Chapter 21 Mrs. LaLone

Kingdom Fungi Mycologists study fungus! Eukaryotic Organisms Ex: Mushrooms, yeasts, molds 70,000+ species of Fungus Mostly Terrestrial Form spores at some stage of lifecycle Have a Cell Wall Composed of chitin – Nitrogen based polysaccharide Resistant to breakdown by microorganisms More resistant than cellulose

Nutrition All are Heterotrophic Most are saprophytic – feed on the remains of dead organisms “decomposers” Fungi secrete enzymes that initiate digestion outside the hypha Then absorb nutrients through the plasma membranes of their cells Some are parasitic – obtain nutrients from living organisms; ex: plant pests

Climate Grow best in moist environments Produce spores in dry environments (resting stage) Optimum pH is slilghtly acidic ~5.6 Range from 2-9 Wide temperature range

Body Plans Unicellular: Yeasts Multicellullar: filamentous molds Mildews Wheat rust Corn smut Mushrooms Other fungi

Body Plans Filamentous molds Mold – consists of long, branched threads (filaments) “hyphae” Form a tangled mass/tissue “mycellium” Some coenocytic – large, multinucleated mass Some have septa – cross-walls with pores Dikaryotic – contain 2 genetically distinct nuclei Monokaryotic – contain only one nucleus See Figure 21-1

Fig. 21-1, p. 407

Fungus Have 2 distinct stages Vegetative stage Often goes unnoticed Conspicuous Reproductive stage The familiar form that people notice Mushrooms, puffballs, bracket fungi

Reproduction Sexual Fruiting bodies (the familiar forms of fungi) Ex: mushroom top Plasmogamy 2 different hyphae come together and cytoplasm fuses 2 haploid nuclei fuse (karyogamy) Results in diploid zygote nucleus Meiosis occurs; producing haploid spores

Reproduction Asexual Fission Budding Spore Formation Spores – nonmotile reproductive cells (wind & animals) Produce on aerial hyphae Allows air currents to disperse cells

Classification Based on: Characteristics of sexual spores Characteristics of fruiting bodies DNA & RNA sequences

Kingdom Fungi 5 Phyla Phylum Chytridiomycota (Chytrids) Phylum Zygomycota (Sporangium Fungi) Phylum Glomeromycota (Mycorrhizae) Phylum Ascomycota (Sac Fungi) Phylum Basidiomycota (Club Fungi)

Phylum Chitridiomycota: Chytrids Fungus that produce flagellated cells at some stage in its life Inhabit ponds, damp soil, & some in saltwater Most are decomposers, some cause diseases in plants and animals Most unicellular or few cells that compose a thallus a simple body that lacks roots, stems, or leaves & rhizoids anchor/root-like

Phylum Zygomycota Black Bread Mold Produce zygospores Coenocytic hyphae See figure 21-6

Fig. 21-6, p. 410 Zygomycetes

Phylum Glomeromycota Mycorrhizae – “Fungus Roots” a symbiotic association between fungus and plant root The roots supply the fungus with sugars, aminoacids, and other organic substances The mycorrhizal fungus benefits the plant by extending the reach of its roots helps plant take in more water and minerals Coenocytic (no septa) hyphae Asexual – blastospore (multinucleate spores)

Fig. 21-8, p. 412 Glomeromycetes

Fig a, p. 419

Fig b, p. 419

Phylum Ascomycota Sac Fungi Their spores are produced in little sacs called asci Hyphae usually have perforated septa Cytoplasm and nuclei can move from one cell to another Examples: Powdery mildews (cause food to spoil) Cup fungi Edible morels and truffles Yeasts Diseases caused: Dutch elm disease, chestnut blight, ergot disease on rye, mildew on fruits Nonmotile Sexual – ascospores (ascocarp=fruiting body) Asexual – spores called conidia

Fig a, p. 415 Ascomycetes

Phylum Basidomycota “Club Fungi” Mushrooms, bracket fungi, puffballs Parasites – wheat rust & corn smut Develop basidium & basidiospores Masses of hyphae form buttons Each button forms a mushroom = stalk + cap Called a “basidiocarp” Have gills on lower surface of cap

Fig , p. 416

Fig , p. 417

Phylum Basidomycota

Ecological Importance Decompose Release CO 2 to Plants Without fungus, minerals would be locked up in dead organic matter; life would cease

Ecological Importance Symbiotic relationships Animals (ex: cattle) cannot digest cellulose and lignin by themselves Fungi in gut do this Mycorrhizae and plant roots Lichens – symbiotic relationships between fungus + photosynthetic organism Ex: green alga or a cyanobacterium + ascomycete fungus

Fig , p. 420 Lichens

3 Growth Forms Crustose – flat and grow tightly attached to rock Foliose – Flat, leaflike lobes, not as tightly attached Fruticose – Grow erect, branched/shrublike

Lichens Tolerate extremes of temperature and moisture Do not grow in heavily polluted cities

Fungi are used to produce Beer – yeasts ferment grain (barley) Bread – yeast produce carbondioxide, and alcohol (evaporates during baking) Cheeses Wine – yeast ferments fruit sugars to become ethyl alcholol Penicillin – produced by a mold 200 species of edible mushrooms 70 poisonous No easy way to distinguish Some have similar chemicals as LSD – trancelike state and colorful visions Used for insecticides Prevent spreading of malaria

Fungal Diseases Superfical infections (only infect skin, hair, or nails) Ringworm Athlete’s foot Jock itch Candidiasis – yeast infection of mouth, throat, and vagina Opportunistic fungi (occur when immune system is compromised) Histoplasmosis – infection of lungs caused by inhaling the spores of a fungus abundant in bird droppings Liver damage and cancer Caused by mycotoxins commonly grow on peanuts, pecans, corn, and other grains