Transcript I. Characteristics of Kingdom Fungi

Characteristics of Kingdom
Fungi
The Kingdom Fungi includes very
important organisms, both in terms of their
ecological and economic roles.
How are fungi “Helpful”?
• By breaking down dead organic material, they
continue the cycle of nutrients in ecosystems.
• Most plants could not grow without the symbiotic
fungi, or mycorrhizae, that inhabit their roots.
• Fungi provide drugs (such as penicillin and other
antibiotics),
• We eat foods like mushrooms, truffles & morels,
they make bubbles in bread, champagne, and beer.
• A number of fungi, in particular the yeasts, are
important "model organisms" for studying
problems in genetics and molecular biology.
Ways Fungi are Harmful:
• Fungi cause a number of plant and animal
diseases: in humans, ringworm, athlete's
foot, and several more serious diseases are
caused by fungi.
• Because fungi are more chemically and
genetically similar to animals than
other organisms, this makes fungal diseases
very difficult to treat.
• Plant diseases caused by fungi include rusts,
smuts, and leaf, root, and stem rots, and may
cause severe damage to crops.
Mycology
Definition - the
study of fungi
http://www.biotec.or.th/mycology/Pictures/IndexPic.gif
B. Fungi Characteristics• Eukaryotic
• Non-photosynthetic,
Hetrotrophic
• Multicellular
–(SOME UNICELLULARexample: YEASTS)
Originally classified as plants• Fungi are not plants, because they are
heterotrophs
• Fungi are more closely related to animals
than to plants.
• BUT- Unlike animals, they absorb their food
rather than ingest it,
• They have cell
walls.
• For these reasons, these organisms are now
placed in their own kingdom, Fungi.
The Mushroom
• Some people associate
fungi with the
mushroom.
• When you think of a
“mushroom” – you are
actually looking at the
fruiting body of
Basidiomycota
• (We will look at several
Amanita muscaria, commonly known as the
phylum)
fly agaric or fly Amanita, is a poisonous and
Image from wilipedia
psychoactive basidiomycete fungus, one of
many in the genus Amanita.
C. Fungi Structures
• Hyphae -A hypha (plural hyphae) is a
long, branching filamentous cell of a
fungus
• Mycelium - is the vegetative part (The
“body”of a fungus), consisting of a mass
of branching, thread-like hyphae
• Basidiocarp - is the spore-producing
part of a fungus (- the fruiting part or
commonly known as the mushroom)
• Cell walls – made of chitin.
Like plants and animals, fungi are
eukaryotic multicellular organisms
• Unlike these other
groups, however,
fungi are composed
of filaments called
hyphae
• their cells are long
and thread-like and
connected end-toend, as you can see
in the picture.
Describing Hyphae
• can be septate (individual cells divided by
cells walls)
• or coenocytic (joined together- not
separate cells).
• Because of this diffuse association of their
cells, the body of the organism is given
the special name mycelium, a term which
is applied to the whole body of any fungus
Reproductive Hyphae
• form a large organized structure
called a basidiocarp, or
mushroom.
• This is produced solely for the
release of spores, and is not
the living, growing portion of the
fungus.
The fungal cell wall:
•
Chitin is a nitrogen-containing
polysaccharide present in the cell walls of
many fungi.
• Notice this is a different polysaccharide
than the cellulose that makes up
plant cell walls.
• Chitin is the same material that makes up
the exoskeleton of insects and
other arthropods like crabs & lobster.
Selected Phylums we’ll discuss:
(Note: Some biologists refer to fungi phylum as divisions.)
1. Phylum Zygomycota- exampleBread fungus – Rhizopus stolonifer
• Black bread mold is the
best known of this phylum
of around 600 species.
• Zygomycota are terrestrial
organisms -can be found
in richly organic soils.
2. Phylum Basidiomycota
• example- button
Agaricus sp.
mushroom
-
• Basidiomycota are often called club
fungi because they produce small
clublike reproductive structures called
basidia (what you call the mushroom).
• Many “mushrooms” in this phylum look
like umbrellas growing from the ground
or like shelves growing on wood, but
some, such as the latticed stinkhorn, can
look quite different.
Remember• A “mushroom” is the above-ground
fruiting body (that is, a sporeproducing reproductive structure) of a
fungus, having a shaft and a cap.
– The rest of the fungus- its mycelium- is
usually hidden under bark, ground, rotted
wood, leaves, etc.
– The technical term for the spore-producing
structure of "true" mushrooms is the
basidiocarp.
– The term "toadstool" is used typically to
designate a basidiocarp that is poisonous
to eat
Among the more famous families in
phylum Basidiomycota are:
• Agaricus -- including the supermarket
variety of button mushrooms
• Amanita -- including species that are
deadly, delicious, or even hallucinogenic;
including the delicious and beautiful
– Chanterelle, one of the most prized wild
mushrooms. These families include but a few of
the mushrooms sought by collectors & gourmets
from among the 25,000 species in this phylum.
