2. Introduction of Fungi
They are classified as eukaryotes,
Fungi can be divided into two basic morphological forms,
yeasts and hyphae
Yeasts are unicellular fungi which reproduce
asexually by blastoconidia formation (budding) or
fission
Hyphae are multi-cellular fungi which reproduce
asexually and/or sexually
3. Most fungi occur in the hyphae form as branching,
threadlike tubular filaments.
- lack cross walls (coenocytic)
- have cross walls (septate)
- clamp connections at the septa which connect the
the hyphae elements.
Coenocytic hyphae
Septated Hyphae
4.
5. COMMON CHARACTERISTICS OF FUNGI
1. Heterotrophy - 'other food'. There are three major categories of
heterotrophs, which include the saprophytes, symbionts, and parasites.
Saprophytes (feed on dead tissues or organic waste); symbionts (mutually
beneficial relationship between a fungus and another organism); parasites
(feeding on living tissue of a host). Parasites that cause disease are called
pathogens. Some parasites are obligate parasites (require a living host to
survive), while others are facultative or nonobligate parasites (do not
require a living host in order to survive).
2. 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)
6. 3. Fungus is often hidden from view. It grows through its
food source (substratum), excretes extracellular digestive
enzymes, and absorbs dissolved food.
4. Indeterminate growth.
5. Spores - asexual (product of mitosis) or sexual (product
of meiosis) in origin.
Purpose of Spores
(a) Allows the fungus to move to new food
source.
(b) Resistant stage - allows fungus to survive
periods of adversity.
(c) Means of introducing new genetic
combinations into a population.
6. Vegetative phase of fungus is generally sedentary.
7. Cell wall present, composed of cellulose and/or chitin.
7. 8. Food storage - generally in the form of lipids and
glycogen.
9. Eukaryotes - true nucleus and other organelles
present.
10. All fungi require water and oxygen (no obligate
anaerobes).
11. 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.
12. Diverse group, number of described species is about
69,000 (estimated 1.5 million species total).
8.
9. Phylums of Fungi
►Phylum Zygomycota -
common mold found on
land
► Reproduce by zygospores
Ex: Rhizopus - common
bread mold
Contain root-like structures
(rhizoids) to anchor in
bread. Stolons on surface
of bread.
10. PHYLUM CHARACTERISTICS
A. ASEXUAL REPRODUCTION:
Sporangiospores (aplanospores) or modified sporangia
(sac-like merosporangia) functioning as conidia.
B. SEXUAL REPRODUCTION:
Two morphologically similar gametangia fuse to produce
a warty, thick zygospore. Meiosis within zygospore.
C. VEGETATIVE HYPHAE:
Haplophase; no dikaryophase except in fused
gametangia; aseptate.
11.
12.
13. Asexual Reproduction:
Sexual Reproduction:
-spores are produced by -two opposite mating types of
sporangia at the ends of hyphae join to produce gametangia
modified, erect hyphae that produce a diploid zygospore
(thick walled spore)
-the zygospore undergoes meiosis
before germination and produces a
haploid mycelium
14. D. CELL WALLS: Chitin and chitosan.
E. ECOLOGY: Free-living to parasitic. Free-living
forms mainly terrestrial saprobes. Parasites mainly
of insects, but of other animals, too. Some parasitic
on microbial eukaryotes.
15. CLASS ZYGOMYCETES
production of asexual aplanospores,
• fusion of gametangia to produce zygospores
• walls of chitin and chitosan;
• asexual development seems to be from many-
spored sporangia, through sporangia with a much-
reduced number of spores,
• to one-spored sporangiola which function as
conidia.
16. ORDER MUCORALES
- Filamentous;
- aplanospores produced in globose,
- multinucleate sporangia,
- narrow cylindrical sac-like merosporangia,
- few-spored sporangiola or singly as conidia;
- zygospores often thick-walled,
- black and warty resting spores;
- large terminal chlamydospores common in
mycorrhizal forms.
- Saprophytic "pin molds".
22. ORDER ENDOGONIALES
- Filamentous
- coenocytic
- saprobic and mycorrhizal
- zygospores produced in
underground sporocarp.
Densospora , Endogone, Pteridiospora,
Sclerogone, Youngiomyces.
23. ORDER DIMARGARITALES
- Filamentous
- hyphae with septa which have a
lens-shaped cavity;
- asexual reproduction by merosporangium of
bispores.
- Zygospore ornamented.
- Parasites of fungi, especially Mucorales.
Dimargaris, Dispira, Spinalia, Tieghemiomyces.
24. ORDER ENTOMOPHTHORALES
- Filamentous
- some saprophytic, but mostly insect parasites
- vegetative phase tending to break up into
segments (hyphal bodies)
- asexual reproduction by forcibly discharged
uni- or multinucleate conidia
- zygospores smooth or ornamented.
Entomophthora, Condiobolus, Completoria,
Meristacrum, Neozygites..
25. Basidiomycota
Club fungi
Tilletia controversa Gymnosporangium
juniperi-virginianae
Amanita rubrovaginata
26. Basidiomycota
- Basidiomycetes - the club fungi, about 22,300 species
3. Includes mushrooms, toadstools, puffballs, shelf fungi,
rusts, bird's nest fungi and smuts
2. Characterized by perforate septate hyphae and the
production of a basidium (club) following sexual
reproduction. The basidia (pl. of basidium) occur in a
mycelium called a basidiocarp and they produce
external basidiospores
3. See your next slide for a typical life cycle
