Overview: Mighty Mushrooms Fungi Are diverse and widespread

1. Figure 31.1 • Overview: Mighty Mushrooms • Fungi • Are diverse and widespread • Are essential for the well-being of most terrestrial ecosystems because they break down organic material and recycle vital nutrients

2. Fungi are heterotrophs that feed by absorption • Despite their diversity • Fungi share some key traits

3. Nutrition and Fungal Lifestyles • Fungi are heterotrophs • But do not ingest their food • Fungi secrete into their surroundings exoenzymes that break down complex molecules • And then absorb the remaining smaller compounds

4. Fungi exhibit diverse lifestyles • Decomposers • Parasites • Mutualistic symbionts

5. Body Structure • The morphology of multicellular fungi • Enhances their ability to absorb nutrients from their surroundings

6. Fungi consist of • Mycelia, networks of branched hyphae adapted for absorption • Most fungi • Have cell walls made of chitin

7. Mycorrhizae • Are mutually beneficial relationships between fungi and plant roots

8. Fungi produce spores through sexual or asexual life cycles • Fungi propagate themselves • By producing vast numbers of spores, either sexually or asexually

9. Key Heterokaryotic stage Haploid (n) Heterokaryotic (unfused nuclei from different parents) PLASMOGAMY (fusion of cytoplasm) Diploid (2n) KARYOGAMY (fusion of nuclei) Spore-producing structures Zygote SEXUAL REPRODUCTION Spores ASEXUAL REPRODUCTION Mycelium MEIOSIS GERMINATION GERMINATION Spore-producing structures Spores Figure 31.5 • The generalized life cycle of fungi

10. Asexual Reproduction • Many fungi can reproduce asexually

11. 2.5 m Figure 31.6 • Many fungi that can reproduce asexually • Grow as mold, sometimes on fruit, bread, and other foods

12. 10 m Parent cell Bud Figure 31.7 • Other asexual fungi are yeasts • That inhabit moist environments • Which produce by simple cell division

13. Fungi descended from an aquatic, single-celled, flagellated protist • Systematists now recognize Fungi and Animalia as sister kingdoms • Because fungi and animals are more closely related to each other than they are to plants or other eukaryotes

14. The Origin of Fungi • Molecular evidence • Supports the hypothesis that fungi and animals diverged from a common ancestor that was unicellular and bore flagella • Fungi probably evolved • Before the colonization of land by multicellular organisms

15. 50 m • The oldest undisputed fossils of fungi • Are only about 460 million years old Figure 31.8 

16. The Move to Land • Fungi were among the earliest colonizers of land • Probably as symbionts with early land plants

17. Fungi have radiated into a diverse set of lineages • The phylogeny of fungi • Is currently the subject of much research • Molecular analysis • Has helped clarify the evolutionary relationships between fungal groups, although there are still areas of uncertainty

18. Arbuscular mycorrhizal fungi Zygote fungi Club fungi Sac fungi Chytrids Zygomycota Ascomycota Basidiomycota Glomeromycota Chytridiomycota Figure 31.9 • The phylogeny of fungi

19. Table 31.1 • A review of fungal phyla

20. Chytrids • Fungi classified in the phylum Chytridiomycota, or chytrids • Are found in freshwater and terrestrial habitats • Can be saprobic or parasitic

21. 25 m Hyphae Flagellum 4 m Figure 31.10 • Chytrids are unique among fungi • In having flagellated spores, called zoospores

22. Zygomycetes • Fungi in the phylum Zygomycota, the zygomycetes • Exhibit a considerable diversity of life histories • Include fast-growing molds, parasites, and commensal symbionts • Are named for their sexually produced zygosporangia

23. Figure 31.13 0.5 mm • Some zygomycetes, such as Pilobolus • Can actually “aim” their sporangia toward conditions associated with good food sources

24. Zygosporangia, which are resistant to freezing and drying • Are capable of persisting through unfavorable conditions • Can undergo meiosis when conditions improve

25. Ascomycetes • Fungi in the phylum Ascomycota • Are found in a variety of marine, freshwater, and terrestrial habitats • Are defined by the production of sexual spores in saclike asci, which are usually contained in fruiting bodies called ascocarps

26. (a)The cup-shaped ascocarps (fruiting bodies) of Aleuria aurantia give this species its common name: orange peel fungus. (b) The edible ascocarp of Morchella esculenta, the succulent morel, is often found under trees in orchards. 10 m (c)Tuber melanosporum is a truffle, an ascocarp that grows underground and emits strong odors. These ascocarps have been dug up and the middle one sliced open. (d)Neurospora crassa feeds asa mold on bread and other food (SEM). Figure 31.16a–d • Ascomycetes • Vary in size and complexity from unicellular yeasts to elaborate cup fungi and morels

27. Ascomycetes reproduce • Asexually by producing enormous numbers of asexual spores called conidia

28. Basidiomycetes • Fungi in the phylum Basidiomycota • Include mushrooms and shelf fungi • Are defined by a clublike structure called a basidium, a transient diploid stage in the life cycle

29. (b) Maiden veil fungus (Dictyphora), a fungus with an odor like rotting meat (a) Fly agaric (Amanita muscaria), acommon species in conifer forests in the northern hemisphere (d) Puffballs emitting spores Figure 31.18a–d (c) Shelf fungi, important decomposers of wood • Basidiomycetes

30. Figure 31.19 • The life cycle of a basidiomycete • Usually includes a long-lived dikaryotic mycelium, which can erect its fruiting structure, a mushroom, in just a few hours

31. Fungi have a powerful impact on ecosystems and human welfare

32. Decomposers • Fungi are well adapted as decomposers of organic material • Performing essential recycling of chemical elements between the living and nonliving world

33. Symbionts • Fungi form symbiotic relationships with • Plants, algae, and animals

34. Mycorrhizae • Mycorrhizae • Are enormously important in natural ecosystems and agriculture • Increase plant productivity RESULTS RESULTS

35. Fungus-Animal Symbiosis • Some fungi share their digestive services with animals • Helping break down plant material in the guts of cows and other grazing mammals

36. Figure 31.22 • Many species of ants and termites • Take advantage of the digestive power of fungi by raising them in “farms”

37. (a) A fruticose (shrub-like) lichen Figure 31.23a–c (b) A foliose (leaf-like) lichen (c) Crustose (crust-like) lichens Lichens • Lichens • Are a symbiotic association of millions of photosynthetic microorganisms held in a mass of fungal hyphae

38. The fungal component of a lichen • Is most often an ascomycete • Algae or cyanobacteria • Occupy an inner layer below the lichen surface

39. (b) Tar spot fungus on maple leaves (a) Corn smut on corn (c) Ergots on rye Figure 31.25a–c Pathogens • About 30% of known fungal species • Are parasites, mostly on or in plants

40. Some of the fungi that attack food crops • Are toxic to humans

41. Practical Uses of Fungi • Humans eat many fungi • And use others to make cheeses, alcoholic beverages, and bread

42. Staphylococcus Penicillium Zone of inhibited growth Figure 31.26 • Antibiotics produced by fungi • Treat bacterial infections

43. Genetic research on fungi • Is leading to applications in biotechnology