Agaricus sp.
a spore print- made by leaving
a mushroom cap overnight on a piece of paper
3. Phylum Ascomycota
• example – yeast –Candida species
• There are many types of Ascomycota, including
what are called sac-fungi that form ascocarp
reproductive features.
•The most commonly known
Ascomycota are”yeasts” like
brewers & baker’s yeast
(Saccharomyces visiae) and
Candida sp.- the yeast that
are parasitic to humans &
other organisms.
http://www.dentalgentlecare.com/images/candidiasis.jpg
Yeast infections
• are a very common cause of disease and
discomfort.
• Most cases of yeast infection in the United
States are caused by Candida albicans.
• "Yeast" is the term for a fungus that exists as a
single-celled organism rather than as hyphae.
• There are about 500 species of yeasts in 60
genera, or about 1000 species of yeasts or
yeast-like organisms.
• Some fungi are called yeast-like because they
exist as a yeast for part of their life cycle, but
can be hyphal for a significant portion of it.
Budding yeast
• The photo shows 2
yeast cells. The right
one is “budding”- one
form of reproduction.
• The term "yeast" is of
no taxonomic
significance. It is
useful only to
describe a
morphological
form of a fungus.
4. Lichens & Mycorrhizae
• These are symbiotic
relationships
between a fungus & another organism.
The result is a new organism distinctly different
from its component species.
• Though no longer considered a proper phylum,
the radically different nature of these symbiots
warrants separate treatment in this overview of
the fungus kingdom.
• Mycorrhizae are symbiotic associations
between a fungus & plant roots. They help
each other- the fungi provide phosphates &
nutrients for the plant & the plant provides
sugar made from photosynthesis to the fungi.
Lichens
• are symbiotic relationships
between a fungus (usually
ascomycetes) & an algae or
cyanobacteria.
• The fungus provides shelter & an
anchor to rocks, bark while the
algae or bacteria provides sugar.
• Lichens are important pioneer
species, and while widespread
through different ecosystems- can
live in harsh environments like the
tundra or on barren rock like on new
volcanic islands. `
E. A warning about poisonous
mushrooms:
• Unless you are absolutely certain about
the identification of a mushroom,
do not eat it! (no eating mushrooms
found on hiking trails)
• NO MUSHROOMS ARE POISONOUS TO
THE TOUCH
• HOWEVER EATING A POISONOUS
MUSHROOM WILL MAKE YOU SICK &
SOME SPECIES ARE LETHAL.
Galerina autumnalis
botit.botany.wisc.edu/toms_fungi/may2003.html
The a-amanitin ultimately affects the
central nervous system and kidneys.
Unlike many fungal toxins it does not
cause symptoms right away. As long
as 6-24 hours after ingestion there may
be an early feeling of unease, followed
by violent cramps and diarrhea. On the
third day, there is a remission of
symptoms,but this is a false remission.
On the 4th to 5th day the enzymes
increase, and liver and kidneys are
severely affected. Death often follows if a
liver transplant or other heroic measures
are not performed. There is no cure for
ingestion of the poison once it gets this
far, but doctors are getting much better at
treating the symptoms. This is *not* a
mushroom you want to mess around with.
From: Tom Volk's Fungus
Death Cap (Amanita phalloides)
NO MUSHROOM is worthier of
fear. This single, widespread
species of mushroom is solely
responsible for the majority of
fatal and otherwise serious
mushroom poisoning cases,
worldwide as well as in North
America. Indeed, one might
argue that the Death Cap's
notorious, relatively frequent
victimization of Homo sapiens is
far and away the best
explanation (or rationalization)
for the widespread fear of edible
wild mushrooms.
www.amanitashop.com/.../deathcap.htm
Amanita verna & Amanita virosa
(the destroying angel).
http://micologia.net/g3/Amanita-virosa/Amanita_virosa
Death takes place within 6-8 days
due to liver and renal failure & cardiac damage.
Historical Note:
• Claviceps purpurea- funus that infects
seeds of grains (like wheat, rye,etc)
• Common name is Ergot
• Chemicals that it produces, when eaten, can
cause mental disturbances, convulsions,
perceptual distortions.
• Disease is called erotism or “St. Anthony’s
Fire”
• Scientists now think that many women
accused of being witches during the 1692
Salem witch trials may have had this
disease.
http://botit.botany.wisc.edu/toms_fungi/oct99.html
II. Humans & Fungi
References (in addition to
those noted on slides)
•
•
•
•
http://www.ucmp.berkeley.edu/fungi/fungi.html
http://en.wikipedia.org/wiki/Fungi
http://www.perspective.com/nature/fungi/
http://botit.botany.wisc.edu/toms_fungi/jan99.
html
• HOLT Biology textbook