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MycologyMycology

Myco = fungus ology = the study of

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Classification of FungiClassification of Fungi Domain Eukarya Kingdom Fungi Phylum -mycota Class -mycetes Order -ales Family -aceae Genus Species

Domineering King Philip Can Order Five Green Shirts

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Pizza with Pizza with Agaricus bisporusAgaricus bisporus

Domain Eukarya Kingdom Fungi Phylum Basidiomycota Class Hymenomycetes Order Agaricales Family Agaricaceae Genus Agaricus Species Agaricus bisporus

White Button Mushroom

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Fungi are probablyFungi are probablymore closely related tomore closely related toanimals that to eitheranimals that to either

plants or protists! plants or protists!

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Characteristics of FungiCharacteristics of Fungi Eukaryotic Non vascular organisms Reproduce by means of

spores Both sexual (meiotic) and

asexual(mitotic) spores may be produced

Typically Non Motile Alteration of generations

– like plants

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Vegetative BodyVegetative Body

Molds: Microscopic threads of cells (hyphae)

Yeasts: UnicellularHyphae a system of thread like, walled, more or less cylindrical cells

singular hypha

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Hyphal GrowthHyphal Growth

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Cell wallsCell walls

– simple chemical composition– fungi cell walls are mostly chitin

chitin synthesized by fungi

– plant cell walls are mostly cellulose (plus lignin in secondary walls)

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ChitinChitin

Resists bacterial degradation

Used in sutures

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CelluloseCellulose

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Cell membranesCell membranes

ergosterol, a unique sterol mammaliam membranes have cholesterol

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Fungal TraitsFungal Traits Heterotrophs

– (“other feeding,” ) must feed on preformed organic material. – Fungi digest then ingest

produce exoenzymes

– Animals ingest then digest Food stored as glycogen

– animal store glycogen– plants store starch

Lysine biosynthesis – different pathway

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More Fungal TraitsMore Fungal Traits Cytoplasmic ultrastructure

– similar to plants cells– significantly different organelles and structures

Mitosis is generally accomplished without dissolution of the nuclear envelope

Tubule protein– different type formed in microtubules during nuclear

division Very small nuclei

– little repetitive DNA

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Lack of Chlorophyll profoundly Lack of Chlorophyll profoundly affects the lifestyle of fungi affects the lifestyle of fungi

not dependent on light can occupy dark habitats can grow in any direction can invade the interior of

the substrate with absorptive filaments

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Vegetative GrowthVegetative Growth

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Anatomy of YeastAnatomy of Yeast

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Nutritional Status of FungiNutritional Status of Fungi

Saprophytes Parasites Mutualists (symbionts)

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SaprophytesSaprophytes use non-living organic material important scavengers in ecosystems Fungi are important in recycling Carbon,

Nitrogen, and essential mineral nutrients.– Along with bacteria

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Fungal ParasitesFungal Parasites use organic material from living organisms,

harming them in some way.

Adhesive Knobs

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Fungal ParasitesFungal Parasites range of hosts: from single celled diatoms to fungi

to plants to animals to humans.

Trapped nematode

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A fungal predatorA fungal predator

Oyster fungus traps a nematode in a ring of hyphae

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Mutualists (symbionts)Mutualists (symbionts)

Fungi that have a mutualistically beneficial relationship with other living organisms. – Mycorrhizae: associations of fungi with plants

roots – Lichens: associations of fungi with algae or

cyanobacteria

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MycorrhizaeMycorrhizae

Plant- Fungal Symbiont– more than 90% of plants in nature have a

mycorrhizal symbiont. Mycorrhizae forms

– ectomycorrhizae – endomycorrhizae

Myco= fungus rhiza= root

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Types of MycorrhizaeTypes of Mycorrhizae

Ectomycorrhizae-- fungus forms a sheath outside the root

Endomycorrhizae--vesicular-arbuscular mycorrhizae (VAM), no sheath

Orchid mycorrhizae are a special type

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EctomycorrhizaeEctomycorrhizae Fungus forms a sheath around the root,

with hyphae emanating through the soil, greatly increasing the surface area

fungus penetrates between cells of the cortex to facilitate nutrient exchange

fungus is almost always a Basidiomycota, although a few are Ascomycota species

dichotomous ectomycorrhizas (upper) and mycelial strands

(lower) of Amanita muscaria on Pinus strobus.

