1. Filamentous fungi - review and Oomycetes
Lecture 3

2. Four phyla of fungi Chytridiomycota - no sexual spore
Zygomycota - zygospore
Ascomycota - ascospore
Basidiomycota - basidiospore

3. Ascomycota

4. Botrytis cinerea - a fungus -causes grey mold

5. Powdery mildew of cucumber

6. Eye spot disease of strawberry Ramularia grevilleana, Mycosphaerella fragariae

7. Canker, Nectria galligena

8. Wilts caused by Fusarium oxysporum
Darkened vascular tissue of cucumber caused by F. ox. f.sp. cucumerinum
Wilt of field grown melon caused by F. ox. formae speciales melonis

9. Characteristics of Basidiomycota
Mycelium is septate
Septa are perforated - sometimes with dolipore (doughnut shaped)

10. Basidiomycetes have clamp connections

11. Fly agaric (flugsvamp)

12. Stem rust of wheat

13. Aecia on barberry

15. Rust of raspberry

16. Rust of rose

17. Rhizoctonia solani
It is a basidiomycete; teliomorph (Thanatephorus cucumeris) is rare.
Has very characteristic mycelium; typical of basidiomycete.
Differentiated into anastomosis groups (AG) (fusion of hyphae only occur if same anastomosis group)

18. Corn smut

19. Corn smut

20. Corn smut

21. The disease cycle of corn smut

22. Oomycota They are very different from true fungi:
Cell walls have cellulose and glucans.
Hyphae have no cross walls (septae).
Spore types:
Oospore = resting spore, sexual spore
Zoospores, zoosporangia = asexual spores
Examples:
Pythium -seed rot, damping off, root rot
Bremia, Peronospora, Plasmopara - downy mildews

23. Oomycetes belong to Chromista

24. Different types of diseases caused by Oomycetes

25. Late blight of potato, caused by Phytophthora infestans

26. The disease cycle of potato late blight (Phytophthora infestans)

27. Mature sporangium

28. There are 8-10 zoospores per sporangium

29. Zoospores are released

30. One zoospore left…

31. Zoospores germinate

32. See movie of zoospore release

33. Grass lawn attacked by Pythium ultimum (damping off)

34. Life cycle of Pythium ultimum

35. Downy mildew of grape

36. Attack of grape berries

37. Symptoms of grape downy mildew (Plasmopara viticola)

38. Disease cycle of Plasmopara viticola, downy mildew of grape

39. Zoospores of downy mildew of hop, landing on leaf and infecting

40. Downy mildew of onion (Peronospora destructor)

41. Downy mildew of cabbage (Peronospora parasitica)

42. Tree and strawberry diseases caused by Phytophthora species

43. Strawberry crown rot, caused by Phytophthora cactorum
Oospore and sporangia

44. Alnus glutinosa attacked by Alder Phytophthora
Brownish red discolouration
Oogonia
Oospore
Amphigyne two-celled antheridia
Alder stembase
Photo: Christer Olsson

45. Symptoms of Phytophthora alni ssp. uniformis on alder (Alnus glutinosa)
The pathogen infects through wounds at the stembase or through the roots.
The tree tops die
The tree dies later

46. Phytophthora ramorum, chlamydospores. (Diameter 20 – 90 µm, 52
Phytophthora ramorum, chlamydospores. (Diameter 20 – 90 µm, 52.5 – 75 µm on this slide). Often germinating with a sporangiophore.
Isolat CH 180, (CBS ; P1357), The Netherlands, Rhododendron.
Heterothallic (A1).
Christer Olsson, 1/7 2002, DIA bilder