1. Objective: Kingdom Fungi

2. Fig. 31-1
Figure 31.1 Can you spot the largest organism in this forest?

3. Fungi Characteristics
The most common body structures are multicellular filaments and single cells (yeasts)
Eukaryotes
Fungi are heterotrophs and absorb nutrients from outside of their body
Cell walls of chitin
Reproduce with spores (sexually and asexually)

4. Fungi are adapted for nutrition by absorption
hyphae: tiny threads of cytoplasm surrounded by a plasma membrane and covered by a cell wall

5. Mycelium mycelium(mycelia): interwoven mat of hyphae Function:
- Feeding structure
Maximizes surface area within food

6. Reproductive structure
Fig. 31-2
Reproductive structure
Hyphae
Spore-producing
structures
Figure 31.2 Structure of a multicellular fungus
20 µm
Mycelium

7. Some fungi have hyphae divided into cells by septa, with pores allowing cell-to-cell movement of organelles
Coenocytic fungi lack septa, continuous cytoplasm

8. Mycorrhizae are mutually beneficial relationships between fungi and plant roots
What do the plants get?
The fungus?

9. Fungi produce spores through sexual or asexual life cycles
Fungi reproduce by producing vast numbers of spores, either sexually or asexually
Fungi can produce spores from different types of life cycles

10. Haploid (n) Heterokaryotic (unfused nuclei from different parents)
Fig
Key
Haploid (n)
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
Spore-producing
structures
Spores
ASEXUAL
REPRODUCTION
Mycelium
Figure 31.5 Generalized life cycle of fungi
GERMINATION

11. Haploid (n) Heterokaryotic stage Heterokaryotic (unfused nuclei from
Fig
Key
Haploid (n)
Heterokaryotic
stage
Heterokaryotic
(unfused nuclei from
different parents)
PLASMOGAMY
(fusion of cytoplasm)
Diploid (2n)
KARYOGAMY
(fusion of nuclei)
Spore-producing
structures
Zygote
SEXUAL
REPRODUCTION
Spores
ASEXUAL
REPRODUCTION
Mycelium
Figure 31.5 Generalized life cycle of fungi
GERMINATION

12. Haploid (n) Heterokaryotic stage Heterokaryotic (unfused nuclei from
Fig
Key
Haploid (n)
Heterokaryotic
stage
Heterokaryotic
(unfused nuclei from
different parents)
PLASMOGAMY
(fusion of cytoplasm)
Diploid (2n)
KARYOGAMY
(fusion of nuclei)
Spore-producing
structures
Zygote
SEXUAL
REPRODUCTION
Spores
ASEXUAL
REPRODUCTION
Mycelium
Figure 31.5 Generalized life cycle of fungi
MEIOSIS
GERMINATION
GERMINATION
Spores

13. Sexual Reproduction Fungal nuclei are normally haploid
Sexual reproduction requires the fusion of hyphae from different mating types (plasmogamy)
At first, nuclei don’t fuse, then when they do (karyogamy), diploid cells produced
Meiosis occurs to produce spores (haploid)

14. Asexual Reproduction
In addition to sexual reproduction, many fungi can reproduce asexually
Molds produce haploid spores by mitosis and form visible mycelia

15. Fig. 31-6
2.5 µm
Figure 31.6 Penicillium, a mold commonly encountered as a decomposer of food

16. Other fungi that can reproduce asexually are yeasts, which inhabit moist environments
Instead of producing spores, yeasts reproduce asexually by simple cell division and the pinching of “bud cells” from a parent cell

17. Fig. 31-7
10 µm
Parent
cell
Figure 31.7 The yeast Saccharomyces cerevisiae in several stages of budding (SEM)
Bud

18. Many molds and yeasts have no known sexual stage
Mycologists have traditionally called these deuteromycetes, or imperfect fungi

19. The ancestor of fungi was an aquatic, single-celled, flagellated protist
Fungi and animals are more closely related to each other than they are to plants or other eukaryotes