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EndomycorrhizaeEndomycorrhizae AKA vesicular-arbuscular mycorrhizae (VAM) fungus does not form a sheath around the roots

– fungus penetrates the cortical cells,– but does not penetrate the cell membrane

fungus is a member of Zygomycota more common than ectomycorrhizae

hyphae and arbuscules of an endomycorrhizal fungus in Asarum (wild ginger) (see Fig 15 in Brundrett & Kendrick 1988 Can. J. Bot. 66: 1153)

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LichensLichens symbiosis between a

fungus and an alga or cyanobacterium

usually neither can survive on its own

most of the fungi involved are Ascomycota -- a few are Basidiomycota

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Lichen EcologyLichen Ecology Lichens can grow in very

inhospitable environments-- on rocks, sides and branches of trees, gravestones

Lichens are very sensitive to air pollution, especially sulfur and nitrogen, and so they are natural indicators of air quality

Lichens grow extremely slowly,~ 1-2 mm per year

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Lichen UsesLichen Uses lichens break down rocks into soil food source for caribou and reindeer on the

tundra, reindeer lichens natural dyes, tweed one lichen was used by the “pioneers” as a wolf

killer. There is evidence that the manna referred to in the

Bible was really a lichen, Lecanora esculenta, that blew down from the mountains

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CommensalismCommensalism One organism uses another to get a better position in the environment

– neither organism is harmed

– there is usually no physiological interaction between the two organisms most often for photosynthesis

– advantages in shaded areas

– very common in rainforests may also be for reproductive advantages

– some fungi “climb” up trees and vines (while not gaining nutrition from them) in order to release their spores from as high a perch as possible

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Fungi are veryFungi are verysuccessful Organisms successful Organisms

genetic plasticity– physiological versatility.

Spores– enormous numbers – effectively spread over a wide area. – asexual (mitotic) and sexual (meiotic) spores. – spores can remain dormant until conditions become

favorable sometimes years (King Tut Beer)

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Many fungi are harmfulMany fungi are harmfulto human intereststo human interests

can cause human disease, either directly or through their toxins

an cause diseases of plants and animals that humans are interested in (e.g. crops, etc.)

cause rot and contamination of foods can destroy almost every kind of

manufactured good– with the exception of plastics and some pesticides

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Many fungi are veryMany fungi are veryuseful to humansuseful to humans

yeasts-- baking and brewing antibiotics--- e.g. penicillin & cephalosporin other drugs-- e.g. cyclosporin many organic acids are commercially produced with

fungi-- e.g. citric acid in Coke is produced by an Aspergillus

steroids and hormones--- e.g. the pill certain “stinky” cheeses-- e.g. blue cheese,

Roquefort and Camembert

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Fungi are importantFungi are importantexperimental organismsexperimental organisms

easily cultured, occupy little space, multiply rapidly, short life cycle. study metabolite pathways study growth, development, and differentiation mechanisms of cell division and development microbial assays of vitamins and amino acids

genetics-- e.g. “one gene one enzyme” in Neurospora won Beadle and Tatum the Nobel prize

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Asexual and SexualAsexual and SexualReproduction in fungiReproduction in fungi

Teleomorph: The sexual (perfect, meiotic) state of a fungus

Anamorph: The asexual (imperfect, mitotic) state of a fungus – many fungi can have both states, especially

Ascomycota– most have either one or the other

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Sexual ReproductionSexual Reproduction(teleomorph)(teleomorph)

Sexual reproduction involves the union of two compatible nuclei (not necessarily in gametes) with a subsequent meiotic division yielding recombinant progeny.

