1. Chapter 31
Fungi

2. Characteristics eukaryotic mostly multicellular, yeasts unicellular
no locomotion
sexual & asexual reproduction in most
heterotrophic by absorption (digestion extracellular)
> 100,000 species
saprophytes (also parasites, mutualistic symbionts)
some pathogenic
decomposers
classified by sexual reproduction
cell walls of chitin (polysaccharide)

3. Structure hyphae – rootlike structures for absorption
which collectively form a network, mycelium
cell walls:
septate – with cross walls with large pores
aseptate(coenocytic)–no cross walls; multinucleate
haustoria – nutrient-absorbing threads that
penetrate tissues of host in some parasitic types
hyphae may grow as fast as 1km/day
mycelia have haploid nuclei, some dikaryons- 2
separate nuclei that are dissimilar

4. Fungal mycelia

5. Cell wall types

6. Figure 31.2x Septate hyphae (left) and nonseptate hyphae (right)

7. Haustoria

8. Reproduction
spores (usu. haploid), diploid in brief sexual reproductive cycles, then meiosis
returns these to haploid
syngamy – nuclear union in fertilization usu. involves some form of conjugation
usu. asexually in optimal condtions, sexually in harsh conditions

9. Generalized life cycle

10. Classification Division Zygomycota – conjugation fungi
-common molds, incl. Rhizopus stolonifer,
Pilobilus
~600 sp. mostly terrestrial in soil or on
decaying plants/animals
-coenocytic hyphae
-asexually produce sporangia
-sexually by zygosporangia formed during
conjugation (+ and – strains fuse)

11. Zygomycete life cycle

12. Conjugation

13. Rhizopus

14. Pilobilus

15. Division Ascomycota – sac fungi
~30,000 sp.
-yeasts (Saccharomyces, Candida), Peziza
(cup fungus), morels, Ceratocystis ulmi –
causes Dutch elm disease
-septate hyphae
-asexually by conidia on conidiophores
-sexually by haploid ascospores in asci
-most fungal symbionts in this group

16. Ascomycete life cycle

17. Peziza, truffle, morel

18. Yeast

19. Penicillium

20. apothecia

21. Division Basidiomycota – club fungi
~25,000 sp.
-mushrooms, puffballs, shelf fungi
-produce > 10 billion spores
-septate hyphae
-asexually none, or conidia in some
-sexually by basidiospores in basidium

22. Basidiomycete life cycle

23. basidiomycetes

24. Gills of a basidiomycete

25. Stinkhorn, Phallis impudicus

26. Amanita (death cap)

27. Fairy ring

28. Division Deuteromycota – imperfect fungi
~25,000 sp.
-ringworm, athlete’s foot fungus, Arthrobotrys –
prey on roundworms in soil
-asexually by conidia
-sexually none observed

29. Symbioses 1) lichens – algae (filamentous green) –
Chlorophyta or blue green (cyanobacteria) &
fungus (ascomycete)
-may reproduce asexually either from
fragments or by dispersing tiny airborne
starters, soredia

30. Lichen structure

31. each organism also reproduces either
sexually or asexually
alga provides food for fungus, fungus
provides moisture, minerals, protection to
alga perhaps
thought to be more of a controlled
parasitism, than mutualism

32. Lichens usu. given genus & specific name 3 types: a) crustose – crusty
b) foliose – leafy
c) fruticose – shrubby
*air pollutant indicators

33. Crustose, fruticose, & folliose lichens

34. Symbioses 2) mycorrhizae – plant roots & fungus
-plant provides nutrients, fungus provides
more surface area to absorb water
-usu. basidiomycetes, may also be
ascomycetes or zygomycetes
*found in ~90% of tree species

35. Benefits of mycorrhizae

36. Mycorrhizae

37. Importance Beneficial: decomposers food source source of antibiotics
used in food and alcohol industries

38. Fungal production of an antibiotic

39. Importance Harmful: decay products cause disease destroy crops
spoil food

40. wheat rust, ergot on rye

41. pink ear disease of corn