Chapter 14

1. Chapter 14 Fungi

2. Importance of Fungi Together with Heterotrophic bacteria Ecological decomposers

3. Decomposing fruit- Rhizopus

4. Root-rot fungus- white mycelial causes disease in living trees Acts as decomposers on dead plants

5. Root rot Ouch!!!

6. Fungi • Composed of Hyphae • Heterotrophic absorbers

7. Characteristics of Fungi • Composed of Hyphae Fungal filaments= “Cobwebby” strands of subterranean “white stuff” Mycelium

9. Fungi form important symbiotic relationships • 80% of all vascular plants species from mutually beneficial associations called mycorrhizae between roots and fungi • Plant nutrition • Lichens form symbiotic relationship with fungi, algal, or cyanobacterial cells

10. Fungi and insects • Endophytes- fungi live in plants produce toxic that protect host

11. Four phyla of fungi • Chytridiomycota • Zygomycota • Ascomycota next week lecture • Basidiomycota next week lecture

12. Chars of Fungi • All have cell wall • Cell wall composed of polysaccharide- chitin • Chitin more resistant to microbial degradation than cellulose

13. All Fungi Heterotrophic Absorbers • Unable to engulf small microorganisms • Secrete enzymes and absorb smaller molecules • Absorb food mostly at or near the growing tips of their hyphae

14. Fungi obtain their food • Either as Saprophytes or • As mutualistic symbionts

15. Some • Obtain energy through fermenation producing ethyl alcohol from glucose (i.e. yeast)

16. Fungi Store energy • Polysaccharide • Glycogen • Lipids

17. Fungi reproduce both sexually and asexually • Reproduce through the formation of spores that are produced sexually or asexually • Most are nonmotile spores • Some are dry and small and airborne • Some are slimy and stick to the bodies of insects and other arthropods • Some propel into air- phototropism

18. Common method of asexual reproduction in fungi • By means of spores • Either produced in sporangia • The sporangium is a saclike structure, the entire contents of which are converted into one or more spores

19. Asexual reproduction • Or • Hyphal cells called conidiogenous cells • Spores produced by conidiogenous cells occur singly or in chains called conidia

20. Asexual repro • Some Reproduce by fragmentation of their hyphae

22. Sexual reproduction • Three distinct phases • First two are phases of fertilization (syngamy) • Plasmogamy- the fusion of protoplasts • Karyogamy- the fusion of nuclei (some don’t fuse forming a dikaryon)

23. Give rise to gametes by differentiation Divide by mitosis gametangia 4 Spores

24. The last phase is meiosis • Sexual reproduction results in the formation of specialized spores such as zygospores, ascospores, basidiospores.

25. Zygospores • Zygospores • Asexual and sexual reproduction (by means of haploid spores) • Sexually producing zygospores require two compatible species

26. Zygomycetes: Phylum Zygomycota • Live on decaying plant and animal matter in soil • Some are parasites of plants, insects or small soil animals • Others form symbiotic relationships- endomycorrhizea- with plants occasionally cause infection in animals • Rhizopus stolonifer- best known zygomycetes

27. Life cycle of Rhizopus stolonifer

28. Gametangia the gamete producing structures are in the Process of producing a zygospore

29. Zygospore develops within the thick walled zygosporangium