1. EUMYCOTA: Phylum Dikaryomycotina Sub-phylum: Ascomycotina
90% of all fungi are in the Dikaryomycotina

2. Ascomycotina Chromistan Fungi Eumycotan Fungi. Ascomycotina
1. Chytridiomycota
2. Zygomycota
3. Dikaryomycota
Ascomycotina
Basidiomycotina
phyla sub-phyla

3. Dikaryomycota Compared to Zygomycota :-
1. have thinner hyphae with thicker walls,
divided into compartments by septae which contain pores.
2. This makes them tougher and much more able to thrive in drier situations
3. More capable of utilizing complex substances - e.g cellulose., lignin, keratin, chitin.

4. Dikaryomycota
4. Hyphae can fuse and exchange nuclei and form heterokaryons, particularly dikaryons - necessary stage to sexual reproduction. Dikaryon = cells have 2 haploid nuclei of different origins in a stable state - continued each time cell divides.

5. Ascomycotina - main features (cf. Basidiomycotina)
restricted dikaryophase (only in special fruiting bodies - ascoma)
Many cells within the ascoma develop into asci. Nuclear fusion and meiosis occurs to form 4, 8, 16 etc ascospores inside each ascus.
simple septal pores
2-layered cell walls
no clamp connections
molecular differences from Basidiomycotina (GC content etc.)

6. Ascomycotina - importance
many pathogenic fungi
e.g. humans (ringworm, athletes foot - attack keratin)
plants - southern corn blight, powdery mildews
important saprophytes: rots and moulds of wood, paper, animals etc
beneficial decomposers of material in soils
producers of mycotoxins (eg aflatoxin)
insect and nematode predators and parasites
useful in food (yeast, cheeses) or antibiotic prep. (penicillin, cyclosporine)

7. Ascomycotina - importance
Many species have developed an association with algae to form lichens.
Includes most yeasts - of major importance in ecology and commerce.
important in molecular and classical genetics

8. Taphrina deformans - peach leaf curl
Claviceps purpurea - ergot of Rye. Caused outbreaks of St Anthony’s Fire in Middle Ages. Source of LSD and medicinal drugs

9. Mushroom-like Ascomycetes
Blue-green Stainer
Orange-peel Cup
Yellow Fairy cups
Photos - Dr. Greg Thorn

10. Mushroom-like Ascomycetes

11. Highly prized edible Morels

12. Highly poisonous - especially to the cook!
Conifer False Morel
Highly poisonous - especially to the cook!
Black Morel - mycelium penetrates roots of nearby plants and trees - Parasitic. Highly-sought after as a delicacy
Trooping Cordyceps
Parasitizes and fruits on moth pupae
Eutypella Canker
Photos - Dr. Greg Thorn

14. Ascomycotina - main groups
Class - Ascomycetes - filamentous species
Class - Saccharomycetes - unicellular yeast species
most Lichen fungi are Ascomycetes
Often the many fungi that have no known teleomorph stages are put in an artificial group ‘Deuteromycetes’

15. Holomorph = Anamorph + Teleomorph
Anamorph = asexual stages - mitosis - usually haploid
Teleomorph = sexual stages - involves dikaryons, diploidy and meiosis

16. Teleomorphs of Ascomycetes
Teleomorph begins when hyphae anastomose (= fuse together), become dikaryotic and aggregate into compact masses (ascoma).
4 kinds of ascoma -
apothecia - open cups
perithecia + pseudothecia - narrow opening flasks
cleistothecia - closed spheres or flasks.

17. Life cycle of typical Ascomycete

18. 1. Apothecium

19. 3. pseudothecium
Types of ascoma
2. perithecium
4. cleistothecium

20. Life cycle of Ergot fungus
Claviceps purpurea.

21. Ascomycetes ascus Basidiomycetes basidium
crozier only found just before ascus formation
Basidiomycetes
basidium
clamp connection every time a hyphal cell divides

22. The 4 main types of asci unitunicate - operculate ascus
unitunicate - inoperculate
unitunicate - operculate ascus
bitunicate ascus
The 4 main types of asci

23. The anamorph-teleomorph problem
In Ascomycetes, anamorphs and teleomorphs often develop at different times and places or in many cases not at all. Each stage is therefore often collected in ignorance of the existence of the other
Normal classification is based on teleomorph stages, but mycologists have had to classify specimens in which they only find anamorph stages.
Thus parallel systems of nomenclature have sprung up - we have teleomorph genera and anamorph genera and mycologists try to draw connections between them where possible.
DNA analyses will make this much easier in future.

24. The anamorph-teleomorph problem
In some cases it has been possible to ‘connect’ the anamorph name with the teleomorph name - but in many others this has not yet been done and may never be possible because the organism may have lost the ability to reproduce sexually.
Of 30,000 known Ascomycetes only 5,000 have been ‘connected’ to their anamorphs - results often ‘messy’
eg teleomorph genera, Nectria and Gibberella, both have anamorphs which have been classified in the anamorph genus Fusarium.
Many anamorphs (85%) have no known teleomorph - are lumped in artificial group Deuteromycetes.

25. Parasexual cycle in the anamorph
Recombination during MITOSIS has been observed in many fungi - it may be particularly well developed in the so-called ‘Deuteromycetes’ Parasexual cycle
Haploid mycelium
Somatic diploids arise through nuclear fusion
Dikaryotic cells
Chromosome loss = haploidization
Mitotic crossing-over > diploid segregants
Mitotic divisions

26. Ascomycetes - the anamorph
The typical anamorph spore in Ascomycetes = conidia produced outside a specialized hyphal cell.
compare with Zygomycetes which produce sporangiospores inside a sporangium.
conidia = asexual spores produced in vast numbers by mitotic divisions. They vary greatly in morphology, in septation and in how they are borne on the conidiophores.

27. Ascomycetes - the anamorph
classification of ascomycete anamorphs based on :-
conidial features
Hyphomycetes - conidiophores never enclosed
Coelomycetes - conidiophores enclosed in a covering.
conidial shape and septation
conidiophore details also used

28. Anamorph classification
conidium
acervulus
Coelomycetes have their conidia in a covered structure.
Covered either by host cells (acervulus) or by fungal hyphae in flask shape (pycnidium)
pycnidium

29. Anamorph classification
conidium
Hyphomycetes have their conidia exposed.

30. Conidia of Aspergillus sp.
conidiophore

31. Skim read Chap 4 pages 45 (“conidium morphology”) to
52 (“Type X”).
No need to memorize this material on types of conidia and conidiation.
Pages Read to get general understanding of the range of Ascomycete species, the ways they differ and their importance.