1. Kingdom Fungi

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. fruiting bodies
both are composed of hyphae
mycelium

4. The Characteristics of Fungi
Heterotrophyic- '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

5. Heterotrophic by Absorption
Fungi get carbon from organic sources
Hyphal tips release enzymes
Enzymatic breakdown of substrate
Products diffuse back into hyphae
Enzymatic breakdown
Most enzyme release (and absorption) at tips
Proteins and other materials synthesized by the entire mycelium are channeled by cytoplasmic streaming to the tips of the extending hyphae.
Nucleus hangs back
and “directs”
Products
Enzymes
Product diffuses back
into hypha and is used

6. Hyphae Tubular Hard wall of chitin
Crosswalls may form compartments (± cells)
Multinucleate
Grow at tips
Chitin is the same material used by Arthropods (Insects, crabs, etc.) in their exoskeletonsa
Nuclei of fungi are hard to see without stains

7. Hyphal growth Hyphae grow from their tips
Mycelium = extensive, feeding web of hyphae
Mycelia are the ecologically active bodies of fungi
This wall is rigid
Only the tip wall is plastic and stretches

8. Modifications of hyphae

9. Fungi as Saprobes and Decomposers

10. Fungi as Symbionts (Mutualism)

11. Mycorrhizae “Fungus roots” Mutualism between: Several kinds
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!
Half of the mushroom-forming fungi (basidiomycota) form mycorrhizas with trees
Some people think that the spongy tissue in roots evolved as a place where fungi could invade to form early links with plants that helped them survive the harsh life on early earth

12. “Ecto” mycorrhizae
Russula mushroom mycorrhizae on Western Hemlock root
Mycorrhiza cross sections
4 of the regions where mycorrhizas are found are circled.
These are “ecto” because the hyphae remain outside the root cells (though they extend inside the root)
Fungal hyphae around root and between cells

13. Lichens “Mutualism” between Fungus – structure
Alga or cyanobacterium – provides food
Three main types of lichens:
Crustose lichens form flat crusty plates, e.g., on rocks
Foliose lichens-leafy in appearance, although structures are not true leaves.
Fruticose lichens-more finely branched and may hang down like beards from branches or grow up from the ground like tiny shrubs.
Thallus is a plant-like body that doesn’t have roots, stems or leaves
Thallus doesn’t look like either partner
Dual nature of thalli was not fully understood until early 1900’s
Fungus gives the name to the lichen (by agreement)
Fungus usually, but not always, an Ascomycote (in 8+ independent orders)
Algae green. If bluegreen bacteria present, lichens fix nitrogen (turn atmospheric nitrogen into amino acid nitrogen in proteins)

14. Lichen internal structure
Lichens are nature’s biological monitors of pollution and air quality
Thalli act like sponges
Some species more sensitive to pollution
Which species are present can indicate air quality
Most resistant species can also be analyzed for pollutants, including bioaccumulation of heavy metals and radioactive isotopes
The nature of lichen symbiosis is may also be described as mutual exploitation instead of mutual benefit.
Lichens live in environments where neither fungi nor algae could live alone.
While the fungi do not not grow alone in the wild, some (but not all) lichen algae occur as free-living organisms.
If cultured separately, the fungi do not produce lichen compounds and the algae do not “leak” carbohydrate from their cells.
In some lichens, the fungus invades algal cells with haustoria and kills some of them, but not as fast as the algae replenish its numbers by reproduction.
Lobaria oregana prefers old-growth conifer canopies in forests with clean air.

15. Fungi as Parasites & Pathogens

16. Fungi are Spore-ific!!!
Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin.
Purpose of Spores
Allows the fungus to move to new food source.
Resistant stage-allows fungus to survive periods of adversity.
Means of introducing new genetic combinations into a population

17. Reproduce by spores Spores are reproductive cells Formed:
Sexual (meiotic in origin)
Asexual (mitotic in origin)
Formed:
Directly on hyphae
Inside sporangia
Fruiting bodies
Fungi reproduce by releasing spores that are produced either sexually or asexually.
The output of spores from one reproductive structure is enormous, with the number reaching into the trillions.
Dispersed widely by wind or water, spores germinate to produce mycelia if they land in a moist place where there is food.
Penicillium hyphae with conidia
Pilobolus sporangia
Amanita fruiting body

18. Hyphal growth from spore
germinating
spore
Fungal mycelia can be huge, but they usually escape notice because they are subterranean.
One giant individual of Armillaria ostoyae in Oregon is 3.4 miles in diameter and covers 2,200 acres of forest,
It is at least 2,400 years old, and weighs hundreds of tons.
(Actually noone has seen this of this extent – but cultures have been taken from soil over that area and all isolates have been found to be the same individual)
Ten cubic centimeters of rich organic soil may have fungal hyphae with a surface area of over 300 cm2
mycelium
Mycelia have a huge surface area

19. The Characteristics of Fungi
Fungus is often hidden from view. It grows through its food source (substratum), excretes extracellular digestive enzymes, and absorbs dissolved food.
Indeterminate clonal growth.
Vegetative phase of fungus is generally sedentary.

20. The Characteristics of Fungi
Cell wall present, composed of cellulose and/or chitin.
Food storage - generally in the form of lipids and glycogen.
Eukaryotes - true nucleus and other organelles present.
All fungi require water and oxygen (no obligate anaerobes).
Fungi grow in almost every habitat imaginable, as long as there is some type of organic matter present and the environment is not too extreme.
Diverse group, number of described species is somewhere between 69,000 to 100,000 (of the estimated 1.5 million species total).

