1. Overview: Mighty Mushrooms
Fungi are diverse and widespread
They are essential for the well-being of most terrestrial ecosystems because they break down organic material and recycle vital nutrients

3. Fungi are heterotrophs that feed by absorption
Despite their diversity, fungi share key traits, most importantly the way in which they derive nutrition
Fungi are heterotrophs but do not ingest their food
They secrete exoenzymes that break down complex molecules, and then they absorb the smaller compounds
Fungi exhibit diverse lifestyles: Decomposers, parasites and mutualistic symbionts

4. Body Structure
The morphology of multicellular fungi enhances their ability to absorb nutrients
Fungi consist of mycelia, networks of branched hyphae adapted for absorption
Most fungi have cell walls made of chitin
Some fungi have hyphae divided into cells by septa, with pores allowing cell-to-cell movement
Coenocytic fungi lack septa
Some unique fungi have specialized hyphae that allow them to penetrate the tissues of their host

5. Reproductive structure
Hyphae
Spore-producing
structures
20 µm
Mycelium

6. Cell wall
Cell wall
Nuclei
Pore
Septum
Nuclei
Septate hypha
Coenocytic hypha

7. Hyphae
25 µm
Nematode
Hyphae adapted for trapping and killing prey
Plant
cell
wall
Fungal hypha
Plant cell
Plant cell
plasma
membrane
Haustorium
Haustoria

8. Mycorrhizae are mutually beneficial relationships between fungi and plant roots
Ectomycorrhizal fungi form sheaths of hyphae over a root and also grow into the extracellular spaces of the root cortex
Endomycorrhizal fungi extend hyphae through the cell walls of root cells and into tubes formed by invagination of the root cell membrane

9. Fungi produce spores through sexual or asexual life cycles
Fungi propagate themselves by producing vast numbers of spores, either sexually or asexually

10. 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
MEIOSIS
GERMINATION
GERMINATION
Spore-producing
structures
Spores

11. Sexual Reproduction Plasomogamy is the union of two parent mycelia
In many fungi, the haploid nuclei from each parent do not fuse right away; they coexist in the mycelium, called a heterokaryon
In some fungi, the haploid nuclei pair off two to a cell; such a mycelium is said to be dikaryotic

12. Hours, days, or even centuries may pass before the occurrence of karyogamy, nuclear fusion
During karyogamy, the haploid nuclei fuse, producing diploid cells
The diploid phase is short-lived and undergoes meiosis, producing haploid spores

13. Asexual Reproduction
In addition to sexual reproduction, many fungi can reproduce asexually
Many of these species grow as mold, sometimes on fruit, bread, and other foods

14. 2.5 µm

15. Other fungi that can reproduce asexually are yeasts, which inhabit moist environments
Instead of producing spores, yeasts reproduce asexually by simple cell division

16. 10 m
Parent
cell
Bud

17. Zygote
fungi
Arbuscular
mycorrhizal
fungi
Sac
fungi
Club
fungi
Chytrids
Chytridiomycota
Zygomycota
Glomeromycota
Ascomycota
Basidiomycota

18. Zygomycetes
The zygomycetes (phylum Zygomycota) exhibit great diversity of life histories
They include fast-growing molds, parasites, and commensal symbionts
The zygomycetes are named for their sexually produced zygosporangia
The life cycle of black bread mold (Rhizopus stolonifer) is fairly typical of the phylum

19. Key PLASMOGAMY 100 µm KARYOGAMY MEIOSIS
Haploid (n)
Heterokaryotic (n + n)
Diploid (2n)
PLASMOGAMY
Rhizopus
growing
on bread
Mating
type (+)
Gametangia with
haploid nuclei
Mating
type (–)
100 µm
Young
zygosporangium
(heterokaryotic)
SEXUAL
REPRODUCTION
Dispersal and
germination
Zygosporangium
(heterokaryotic)
Sporangia
KARYOGAMY
Diploid
nuclei
Sporangium
ASEXUAL
REPRODUCTION
MEIOSIS
Dispersal and
germination
Mycelium
50 µm

20. Zygosporangia, which are resistant to freezing and drying, can survive unfavorable conditions
Some zygomycetes, such as Pilobolus, can actually “aim” their sporangia toward conditions associated with good food sources

