Zvyšování
konkurenceschopnosti
studentů oboru botanika
a učitelství biologie
CZ.1.07/2.2.00/15.0316
© 2011 B. Mieslerová, A. Lebeda, (KB PřF UP v Olomouci)
REPRODUCTION OF FUNGI
Asexual reproduction
Sexual reproduction
ASEXUAL REPRODUCTION
The ability to reproduce asexually is common to almost all fungi.
2. Fragmentation
1. Bud formation in yeasts
Any mycelium that is
fragmented or disrupted,
provided that the
fragment contains the
equivalent of the
peripheral growth zone,
can grow into a new
colony.
3. Sporulation
Most important type of asexual reproduction of fungi
Responsible for the production of large numbers of spores .
SPORULATION
Asexual spores are formed after mitosis in anamorphic phase of
the fungal life cycle
There can be more than one mitosporic state for each species of
fungus, and in some cases the mitosporic state of very different
species can look very similar.
Sexual spores are formed after meiosis in teleomorphic phase of
the fungal life cycle
Characteristics of this phase of the life cycle are much more stable
Asexual reproductive structures of main fungal groups
Group
Asexual
spores
Myxomycota
None
Oomycota
Zoospores in sporangia
Chytridiomycota
Zoospores in sporangia
Zygomycotina
Sporangiospores in sporangia
Ascomycotina
Yeast buds, conidia in conidiophores
Deuteromycotina
Conidia in conidiophores
Basidiomycotina
Aeciospores urediniospores, conidias
ASEXUAL REPRODUCTION IN OOMYCOTA
 Asexual reproduction is by the production of motile
zoospores in sporangia, with a one or two flagella, one of
them with mastigonemata in sporangia.
 Sometimes whole sporangium germinates producing germ
tube similarly as conidium
Zoosporangium
Phytophthora palmivora
with zoosporas
Two flagella, one with
mastigonemata
Sporangiophore
characteristics of five
genera of Peronosporales
ASEXUAL REPRODUCTION IN CHYTRIDIOMYCOTA
 Very simple in structure and may only consist of a single cell,
perhaps with rhizoids to anchor it on to a substrate.
 Asexual reproduction is by the production of motile zoospores,
with a single, posterior flagellum, in sporangia.
Zoosporangium
Uniflagellate
zoospora
ASEXUAL REPRODUCTION IN ZYGOMYCOTINA
Zygomycete fungal mycelium is coenocytic
Creating of sporangium with columela
The large sporangia can contain up to 100,000 spores
Sporangium with nonmotile spores
Many species with smaller, specialized sporangia,
called merosporangia and some are almost conidial,
forming single spored sporangia (double spore wall)
Order Zoopagales
sporangia that break up at
maturity, looking rather like
the thallic-arthric conidia of
some ascomycetes and
basidiomycetes
ASEXUAL REPRODUCTION IN THE ASCOMYCOTINA
(AND DEUTEROMYCOTINA)
 As asexual reproduction is sometimes the only form of
reproduction seen in some fungi
 Conidia are formed on conidiophores by blastic process
 In some groups the conidiophores (the structures that bear the
conidia) are aggregated forming specialised structures (pycnidia,
acervuli, coremia and sporodochia)
7 group of spores based on morphology
DIFFERENT METHODS OF CONIDIAL DEVELOPMENT
A. Thallic development: no
enlargement of the
conidium initial
B.Holoblastic development:
all layers of wall form a
conidium which is larger
than the conidiogenous
cell
C,D. Enteroblastic
development: Only inner
wall layers of the
conidiogenous cell are
involved in conidium
formation
C. tretic
D. phialidic: the conidiogenous cell
is a phialide. The wall of the
phialide is not continuous with the
wall surrounding the conidium
DIFFERENT METHODS OF CONIDIAL DEVELOPMENT
Thallic
conidiogenesis
Blastic-phialidic
conidiogenesis
Blastic
conidiogenesis
Septoria apiicola
Pycnidium
Acervulus
Colletotrichum graminicola
Penicillium
Coremium
Single
conidiophores
Stigmina
Sporodochium
ASEXUAL REPRODUCTION IN BASIDIOMYCOTINA
Not very often, in most of groups missing, partly by conidia
and in some highly specialised groups (Uredinales) creating
various types and shapes
Telia with
teliospores
Aecia with
aeciospores
Uredia with
uredinospores
SEXUAL REPRODUCTION
 To achieve sexual reproduction it is necessary to have
two mating type haploid nuclei (n + n), or a diploid (2n)
nucleus
 Two haploid nuclei fuse to form a diploid first, then the
nuclei undergo meiosis, which is the reduction division
that potentially brings about variation
 These event are followed by the formation of spores,
which in most cases are resting spores that can withstand
adverse conditions.
