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 Nuclei Cell wall Cytoplasm Cross wall Hyphae With Cross Walls Hyphae Without Cross Walls

Kingdom Fungi Fruiting Body Hyphae Mycelium

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 Fungi are divided into the phyla Ascomycota Zygomycota Basidiomycota Deuteromycota includes includes includes includes Common molds Sac fungi Club fungi Imperfect fungi

What are the characteristics of the four major phyla of Fungus? 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 Sporangium Gametangia Spores (N) Zygospore (2N) Spores (N) Sporangium + Mating type (N) Stolons Rhizoids - Mating type (N) Sporangiophore Gametangia FERTILIZATION MEIOSIS Sexual Reproduction Asexual Reproduction Diploid Haploid

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 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 FERTILIZATION HYPHAE FUSE Haploid Diploid MEIOSIS

Basidiomycete Pictures Puffballs Shelf Fungi: form next to dead/decaying trees

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 UP CLOSE!!! Mold on an orange

Importance of Fungi FOOD SOURCE MEDICINES: 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