21. Generalized Life Cycle of a Fungus

22. Molecular studies indicate that animals, not plants, are the closest relatives of fungi.
Both Animals and Fungi are related most closely to a group of Protists known as the choanoflagellates (collar flagellates)
Kingdom began in ocean during Precambrian (Late Proterozoic era)
More than 100,000 species of fungi are known and mycologists estimate that there are actually about 1.5 million species worldwide.
Evolution of the fungi

23. Classification & Phylogeny
asci
basidia
The phyla of fungi are determined by
1. motility of spores
2. nature of sexual stage
Fungi moved onto land with the plants in the Early Paleozoic
Much of the evolution of fungi was in conjunction with the evolution of plants and plant parts
For example, when roots evolved, fungi were there and helped (mycorrhizas)
When wood evolved, fungi evolved to take advantage of it
Other evolutionary changes related to animals
zygosporangia
Classification & Phylogeny
motile spores

24. Chytridiomycota – “chytrids”
Simple fungi
Produce motile spores - zoospores
Mostly saprobes and parasites in aquatic habitats, e.g. those devastating amphibian populations
Could just as well be Protists
Chytridium growing on spores
Classified in CMR as true fungi (because of their molecular relationships)
Remainder of the phyla are almost exclusively terrestrial (a few molds on wet plant material)
Chytriomyces on pine pollen

25. Zygomycota – “zygote fungi”
Sexual - zygosporangia
Asexual – 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
Most of the 600 zygomycote, or zygote fungi, are terrestrial, living in soil or on decaying plant and animal material.
Asexual reproduction in sporangia
One zygomycote group form mycorrhizas, mutualistic associations with the roots of plants.
Rhinocerebral zygomycosis

26. Sexual zygsporangium with one zygospore
Asexual sporangium with spores inside
Life cycle of Rhizopus, a saporobe that may be opportunistically infectious in humans

27. Ascomycota – “sac fungi”
Sexual reproduction – ascus (asci)
Asexual – common
Cup fungi, morels, truffles
Important plant parasites & saprobes
Yeast - Saccharomyces
Decomposers, pathogens, and found in most lichens
Mycologists have described over 60,000 species of ascomycetes, or sac fungi.
Ascomycota tend to grow from spore to spore in one year and relate well to living plant tissues
There is diverse form in the growth and fruiting structures – yeasts to morels, many intermediate (and small)
Asexual reproduction by conidia (externally produced, not in sporangia)
Half of the Ascomycota form lichens (evolved 8 or more times in different orders) but not all lichens are Ascomycotes
A cluster of asci with spores

28. Sac fungi diversity
This begins the first of several photographic reviews of fungal diversity. Enjoy the pictures and try and get a feeling of some of the different forms these fungi take and their roles in the environment.

29. Basidiomycota – “club fungi”
Sexual reproduction – basidia
Asexual – 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
Asexual spores conidia
Ecologically important on wood as decomposers and parasites
Half the mushrooms form mycorrhizas
SEM of basidia and spores

30. Mushroom Life Cycle haploid mycelium N 2N N+N Meiosis
mycelium and fruiting
body are dikaryotic
Hyphal fusion of haploid mycelia
haploid mycelium
Mushroom Life Cycle
N N N+N
Meiosis
Nuclear fusion in basidium
young basidia - the only diploid cells

31. Bioluminescence in Mycena

32. Some fungi have more than one scientific name – Why?
Teleomorph: the sexual reproductive stage (morph), typically a fruiting body (e.g., Morchella esculenta, Agaricus brunescens).
Anamorph: an asexual reproductive stage (morph), often mold-like (e.g. Aspergillus flavus, Fusarium solani). When a single fungus produces multiple morphologically distinct anamorphs, they are called synanamorphs.
Holomorph: the whole fungus, including all anamorphs and the teleomorph.

33. Deuteromycota – Form Phylum “Imperfect Fungi”
Fungi that seldom or never reproduce sexually.
Asexual reproduction by vegetative growth and production of asexual spores common.

34. Yeasts Single celled fungi Adapted to liquids Plant saps Water films
Moist animal tissues
Bread and wine yeast, the budding yeast, Saccharomyces
Easily cultured. For a time, this was the most important organism for studying the molecular genetics of eukaryotes
Thus, Saccharomyces is arguably the most important organism known to humans
Candida causes diseases of humans, usually experiencing chemical imbalance or immune problems
Candida
Saccharomyces

35. Molds Rapidly growth Asexual spores Many human importances
Food spoilage
Food products
Antibiotics, etc.
A mold is a rapidly growing, asexually reproducing fungus.
The mycelia of these fungi grow as saprobes or parasites on a variety of substrates.
Also used in foods (Blue cheese, Tempeh) and in industrial production of drugs
Early in life, a mold, a term that applies properly only to the asexual stage, produces asexual spores.
Later, the same fungus may reproduce sexually, producing zygosporangia, ascocarps, or basidiocarps
Some molds go through a “fake sex” process
Noble Rot - Botrytis
Antibiotic activity

36. HUMAN-FUNGUS INTERACTIONS
Beneficial Effects of Fungi
Decomposition - nutrient and carbon recycling
Biosynthetic factories. Can be used to produce drugs, antibiotics, alcohol, acids, food (e.g., fermented products, mushrooms)
Model organisms for biochemical and genetic studies
Harmful Effects of Fungi
Destruction of food, lumber, paper, and cloth
Animal and human diseases, including allergies
Toxins produced by poisonous mushrooms and within food (e.g., grain, cheese, etc.)
Plant diseases.