This document provides an overview of key features of the ascomycota phylum. It describes their cell walls, hyphae, ability to fuse, and occurrence of dikaryotic cells. It then discusses important aspects of their life cycle including the meiosporangia or ascus, teleomorph and anamorph stages, and types of ascomata. It also details the different types of asci and ascospores as well as methods of asexual reproduction.

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. OSTIOLE
COELOMYCETES
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
2
1

32. EXAMPLES OF BLASTIC
4
3

33. EXAMPLES OF BLASTIC
4
5

35. ANSWER TO GUIDE QUESTIONS
• Haplobion0c: haploid
• Diplobion0c: diploid
• Haplodiplobion0c: haploid and diploid
• Ascomycetes bear two scien0fic names
– Anamorph (asexual) name
– Teleomorph (sexual) name