1. “The Mighty Mushroom” take a walk through a forest
mushrooms are truly are the largest organisms in the forest
Kingdom Fungi:
not just mushrooms!
approximately 100,000 species now described
may be as many as 1.5 million species
range from unicellular to complex multicellular organisms
just about every terrestrial and aquatic environment
essential decomposers in ecosystems
critical for the release of nutrients into the ecosystem
included with animals and plants in the Clade Opisthokonta
diverged about a billion years ago

2. Nutrition like animals, fungi are heterotrophs
cannot make their own food like algae and plants
must go and find it
unlike animals – they do not ingest their food (i.e. eat)
fungi decompose & absorb nutrients from its environment
digestion of both living and dead sources

3. Body Structure most common body structures of a fungus are:
Reproductive structure
Hyphae
Spore-producing
structures
Mycelium
20 µm
most common body structures of a fungus are:
1. multicellular filaments = mycelium
2. yeasts
mycelium made up of multicellular filaments called hyphae (hypha – singular)

4. The Mycelium mycelium body structure:
the mycelium is a haploid (n) multi-cellular organism
hyphae enhances the ability to absorb nutrients
a mycelium infiltrates the material on which it feeds
the emphasis is on increasing mycelium length NOT width
The Mycelium

5. Reproduction definitions:
fungus reproduce asexually & sexually through the production of spores
spores are haploid
spores are carried by wind or water
germination upon exposure to moisture to produce a new mycelium
definitions:
karyogamy: fusion of two haploid nuclei in fungi
production of a diploid zygote
plasmogamy: fusion of the cytoplasm NOT the nuclei
plasmogamy produces a heterokaryotic stage – means different nuclei
Haploid (n)
Key
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
PLASMOGAMY
(fusion of cytoplasm)
stage
KARYOGAMY
(fusion of nuclei)
Mycelium
SEXUAL
REPRODUCTION
Zygote
Spores
GERMINATION
MEIOSIS
Spore-producing
structures
ASEXUAL

6. Asexual Reproduction
fungal asexual reproduction: through the production of haploid spores by mitosis
the mycelium is haploid and so are the spores = MITOSIS
single-celled yeasts don’t produce a mycelium or spores but simply divide by mitosis or form progeny by budding
Haploid (n)
Key
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
ASEXUAL
REPRODUCTION
Spores
GERMINATION
Spore-producing
structures
Mycelium
10 m
Parent
cell
Bud

7. Sexual Reproduction
fungal sexual reproduction: consists of three stages – plasmogamy karyogamy  meiosis
two hyphae of opposite mating type meet and fuse
two cytoplasms fuse = plasmogamy
the two nuclei do not fuse right away – hypha is now called a heterokaryon (different nuclei)
Haploid (n)
Key
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
PLASMOGAMY
(fusion of cytoplasm)
stage
KARYOGAMY
(fusion of nuclei)
Mycelium
SEXUAL
REPRODUCTION
Zygote
Spores
GERMINATION
MEIOSIS
Spore-producing
structures
ASEXUAL

8. Sexual Reproduction The mycelium is a HAPLOID multi-cellular organism
hours or decades later (!) the nuclei will fuse inside the hypha = karyogamy
production of a diploid zygote (2n)
zygote develops into a spore producing structure called a sporangium
MEIOSIS takes place in the sporangium - producing haploid spores (n)
spores are dispersed to germinate and form a new mycelium
Haploid (n)
Key
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
PLASMOGAMY
(fusion of cytoplasm)
stage
KARYOGAMY
(fusion of nuclei)
Mycelium
SEXUAL
REPRODUCTION
Zygote
(2n)
Spores (n)
GERMINATION
MEIOSIS
Spore-producing
structures
ASEXUAL
Spores
The mycelium is a HAPLOID
multi-cellular organism

9. Fungal Diversity
fungi are thought to be descended from a unicelluar, aquatic flagellated protist
then moved to land
fossils of the earliest vascular land plants have fungal associations (mycorrhizea)
radiated into 5 Phyla:
1. Chytridiomycota
2. Zygomycota
3. Glomeromycota
4. Ascomycota
5. Basidiomycota
Chytrids
Zygote
fungi
Arbuscular
mycorrhizal
Sac
Club

10. Molds 1,100 known species in Phylum Zygomycota diverse in lifestyles
fast-growing molds
e.g. Rhizopus stolonifer – black bread mold
typical of a zygomycete
mycelium forms as a spread of horizontal hyphae over the food – penetrates it and absorb the nutrients
spore dispersal through the air eventually passes it onto other substrates for continued growth

11. sexual reproduction: “parents” are mycelia with hyphae or two mating types: “-” and “+”
fusion of two “parental” mycelia with “+” and “-” hyphae
plasmogamy produces a unique structure called a zygosporangium
heterokaryotic – no nuclear fusion yet!!
zygosporangium can remain dormant for months
Rhizopus
growing
on bread
Mating
type (+)
type (–)
PLASMOGAMY
Key
Haploid (n)
Heterokaryotic (n + n)
Diploid (2n)
100 µm
Young
zygosporangium
SEXUAL
REPRODUCTION
KARYOGAMY
Zygosporangium
Diploid
nuclei
MEIOSIS
Sporangium
Mycelium
Dispersal and
germination
ASEXUAL
Sporangia
50 µm

