Chapter 21

Kingdom Fungi

20-1 Learning Targets

• What are the characteristics of Fungi?• What is the internal structure of a

fungus?• How do fungi reproduce?

Fungi Characteristics• VERY different from plants:

– No roots, stems or leaves – Have no chlorophyll

• Eukaryotic heterotrophs with cell walls– Cell wall made of CHITIN– Digest food outside of body and THEN

absorb it through cell wall• Some absorb nutrients from decaying matter

– Called Detritus Feeders– Example of Detritus feeder: Club fungi/mushrooms

• Some live as parasites– Example of Parasitic feeder: Ring worm

• Some live in symbiotic relationship that benefits both sides

More Characteristics

• All fungi are multicellular (except yeast)• Multicellular fungi are made of tiny

filaments called hyphae– Hyphae tangle together in a thick mass

to form the mycelium or fungal body– Mycelium lies below the ground and the

fruiting body or reproductive structure is above ground (the “mushroom”)

Hyphae

Hyphae Without Cross Walls

Nuclei

Cell wall

Nuclei

Cytoplasm

Cross wall

Cell wall

Cytoplasm

Hyphae With Cross Walls

Kingdom Fungi

Mycelium

Fruiting Body

Hyphae

Fairy Rings

• Some mycelia can live for many years– Over time, the

nutrients at the center of the mycelium become depleted

– New mushrooms only sprout at the edges of the mycelium, causing a ring• Called a “FAIRY RING”

Reproduction in Fungi

• Fungi reproduce both sexually and asexually

• Fungi are classified according to their structure and method of reproduction

• General Groups:– Common Molds – Sac Fungi– Club Fungi– Imperfect Fungi

are divided into the phyla

includesincludesincludesincludes

Fungi

Common molds

Imperfect fungi

Sac fungiClub fungi

AscomycotaZygomycota Basidiomycota Deuteromycota

20-2 Learning Targets

•What are the characteristics of the four major phyla of Fungus?

Common Molds• Phylum Zygomycota: called zygomycetes

– Common molds that grow on meat, cheese and bread

• Best Known Zygomycete: – Rhizopus stolonifer (black bread mold)

• Structure– The mycelium is the cottony white mass of a bread mold.– The black balls at the top of the filaments are called

SPORANGIA or spore cases.– This fungus sends out filaments across the top of the

bread.– These filaments secrete digestive enzymes and absorb

the digested food externally

Rhizopus

Rhizopus Reproduction• Rhizopus reproduces asexually by spore

formation– Each spore has a nucleus and is surrounded

by a black wall.– The outer wall of the sporangium is very

delicate and easily torn.• When torn, the exposed spores are quickly carried

away by air • The spores then grow and reproduce on a moist

surface.

• The mold also reproduces sexually– We will not learn this process in detail, you

just need to know that it is possible!

Rhizopus Life Cycle

FERTILIZATION

Diploid

Haploid

MEIOSIS

Sexual ReproductionAsexual Reproduction

Zygospore (2N)

Spores (N)

Sporangium

Zygospore (2N)

+ Mating type (N)Stolons

Rhizoids

- Mating type (N)Spores (N)

Sporangiophore

Sporangium

Gametangia

Sac Fungi

• Phylum Ascomycota: called Ascomycetes – Named for the ASCUS, their

reproductive structure that contains spores

– Largest Phylum of Kingdom Fungi– Some ascomycetes such as cup fungi

are visible on the ground, others like yeasts are microscopic

– EXAMPLES: Morels, Truffles

YEAST• Yeast are unicellular fungi used by humans for

baking and brewing– Cause bread to rise by producing CO2 in

fermentation

• They can reproduce sexually and form ascospores

• They reproduce asexually by budding– A bulge appears on the cell wall.– The nucleus splits and moves into the bulge.– The bulge grows but may remain attached

to the mother cell.– Chains grow and may eventually break.

Yeast Budding

Club Fungi• Phylum Basidiomycota: called basidiomycetes

or club fungi– Gets name from reproductive structure that

resembles a club (called a basidium)– The cap of the basidiomycete (like a

mushroom) is made of tightly packed hyphae•The lower side of the cap is made of GILLS

– Gills are thin blades of tissue lined with cells that produce spores

– Spores are scattered to produce more mushrooms

– Examples: Mushrooms, Shelf Fungi, Puffballs, Earthstars, jelly fungi

Basidiomycete Life Cycle

FERTILIZATION

MEIOSIS

HYPHAE FUSE

Fruiting body (N + N)

Button

Secondary mycelium (N + N)

Primary mycelium (N)

+ Mating type (N)

- Mating type (N)

Basidiospores (N)

Zygote (2N)

Basidia (N + N)

Gills lined with basidia

Gills

Stalk

Base

Cap

Haploid

Diploid

Basidiomycete Pictures

Shelf Fungi: form next to dead/decaying trees

Puffballs

Stinkhorns• Stinkhorns are a family of basidiomycetes

– They produce a foul-scented mushroom

• Their method of reproduction is different than most mushrooms, which use the air to spread their spores– Stinkhorns produce a sticky spore mass

on their tip which has an odor that attracts flies

– The flies land on the stinkhorn and collect the spores on their legs and carry it to other locations.

Stinkhorn

Just a Warning• Many types of fungi are delicacies and are

cultivated for food (Portabellas are yummy!)

• Many wild mushrooms are also edible, BUT many are POISONOUS– Many species of edible mushrooms look

identical to poisonous mushrooms

• Moral of the Story: Don’t pick and eat mushrooms unless you know what you are doing!

Imperfect Fungi

• Phylum Deuteromycota: called deuteromycetes or imperfect fungi

• Extremely diverse group– basically the misfit fungi – Fungi go here when researchers have

not found a sexual phase in their life cycles

• EXAMPLES: Penicillium, Ringworm, Athlete’s Foot

Penicillium

• Penicillium is mold that grows on fruit and is source of antibiotic

Mold on an orange

UP CLOSE!!!

Importance of Fungi

• FOOD SOURCE– Mushrooms – Morels – a delicacy– Yeast – used in baking and fermentation– Truffles – very expensive delicacy

• MEDICINES:– Penicillin – from Penicillium– Cyclosporin – anti-rejection drug

Morels and Truffles

Importance of Fungi

• DISEASES– Ringworm-from deuteromycete– Athlete’s foot fungus-from

deuteromycete– Thrush – Candida albicans– Yeast infections

• Using antibiotics increases risk of yeast infections because the medicines kill helpful, symbiotic bacteria in humans.

– Dutch elm disease– Chestnut blight

Ringworm

Importance of Fungi• IN NATURE:

– Decompose and recycle detritus.– Lichens – symbiotic relationship between a

fungus and algae (see p. 540)• Usually neither can grow on their own• Can grow in harsh environments due to relationship (fungus

gets water, minerals, and other carries out photosynthesis)

– Mycorrhizae –symbiotic relationships between plants and fungi

• Fungus helps obtain more nutrients by increasing surface area (plant also provides nutrients)

• About 90% of plants have a miycorrhizal relationship

– Fungi kill nematodes – a roundworm that attacks crops

Lichens