(click
on the main point headings to jump to the selected
location in the notes)
Review
Definition of Fungi
Eukaryotic, heterotrophic and absorptive organisms,
which have cell walls, typically reproduce
asexually and/or sexually by producing spores, and
grow either reproductively by budding or
nonreproductively by hyphal tip elongation.
Definition excludes:
1. bacteria & blue-green algae (prokaryotes)
2. slime molds
3. true algae & higher plants
4. animals
5. etc.
Definition may include some non-fungi
1. Oomycetes (water molds)
2. etc.
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About Fungal Thalli (pl), Thallus (sing):
Many fungi characterized by a distinctive,
multinucleate, vegetative (somatic) thallus (body)
called
the mycelium* (singular)
mycelia* (plural).
The mycelium consists of a branching system of
walled tubes called
hyphae (plural)
hypha (singular)
Mechanisms of hyphal growth** are
apical extension &
lateral branching.
* term usually used with filamentous fungi
**nonreproductive growth vs reproductive yeast
growth
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Vegetative
hyphal growth
vs yeast growth
hyphal growth = apical extention
yeast growth= budding
hyphal growth= nonreproductive
yeast growth = reproductive
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Fungal
nutrition
A. Absorptive mode
1. over whole surface or
2. via restricted absorbing regions , e.g.
a. rhizoids in "lower" fungi
b. substrate hyphae* in "higher" fungi
c. apical tips of hyphae
*The substrate hyphae of molds nourish the aerial
hyphae and reproductive hyphae
B. Extracellular digestion
Fungi secrete enzymes that depolymerize complex
natural products (proteins, carbohydrates, lipids,
etc.) so they can be absorbed as sources of carbon
and energy.
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Question: What are fungi?
1. Because of nutritional mode they are
ecologically considered among the primary
decomposers*.
2. Because of size, nutrition and history, they are
considered to be microbes by microbiologists.
3. Because of structure and history, they have
historically been considered to be plants by
botanists.
Question: Are fungi plants?
No!…opinions of Whitaker, Margulis,
Cavalier-Smith, Kendrick, PJS, etc.
* Reducers
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Questions
1.
What was the pre-molecular biology basis
for the reclassifications among the
pre-Whittaker "fungi?"
2.
What is the reality of the molecular
revolution to the "new taxonomy"
of the Kingdom Fungi?
2-1(new)
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Reasons Fungi not Plants:
1. Ultrastructural studies suggest uniqueness
- certainly more "primitive" fungi (Chytridiomycota)
are not plants
- flagellation patterns of Chytridiomycota and
other fungal-like protists suggest independent
origins*
- derivation from nonphotosynthetic ancestors
* polyphyletic
2. Fungal organization is different from and
nonhomologous with that of plants.
- convergent evolution -- similar structures and
life cycles.
- tissue-like structure of hyphal origin*
* hyphal aggregates
3. Nutrition - fungi and most fungal-like protists
were most-likely never photosynthetic.
Therefore, no more related to higher animals than
higher plants.
Fungal Nutrition - Absorptive
Plant Nutrition - Photosynthetic
Animal Nutrition - Endocytotic or ingestive and
absorptive
If not plants, then what?
10/11
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Kingdom
Systems
Systems
|
Kingdoms
|
1.
2 kingdoms
|
1.
Plantae
|
|
2.
Animalatae
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2.
3 kingdoms
|
1.
Protista*
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|
2.
Metaphyta
|
|
3.
Metazoa
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3.
4 kingdoms
|
1.
Monera
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2.
Protista*
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3.
Metaphyta
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4.
Metazoa
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4.
Whittaker's 5 kingdom system
(~ 1969)
|
|
*Concept #1 Protista = unicells or their colonial
associations
*Concept #2 Protista = unicells or/and other
organisms which lack tissue specialization of
higher plants.
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What
are fungi? - Question
Fungi are fungi. - Answer!
1) Fungi are accepted as the third kingdom of
higher organisms whose origins flow naturally from
a primitive eucaryotic protist.
2) Fungal origins are obscured but probably flowed
from the Chytridiomycota, a group that we will
study in this course, together with a few other
fungal-like protists tradition ally studied by
mycologists.
