Fungi

1
Fungi

• Chapter 19
• Señora Ettinger

2

• Answer these questions
• How do fungi differ from other organisms?
• How does the lifestyle of a fungus enable it to
  obtain food?
• What factors make each phylum of fungi
  distinctive?
• How do fungi affect humans?

3

• Look at page 406 of your textbook
• What do you see in the main picture on this page?
• Read the caption. What is really shown in the
  picture?
• Are fungus flowers made of fungus?
• Why would a fungus go to all the trouble of
  making a plant imitate a flower?

4
Page 406 continued

• Do you think this fungus hurts or helps the rock
  cress plant?
• Would you guess that fungi could flower on its
  own?

5
Characteristics of Fungi

• Cell structure
• Lifestyle
• Food acquisition
• Habitat
• Cell walls

6
Fungiplants?

• Cell wall
• Mitosis
• Chlorophyll
• Dikaryon stage

7
Other characteristics of Fungi

• Heterotrophs
• Digest food outside its body by secreted enzymes
  then absorb the nutrients
• Typically terrestrial
• Key decomposers of plant material
• Most derive their nutrition from plants
• Cell walls made of chitin

8
Fungal Niches

• Saprobes-
• Parasites-
• Symbiotic
• Mutuals

9
(No Transcript)
10
Fungi Structures, page 408, draw and label figure
19-2 here
11
Hyphae structure, draw Figure 19-3, page 408 here
12
Hyphae

• The dominant structure of fungi
• Long, multinucleated, typically multicelled,
  one-cell thick fungal tissue
• Typically hidden from sight since fungi grow
  their hyphae into their food
• Serve as vascular channels along which nutrients
  are passed

13
(No Transcript)
14
Mycelium

• What is it?

15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
Septa

• What is it?

19
(No Transcript)
20
Septate
21
coenocytic
22
RecessRead Armillaria ostoyae
23
Part 2

• Reproduction
• Fungal Divisions

24
Reproduction

• All nuclei are haploid except for zygote nuclei
  (except some Chytridiomycota)
• In the sexual reproduction, hyphae of two
  different mating strains meet and fuse but the
  two types of nuclei may coexist without fusion
  for most of the life of the fungus
• Fungi reproduce by relasin spores

25
Reproduction

• Monokaryotic compartment has a single nucleus
• Dikaryotic compartment has two genetically
  distinct nuclei
• Heterokaryotic hyphae have two kinds of
  genetically different nuclei
• Homokaryotic hyphae have genetically similar
  nuclei

26
Reproductive Structures

• Sporangia
• Gametangia
• Conidia

27
Fungal Divisions

• Plant-like, this groupings are called divisions
  instead of phyla
• Presently differentiated from slime molds and
  water molds

28
Chytridiomycota
29
Fungal Divisions

• Chytridiomycota
• Zygomycota
• Ascomycota
• Basidiomycota
• Deuteromycota (Fungi imperfecti) Your book
  doesnt mention this one.

30
Chytridiomycota
31
Chytridiomycota
32
Read

• Modern Genetics Versus Ancient Frog-Killing
  Fungus.
• Write a synopsis in the space provided.
• Be ready to answer questions

33
Chytridiomycota
Zygomycota
34
Zygomycota What does the name imply?

• What does the name imply?

35
Zygomycota some characteristics
36
Zygomycota

• Non-reproductive hyphae lack septa
• Include the common bread molds
• Produce zygospores

37
Life Cycle and Sexual Reproduction

• Sexual reproduction is via fusion of
  multinucleate gametangia
• May occur between same or different mating types
• Massive, haploid zygospore forms around diploid
  zygote nuclei
• Meisois occurs during germination

38
(No Transcript)
39
Asexual Reproduction

• Haploid spores are produced within sporangia
• Sporangium forms at the tip of erect hypha, with
  separating septum
• Spores shed above substrate, dispersed by wind

40
Chytridiomycota
Ascomycota
41
Ascomycota

• Beneficial
• Harmful forms

42
Yeast
43
Mold
44
Morels
True Morel
False Morel
45
Truffles
46
Truffles
47
Cup Fungi
48
Chestnut Blight
49
Chestnut Blight
50
Dutch Elm Disease
51
Ascomycota