21. 0.5 mm

22. Ascomycetes
Ascomycetes (phylum Ascomycota) live in marine, freshwater, and terrestrial habitats
The phylum is defined by production of sexual spores in saclike asci, usually contained in fruiting bodies called ascocarps
Ascomycetes vary in size and complexity, from unicellular yeasts to elaborate cup fungi and morels

23. The cup-shaped ascocarps (fruiting bodies) of Aleuria aurantia give this species its common name: orange peel fungus.
The edible ascocarp of Morchella esculenta, the succulent morel is often found under trees in orchards.
10 µm
Tuber melanosporum is a truffle, an ascocarp that grows underground and emits strong odors. These ascocarps have been dug up and the middle one sliced open.
Neurospora crassa feeds as a mold on bread and other food (SEM).

24. 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

25. Key
Conidia;
mating type (–)
Haploid (n)
Dikaryotic (n + n)
Diploid (2n)
Dispersal
Germination
Mating
type (+)
ASEXUAL
REPRODUCTION
Mycelium
PLASMOGAMY
Ascus
(dikaryotic)
Mycelia
Conidiophore
Dikaryotic hyphae
extended from
ascogonium
SEXUAL
REPRODUCTION
Germination
KARYOGAMY
Dispersal
Diploid nucleus
(zygote)
Asci
Eight
ascospores
Four
haploid
nuclei
MEIOSIS
Ascocarp

26. Basidiomycetes
Basidomycetes (phylum Basidiomycota) include mushrooms and shelf fungi
The phylum is defined by a clublike structure called a basidium, a transient diploid stage in the life cycle

27. Maiden veil fungus (Dictyphora), a fungus with an odor like rotting meat
Fly agaric (Amanita muscoria), a common species in conifer forests in the northern hemisphere
Puffballs emitting spores
Shelf fungi, important decomposers of wood

28. 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

30. Dikaryotic
mycelium
PLASMOGAMY
Mating
type (–)
Mating
type (+)
Haploid
mycelia
Gills lined
with
basidia
SEXUAL
REPRODUCTION
Basidiocarp
(dikaryotic)
Dispersal and
germination
Basidiospores
Basidium with
four appendages
Basidia
(dikaryotic)
Basidium
Basidium containing
four haploid nuclei
KARYOGAMY
MEIOSIS
Key
Diploid
nuclei
Haploid (n)
1 µm
Basidiospore
Dikaryotic (n + n)
Diploid (2n)

31. Fungi have a powerful impact on ecosystems and human welfare
Decomposers
Fungi are efficient decomposers
They perform essential recycling of chemical elements between the living and nonliving world
Symbionts
Fungi form symbiotic relationships with plants, algae, and animals
All of these relationships have profound ecological effects

32. Mycorrhizae
Mycorrhizae are enormously important in natural ecosystems and agriculture
They increase plant productivity
RESULTS
RESULTS

33. Fungus-Animal Symbiosis
Some fungi share their digestive services with animals
These fungi help break down plant material in the guts of cows and other grazing mammals
Many species of ants and termites use the digestive power of fungi by raising them in “farms”

34. Lichens
Lichens are a symbiotic association of millions of photosynthetic microorganisms held in a mass of fungal hyphae
The fungal component of a lichen is most often an ascomycete
Algae or cyanobacteria occupy an inner layer below the lichen surface

35. A fruticose (shrub-like) lichen
A foliose (leaf-like) lichen
Crustose (crust-like) lichens

36. Ascocarp of fungus
Soredia
Fungal
hyphae
Algal
layer
Algal cell
Fungal hyphae
10 µm

37. Pathogens
About 30% of known fungal species are parasites, mostly on or in plants
Animals are much less susceptible to parasitic fungi than are plants
The general term for a fungal infection in animals is mycosis

38. Corn smut on corn
Tar spot fungus of sycamore leaves
Ergots on rye

39. Practical Uses of Fungi
Humans eat many fungi and use others to make cheeses, alcoholic beverages, and bread
Genetic research on fungi is leading to applications in biotechnology
Antibiotics produced by fungi treat bacterial infections

40. Staphylococcus
Penicillium
Zone of
inhibited
growth

41. Animations and Videos
Life Cycles of Zygomycetes, Ascomycetes and Basidomycetes
The Ascomycetes
Ascus Animation
Basidium Animation
The Basidiomycetes
Conidia Animation
Life Cycle of Cycle of a Zygomycetes
Life Cycle of a Bread Mold