*Chytridiomycota are currently said to be most
likely ancestor group
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Subdisciplines
of taxonomy
1. Identification
Recognition of organism
2.* Classification
Recognition of relationships
(or nonrelationships)
3. Nomenclature
Correct naming of organisms (use of rules of
botanical nomenclature)
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Classification
hierarchy and fungal classification suffixes
Kingdom-Fungi
Subkingdom-mycotera
Division/phylum-mycota
Subdivision/subphylum-mycotina
Class-mycetes
Order-ales
Family-aceae
Genus, Saccharomyces
Species, S. cerevisiae
Organisms in the same taxon are more related than
are organisms in different taxa.
17=2b
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Pre-Whitaker
fungal classification (1969)
Kingdom - Plantae (Metaphyta)
Division - Eumycota
Class - Phycomycetes*
Class - Ascomycetes
Class - Basidiomycetes
Class - Deuteromycetes (Fungi Imperfecti)
* The so-called traditional "lower fungi"
*All produce their mitotically-derived reproductive
cells in a cell called a sporangium. (sporangia)(pl)
* Lumping into single class erroneously suggested
relatively close relationships
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Where
are the Phycomycetes* today?
Kingdom - Protozoa**
Division - Plasmodiophoromycota
Kingdom - Chromista
Division - Hyphochytridiomycota
Division - Oomycota
Kingdom - Fungi
Subkingdom - Mastigomycotera***
Division - Chytridiomycota
Subkingdom - Amastigomycotera
Division - Zygomycota
*The lower fungi
**see lab manual, appendix a, for members, etc.
***Historically also:
Acrasiomycota - cellular slime molds
Labyrinthalomycota - gliding slime molds
Myxomycota - plasmodial slime molds, etc. (see
other materials on reserve)
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Factors
that originally led to the grouping of these
different kinds of organisms into single class
"Phycomycetes."
1. Their tendency to be vegetatively aseptate &
multinucleate (coenocytic)
2. Their tendency to produce their mitotically
derived, reproductive propagules (zoospores or
sporangiospores) in a cell called a
sporangium/sporangia (pl).
3. Their tendency to look alike and have
superficially similar biologies that were clearly
different than those of "higher
fungi"
20
(revised 1/23/00)
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Major diagnostic characteristic of
sporangial
fungi and
of some fungal-like protists
Phylum/Division
|
Sporangial
propagule type
|
Plasmodiophoromycota
|
Zoospore*
(1
whip-lash and one stub type rudiment of a
flagellum
|
Hyphochytridiomycota
|
Zoospore
(1
tinsel-type anterior flagellum)
|
Oomycota
|
Zoospore
(1
tinsel- and 1 whip-lash flagellum)
|
Chytridiomycota
|
Zoospore
(1
whip-lash posterior flagellum)
|
Zygomycota
|
Sporangiospore**
|
*
Zoospores
are mycotically-derived reproductive cells lacking
dormancy qualities and cell walls and having
undulopodia.
