusion of two (n) hyphae of different mating types. Basidiospores forming Plasmogamy HAPLOID (n) STAGE 3 Fast-growing secondary mycelium is produced, composed of dikaryotic (n + n) hyphae. Second meiotic division DIKARYOTIC STAGE (n + n) First meiotic division DIPLOID (2n) STAGE 4 Basidiocarps periodically develop from secondary mycelium. Figure 21.14: Life cycle of a typical basidiomycete. Note the dikaryotic stage and the separation of plasmogamy and karyogamy. Asexual reproduction is uncommon in this group. 6 Meoisis occurs, producing four haploid nuclei that become basidiospores. Zygote nucleus Meiosis Karyogamy Gills Basidiocarp 5 Basidia form along gills of basidiocarps. In each basidium karyogamy occurs, producing a zygote nucleus. Secondary mycelium Fig , p. 418

49 Animation: Club Fungus Life Cycle

50 LEARNING OBJECTIVE 4 Explain the ecological significance of fungi as decomposers

51 Decomposers Most fungi are decomposers
Break down organic compounds in dead organisms, leaves, garbage, and wastes into simpler materials that can be recycled Without continuous decomposition Essential minerals would be unavailable for use by new generations of organisms Life would cease

52 LEARNING OBJECTIVE 5 Describe the important ecological role of mycorrhizae

53 Mycorrhizae Mutualistic relationships between fungi and roots of plants Fungus supplies minerals to plant Plant secretes organic compounds needed by fungus

Fungi that form mycorrhizae that extend into plant roots ECTOMYCORRHIZAL FUNGI Fungi that form mycorrhizae consisting of a dense sheath over the root’s surface

55 Experiment: Mycorrhizae

56 Mycorrhizae “myco” = fungus and “rhiza” = root
Symbiotic association between plant roots and fungi Several different types of association (defined by structure of fungus:plant interface) Types of mycorrhizae are defined by interface structures VAM - hyphae and arbuscules of an endomycorrhizal fungus in Asarum (wild ginger) (see Fig 15 in Brundrett & Kendrick 1988 Can. J. Bot. 66: 1153) Colonization of a root by an endomycorrhizal fungus. Note hyphae, arbuscules and vesicles. (Fig. 21 in Brundrett et al Can. J. Bot. 63: 184-) ECTO - page dichotomous ectomycorrhizas (upper) and mycelial strands (lower) of Amanita muscaria on Pinus Pictorial Supplement to The Fifth Kingdom - Chapter 17 Mycorrhizae - mutualistic plant-fungus symbioses. Photo posted by Bryce Kendrick and Mycologue Publications. Other acknowledgements

57 Mycorrhizae Endomycorrhizae:
Vesicular-Arbuscular Mycorrhizae (VAM, AM). Most common type of mycorrhizae (textbook: ~240,000 plant species, ~6000 fungal species; Trappe, 1987: ~2/3 of all plant species). Fungi = Zygomycetes, many kinds of plants (bryophytes, ferns, gymnosperms, angiosperms) Important step in evolution of land plants? VAM Fungi haven’t been cultured, can’t degrade complex organic matter, rely on simple C compounds from plants. Survive as chlamydospores in soil untilinfection. Plants can usually live without association, but not as well. Important for P uptake, recently shown to transfer organic N to plant. Vesicles: survival structures within plant. Fungus can grow along the inside of the root as root grows. Arbuscules: highly branched hyphae - transfer nutrients when arbuscules are digested by plant.

58 Almost ALL plant species depend on mycorrhizae to some extent
Types of mycorrhizae Plant partners Vesicular-arbuscular (VAM) ~150 species of fungi Nearly all terrestrial plants (200,000 species including grasses, crops, flowering plants, and flowering trees not listed below) Ectomycorrhizae ~5,000-10,000 species of fungi Conifer trees, oaks, birches, beeches, Eucalyptus) (~2000 species of trees) See table on overhead for more info Other types are: Ericoid (Heath family) Arbutoid (Heath family) Orchid Monotropoid

59 Effect of mycorrhizal symbiosis (with a fungus) on pine seedlings
Mycorrhizal fungi increase survival and growth of seedlings

