Fungi have heterotrophic metabolism and absorb nutrients from their surroundings. Their bodies are made of thread-like hyphae that form a mycelium. They can reproduce both sexually through spores or asexually through fragmentation. Fungi play important ecological roles as decomposers, symbionts, and parasites. They are classified into phyla based on characteristics like spore production.

1. Kingdom Fungi
• The characteristics
of fungi
• The evolution of
the fungi
• Fungal
classification
• Fungal life cycles

2. Characteristics of Fungi
1. Fungi are eukaryotic microorganisms with heterotrophic
metabolism. Most fungi consist of masses of hyphae that
form a mycelium. Cross-walls separate the cells of hyphae in
many fungal species. Most fungi are coenocytic.
2. Fungi secrete enzymes into the surrounding environment
and absorb the breakdown products. Tremendous absorption
can occur when there is a large mycelium surface. Most fungi
are aerobic, grow best around 25°C, and prefer slightly acidic
conditions.
3. Reproductive structures generally occur at the tips of
hyphae. Masses of asexually- or sexually-produced spores
are formed within or at the tips of fruiting bodies.

3. The Characteristics of Fungi
• Body form
* unicellular
* filamentous (tube-like
strands called hypha
(singular) or hyphae
(plural)
* mycelium = aggregate
of hyphae
* sclerotium = hardened
mass of mycelium that
generally serves as an
overwintering stage.
* multicellular, such as
mycelial cords,
rhizomorphs, and fruit
bodies (mushrooms)

4. mycelium
fruiting bodies
both are
composed
of hyphae

5. The Characteristics of Fungi
• Heterotrophy - 'other food'
* Saprophytes or saprobes - feed on dead
tissues or organic waste (decomposers)
* Symbionts - mutually beneficial
relationship between a fungus and
another organism
* Parasites - feeding on living tissue of a
host.
• Parasites that cause disease are called
pathogens.

6. Heterotrophic by Absorption
• Fungi get carbon from organic sources
• Hyphal tips release enzymes
• Enzymatic breakdown of substrate
• Products diffuse back into hyphae
Product diffuses back
into hypha and is used
Nucleus hangs back
and “directs”

7. Hyphae
• Tubular
• Hard wall of chitin
• Crosswalls may
form compartments
(± cells)
• Multinucleate
• Grow at tips

8. Hyphal growth
• Hyphae grow from their tips
• Mycelium = extensive, feeding web of hyphae
• Mycelia are the ecologically active bodies of
fungi
This wall is rigid Only the tip wall is plastic and stretches

9. Modifications of hyphae

10. Fungi as Saprobes and
Decomposers

11. Fungi as Symbionts (Mutualism)

12. Mycorrhizae
• “Fungus roots”
• Mutualism between:
* Fungus (nutrient & water uptake for plant)
* Plant (carbohydrate for fungus)
• Several kinds
* Zygomycota – hyphae invade root cells
* Ascomycota & Basidiomycota – hyphae invade root but
don’t penetrate cells
• Extremely important ecological role of fungi!

13. Fungi as Parasites & Pathogens

14. Fungi are Spore-ific!!!
• Spores - asexual (product of
mitosis) or sexual (product of
meiosis) in origin.
• Purpose of Spores
* Allows the fungus to move
to new food source.
* Resistant stage - allows
fungus to survive periods of
adversity.
* Means of introducing new
genetic combinations into a
population

15. Reproduce by spores
• Spores are reproductive cells
* Sexual (meiotic in origin)
* Asexual (mitotic in origin)
• Formed:
* Directly on hyphae
* Inside sporangia
* Fruiting bodies
Amanita fruiting body
Pilobolus sporangia
Penicillium hyphae
with conidia

16. The Characteristics of Fungi
• Fungus is often hidden from view. It grows
through its food source (substratum),
excretes extracellular digestive enzymes,
and absorbs dissolved food.
• Indeterminate clonal growth.
• Vegetative phase of fungus is generally
sedentary.

17. The Characteristics of Fungi
• Cell wall present, composed of cellulose and/or chitin.
• Food storage - generally in the form of lipids and glycogen.
• Eukaryotes - true nucleus and other organelles present.
• All fungi require water and oxygen (no obligate anaerobes).
• Fungi grow in almost every habitat imaginable, as long as there
is some type of organic matter present and the environment is
not too extreme.
• Diverse group, number of described species is somewhere
between 69,000 to 100,000 (estimated 1.5 million species total).

18. The Classification of Fungi
4A. The phylum Chytridiomycota is characterized by motile cells,
while the Glomeromycota represent fungi living
symbiotically with land plants.
4B. In the phylum Zygomycota, the sexual phase is characterized
by the formation of a zygospore, which releases haploid spores that
germinate into a new mycelium.
4C. The phylum Ascomycota includes the unicellular yeasts and
filamentous molds. Ascospores are produced that germinate to
form a new haploid mycelium, while asexual reproduction is
through the dissemination of conidia. Lichens are a mutualistic
association between an ascomycete and either a cyanobacterium or
a green alga.

19. 4D. The phylum Basidiomycota includes the mushrooms.
Within these fruiting bodies, basidiospores are produced.
On germination, they produce a new haploid mycelium.
“Rusts” and “smuts” that cause many plant diseases are
additional members of the phylum.
4E. The mitosporic fungi lack a sexual phase. Many
human fungal diseases involve fungi in this informal
group.
5. Saccharomyces is a notable unicellular ascomycete
yeast involved in baking and brewing, and scientific
research.