**
Sporangiospores have dormancy qualities
and cell walls, but lack undulopodia
21=2-4
(rev. 1/23/00)
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Kingdom
Protozoa
Division – Plasmodiophoromycota
Class - Plasmodiophoromycetes
Order - Plasmodiophorales**
* both hyphal and nonhyphal types
** intracellular plasmodial parasites of plants,
algae and fungi - maybe more similar to animals
than higher fungi
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Kingdom
Chromista
Division - Hyphochytridiomycota*
Class - Hyphochytridiomycetes
Order - Hyphochytridiales
* Mostly parasites of algae and fungi or
saprophytic plant and insect materials
* Nonhyphal and rudimentary hyphal representatives
Division - Oomycota**
Class - Oomycetes
Order - Saprolegniales
Order - Leptomitales
Order - Lagenidiales
Order - Olpidiopsidales
Order - Peronosporales
Order - Pythiales
** nonhyphal and hyphal members, orders in
transition
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Kingdom
Fungi
Kingdom - Fungi
Subkingdom - Mastigomycotera*
Division - Chytridiomycota**
Subkingdom - Amastigomycotera***
Division - Zygomycota
Subkingdom - Eumycotera
Division - Ascomycota
Division - Basidiomycota
Division - Fungi Imperfecti
(Deuteromycota)
*members produce zoospores
** presence of sporangia led to original inclusion
among Phycomycetes
*** members produce sporangiospores
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Orders
of Chytridiomycota
Kingdom - Fungi
Subkingdom - Mastigomycotera
Division - Chytridiomycota*
Class - Chytridiomycetes
Order - Chytridiales
Order - Spizellomycetales
Order - Blastocladiales
Order - Monoblephariadales
Order - Neocallimasticales
Order - Harpocyhytriales
*
Both hyphal and nonhyphal types show signs
of parallel evolutionary trends with
Oocmycota members
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Classification
of Zygomycota
Kingdom - Fungi
Subkingdom - Amastigomycotera*
Phylum - Zygomycota+
(cont below)
*Fungi that produce nonflagellate mitospores (sporangiospores**)
in a sporangium (species once classified among the
phycomycetes)
**Sporangiospores (vs zoospores) have cell walls,
dormancy qualities, no flagella, & tend to be
wind disseminated
+Also characterized often by hyphae and the
production of a karyospore (type of sexual spore)
called a zygospore
(cont from above)
Class - Zygomycetes*
Order - Mucorales (black bread molds)
Order - Entomophthorales (many insect pathogens)
Order - Zoopagales (insect gut symbionts)
Order - Endoganales (endomycorrhizal fungi)
Order - Glomales (endomycorrhizal fungi)
Class – Trichomycetes**
* mostly hyphal organisms with a total of 7 orders
** 4 orders of poorly studied species that include
numerous arthropod gut symbionts that are hyphal
or rudimentarially hyphal. We will not study this
group.
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Eumycotera Classification
Division
|
Major
Characteristics(s)
|
Ascomycota
|
Ascus/Asci
& Ascospores
|
Basidiomycota
|
Basidium/Basidia
& Basidiospores**
|
Fungi
Imperfecti
|
Absence
of Sporangia, Asci or Basidia, Ascospores or
Basidiospores
|
* ascospores = endogenous meiospores***
** basidiospores = exogenous meiospores***
*** true spores with cell walls and dormancy
qualities.
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Eumycotera
Classification (cont)
Kingdom Fungi
Subkingdom - Eumycotera*
Phylum - Ascomycota**
Phylum - Basidiomycota**
Phylum - Fungi Imperfecti***
* absence of mitosporangia (the higher fungi, the
nonsporangial fungi)
** sometimes combined in one group (e.g.
dikaryomycota).
*** a nonphylogenetic (artificial) phylum whose
members may or may not be related (taxonomy does
not reflect relationships) The relationships
among these fungi are being clarified by DNA and
protein sequencing.
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Eumycotera
Classification (cont)
Division
|
Major
Characteristics(s)
|
Ascomycota
|
Meiosporangium
called an ascus, which produces endo-genous
meiospores called ascospores
|
Basidiomycota
|
Meiosporangium
called a basidium, which produces exo-genous
meiospores called basidiospores*
|
Fungi
Imperfecti
|
No
known or observed meiosporangia, therefore
no ascospores or basidio-spores, therefore
no absolute ability to classify
morphologically.**
|
*true
spores with dormancy qualities
**possibly can now by molecular biology
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Ascomycota
classification
Division - Ascomycota
Subdivision - Hemiascomycotina*
Class - Hemiascomycetes
Order - Saccharomycetales
(Ascus
from diploid nucleus w/o N+N state)
Class - Archaeascomycetes
Order - Taphrinales
(Ascus from N+N cell)
Order - Schizosaccharomycetales (fission
yeasts)
Order - Pneumocystidales (for Pneumocystis carinii, etc.)
Order - Protomycetales
*lack ascocarps (multihyphal tissue-like structures
surrounding their asci. both hyphal &
nonhyphal members.
Subdivision - Euascomycotina**
**have ascocarps associated with their asci.
N+N = dikaryon state
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Classes of Euascomycotina
Class
|
Ascoma
or Ascocarp type
|
1.
Plectomycetes
|
Cleistothecia
(a)
|
2.
Pyrenomycetes
|
Perithecia
(b)
|
3.