20. UNICELLULAR, FLAGELLATED Nucleariids ANCESTOR Opisthokonts Chytrids
Fig. 31-8
Animals (and their close
protistan relatives)
UNICELLULAR,
FLAGELLATED
ANCESTOR
Nucleariids
Opisthokonts
Chytrids
Figure 31.8 Fungi and their close relatives
Fungi
Other fungi

21. Fungi and animals evolved from a common flagellated unicellular ancestor and multicellularity arose separately in the two groups

22. The Move to Land
Fungi were among the earliest colonizers of land and probably formed mutualistic relationships with early land plants

23. Figure 31.11 Fungal diversity
Hyphae
25 µm
Chytrids (1,000 species)
Zygomycetes (1,000 species)
Fungal hypha
Glomeromycetes (160 species)
Ascomycetes (65,000 species)
Figure Fungal diversity
Basidiomycetes (30,000 species)

24. Fig. 31-UN6

25. Chytrids
Chytrids (phylum Chytridiomycota) are found in freshwater and soil
They can be decomposers, parasites, or mutualists
Molecular evidence supports the hypothesis that chytrids diverged early in fungal evolution
Chytrids are unique among fungi in having flagellated spores, called zoospores

26. Fig
Figure Flagellated chytrid zoospore (TEM)
Flagellum
4 µm

27. Zygomycetes
The zygomycetes (phylum Zygomycota) exhibit great diversity of life histories
They include fast-growing molds, parasites, and commensal symbionts
Sporangia:
In asexual repro, the structure that produces haploid spores
Zygosporangia
- In sexual repro, Zygosporangia (diploid spores), which are resistant to freezing and drying, can survive unfavorable conditions

28. Key Haploid (n) Heterokaryotic (n + n) Diploid (2n) Mating
Fig
Key
Haploid (n)
Heterokaryotic (n + n)
Diploid (2n)
PLASMOGAMY
Mating
type (+)
Gametangia with
haploid nuclei
Mating
type (–)
100 µm
Young
zygosporangium
(heterokaryotic)
Rhizopus
growing
on bread
SEXUAL
REPRODUCTION
Dispersal and
germination
Zygosporangium
Sporangia
KARYOGAMY
Figure The life cycle of the zygomycete Rhizopus stolonifer (black bread mold)
Spores
Diploid
nuclei
Sporangium
ASEXUAL
REPRODUCTION
MEIOSIS
Dispersal and
germination
50 µm
Mycelium

29. Fig
Figure Pilobolus aiming its sporangia
0.5 mm

30. Glomeromycetes Glomeromycetes form mycorrhizae
Why is this important to plants?

31. Ascomycetes
Ascomycetes (phylum Ascomycota) live in marine, freshwater, and terrestrial habitats
The phylum is defined by production of sexual spores in saclike asci (ascus)
Ascomycetes are commonly called sac fungi
Ascomycetes vary in size and complexity from unicellular yeasts to elaborate cup fungi and morels

32. Tuber melanosporum, a truffle
Fig
Morchella esculenta,
the tasty morel
Tuber melanosporum, a truffle
Figure Ascomycetes (sac fungi)

33. Ascomycetes include plant pathogens, decomposers, and symbionts
Ascomycetes reproduce asexually by enormous numbers of asexual spores called conidia
Conidia are not formed inside sporangia; they are produced asexually at the tips of specialized hyphae called conidiophores

34. Key Conidia; mating type (–) Haploid spores (conidia) Haploid (n)
Fig
Conidia;
mating type (–)
Haploid spores (conidia)
Key
Haploid (n)
Dikaryotic (n + n)
Diploid (2n)
Dispersal
Germination
Mating
type (+)
ASEXUAL
REPRODUCTION
Hypha
PLASMOGAMY
Ascus
(dikaryotic)
Conidiophore
Mycelia
Dikaryotic
hyphae
Mycelium
Germination
SEXUAL
REPRODUCTION
KARYOGAMY
Dispersal
Diploid nucleus
(zygote)
Asci
Eight
ascospores
Ascocarp
Figure The life cycle of Neurospora crassa, an ascomycete
Four
haploid
nuclei
MEIOSIS