42. Animations and Videos Life Cycle of a Slime Mold
Chapter Quiz Questions – 1
Chapter Quiz Questions - 2

43. You are presented with several single-celled organisms, including one thought to belong to the kingdom Fungi. What unique feature helps you identify the fungus?
presence of mitochondria
absence of chloroplasts
presence of nuclei
presence of chitinous cell walls
Answer: d 43

44. You are presented with several single-celled organisms, including one thought to belong to the kingdom Fungi. What unique feature helps you identify the fungus?
presence of mitochondria
absence of chloroplasts
presence of nuclei
presence of chitinous cell walls 44

45. You are given a fungus to identify
You are given a fungus to identify. It has a fruiting body that contains many structures with eight haploid spores lined up in a row. What kind of fungus is this?
zygomycete
chytrid
deuteromycete
ascomycete
Answer: d 45

46. You are given a fungus to identify
You are given a fungus to identify. It has a fruiting body that contains many structures with eight haploid spores lined up in a row. What kind of fungus is this?
zygomycete
chytrid
deuteromycete
ascomycete 46

47. Many fungi produce antibiotics, for example, penicillin, that are effective at stopping bacterial growth. Which do you think is the evolutionary advantage to the fungus of secreting antibacterial chemicals?
defense: preventing bacteria from infecting the fungus
defense: preventing bacteria from killing fungal spores
symbiosis: attracting helpful bacteria
competition: destroying bacteria that compete for their food
predation: eventually consuming the bacteria
Answer: d 47

48. Many fungi produce antibiotics, for example, penicillin, that are effective at stopping bacterial growth. Which do you think is the evolutionary advantage to the fungus of secreting antibacterial chemicals?
defense: preventing bacteria from infecting the fungus
defense: preventing bacteria from killing fungal spores
symbiosis: attracting helpful bacteria
competition: destroying bacteria that compete for their food
predation: eventually consuming the bacteria 48

49. Which of the following phyla includes aquatic, flagellated fungi?
Ascomycota
Basidiomycota
Chytridiomycota
Zygomycota
Answer: c 49

50. Which of the following phyla includes aquatic, flagellated fungi?
Ascomycota
Basidiomycota
Chytridiomycota
Zygomycota 50

51. Which of the following statements about mycorrhizae is false?
They are important in natural systems and agriculture.
Almost all vascular plants have them.
Foresters inoculate pine seedlings with them to promote growth.
They colonize soils by dispersing spores that form new mycelia.
They are in a commensalistic relationship with plants.
Answer: e

52. Which of the following statements about mycorrhizae is false?
They are important in natural systems and agriculture.
Almost all vascular plants have them.
Foresters inoculate pine seedlings with them to promote growth.
They colonize soils by dispersing spores that form new mycelia.
They are in a commensalistic relationship with plants.

53. All of the following are lineages of fungi except
a) chytrids.
b) zygomycetes.
c) glomeromycetes.
d) ascomycetes.
e) conidia.
Answer: e

54. All of the following are lineages of fungi except
a) chytrids.
b) zygomycetes.
c) glomeromycetes.
d) ascomycetes.
e) conidia.

55. Lichens are
mutually beneficial relationships between fungi and plant roots.
symbiotic associations between photosynthetic organisms and fungi.
a type of plant pathogen.
a type of marine eukaryote.
single-celled, flagellated protist ancestors of fungi.
Answer: b

56. Lichens are
mutually beneficial relationships between fungi and plant roots.
symbiotic associations between photosynthetic organisms and fungi.
a type of plant pathogen.
a type of marine eukaryote.
single-celled, flagellated protist ancestors of fungi.

57. Chytrids are unique among fungi in that they
have flagellated spores
form mutualistic relationships with amphibians
have led to the decline of sheep and cattle populations
have chitinous cell walls
Answer: a

58. Chytrids are unique among fungi in that they
have flagellated spores
form mutualistic relationships with amphibians
have led to the decline of sheep and cattle populations
have chitinous cell walls

59. The practical uses of fungi include all of the following except
systemic mycoses.
reducing high blood pressure.
stopping maternal bleeding after childbirth.
treating bacterial infections.
fuel production.
Answer: a

60. The practical uses of fungi include all of the following except
systemic mycoses.
reducing high blood pressure.
stopping maternal bleeding after childbirth.
treating bacterial infections.
fuel production.