Discomycetes
|
Apothecia
(c)
|
4.
Loculoascomycetes
|
Ascostroma
(d)
|
5.
Laboulbeniomycetes
|
Very
specialized Perithecia
|
a.
closed ascocarps
b. flask-shaped ascocarps
c. cup or goblet shaped ascocarps
d. stroma with locuoles (cavities)
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Basidiomycota
Classification
Subkingdom - Eumycotera
Phylum - Basidiomycota
Subphylum - Heterobasidiomycotina*,**
Class - Urediniomycetes (rusts)
Order - Uredinales
Class - Ustomycetes (smuts)
Order - Ustilaginales
* basidia from teliospores (dikaryotic spores)
**no "mushroom-like" basidiocarps
Subphylum - Holobasidiomycotina
Class - Phragmobasidiomycetes* (5 orders)
Order - Tremellales
(have cruciately septate Basidia)
Order - Auriculariales
(have transversely septate Basidia)
* have septate basidia
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Basidiomycota
Classification (cont.)
Subphylum - Holobasidiomycotina * (cont.)
Class – Holobasidiomycetes (27 orders)
Order - Dacrymycetales
(have tuning-fork type basidium)
Order - Tulasnellales (have Holobasidia with
swollen sterigmata)
Order - Agaricales (the mushrooms)
Order
– Boletales (the fleshy pore fungi)
Order – Cantharelles (chantarelles, and tooth
fungi, etc.)
Order - Exobasidials
Order - Gautieriales
Order - Hymenogastrales
Order - Lycoperdales (the puffballs, earth stars,
etc.)
Order - Melanogastrales
Order - Nidulariales (the bird's nest fungi)
Order - Phallales (the stinkhorns)
Order - Porales (woody shelf fungi or woody bracket
fungi)
Order – Thelephorales (the coral and leather
fungi)
Order – Sclerodermatales (the earth balls)
* most have typical holobasidum, but different
kinds of basidiocarps
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Review - Kingdom Fungi
Kingdom – Fungi
Subkingdom - Mastigomycotera
Phylum - Chytridiomycota
Subkingdom - Amastigomycotera
Phylum - Zygomycota
Class - Zygomycetes
Orders- Mucorales (etc)
Class - Trichomycetes
Orders - 1 to 4
Subkingdom - Eumycotera
Phylum - Ascomycota
Subphylum - Hemiascomycotina
Class - Hemiascomycetes
Order - Saccharomycetales
(Ascus
from diploid nucleus w/o N+N state)
Class - Archaeascomycetes
Order - Taphrinales
(Ascus from N+N cell)
Order - Schizosaccharomycetales (fission
yeasts)
Order - Pneumocystidales (for Pneumocystis carionii, etc.)
Order – Protomycetales
Subphylum - Euascomycotina
Class - Plectomycetes
Class - Pyrenomycetes
Class - Discomycetes
Class - Loculoascomycetes
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Review - Kingdom Fungi (cont.)
Subkingdom - Eumycotera
Phylum - Basidiomycota
Subphylum - Heterobasidiomycotina
Class - Urediniomycetes
Order - Uredinales
Class - Ustomycetes
Order - Ustilaginales
Subphylum - Heterobasidiomycotina
Class - Phragomobasidiomycetes
Orders - Tremelales*, Auriculariales
Class - Holobasidiomyetes
Orders - Dacrymycetales, Tulasnellales,
Exobasideals,
Aphyllophorales, Hymenogastrales, Gautieriales,
Phallales, Lycoperdales, Tulostomatales,
Sclerodermatatales, Nidulareales, Agaricales,
Melanogadstrales, Porales
See my reference guide to Fungi & Fungal-like
Protists (circa 1999), & handout
*Current most accepted order for F.(C) neoformans
but may be a member of the Ustomycetes class
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FUNGI
IMPERFECTI
(Deuteromycota)
Nonphylogenetic group of fungi without known sexual
cycles or with unobserved sexual cycles.
Unique
Phylum/Division
1. Groupings may or may not represent
phylogeny e.g., species in same genus may be less
related than species in different genera
2. Most members probably should be included
in another Division, particularly Ascomycota and
Basidiomycota
3. Members often have two and sometimes more
acceptable scientific names
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WHY
FUNGI IMPERFECTI?