60 LEARNING OBJECTIVE 6 Characterize the unique nature of a lichen

61 KEY TERMS LICHEN A compound organism consisting of a symbiotic fungus and an alga or cyanobacterium Lichens have three main growth forms: crustose, foliose, and fruticose

62 Lichens

63 Fruticose lichen (Ramalina)
Surface layer (fungal hyphae) Soredia Fungal hyphae interwoven with photosynthetic organism Loosely woven hyphae Bottom layer (fungal hyphae) Rock or other surface to which lichen is attached Crustose lichens (Bacidia, Lecanora) This cross section of a typical lichen shows distinct layers. The soredium, an asexual reproductive structure, consists of clusters of algal or cyanobacterial cells enclosed by fungal hyphae. Figure 21.16: Lichens. Foliose lichen (Parmelia) (b) Lichens vary in color, shape, and overall appearance. Three growth forms–crustose, foliose, and fruticose–are shown on a maple branch in Washington State. Fig , p. 420

64 Recap of mycorrhizal benefits
Greater plant productivity (larger profits in the timber, fiber industries) Greater reproductive success for plants (higher yields for agriculture) Greater ecosystem stability (Lewis & Koide 1990, Stanley et al. 1993). Write on white board: Benefits to plant from mycorrhizal association 1. Increased plant nutrient supply by extending the volume of soil accessible to plants. 2. Increased plant nutrient supply by acquiring nutrient forms that would not normally be available to plants. 3. Increased drought tolerance. 4. Protection from parasitic fungi and nematodes. 5. Link plants together in physiological networks Root colonisation by ECM and VAM fungi can provide protection from parasitic fungi and nematodes (Duchesne et al. 1989, Grandmaison et al. 1993, Newsham et al. 1995, Little & Maun 1996, Cordier et al. 1998, Morin et al. 1999). Suppression of competing non-host plants, by mycorrhizal fungi has been observed (Allen et al. 1989). Significant amounts of carbon transfer through ECM fungus mycelia connecting different plant species has been measured (Simard et al. 1997). This could reduce competition between plants and contribute to the stability and diversity of ecosystems. Networks of hyphae supported by dominant trees may help seedlings become established or contribute to the growth of shaded understorey plants (Hogberg et al. 1999, Horton et al. 1999). Nutrient transfer from dead to living plants can occur (Eason et al. 1991). Left: No mycorrhizal fungi Right: With mycorrhizal fungi

65 Economic Impact Foods: Food production:
Mushrooms, morels, truffles Food production: Beer, wine, bread, cheeses, soy sauce Production of industrial chemicals: Citric acid

66 LEARNING OBJECTIVE 7 Summarize some of the ways that fungi impact humans economically

67 Economic Impact Foods: Food production:
Mushrooms, morels, truffles Food production: Beer, wine, bread, cheeses, soy sauce Production of industrial chemicals: Citric acid

68 Fungal Food Products

69 Edible Ascomycetes

70 LEARNING OBJECTIVE 8 Summarize the importance of fungi to biology and medicine

71 Biology and Medicine 1 Production of medications:
Penicillin and other antibiotics Cause important plant diseases: Wheat rust, Dutch elm disease, chestnut blight

72 Biology and Medicine 2 Opportunistic pathogens in humans:
Ringworm, athlete’s foot, candidiasis, histoplasmosis Produce mycotoxins: Aflatoxins cause liver damage and cancer

73 The Destroying Angel

74 Ergot

75 Ergot Figure 21.20: Claviceps purpurea infecting rye flowers. This fungus produces a brownish black structure called an ergot (left ) where a seed would normally form in the grain head. A healthy grain head is shown for comparison (right ). Fig , p. 423

76 Fungal Parasite

77 Spore Hypha Epidermis Stoma Leaf Air space Haustoria
Figure 21.21: How a fungus parasitizes a plant. In this example, the hypha enters the leaf through a stoma. As the hypha grows, it branches extensively through the internal air spaces and penetrates plant cells with specialized hyphal extensions called haustoria. Haustoria Fig , p. 424

78 Fungal Plant Pathogens

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