12. sexual reproduction:
under favorable conditions – the nuclei in the zygosporangium fuse to make diploid (2n) nuclei (karyogamy)
zygosporangium starts to make haploid spores (n) via Meiosis
these spores are contained in and released by a sporangium that “sprout” from the zygosporangium
this is what you see as the fluffy black stuff in black mold
spores are released to land and germinate into new mycelia on a new substrate
Rhizopus
growing
on bread
Mating
type (+)
type (–)
PLASMOGAMY
Key
Haploid (n)
Heterokaryotic (n + n)
Diploid (2n)
100 µm
Young
zygosporangium
SEXUAL
REPRODUCTION
KARYOGAMY
Zygosporangium
(heterokaryotic)
Diploid
nuclei
MEIOSIS
Sporangium
Mycelium
Dispersal and
germination
ASEXUAL
Sporangia
50 µm

13. Mushrooms club fungus – Phylum Basidiomycota 30,000 species
Fly agaric (Amanita muscoria), a common species in conifer forests in the northern hemisphere
Maiden veil fungus (Dictyphora), a fungus with an odor like rotting meat
Shelf fungi, important decomposers of wood
Puffballs emitting spores
club fungus – Phylum Basidiomycota
30,000 species
includes the mushrooms, shelf fungi, molds and mycorrizhae, rusts and smuts
important decomposers of wood
saprophoric (decomposing) and parasitic species (rusts and smuts)

14. The Common Mushroom basidium = “little pedestal”
pileus
basidium = “little pedestal”
spore forming part of the mushroom
the part of the mushroom we see is a reproductive structure called a basidiocarp
basidiocarp = cap (pileus) with the gills on the underside + the supporting stalk = stipe
the basidiocarp is actually a large aggregation of hyphae forming the mushroom
underground is the actual mycelium
basidiocarp
stipe
stipe
gills

15. sexual reproduction:
two haploid mating types ‘+’ and ‘–’ undergo plasmogamy and a heterokaryotic mycelium made of two different nuclei per cell forms
rain or temperature changes induce the mycelium to form many basidiocarps (mushroom) that poke up above the ground
PLASMOGAMY
Key
Haploid (n)
Dikaryotic (n + n)
Diploid (2n)
SEXUAL
REPRODUCTION
KARYOGAMY
MEIOSIS
Mycelium
Basidium containing
four haploid nuclei
Dispersal and
germination
Basidium
1 µm
Mating
type (+)
type (–)
Haploid
mycelia
Gills lined
with
basidia
Basidiocarp
Basidia
(dikaryotic)
Diploid
nuclei
Basidiospore
Basidiospores

16. sexual reproduction cont…..:
the gills of the basidiocarp are lined with spore-producing structures (i.e. sporangia) called basidia (basidium = singular)
within each basidium the 2 nuclei fuse to make a diploid parental cell (i.e. karyogamy)
the parental cell undergoes meiosis 4 haploid nuclei total per basidium
each haploid nuclei develops into a basidiospore (4 basidiospores per basidium)
basidiospores are released and are carried by the wind – germinate into new mycelia which rapidly undergo more sexual reproduction
4 basidiospores on a basidium
PLASMOGAMY
Key
Haploid (n)
Dikaryotic (n + n)
Diploid (2n)
SEXUAL
REPRODUCTION
KARYOGAMY
MEIOSIS
Dikaryotic
mycelium
Basidium containing
four haploid nuclei
Dispersal and
germination
Basidium
1 µm
Mating
type (+)
type (–)
Haploid
mycelia
Gills lined
with
basidia
Basidiocarp
(dikaryotic)
Basidia
Diploid
nuclei
Basidiospore
Basidiospores

17. Yeasts 1500 species of unicellular fungi
not a single taxonomic or phylogenic grouping
divided up between Phylum Ascomycota & Phylum Basidiomycota
often a synonym for the species Saccharomyces cerevisiae
but there are several species of yeasts

18. Yeasts
are chemotrophs – convert carbohydrates into CO2 and alcohol (fermentation)
yeasts are either obligate aerobes (for cellular respiration) or anaerobic (fermentation)
naturally occurring on skins of fruits & berries – even on the skin or epithelial linings of humans
Candida albicans - yeast infections or athlete’s foot
also found in guts of mammal and insects
e.g. bees and ants
even in deep sea environments
most reproduce asexually through budding or fission (mitosis)

19. Fungal Associations: Lichens
Lichens: 25,000 species
fungus + green algae (or cyanobacteria)
algae provide organic compounds, the cyanobacteria fix nitrogen
algae nestle among the fungal hyphae and are protected
types of lichens:
1. Crustose lichens – grow as a crust on a surface
2. Foliose lichens – leafy in appearance
3. Fructicose lichens – shrublike with branching and intertwined fibrous parts
A fruticose (shrub-like) lichen
A foliose (leaf-like) lichen
Crustose (crust-like) lichens

20. Lichens most reproduce asexually: either through fragmentation
or by the formation of soredia – small clusters of hyphae with embedded algae - may be carried by the wind to new locations
Fungal hyphae
Algal cell
Soredia
Algal
layer
Fungal
hyphae
Ascocarp of fungus
10 µm