1. Recognition that sexual cycles of fungi,
particularly of Ascomycota and Basidiomycota, were
important for understanding relationships created
the problem
2. Problem was what to do taxonomically with
fungi that had no known sex cycles?*
3. Problem solved by creating a Division of
fungi in which fungi are named with little regard
for relationships. Identification without
regard to classification; based on observations
and naming of asexual states.
*majority
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Question
-
Why are asexual states usually known before
sexual states?
1. If organism grows then it usually exhibits
its asexual (anamorphic) phase first.
asexual (anamorphic) phase first
vegetative growth ------> asexual
reproduction -------------> sexual reproduction
2. With practically important fungi, one can
identitfy and work with fungus without knowing
about sexual stage.
3. Induction of sexuality is often dependent
upon inducing sex in mated strains.
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Homothallism
vs Heterothallism
Many fungi are heterothallic*
Haploid self-sterile (nonsexual) strains
A***
A A ****
A ( haploid/1N)
(1N) A
A A
X--------------------> Aa -------->
meiosis** -------> mitosis ----->
a ( haploid/1N) (2N)
a
a a
a
a a
Only a few are homothallic (self-fertile)
* sex requires = pairs of
opposite mating strains
** meiosis often requires special
physiological conditions
*** meitotic nuclei incorporated into
meiospores
ascospores
basidiospores
**** somtimes, etc.
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ASEXUAL STATES = IMPERFECT STATE
Therefore:
Fungi Imperfecti = Deuteromycota
1. Fungi Imperfecti named according to rules
of Botanical Nomenclature for asexual fungi
2. When perfect states (sexual) become known
they are classified and renamed according to rules
of Botanical Nomenclature for sexual fungi
Older Fungi Imperfecti names usually better known
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Review
Fungi Imperfecti
1. Fungi having no known or observed sexual state (teleomorph)
2. Usually asexual states (anamorphs) of ascomycota
or basidiomycota
3. When sexual state of an imperfect (asexual)
fungus is observed and described the fungus is
a. renamed according to rules of botanical
nomenclature
b. reclassified according to characteristics of the
holomorph = whole fungus considering biology of
both anamorph and teleomorph
4. Until discovery of teleomorph fungus is a member
of the fungi imperfecti and included in its
"hierarchy" of categorization.
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FUNGI
IMPERFECTI
Hierarchy
of Categorization*
Form - Class
Form - Order
Form - Families
Form - Genera
Form - Species
*System useful for communication and
identification, but does not necessarily reflect
relationships (phylogeny)
*Not a classification system
1. Form class - Blastomycetes
nonsexual yeasts
2. Form class - Hyphomycetes
Mycelial (hyphal) conidial fungi
3. Form class - Coelomycetes
Mycelial (hyphal) conidial fungi with conidiogenous
structures associated with multihyphal
aggregates.**
4. Form Class - Mycelia sterilia
nonsporulating hyphal fungi.
** Conidioma
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Examples
of common anamorphic genera (Fungi imperfecti)
whose teleomorphic names are often established but
seldom used.
Anamorphic name
|
Teleomorphic name
|
Penicillium
|
Telaromyces,
etc.
|
Aspergillus
|
Eurotium,
etc.
|
Rhodotorula
|
Rhodosporidium
|
Trichophyton
|
Arthroderma
|
Microsporum
|
Arthroderma
|
Blastomyces
|
Ajellomyces
|
Cryptococcus
|
Filobasidiella
|
Candida
|
Saccharomyces
|
Pichia
|
Hansenula
etc
|
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Today's
Problems with Division Fungi Imperfecti
Good News - perfect states of many fungi have been,
and continue to be, discovered
Bad News - hundreds of common fungi have new names
More Bad News - great resistance to learning and
understanding about why we are having
reclassifications*
Great resistance to use of new names by
non-mycologists and professionals.
Both imperfect and perfect names of sexual fungi
commonly used.
Particularly true in regard to applied fields like
·
medical mycology
·
plant pathology
·
industrial mycology
* will be compounded by molecular classifications
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|