• Has a characteristic reproductive structure
  called an ascus.
• A diploid zygote forms within ascus.
• Asci form on ascocarp of densely interwoven hyphae

52
(No Transcript)
53
Sexual Reproduction

• Ascogonia are female, have trichogyne
• Antheridia are male, fuse with trichogyne
• Male nuclei travel to ascogonium to pair with
  opposite nuclei
• Heterokaryotic hyphae arise from point of fusion
• An ascus containing two nuclei forms at the
  hyphal tip

54
Sexual Reproduction

• Nuclei within the ascus fuse, forming diploid
  zygote which immediately undergoes meiosis
• Four haploid daughter nuclei are the result.
• These haploid daughter nuclei undergo mitosis to
  form 8 ascospores
• The ascospores are then released, in most cases
  by the ascus bursting.

55
Asexual Reproduction

• Conidia are produced at the ends of
  conidiophores. Conidiophores are the stalk-like
  vertical growths on the hyphae. Spores are formed
  at the end of the conidiophores and are separated
  by septum and are called conidia.
• The spores are released and then germinate

56
Chytridiomycota
Basidiomycota
57
Basidiomycota

• Includes mushrooms, jelly fungi, puffballs, rusts
  and smuts
• Includes edible as well as poisonous varieties

58
Mushrooms
59
Mushrooms
60
Mushrooms
61
Jelly Fungus
62
Jelly Fungus
63
Puffballs
64
Rusts
65
Rusts
66
Corn Smut
67
Basidiomycota

• Characteristic reproductive structure is called a
  basidium.
• Syngamy occurs within basidium
• Meiosis occurs immediately, forming four haploid
  basidiospores
• Four basidiospores are borne on one basidium

68
(No Transcript)
69
Sexual Reproduction

• Spore germinates forming homokaryotic hyphae
• Eventually septa form between nuclei of primary
  mycelium
• Dikaryotic, heterokaryotic secondary mycelium
  forms when hyphae of different mating types fuse
• Basidiocarps form of completely dikaryotic hyphae
• Basidia line the gills of typical mushrooms

70
Deuteromycota

• Commonly called Fungi Imperfecti because they
  exhibit only asexual reproduction
• Mostly ascomycetes, few zygomycetes and
  basidiomycetes
• Many are human and plant pathogens
• Others produce important chemicals such as
  penicillin

71
Parasexuality

• Parasexuality occurs when two different hyphae
  fuse forming heterokaryotic hyphae. The two
  different nuclei may exchange portions of
  chromosomes between nuclei.
• Provides a certain amount of genetic
  recombination.

72
Fungal Associations

• Lichens
• Mycorrhizae

73
Lichens

• Mostly ascomycetes with green algae and/or
  cyanobacterium
• Specialized hyphae penetrate or envelop
  photosynthetic cells
• Fungal chemical signals direct photosynthetic
  metabolism
• Could be considered a form of controlled
  parasitism

74
Lichens

• Reproduction of the fungal portion is via normal
  fungal sexual reproduction
• Reproduction of the photosynthetic component is
  asexual
• The lichen as a whole can fragment and be
  transported by wind to a new location to form a
  new individual

75
Lichens

• Can inhabit cold, dry, generally harsh
  environments
• Help break rock surfaces and prepare habitat for
  other organisms
• Coloration of lichen protects photosynthetic
  partner
• Can survive adverse conditions by nearly halting
  metabolism

76
(No Transcript)
77
(No Transcript)
78
(No Transcript)
79
(No Transcript)
80
(No Transcript)
81
Mycorrhizae

• Most plant roots associated with certain fungi
• Fungus aid in transfer of soil nutrients into
  roots
• Plant provides organic carbon to fungus
• Arbuscular mycorrhizae and ectomycorrhizae

82
Arbuscular Mycorrhizae

• Hyphae penetrate outer cells of root
• More common mycorrhizae, generally a zygomycetes
• May increase yield of crops with less energy input

83
Ectomycorrhizae

• Hyphae surround, but do not penetrate roots
• Less common, mostly basidiomycetes, some
  ascomycetes
• Characteristic symbiont of shrubs and trees

84
Advantages

• Plants more resistant to drought, cold and harsh
  conditions
• May provide better protection against acid
  precipitation
• Prevent accumulation of toxic metals
• Speed germination of orchid seeds
• Provide better growth in poor soils

85
(No Transcript)