Ascomycota

1. ASCOMYCOTA

Special
Reference:


h*p://www.mycolog.com/


2. IMPORTANT
FEATURES

• Chi0nous
cell
walls

• Hyphae
with
septa
(cross‐walls)

– Except
for
Yeasts
(non‐hypha)

• Ability
of
soma0c
assimila0ve
hypha
to
fuse
with

one
another
and
to
exchange
nuclei

(anastomosis)

• Occurrence
in
their
life
cycle
of
a
dikaryon












(diploid)


3. THE
MEIOSPORANGIA
OR
ASCUS


4. IMPORTANT
CHARACTERS
IN
AN

ASCOMYCETE
LIFE
CYCLE

HOLOMORPH
=
ANAMORPH
+
TELEOMORPH

WHOLE
FUNGUS
=
ASEXUAL
REPRODUCTION
+

SEXUAL
REPRODUCTION


5. THE
TELEOMORPH
(SEXUAL)

• When
an
ascospore
germinates,
it

establishes
a
haploid
mycelium.

• In
heterothallic
ascomycetes,
this

can't
undergo
sexual
reproduc0on

un0l
it
meets
another
compa0ble

haploid
mycelium.

• When
this
rare
event
takes
place,

the
fungus
cleverly
maximizes
the

ensuing
poten0al
for
gene0c

recombina0on.

• One
would
expect
a
single
sexual

fusion,
resul0ng
in
a
single
zygote


6. THE
ASCOMA
OR
ASCOMATA


7. ASCOMYCETE
FRUITING
STRUCTURES

• The
mul0cellular
structures
(ascomata)
that

produce
the
asci,
and
act
as
the
plaMorms

from
which
the
spores
are
launched

• Four
Types

– Apothecial


– Perithecial

– Pseudothecial

– Cleistothecial


8. APOTHECIAL
ASCOMA

• The
construc0on
of
the

ascoma
may
allow

several
or
many
asci
to

discharge

simultaneously
because

the
en0re
fer0le
layer

or
hymenium
is

exposed...





9. PERITHECIAL
ASCOMATA

• contain
unitunicate‐
inoperculate
asci


10. PSEUDOTHECIAL
ASCOMATA

• contain
bitunicate
asci


11. CLEISTOTHECIAL
ASCOMATA

• asci
oPen
spherical
and
no

longer
shoot
their
spores:
the

fungus
has
evolved
a
new

dispersal
strategy

• the
fungus
fruits
in
a
confined

space
(for
example,
under

bark,
or
below
the
surface
of

the
ground)
where
airborne

dispersal
cannot
operate

• asci
are
clearly
visible

and
not

arranged
in
a
layer
or

hymenium
(as
they
were
in

the
other
three
kinds
of

ascoma)


12. THE
ASCUS/ASCI

The
Ascomycete
Spores


13. FOUR
TYPES
OF
ASCUS/ASCI

• Unitunicate
Operculate

• Unitunicate
Inoperculate

• Protunicate

• Bitunicate


14. UNITUNICATE
OPERCULATE
ASCI

• have
a
single
wall

• have
a
built‐in
lid
or
operculum

which
pops
open
so
that
the

spores
can
be
ejected

• found
only
in
apothecial

ascomata


15. UNITUNICATE
INOPERCULATE
ASCI

• have
no
operculum,
but
have
a
special
elas0c
ring

mechanism
built
into
their
0p
(apical
ring)

• this
is
a
pre‐set
pressure
release
valve,
or

sphincter,
and
the
ring
eventually
stretches

momentarily,
or
turns
inside
out,
to
let
the
spores

shoot
through

• found
in
perithecial
and
some
apothecial

ascomata


17. PROTUNICATE
ASCI

• have
no
ac0ve
spore‐shoo0ng
mechanism

• usually
more
or
less
spherical;
found
in

cleistothecial
(occasionally
perithecial)

• wall
dissolves
at
maturity
and
releases
the

ascospores,
which
can
then
ooze,
rather
than
be

shot,
out
of
the
ascoma;
or
they
may
wait
inside

un0l
it
decays
or
is
ruptured

• believed
to
have
evolved
from
unitunicate
asci


19. BITUNICATE
ASCI

• have
a
double
wall

– OUTER
wall:
thin,
inextensible

– INNER
wall:

thick,
elas0c
inner
wall

• At
maturity
the
thin
outer
wall
splits,
and
the

thick
inner
wall
absorbs
water
and
expands

upward,
carrying
the
ascospores
with
it

• design
allows
the
ascus
to
stretch
up
into
the

neck
of
the
ascoma
to
expel
its
spores


21. UNITUNICATE
VERSUS
BITUNICATE

• unitunicate
ascomycetes

– perithecial
ascoma
develops
only
aPer
the
sexual
s0mulus,

so
that
the
asci
can
grow
into
an
ac0vely
enlarging
cavity

• bitunicate
ascomycetes

– fer0liza0on
doesn't
happen
un0l
aPer
a
solid
primordium

or
stroma
has
developed

– so
room
has
to
be
made
for
the
asci
by
dissolving
away

exis0ng
0ssue

– asci
themselves
do
the
job
or
the
special
sterile
hyphae

(pseudoparaphyses)
growing
down
from
the
upper
layer
of

the
stroma

– NOTE:
pseudothecial
ascomata
always
produce
bitunicate

asci.



22. THE
ANAMORPH
(Asexual)


23. ANAMORPH
CLASSIFICATION


BASED
ON:

• Mitospores
or
conidia

• Diverse
Structures
Bearing
the
Conidia

– Conidiogenous
cells

– Conidiophores

– Conidiomata

• The
ways
in
which
they
develop
(conidiogenesis)

• Either
Coelomycetes
(covered
conidiomata)
or

Hyphomycetes
(exposed
conidiomata/molds)


24. COELOMYCETES

OSTIOLE

ACERVULUS


25. HYPHOMYCETES
OR
MOLDS


26. TYPES
OF
CONIDIOPHORES
/

CONIDIOMATA


27. THE
CONIDIA
OR
ASEXUAL
SPORES

CAN
YOU
NAME
THE
TYPE
OF
CONIDIA???


28. TYPES
OF
SPORE
DEVELOPMENT

• blas0c
conidiogenesis

– the
young
conidium
is

recognizable
before
it
is
cut

off
by
a
cross‐wall

(BUDDING)

• thallic
conidiogenesis

– cross‐wall
is
laid
down

before
differen0a0on
of
the

conidium
begins


29. TYPES
OF
SPORE
DEVELOPMENT

• schizoly0c
dehiscence
the

halves
of
a
double
septum

split
apart
by
the

breakdown
of
a
kind
of

middle
lamella

• rhexoly0c
dehiscence
the

outer
wall
of
a
cell

beneath
or
between

conidia
breaks
down


31. EXAMPLES
OF
BLASTIC

1

2


32. EXAMPLES
OF
BLASTIC

3

4


33. EXAMPLES
OF
BLASTIC

5

4


35. ANSWER
TO
GUIDE
QUESTIONS

• Haplobion0c:
haploid


• Diplobion0c:
diploid

• Haplodiplobion0c:
haploid
and
diploid

• Ascomycetes
bear
two
scien0fic
names

– Anamorph
(asexual)
name

– Teleomorph
(sexual)
name