Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 31 Fungi

Fig. 31-1

Fungi Belong to own kingdom Unlike plants and animals Absorption of food Use of exoenzymes However, composed of Chitin, found in many arthropods, or insects. Primarily to absorb food underground, bodies composed of a network of tiny filaments are called Hyphae and the interwoven mass they form are called Mycelium. Movement

Fig Reproductive structure Spore-producing structures Hyphae Mycelium 20 µm

Division of Hyphae Septate hypha include septum, or “dividers” between different nuclei. Contain pores that allow flow of organelles Coenocytic hypha do not have septum. Resembles plasmodial slime molds Cytoplasmic streaming can take place in these hyphae, allowing the mycelium to grow around the origin of spore’s life. Porous Septa

Fig (b) Coenocytic hypha Septum (a) Septate hypha Pore Nuclei Cell wall

Mycorrhizal Fungi Some fungi have special hyphae to allow them to feed on living animals Haustoria enable fungi to penetrate the tissue of host Mutually beneficial relationship, deliver minerals. Ectomycorrhizal fungi: sheaths over root Endomycorrhizal fungi: sheaths through root

Fig (b) Haustoria (a) Hyphae adapted for trapping and killing prey Nematode Plant cell wall Haustorium Plant cell plasma membrane Plant cell Fungal hypha Hyphae 25 µm

Fig. 31-4a (a) Hyphae adapted for trapping and killing prey Nematode Hyphae 25 µm

Fig. 31-4b (b) Haustoria Plant cell wall Haustorium Plant cell plasma membrane Plant cell Fungal hypha

Fungi Reproduction Asexual Reproduction Clones are produced from mitotic production of spores. Some grow as mold or yeast. Yeast: budding. Budding may not produce same size cells. Also can reproduce sexually.

Fungi Reproduction Sexual Reproduction –Begins with the release of pheromones –Hyphae become attracted to source –Union of the cytoplasms of hyphae plasmogamy –Haploid nuclei contributed by both parents –Soon, later, or a long while both haploids form, which is karyogamy. Only diploid state –Meiosis begins, converting back to haploid and ensuring genetic variability with distribution of spores.

Fig Spores Spore-producing structures GERMINATION ASEXUAL REPRODUCTION Mycelium Key Heterokaryotic (unfused nuclei from different parents) Haploid (n) Diploid (2n)

Fig Spores Spore-producing structures GERMINATION ASEXUAL REPRODUCTION Mycelium Key Heterokaryotic (unfused nuclei from different parents) Haploid (n) Diploid (2n) SEXUAL REPRODUCTION KARYOGAMY (fusion of nuclei) PLASMOGAMY (fusion of cytoplasm) Heterokaryotic stage Zygote

Fig Spores Spore-producing structures GERMINATION ASEXUAL REPRODUCTION Mycelium Key Heterokaryotic (unfused nuclei from different parents) Haploid (n) Diploid (2n) SEXUAL REPRODUCTION KARYOGAMY (fusion of nuclei) PLASMOGAMY (fusion of cytoplasm) Heterokaryotic stage Zygote Spores GERMINATION MEIOSIS

Fig µm

Fig µm Parent cell Bud

Fungal Ancestors Fungi evolved from a flagellated ancestor –(many chytrids, a phylum of fungi, still posses a flagella) –Protists also share a similar ancestor –Animals, protists, and fungi are called Opishtokonts. Ancestor was unicellular Gradually moved toward land (diversity due to adaptive radiation)

Fig µm

Fig µm Host cell nucleus Developing microsporidian Spore

Fig Chytrids (1,000 species) Zygomycetes (1,000 species) Hyphae 25 µm Glomeromycetes (160 species) Fungal hypha Ascomycetes (65,000 species) Basidiomycetes (30,000 species)

Fig a Chytrids (1,000 species) Hyphae 25 µm

Fig b Zygomycetes (1,000 species)

Fig c Glomeromycetes (160 species) Fungal hypha

Fig d Ascomycetes (65,000 species)

Fig e Basidiomycetes (30,000 species)

Fig mm

Fig µm

Fig Tuber melanosporum, a truffle Morchella esculenta, the tasty morel

Fig Shelf fungi, important decomposers of wood Maiden veil fungus (Dictyphora), a fungus with an odor like rotting meat Puffballs emitting spores

Fig

Fig Both endophyte and pathogen present (E+P+) Endophyte not present; pathogen present (E – P+) Leaf area damaged (%) Leaf mortality (%) E+P+ E–P+ E+P+ RESULTS

Fungi relationships Decomposers Break down cellulose and lignin of plant cell walls. Also break down inorganic material, like jetfuel and wall paint. They help release essential elements to ecosystem like carbon and nitrogen

More Relationships Symbionts –Mycorrhizae (discussed earlier) –Fungus animal symbiosis: –Live in digestive tracts of animals (cows and termites) –Leaf-cutting ants depend on fungi to digest leaves to make food available for ants. –In some cases, one can’t live without the other.

Fig

Fungi Relationships again Parasitic –Exclusively benefits fungi at host’s expense –Many are diseases or infections –Lead to deaths of many plants, and the annoyance of animals

Pathogenic fungi Dutch Elm Disease (Ophiostoma ulmi) –Accidentally introduced from europe on logs during WWI as payment. Fungus carried by beetles on trees. Kills thousands of Dutch elms a year. Chestnut Blite(Cryphonectria parasitica) –Has killed almost 4 billion native american chestnut trees on the Eastcoast. Stem Rust (Puccinia graminis) –Agricultural pest that helps spoil 10-15% of world’s harvest each year

Pathogenic Fungi (Claviceps purpurea) Creates purple ergots on rye. If diseased rye is milled into flour and eaten, causes ergotism. Condition characterized by spasms, sensations. Etc. Infection called mycosis Lysergic acid isolated from ergots. Used in methamphetamine labs all over the world

Fig (c) Ergots on rye(a) Corn smut on corn (b) Tar spot fungus on maple leaves

Mycosis in animals Skin mycosis occurs on animals (not deadly now) –ringworm –Athlete’s foot Systemic mycosis also occurs on animals (deadly) –Coccidiomycosis, produces tuberculosis-like systems Opportunistic mycosis occur with changes of chemistry in organisms Yeast Infections (Candida albicans)

Chin- Ringworm Back- Yeast infection

Not all Fungi are bad! Food industry –Mushrooms –Morels and truffles –Alcohol –Baked goods Medicine –Antibiotics –Childbirthing

Fig Staphylococcus Zone of inhibited growth Penicillium

Fig. 31-UN6

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