1. Chapter 22
Fungi Evolution
And Diversity

2. Although fungi were once classified as plants, they are more like animals
Fungi are heterotrophs, but digest their food externally and then absorb it
Largest living organism is a honey mushroom which covers 2200 acres underground in Blue mountains of Oregon

3. Fungi release digestive enzymes into the environment then absorb the resulting nutrients
Chytrids are different from all other fungi because they are aquatic and have flagellated spores and gametes
Fungi trace their ancestry to protists and share common ancestor with animals after plants split away
Most likely ancestor of fungi and animals was a flagellated unicellular protist
Very early plant fossils have mycorrhizae associations
Some fungi including yeasts are unicellular, but vast majority are multicellular

4. Thallus or body of most fungi is a multicellular structure called a mycelium
A mycelium is a network of filaments called hyphae allowing a large surface area to volume ratio

5. Fungal cells are quite different from plant cells because they lack chloroplasts and have cell walls that contain chitin not cellulose
Chitin is a polymer of glucose molecules with a nitrogen-containing amino acid group attached to it
Fungi store energy in glycogen like animals
Terrestrial fungi lack mobility and move toward food by growing the hyphae
Fungi that have cross walls are called septate
Nonseptate fungi are multinucleated with many nuclei in hyphae cytoplasm

6. Terrestrial fungi sexual reproduction involves these steps
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Terrestrial fungi sexual reproduction involves these steps
During sexual reproduction, hyphae from two different mating types make contact and fuse
Paired haploid nuclei n + n is called dikaryotic
They eventually fuse
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haploid
hyphae
dikaryotic
stage
diploid
zygote
meiosis

7. As adaptations to life on land, fungi produce nonmotile, but windblown sexual and asexual spores
Spore is a reproductive cell that develops into new organism without need to fuse with another reproductive cell
Large mushrooms may produce billions in a few days
When a spore lands on an appropriate food source, it germinates and begins to grow
R.H. Whittaker separated fungi from the other eukaryotic kingdoms because they are the only multicellular saprotrophs
Today some place fungi in supergroup Opisthokonts with animals and certain heterotrophic protists

8. Fungi differentiated by life cycle and type of structure used to produce spores:
Chytrids are the simplest and resemble first fungi
They are aquatic or live on moist soil with flagellated cells
Most reproduce asexually, but some have an alternation of generations life cycle like green plants and some algae

9. Zygospore fungi are saprotrophic living on plant and animal remains or bakery goods
Black bread mold, Rhyopus stolonifer, is often found on bread
Stolons are horizontal hyphae on the surface of the bread and rhizoids grow into the bread to carry out digestion
A sporangium is a capsule that produces spores called sporangiospores
Hyphae of opposite mating types, termed plus and minus, are chemically attracted, touch, and form gametangia

10. These merge and result in a large nucleate cell where mating types pair and fuse
It becomes a zygospore that undergoes meiosis and germination

11. AM fungi stands for arbuscular mycorrhizal fungi
Arbuscules are branching invaginations the fungus makes as it invades plant roots
Mycorrhizae are a mutualistic association that benefits both fungus and plant
Sac fungi are divided into two main groups: the sexual sac fungi in which sexual reproduction has been known and
Asexual sac fungi in which sexual reproduction has not been observed
Examples of sexual sac fungi include:
Yeast, Saccharmyces, that are used in baking and brewing industries

12. Neurospora, the experimental material for one-gene-one-enzyme studies
Red bread molds, morels, and truffles
Asexual sac fungi were in the phylum Deuteromycota, the imperfect fungi
They include yeast Candida and molds Aspergillus and Penicillium which is now named Talaromyces

13. Asexual reproduction in sac fungi is the norm
Yeasts reproduce by budding where a small cell forms and pinches off as it grows to full size
Others produce spores called conidiospores
The conidia develop at the tips of specialized aerial hyphae called conidiophores
Sexual reproduction in sac fungi includes an ascus or sac that develops during sexual reproduction
A fruiting body is a reproductive structure where spores are produced and released
Because mitosis follows meiosis, each ascus contains eight haploid nuclei and produces eight spores

14. Sac fungi are essential in decomposing materials containing cellulose, lignin, or collagen
Some are symbiotic with algae to form lichens while others with plant roots to form mycorrhizae. Some are pathogens causing powdery mildews, leaf curl, chestnut blight, and Dutch elm disease
Ergot infects rye and other grains
Produces the drug penicillin used against infections and cyclosporine that suppresses immune response in transplantation operations
Others used to make foods like blue cheese
Some diseases include ringworm, rose gardener’s disease, Chicago disease, and basketweaver’s disease

15. Yeasts are both beneficial and harmful
Used to make wines and beer and cause bread to rise in baking
When normal balance of microbes is distrubed in organs like the vagina, yeast like Candida albicans causes inflammation
Molds like Aspergillus used to make soy sauce, citric acid, inks, medicines, dyes, plastics, toothpaste, soap, and chewing gum
Others like Aspergillus flavus grows on moist seeds and is the most potent natural carcinogen known
Mold Stachybotrys chartarum or black mold causes “sick-building” syndrome

16. Athlete’s foot and ringworm are termed tineas
Fig. 22.8
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Athlete’s foot and ringworm are termed tineas a. b.
a: © Dr. P. Marazzi/SPL/Photo Researchers, Inc.; b: © John Hadfield/SPL/Photo Researchers, Inc.

17. Club fungi are the mushrooms, toadstools, puff balls, shelf fungi, jelly fungi, bird’s nest fungi, stinkhorns, smuts, and rusts
At least 75 species are poisonous
Most are saprotrophs with some parasitic species
Possess a basidium or club-shaped structure in which spores called basidospores form
Smuts and rusts are club fungi that parasitize cereal crops like corn, wheat, oats, and rye

18. © R. Calentine/Visuals Unlimited
Fig. 22B
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ergot
© R. Calentine/Visuals Unlimited

19. Lichens are an association between fungus, usually sac fungus, and a cyanobacterium or green algae
They were assumed to be mutualistic, but may involve a controlled form of parasitism of the algal cells by the fungus with no benefit to algae
Mycorrhizae are mutualistic relationships between soil fungi and roots of most plants
Plants grow more successfully in poor soils especially those deficient in phosphates with mycorrhizae