Transcript Mycology Myco = fungus  ology = the study of  11/6/2015 Classification of Fungi Domain Eukarya  Kingdom Fungi  Phylum -mycota  Class -mycetes  Order -ales 

Mycology
Myco = fungus
 ology = the study of

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11/6/2015
Classification 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 Agaricus bisporus
Domain Eukarya
 Kingdom Fungi
 Phylum Basidiomycota
 Class Hymenomycetes
 Order Agaricales
 Family Agaricaceae
 Genus Agaricus
 Species Agaricus bisporus
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White Button Mushroom
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Fungi are probably
more closely related to
animals that to either
plants or protists!
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Characteristics 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
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– like plants
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Vegetative Body
Molds: Microscopic threads of
cells (hyphae)
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Hyphae a system of thread like,
walled, more or less cylindrical cells
singular hypha
Yeasts: Unicellular
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Hyphal Growth
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Cell walls
– simple chemical composition
– fungi cell walls are mostly chitin
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chitin synthesized by fungi
– plant cell walls are mostly cellulose
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(plus lignin in secondary walls)
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Chitin
Resists bacterial degradation
Used in sutures
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Cellulose
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Cell membranes
ergosterol, a unique sterol
 mammaliam membranes have cholesterol
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Fungal Traits

Heterotrophs
– (“other feeding,” ) must feed on preformed organic
material.
– Fungi digest then ingest

produce exoenzymes
– Animals ingest then digest
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Food stored as glycogen
– animal store glycogen
– plants store starch
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Lysine biosynthesis
– different pathway
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More 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
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Very small nuclei
– little repetitive DNA
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Lack of Chlorophyll profoundly
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 Growth
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Anatomy of Yeast
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Nutritional Status of Fungi
Saprophytes
 Parasites
 Mutualists (symbionts)
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Saprophytes
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 Parasites

use organic material from living organisms,
harming them in some way.
Adhesive Knobs
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Fungal Parasites

range of hosts: from single celled diatoms to fungi
to plants to animals to humans.
Trapped nematode
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A fungal predator
Oyster fungus traps a nematode in a ring of hyphae
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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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Mycorrhizae

Plant- Fungal Symbiont
– more than 90% of plants in nature have a
mycorrhizal symbiont.
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Mycorrhizae forms
– ectomycorrhizae
– endomycorrhizae
Myco= fungus rhiza= root
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Types of Mycorrhizae
Ectomycorrhizae-- fungus forms a sheath
outside the root
 Endomycorrhizae--vesicular-arbuscular
mycorrhizae (VAM), no sheath
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Orchid mycorrhizae are a special type
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Ectomycorrhizae
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
ectomycorrhizas
Basidiomycota, although a few (upper)dichotomous
and mycelial strands (lower)
of Amanita muscaria on Pinus
are Ascomycota species

strobus.
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Endomycorrhizae
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

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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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Lichens
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 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 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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Commensalism

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
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Fungi are very
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
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sometimes years (King Tut Beer)
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Many fungi are harmful
to 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
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– with the exception of plastics and some
pesticides
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Many fungi are very
useful 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 important
experimental 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
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Asexual and Sexual
Reproduction 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 Reproduction
(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 Reproduction

All sexual fungal life cycles consist of:
– Plasmogamy—cell fusion
– Karyogamy—nuclear fusion
– Meiosis
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Gametangi
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 vs 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
Chytridiomycota
 Zygomycota
 Ascomycota
 Basidiomycota
 “Deuteromycetes”

based on the method of producing sexual spores
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Chytridiomycota
sexual and asexual
spores
 motile spores
 posterior flagella
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Chytridiomycota
Flagellum has whip-like motion
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Zygomycota
Sexual spores are thick walled resting spores
called zygospores
asexual spores are borne internally in a
sporangium
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Ascomycota
Sexual spores borne internally in
a sac called an ascus
Asexual spores are borne
externally as conidia
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Ascomycota
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Basidiomycota
Sexual spores borne externally on
a club-shaped structure called a basidium.
Usually no asexual spore
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World’s largest Basidocarp
5ft
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At Yew Gardens
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Basidomycota life cycle
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“Deuteromycetes”
No known sexual state,
usually reproduces by conidia as asexual state
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Asexual 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 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 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 reproduction
Fission
 Budding
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Yeast Reproduction: Fission
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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: 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 Budding
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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 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
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their fruiting bodies

Mycoses & Mytoxicosis
Mycoses fungal infections
 Mytoxicosis- intoxicaton
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DONE!!!
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