35. Basidiomycetes
Basidomycetes (phylum Basidiomycota) include mushrooms, puffballs, and shelf fungi, mutualists, and plant parasites
The phylum is defined by a clublike structure called a basidium, a diploid stage in the life cycle
The basidiomycetes are also called club fungi

36. Fig
Maiden veil fungus
(Dictyphora), a
fungus with an
odor like rotting
meat
Puffballs emitting
spores
Shelf fungi, important
decomposers of wood
Figure Basidiomycetes (club fungi)

37. The life cycle of a basidiomycete usually includes a long-lived dikaryotic mycelium
In response to environmental stimuli, the mycelium reproduces sexually by producing elaborate fruiting bodies call basidiocarps
Mushrooms are examples of basidiocarps
The numerous basidia in a basidiocarp are sources of sexual spores called basidiospores

38. Dikaryotic mycelium Haploid mycelia Mating type (–) Mating type (+)
Fig
Dikaryotic mycelium
Haploid mycelia
PLASMOGAMY
Mating
type (–)
Mating
type (+)
Gills lined
with basidia
Haploid mycelia
SEXUAL
REPRODUCTION
Basidiocarp
(n+n)
Dispersal and
germination
Basidiospores
(n)
Basidium with
four basidiospores
Basidia
(n+n)
Basidium
Figure The life cycle of a mushroom-forming basidiomycete
Basidium containing
four haploid nuclei
KARYOGAMY
MEIOSIS
Key
Haploid (n)
Dikaryotic (n +n)
Diploid
nuclei
1 µm
Basidiospore
Diploid (2n)

39. Fungi as Decomposers Fungi are efficient decomposers
They perform essential recycling of chemical elements between the living and nonliving world

40. Fungus-Plant Mutualisms
Mycorrhizae are enormously important in natural ecosystems and agriculture
Plants harbor harmless symbiotic endophytes that live inside leaves or other plant parts
Endophytes make toxins that deter herbivores and defend against pathogens

41. Fungus-Animal Symbioses
Some fungi share their digestive services with animals
These fungi help break down plant material in the guts of cows and other grazing mammals

42. Fig
Figure Fungus-gardening insects
For the Discovery Video Leafcutter Ants, go to Animation and Video Files.

43. Lichens
A lichen is a symbiotic association between a photosynthetic microorganism and a fungus in which millions of photosynthetic cells are held in a mass of fungal hyphae

44. Crustose (encrusting) lichens A foliose (leaflike) lichen
Fig
 Crustose
(encrusting)
lichens
A fruticose (shrublike) lichen
 A foliose
(leaflike)
lichen
Figure Variation in lichen growth forms

45. The fungal component of a lichen is most often an ascomycete
Algae or cyanobacteria occupy an inner layer below the lichen surface

46. Lichens are important pioneers on new rock and soil surfaces
Lichens are sensitive to pollution, and their death can be a warning that air quality is deteriorating

47. Disease-causing fungi
30% of fungi are parasitic
Yeast infections
Ringworm
Athlete’s Foot

48. Fungi as Pathogens
About 30% of known fungal species are parasites or pathogens, mostly on or in plants
Some fungi that attack food crops are toxic to humans
Animals are much less susceptible to parasitic fungi than are plants
The general term for a fungal infection in animals is mycosis

49. (a) Corn smut on corn (b) Tar spot fungus on maple leaves
Fig
Figure Examples of fungal diseases of plants
For the Discovery Video Fungi, go to Animation and Video Files.
(a) Corn smut on corn
(b) Tar spot fungus on
maple leaves
(c) Ergots on rye

50. Practical Uses of Fungi
Humans eat many fungi and use others to make cheeses, alcoholic beverages, and bread
Some fungi are used to produce antibiotics for the treatment of bacterial infections, for example the ascomycete Penicillium

51. Staphylococcus Penicillium Zone of inhibited growth Fig. 31-26
Figure Fungal production of an antibiotic

52. Fig. 31-UN6