Domain Eukarya
Kingdom Fungi
Anatomy of a fungus
• Most fungi grow as
multicellular mycelia
made up of long, thin
filaments called
hyphae.
• Most of a fungi will be
invisible to us. Only
the reproductive
structures above
ground will be seen.
Anatomy of a fungus
• The hyphae of fungi may or
may not be divided into
separate cells by septa
• Septa
No septa
Fungi can be multicellular or
unicellular
• Multicellular mycelia: .
This mycelium is from the
rind of a piece of Melbury
cheese.
• The yeast pictured here is
baker’s yeast,
Saccharomyces cerevisiae.
Fungi are absorptively heterotrophic
• Fungi can break down almost
any type of organic substance
– secrete enzymes to digest
Cell wall
food outside
– absorb nutrients back in
– may be saprobes,
Hyphae
detritivores, parasitic,
mutualistic, predatory
Pore
Septa
Reproductiv
structure
Mycelium
• Fungal morphology is associated with their mode of
nutrition: the fungal mycelium maximizes surface area in
relation to volume.
Fungal decomposition (saprophytic)
Parasitism
• Although many fungi infect humans, relatively
little human disease is due to fungi.
• Parasitic fungi cause major damage to crops
such as wheat, corn, and barley.
Fungi reproduce by producing spores
• The reproductive structures
of fungi produce haploid
spores
spore
• A new fungal mycelium
begins with the germination
of a haploid spore
The Fungal Life Cycle
•‘vegetative’ life form typically haploid
•May reproduce asexually through haploid spores
The Fungal Life Cycle
•Sexual reproduction through
–cytoplasm fusion --> dikaryotic stage (n + n) or heterokaryotic
–nuclear fusion--> diploid stage
–typically rapid meiosis--> haploid spores
Four groups of Fungi
Chytridiomycota
• Mainly aquatic
• Flagellated spores
• Basal group of the
Fungi
Phylum Zygomycota
• Rhizopus (bread mold),
fruit rot
• when two different
hyphae join together for
sexual reproduction,
they form a swollen,
thick-walled structure
(zygosporangia) that
links the hyphae
together
Figure 31.7 The life cycle of the zygomycete Rhizopus (black bread mold)
Figure 31.7x2 Mature zygosporangium
Bread mold
Bread Molds, Black Bread Mold, Rhizopus stolonifera, not
only grow on Bread, but anywhere there are water and
nutrients.
Phylum Ascomycota
• Sac Fungi
• Fruiting
structure called
an ascocarp
• Produce spores
in sac-like
compartments
called asci
Truffle
Morel
Figure 31.10 The life cycle of an ascomycete
Asexual
spores
produced
in conidia
Sexual
spores
produced
in
ascocarps
Other Ascomycetes
Baker’s yeast:
Saccharomyces
cerevisiae
Penicillin molds
Chestnut blight
Phylum Basidiomycota
• Club Fungi:
Mushrooms,
shelf fungi,
rusts and
smuts, puffballs
• Seldom
reproduce
asexually.
Club fungi reproduce sexually by forming spores in
a structure called a BASIDIUM (BASIDIA) which
can be found lining gills inside the BASIDIOCARP
(the mushroom cap).
Edible
Hallucinogenic
Mushrooms
Poisonous
Table 31.1 Review of Fungal Phyla
“Phylum” Glomeromycota?
• Mycorrhizae are fungi that associate with
plant roots and receive sugars from them.
• Two types:
– Exomycorrhizae
– Endomycorrhizae (also called arbuscular)
Ectomycorrhizae grow on the surface of plant
roots without penetrating the cells.
Root
cells
EMF
•Common in colder northern climates (decomposition is slow)
•The fungus breaks down organic material and delivers nitrogen
to the plant.
Arbuscular mycorrhizae penetrate the cells of
the plant root.
Root
cells
AMF
Root
hair
•Common in warmer grasslands & forests (decomposition
is rapid).
•The fungus delivers phosphorus to the plant.
Mutualisms:
• Increasing the diversity of mycorrhizae in a given
habitat increases plant species richness and
productivity.
0.8
130
Shoot biomass
Plant species diversity
Effect of AMF species diversity on plants:
0.6
0.4
0.2
110
90
70
0
0 1 2
4
8
Number of AMF species
14
0 1 2
4
8
Number of AMF species
14
Mutualisms
• Lichens
– Lichens are associations of a fungus with
either an alga or cyanobacterium.
• Lichens are the dominant species in tundra
habitats and are important in breaking down
rock to form soil.
Figure 29.11a
Asexual reproduction
occurs when “mini-lichens”
are produced.
Fungal layer
Algal layer
Fungal layer
Substrate
Asci
produced by
fungus
Types of Lichens
•crustose, fruticose, foliose
Dutch Elm Disease
• Entered the U.S. in the
1930’s
• Has been moving
westward ever since
• Chicago lost 119,000
trees in 3 years
Chestnut blight
• Entered the U.S. early 20th
century
• Before: as many as 1 in 4
trees were chestnuts (e. of
Mississippi)
• 100,000s of trees lost (3.5
billion in 40 years?)
• Tree now present as an
understory tree produced
by sprouting from roots
Cell walls of fungi are made of chitin
(Cell walls of plants are
made of cellulose)
Chitin also makes up the
exoskeleton of arthropods
Fungi used to be classified with plants
…but there are major differences
Plants
• Photosynthetic
• Cell wall made of
cellulose
• Develop from embryos
Fungi
• Heterotrophic
• Cell wall made of
chitin
• Develop from spores