TYPES OF SEXUAL REPRODUCTION
Isogamy - fusion of morphologically identical gametes
(Chytridiomycota, Myxomycota).
Anisogamy – fusion of the morphologically different gametes
(Chytridiomycota)
Gametangiogamy – fusion of the male and female gametangia
(Zygomycotina, Ascomycotina)
Oogametangiogamy– fusion of the male gametangium and
female oogonium (Oomycota)
Gameto- gametangiogamy – fusion of the gametangium
(female) and gamete (male) – example – spermatisation
(Ascomycotina)
Somatogamy – fusion of the somatic structures
(Basidiomycotina)
Sexual process of main fungal groups
Group
Sexual process
Myxomycota
Isogamy
Oomycota
Oogametangiogamy
Chytridiomycota
Isogamy, anisogamy, somatogamy,
oogametangiogamy
Zygomycotina
Gametangiogamy
Ascomycotina
Gametangiogamy, gameto-gametangiogamy
Deuteromycotina
None
Basidiomycotina
Somatogamy, gameto-somatogamy (rusts)
SEXUAL REPRODUCTION IN MYXOMYCOTA
 Isogamy (copulation of myxomonadas or myxamoebas) –
following karyogamy – and forming sporocarps with sporas
Two myxoamoebae
During
sexual
reproduction
myxoamoebae will also function as
gametes (isogametes)
Life cycle of
Myxomycota
Life cycle of
Plasmodiophoromycota
SEXUAL REPRODUCTION IN OOMYCOTA
Oogametangiogamy – fuse of oogonium (♀),
anteridium (♂), forming oospora (one or more)
Oogonium with one
oospora
(Bremia lactucae)
Oogonium with more
oosporas (Saprolegnia sp.)
Life cycle of
Plasmopara viticola
SEXUAL REPRODUCTION IN CHYTRIDIOMYCOTA
 After gametic or somatic fusion of two different mating types
production of diploid zygote (isogamy, anisogamy, somatogamy)
 The resulting spore (zygote) may germinate to produce a diploid
vegetative thallus or it may undergo meiosis to produce a haploid
thallus
 The diploid thallus can also produce resting sporangia in which
meiosis occurs, generating haploid zoospores that germinate to
produce haploid vegetative thallus
SEXUAL REPRODUCTION IN ZYGOMYCOTINA
 Reproduce sexually by the physical blending - fusion or conjugation
of morphologically similar gametangia (Gametangiogamy) to form a
diploid zygosporangium. Zygosporangia usually develop thick walls,
and act as resting spores. Meiosis occurs, producing sporangium with
haploid spores
 HOMOTHALLIC - describes fungi in which a single strain can
undertake sexual reproduction; self-compatible
 HETEROTHALLIC - describes fungi in which two genetically distinct
but compatible mycelia must meet before sexual reproduction can take
place
Progametangia
Copulation of
gametangia
Formation of a
zygospora
Life cycle of
Rhizopus nigricans
SEXUAL REPRODUCTION IN ASCOMYCOTINA
 There are specialized organs of hyphal fusion (ascogonium with
trichogyn (♀) and antheridium (♂)) which fuse with each other to
form dikaryons (Gametangiogamy)
 Similarly fusion is possible with ascogonium (♀) and spermatia
forming in spermogonia (gameto-gametangiogamy)
 Most ascomycetes interpolate a dikaryophase, during which the
number of pairs of compatible nuclei is multiplied, often enormously,
as dikaryotic hyphae (often called ascogenous hyphae)
 Nuclei in tip cells fuse to produce diploid cell
 Diploid nucleus undergo meiosis then each progeny nucleus
undergo a single mitosis to produce 8 ascospores
 The asci can be aggregated together in various sorts of fruit body
(cleistothecia, perithecia, apothecia, pseudothecia)
 In yeasts, a single, diploid yeast will undergo meiosis, producing
four haploid progeny cells
How operculate asci develop
and shoot
Life cycle of
Podosphaera
leucotricha
SEXUAL REPRODUCTION IN BASIDIOMYCOTINA
 Acquisition of two mating types of nuclei by the fusion of
compatible mycelium (somatogamy)
 This creates a dikaryon; maintenance of the dikaryon requires
elaborate septum formation during growth and nuclear division
 Environmental conditions trigger the formation of a fruit body
primordium
 The primordium expands and differentiates to form the large fruit
bodies
 The mycelium within this structure remains as a dikaryon, diploid
formation only occurring within the modified hyphal tip called the
basidium
 Meiosis occurs within the basidium, and the four basidiospores
are extruded from the tip of the basidium on sterigma
Caryogamy, meiosis and
basidiospore formation in
Basidiomycotina
Life cycle of
Basidiomycotina
Life cycle in
rusts
(Uredinales)
Spermogonia with spermatia
and receptive hyphae
(gameto-gametangiogamy)
Aecia with aeciospores