1. Downloded from www.pharmacy123.blogfa.com
Chapter 31: Fungi
Downloded from

2. Variations on the Fungi Theme
Mushrooms are sexual structures (fruiting bodies)
The bulk of fungal mass is found within their food
Variations on the Fungi Theme
Fungi which do not have sex (including most molds and yeasts) are described as imperfect fungi, or deuteromycete

3. Fungal Ecology Fungi along with bacteria are the principle decomposers
The secrete exoenzymes to digest nutrients extracellularly, which are then brought into cells directly across plasma membranes
Fungi (especially club fungi) are virtually the only organism capable of breaking down lignin (the stuff that makes wood woody)
Some fungi act as disease-causing organisms of animals and, especially, of plants (mycosis = fungus-caused disease)
Fungi produce antibiotics (e.g., Penicillin) which they use to limit ecological competition from bacteria
We take advantage of fungus-mediated decomposition in the production of bread, beer, wine, cheeses, and soy sauce!
Fungal Ecology

4. Recall that fungi have chitin cell walls
All “fungi are heterotrophs that feed by adsorption.” p. 608, Campbell & Reece (2005)
Recall that fungi have chitin cell walls
Fungi Phyla
Also, befitting terrestrial adapted organisms, all fungi except that chytrids have no flagellated stage

5. A Multicellualr Fungus
Hyphae are tubular filaments of cells
A Multicellualr Fungus
Mycelia are tangled masses of hyphae

6. Separation Between Cells
Cytoplasms are continuous, even nuclei cans move between cells
Free movement of everything
Movement of water and nutrients between cells is rapid because septa are either porous or absent

7. Fungi grow into their food
Hyphae
A single gram of rich, fungus-containing soil may have as much as a kilometer of hyphae within it
“The fungus concentrates its energy and resources on adding hyphal length and thus overall absorptive surface” p. 609, Campbell & Reece (2005)
Fungi grow into their food

8. General Fungi Life Cycle
Dikaryotic if “hetero” is 2 haploid nuclei/cell
Note mostly haploid or heterokaryotic
Diploid only transient in most fungal species
Mitosis products

9. Molds are asexually reproducing (i. e
Molds are asexually reproducing (i.e., spore-forming), filamentous fungi (i.e., not yeasts)
Molds
This is the mold Penicillium from which the antibiotic penicillin is isolated

10. Penicillium as Antibacterial

11. Yeasts tend to inhabit very moist habitats, which includes plant and animal tissues
Yeasts are single-celled fungi
Yeasts
Yeasts tend to grow asexually (no spores)
Yeasts as a taxon would be polyphyletic

12. Animals are the fungal sister group
Fungal Phylogeny
Animals are the fungal sister group
The move to land

13. Chitrids are “primitive” fungi that retain flagella on their zoospores
Chytrids
Chitrids are found especially in very moist environments

14. Chytrids

15. Zygomycetes
Zygomycetes are named for their zygosporangia, which are a multinucleate, pre-meiotic resistant stage

16. Zygomycete Life Cycle

17. Zygomycetes: Zygote Fungi
Glomeromycetes are endomycorrhizal fungi which live as mutualistic symbionts with plants

18. Plants w/ & w/o Mycorrhizae

19. Glomeromycete
Mycorrhizal fungi are to plants what the fungi in lichens are to the mutualistic algae
Mycorrhizal fungi supply plants with minerals in exchange for organic molecules
Arbuscular mycorrhizae
These are endomycorrhizal fungi branched hyphal tips surrounded by plant plasma membrane
Invagination into a plant cell
This is a plant cell wall

20. Ascomycetes: Sac Fungi
Asexually produced reproductive cells are called conidia
Ascomycete form asci, which are linear sacs containing eight ascospores
Have extended dikaryotic stage
Ascomycetes: Sac Fungi
In many the ascomycetes the asci are arrayed into fruiting bodies called ascocarps
Many ascomycetes are important plant saprobes: they decompose dead plant material

21. Asci with Ascospores
Sordaria macrospora is a filamentous ascomycete which is closely related to Neurospora crassa. But in contrast to Neurospora, Sordaria is homothallic, which means that a single strain produces fruiting bodies without the need for a partner of opposite mating type. The life cycle of S. macrospora is shown in the picture. It starts with an ascospore which germinates and produces a mycelium. Within a week, fruiting bodies develop in which asci are produced that contain eight ascospores each. The ascospores are ejected from the fruiting body and the cycle starts again.

22. Ascomycetes: Sac Fungi
These are not mushrooms!!!
They are ascocarps
Ascomycetes: Sac Fungi

23. Ascomycete Life Cycle

24. Basidiomycetes: Club Fungi
Both mushrooms and shelf fungi are club fungi
Club fungi are not limited to just mushrooms and shelf fungi, however
Basidiocarps produce basidiospores
Basidiomycetes: Club Fungi
Like sac fungi, have a long-lived dikaryotic stage
Best lignin decomposers of all fungi

25. Mushrooms, etc., are basidiocarps
“By concentrating growth in the hyphae of mushrooms, a basidiomycete mycelium can quickly erect its fruiting structures in just a few hours” p. 618, Campbell & Reece (2005)
Basidiocarps

26. Basidicarps and Basidia
Basidia with basidiospores

27. Basidiomycete Life Cycle

28. Lichen are Symbioses

29. Protection, minerals, water, anchoring
Reduced carbon
Fixed nitrogen
Protection, minerals, water, anchoring
Lichen Anatomy

30. Plant Pathogenic Fungi

31. The End