20. Three Domain System

21. Generalized Life Cycle of a Fungus

22. Chytridiomycota – “chytrids”
• Simple fungi
• Produce motile spores -
zoospores
• Mostly saprobes and
parasites in aquatic habitats
• Could just as well be
Protists Chytridium growing on spores
Chytriomyces growing on pine pollen

23. Zygomycota – “zygote fungi”
• Sexual Reproduction -
zygosporangia
• Asexual reprod. – common
(sporangia – bags of asexual
spores)
• Hyphae have no cross walls
• Grow rapidly
• Decomposers, pathogens, and
some form mycorrhizal
associations with plants
Rhizopus on strawberries
Rhinocerebral zygomycosis

24. Life cycle of Rhizopus
Asexual sporangium
with spores inside
Sexual zygsporangium
with one zygospore

25. Ascomycota – “sac fungi”
• Sexual Reproduction – asci
(sing. = ascus)
• Asex. Reprod. – common
• Cup fungi, morels, truffles
• Important plant parasites &
saprobes
• Yeast - Saccharomyces
• Decomposers, pathogens,
and found in most lichens
A cluster of asci with spores inside

26. Sac fungi diversity

27. Basidiomycota – “club fungi”
• Sexual Reproduction – basidia
• Asexual reprod – not so
common
• Long-lived dikaryotic mycelia
• Rusts & smuts –plant parasites
• Mushrooms, polypores,
puffballs, boletes, bird’s nest
fungi
• Enzymes decompose wood,
leaves, and other organic
materials
• Decomposers, pathogens, and
some form mycorrhizal
associations with plants SEM of basidia and spores

28. Some fungi have more than
one scientific name – Why?
• Teleomorph: the sexual reproductive stage
(morph), typically a fruiting body (e.g., Morchella
esculenta, Agaricus brunescens).
• Anamorph: an asexual reproductive stage
(morph), often mold-like (e.g. Aspergillus flavus,
Fusarium solani). When a single fungus produces
multiple morphologically distinct anamorphs, they
are called synanamorphs.
• Holomorph: the whole fungus, including all
anamorphs and the teleomorph.

29. Deuteromycota – Form Phylum
“Imperfect Fungi”
• Fungi that seldom or never reproduce
sexually.
• Asexual reproduction by vegetative growth
and production of asexual spores common.

30. HUMAN-FUNGUS INTERACTIONS
• Beneficial Effects of Fungi
* Decomposition - nutrient and carbon recycling.
* Biosynthetic factories. Can be used to produce drugs, antibiotics,
alcohol, acids, food (e.g., fermented products, mushrooms).
* Model organisms for biochemical and genetic studies.
• Harmful Effects of Fungi
* Destruction of food, lumber, paper, and cloth.
* Animal and human diseases, including allergies.
* Toxins produced by poisonous mushrooms and within food (e.g.,
grain, cheese, etc.).
* Plant diseases.

31. End of slide show for notes
• The following slides contain additional
information that may be fun to learn, but is
not part of our curriculum. You do not need
to take any notes beyond this point.

32. “Ecto”mycorrhizae
Russula
mushroom
mycorrhizas on
Western
Hemlock root
Fungal hyphae
around root and
between cells
Mycorrhiza cross sections

33. Lichens
• “Mutualism” between
* Fungus – structure
* Alga or cyanobacterium –
provides food
• Three main types of lichens:
* Crustose lichens form flat
crusty plates.
* Foliose lichens are leafy in
appearance, although lobed or
branched structures are not true
leaves.
* Fruticose lichens are even more
finely branched and may hang
down like beards from branches
or grow up from the ground like
tiny shrubs.

34. Lichen internal structure
Lobaria
Lichens are nature’s biological monitors
of pollution and air quality
•Thalli act like sponges
•Some species more sensitive to
pollution
•Which species are present can
indicate air quality
•Most resistant species can also be
analyzed for pollutants, including
bioaccumulation of heavy metals and
radioactive isotopes

35. Hyphal growth from spore
mycelium
germinating
spore
• Mycelia have a huge surface area

36. Evolution of the fungi

37. • Evolution of the Fungi
• The fossil record provides evidence that
fungi and plants “hit the land” about the
same time. There are fossilized fungi that
are over 450 million years old, which is
about the time that plants started to colonize
the land. In fact, as described in this
chapter, some fossilized plants, perhaps
representing some of the first to colonize
land, appear to have mycorrhizal
associations.

38. • Taxonomists believe that a single ancestral species gave
rise to the five fungal phyla (Chytridiomycota,
• Glomeromycota, Zygomycota, Ascomycota, and
Basidiomycota). Only the Chytridiomycota (chytrids) have
flagella, suggesting they are the oldest line and that fungal
ancestors were flagellated and aquatic. The chytrids may
have evolved from a protistan ancestor and, as fungi
colonized the land, they evolved different reproductive
styles, which taxonomists have separated into the four
nonflagellated phyla described in this chapter.
• So, what evolutionary relationships do the fungi have with
the eukaryotic kingdoms Plantae and Animalia?

39. Classification
& Phylogeny
motile spores
zygosporangia
asci
basidia

40. Mushroom
Life Cycle
Nuclear
fusion in
basidium
Meiosis
Hyphal fusion
of haploid
mycelia
haploid
mycelium
young basidia - the
only diploid cells
mycelium and fruiting
body are dikaryotic
N 2N N+N

41. Bioluminescence in Mycena

42. Yeasts
• Single celled fungi
• Adapted to liquids
* Plant saps
* Water films
* Moist animal tissues
Candida
Saccharomyces

43. Molds
• Rapidly growth
• Asexual spores
• Many human importances
* Food spoilage
* Food products
* Antibiotics, etc.
Noble Rot - Botrytis