True Fungi
• break down dead
organic material
• provide
numerous drugs
• foods like
mushrooms
• Plant and animal
diseases
Characteristics of fungi
• Fungi exist primarily
as filamentous threads,
the hyphae, forming a
mass, a mycelium.
Normally never see
the mycelium, only the
fruiting bodies.
• Cell walls contain
• Fungi are
chitin.*
heterotrophic by
absorption
• Reproduction is due to
fusion of hyphae*
Groups of fungi
•
•
•
•
•
Chytridiomycota (chytrids)
Zygomycota (bread molds)
Ascomycota (yeasts and sac fungi)
Basidiomycota (club fungi)
Deuteromycota (asexual forms of
ascomycetes and basidiomycetes)
Generalised Life cycle of fungi
Fusion of
hyphae*
Haploid
mycelia
of different
mating
types
Nuclear
fusion
Dikaryotic
mycelium
gives fruiting
body
Meiosis
to give spores
Diploid
stage
Not in chytrids*
Zygomycetes - V. small fruiting body
Ascomycetes - small fruiting body
Basidiomycetes - long-lived hyphae then
a large fruiting body
Comparison of different groups
C h y trid io m y cetes
Zy g o m y cetes
A sco m y cetes
B a sid io m y cetes
D eu tero m y cetes
sep tate
sep tate
C ell w all
o f chitin+
cellulo se in
so m e sp
M ycelium
co eno cytic
co eno cytic
sep tate
R ep ro d uctio n
flagellated
zo o sp o res
zygo sp o res
fro m b lack
zygo sp o rangia
asco sp o res b asid io fro m cup , sp o res
sac, m o rel fro m
m ushro o m
no sexual
stages
Chytridiomycota (chytrids)
• The oldest fossil fungi
so far known and may
form a ‘missing link’
with protists.
• Flagellated zoospores
fuse, their nuclei fuse
then immediate
meiosis to give spores
Zygomycota (bread molds)
• Important
decomposers
• Dominant haploid
phase with dikaryon
restricted to formation
of zygosporangium
• asexual spores are
produced
Spores produced by mitosis
The life cycle
of a zygomycete
Sporangium
forms by
Gametangia
mitosis
develop
Zygosporangium
develops
Hyphae
grow
to each
other
Coenocytic mycelia
of 2 mating types
Spores germinate
to give mycelium
Zygosporangium
formed
Zygospores
Spores produced
by meiosis
Ascomycota (yeasts and sac
fungi)
• Sexual spores (ascospores) are produced in
a specialized sac-like structure called an
ascus on the surface of an ascocarp.
• Reproduced asexually by conidia
• Decomposers that include economically
important foods such as truffles and Morels
and pests such as powdery mildews and
ergots. Yeasts used in baking and brewing.
Sporing structures (ascocarps)
• A vegetative layer of
‘sterile’ dikaryotic
hyphae (2 nuclei)
forms the body of the
ascocarp with a layer
of asci on the surface
(produce spores)
Sporing structures
Tissues within the ascocarp
Cup fungi
Morels
Flask fungi
Sterile body of ascocarp formed from dikaryotic hyphae
Layer of asci
Basidiomycota (club fungi)
• Septate hyphae
• Produce long-lived
dikaryons (mycelia
where the cells have 2
nuclei)
• Produce sporing
structures, the basidia,
on basidiocarps.
•
•
•
•
•
•
Wood rotting fungi
Rusts
Smuts
Mushrooms
Puffballs
Life cycle a bit like
ascomycetes, but
individual spores
produced
Yeasts
• Unicellular forms of
ascomycetes and
basidiomycetes.
• Some reproduce
sexually some don’t.
• Baking
• Brewing
• Human pathogens e.g.
Candida
Deuteromycota (asexual forms of
ascomycetes and basidiomycetes)
• No sexual stages
known and propagate
solely by spores called
conidia on structures
called conidiaphores.
• Includes commercially
important species such
as Penicillium (gives
penicillin from fungal
fermentations)
Conidia
Conidiophore
Mycelium
Lichens
• Lichens are unusual
creatures. A lichen is a
combination of two
organisms which live
together intimately.
Most of the lichen is
composed of fungal
filaments, but living
among the filaments
are algal cells, usually
from a green alga or a
Cyanobacterium.