KOUSIK_GHOSHEVOLUTION-FUNGI2020-04-05EVOLUTION-FUNGI.ppt
- 1. Kingdom Fungi • The characteristics of fungi • The evolution of the fungi • Fungal classification • Fungal life cycles
- 2. The Characteristics of Fungi • Body form * unicellular * filamentous (tube-like strands called hypha (singular) or hyphae (plural) * mycelium = aggregate of hyphae * sclerotium = hardened mass of mycelium that generally serves as an overwintering stage. * multicellular, such as mycelial cords, rhizomorphs, and fruit bodies (mushrooms)
- 3. The Characteristics of Fungi • Heterotrophy - 'other food' * Saprophytes or saprobes - feed on dead tissues or organic waste (decomposers) * Symbionts - mutually beneficial relationship between a fungus and another organism * Parasites - feeding on living tissue of a host. • Parasites that cause disease are called pathogens.
- 4. Heterotrophic by Absorption • Fungi get carbon from organic sources • Hyphal tips release enzymes • Enzymatic breakdown of substrate • Products diffuse back into hyphae Product diffuses back into hypha and is used Nucleus hangs back and “directs”
- 5. Fungi as Saprobes and Decomposers
- 6. Fungi as Symbionts (Mutualism)
- 7. Mycorrhizae • “Fungus roots” • Mutualism between: * Fungus (nutrient & water uptake for plant) * Plant (carbohydrate for fungus) • Several kinds * Zygomycota – hyphae invade root cells * Ascomycota & Basidiomycota – hyphae invade root but don’t penetrate cells • Extremely important ecological role of fungi!
- 8. Lichens • “Mutualism” between * Fungus – structure * Alga or cyanobacterium – provides food • Three main types of lichens: * Crustose lichens form flat crusty plates. * Foliose lichens are leafy in appearance, although lobed or branched structures are not true leaves. * Fruticose lichens are even more finely branched and may hang down like beards from branches or grow up from the ground like tiny shrubs.
- 9. Fungi as Parasites & Pathogens
- 12. Evolution of Fungi • Earliest fossil fungi * Fungal spores * 460 million years old
- 13. Opisthokonts • Sister taxon to Fungi: Nucleariids
- 14. Evolution of the fungi
- 18. Chytridiomycota – “chytrids” • Simple fungi • Produce motile spores - zoospores • Mostly saprobes and parasites in aquatic habitats • Could just as well be Protists Chytridium growing on spores Chytriomyces growing on pine pollen
- 19. Zygomycota – “zygote fungi” • Sexual Reproduction - zygosporangia • Asexual reprod. – common (sporangia – bags of asexual spores) • Hyphae have no cross walls • Grow rapidly • Decomposers, pathogens, and some form mycorrhizal associations with plants Rhizopus on strawberries Rhinocerebral zygomycosis
- 20. Life cycle of Rhizopus Asexual sporangium with spores inside Sexual zygsporangium with one zygospore
- 21. Ascomycota – “sac fungi” • Sexual Reproduction – asci (sing. = ascus) • Asex. Reprod. – common • Cup fungi, morels, truffles • Important plant parasites & saprobes • Yeast - Saccharomyces • Decomposers, pathogens, and found in most lichens A cluster of asci with spores inside
- 23. Basidiomycota – “club fungi” • Sexual Reproduction – basidia • Asexual reprod – not so common • Long-lived dikaryotic mycelia • Rusts & smuts –plant parasites • Mushrooms, polypores, puffballs, boletes, bird’s nest fungi • Enzymes decompose wood, leaves, and other organic materials • Decomposers, pathogens, and some form mycorrhizal associations with plants SEM of basidia and spores
- 24. Mushroom Life Cycle Nuclear fusion in basidium Meiosis Hyphal fusion of haploid mycelia haploid mycelium young basidia - the only diploid cells mycelium and fruiting body are dikaryotic N 2N N+N
- 26. Deuteromycota – Form Phylum “Imperfect Fungi” • Fungi that seldom or never reproduce sexually. • Asexual reproduction by vegetative growth and production of asexual spores common.