There are a variety of methods by which this is accomplished, and this is the basis for most systematics

Life cycles-there is a lot of variation within the fungi

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Sexual ReproductionSexual Reproduction

All sexual fungal life cycles consist of: – Plasmogamy—cell fusion – Karyogamy—nuclear fusion – Meiosis

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GametangiGametangi

The sex organs in fungi are called gametangia (sing. gametangium)

May be differentiated into distinguishable male and female organs

Bear either differentiated sex cells (gametes) or one or more "gamete nuclei.”

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Homothallic Homothallic vsvs Heterothallic Heterothallic

Homothallic: a single mycelium that is capable of reproducing sexually

Heterothallic: two mycelia are required to reproduce sexually– Heterothallic forms may have both male and

female gametangia on the same mycelium, but they are incompatible with one another.

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Major Fungal Phyla Major Fungal Phyla

Chytridiomycota Zygomycota Ascomycota Basidiomycota “Deuteromycetes”

based on the method of producing sexual spores

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Chytridiomycota Chytridiomycota sexual and asexual

spores motile spores posterior flagella

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Chytridiomycota Chytridiomycota

Flagellum has whip-like motion

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ZygomycotaZygomycota

Sexual spores are thick walled resting spores called zygospores

asexual spores are borne internally in asporangium

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AscomycotaAscomycota

Sexual spores borne internally ina sac called an ascus

Asexual spores are borneexternally as conidia

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AscomycotaAscomycota

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BasidiomycotaBasidiomycota

Sexual spores borne externally ona club-shaped structure called a basidium.

Usually no asexual spore

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World’s largest BasidocarpWorld’s largest Basidocarp

At Yew Gardens

5ft

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Basidomycota life cycleBasidomycota life cycle

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““Deuteromycetes”Deuteromycetes”

No known sexual state,usually reproduces by conidia as asexual state

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Asexual reproductionAsexual reproduction “deuteromycetes” or Fungi Imperfecti, have no

known sexual state in their life cycle. – ~1680 genera and 17,000 species classified here. – Most of these have affinities to Ascomycota.

When the teleomorph is discovered, the technically correct name for the fungus is that of the teleomorph.

The large majority of these fungi are terrestrial, and are either saprophytes or parasites of plants– relatively few are parasites of animals

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Asexual SporesAsexual Spores Spores

– a general term for dissemination and resting structures in fungi

– The most common method of asexual reproduction in fungi

Fungal spores exhibit a wide variability in coloration,surface sculpturing, size, shape, number of cells, cellular arrangement, and the manner in which they are borne on the mycelium.

Used for identification of genera and species

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Asexual sporesAsexual spores In the Zygomycota, asexual spores may be

delimited within a sac-like structure, a sporangium (plural -- sporangia), in which case they are called sporangiospores, borne on a sporangiophore.

in the Ascomycota, spores may be borne at the tips or sides of hyphae, and are called conidia (sing. -- conidium), borne on a conidiophore.

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Yeast reproductionYeast reproduction Fission Budding

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Yeast Reproduction: FissionYeast Reproduction: Fission The simple splitting of a cell into two daughter

cells is another means of increasing the population and is characteristic of bacteria and some yeasts.

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Yeast Reproduction: BuddingYeast Reproduction: Budding a small outgrowth is formed on the parental cell. The nucleus of the parent cell divides and one

daughter nucleus migrates into the bud. The bud increases in size and eventually breaks

off.

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Yeast BuddingYeast Budding

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Fruiting bodies Fruiting bodies

Function – produce sexual spores for dissemination – raise or project the spores into the air where

they can be caught in the air currents and dispersed

– dumping area for wastes from the mycelium

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Surface area and reproductionSurface area and reproduction Most fungi have a very specialized niche in the environment.

Since they can’t move, they must use their spores to get to a new niche

the chance of any single spore landing on a substrate it can exploit are very small

thus, fruiting bodies must produce as many spores as possible so that a few of them will, by chance, be successful

Fungi have a great variety of ways of increasing the spore-bearing surface (hymenophore) area of their fruiting bodies

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Mycoses & MytoxicosisMycoses & Mytoxicosis

Mycoses fungal infections Mytoxicosis- intoxicaton

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DONE!!!DONE!!!