1. ASCOMYCETES (CONT.) PYRENOMYCETES I
IB 371
General Mycology
Lecture 22
Tuesday November 11, 2003

2. ASCOMYCETES (CONT.) PYRENOMYCETES
Ascomata perithecial or sometimes cleistothecial
Ovoid to cylindrical unitunicate asci, usually formed from ascogenous hyphae and croziers in a hymenium or becoming scattered throughout the ascomata
Hamathecial tissue present or absent at maturity

3. PYRENOMYCETES Asci persistent or evanescent
Ascospores usually forcibly discharged from persistent asci
Ascospores comprising a wide range of morphologies
Asexual reproduction by conidia

4. PYRENOMYCETES Include numerous and important plant pathogens
Parasites and symbionts of arthropods
Saprophytes capable of degrading lignocellulose
Endophytes of a variety of plants
Mycotoxin producers
Etc.

5. In-class Activity

6. XYLARIALES - ASCOMATA Dark, leathery or carbonaceous
Usually a perithecium but sometimes a cleistothecium
Sometimes embedded in a stroma

7. Stromata

8. XYLAIALES - ASCI Formed in a peripheral or basal hymenial layer
Usually cylindrical, sometimes club shaped or subglobose
Usually with an apical ring surrounding a pore through which ascospores are discharged
Apical ring may be amyloid and stain blue in iodine

9. XYLARIALES - HAMATHECIUM
Paraphyses present - attached at base, growing upward and inward, and interspersed among the asci
Periphyses present in the beak of the perithecium

10. XYLARIALES - ASCOSPORES
Usually pigmented
One celled or sometimes transversely septate
With germ pores or slits
Sometimes with a gelatinous sheath

11. XYLARIALES - ANAMORPHS
Mostly holoblastic development with conidiogenous cells proliferating sympodially or percurrently

12. Hypoxylon multiforme

13. Hypoxylon ascospores

14. Xylaria stroma

15. Xylaria asci

16. Xylaria asci

17. XYLARIALES
Remember
Xylaria polymorpha – dead man’s fingers

18. SORDARIALES Primarily saproprobic on plant or animal remains, dung
Ascomata rarely in a stroma
Ascomata perithecial or cleistothecial
Peridium thin or thick, transparent to darkly pigmented

19. SORDARIALES
Asci cylindric to club-shaped with apical pores and often some type of apical apparatus
Paraphyses may or may not be present at maturity
Ascospores various in pigmentation and septation

20. Sordaria fimicola Used extensively for genetic studies
Found on dung (fimicolous)
Color mutations in ascospores used as markers in genetic studies
Beaks are positively phototrophic and direct forcibly shot ascospores away from the substrate

21. Sordaria

24. Podospora on dung

25. Podospora

26. Cercophora alleghensis

27. CHAETOMIUM Ubiquitous Cellulose decomposers
Mesophilic, thermotolerant, thermophilic species
Tooth paste fungus

28. CHAETOMIUM Perithecia ostiolate, covered with hairs
Asci thin-walled, evanescent
Ascospores lemon-shaped w. apical or sub-apical germ pores
Conidia, when produced, chlamydospores or phialospores

29. CHAETOMIUM - PERITHECIA

30. CHAETOMIUM

31. CHAETOMIUM

32. CHAETOMIUM

33. Neurospora crassa
Gets its name from the nerve-like striations on the ascospores
Used extensively in genetic studies (1 gene for 1 enzyme theory - Beadle & Tatum)
Field of haploid genetics - all genotypes expressed
Lab pest - very fast growth and conidiation rate, conidia hydrophobic & easily dispersed

35. Halosphaeriales
Occur primarily in seawater with some species in freshwater habitats
Ascomata membranous or carbonaceous
Hamathecium absent or as catenophyses
Asci thin-walled, usually without apical structures, deliquescing to release ascospores
Ascospores modified for dispersal & attachment in aquatic habitats

36. Ascospore appendages

37. HALOSPHAERIALES

38. HALOSPHAERIALES

39. HALOSPHAERIALES

40. Corollospora lacera

41. HALOSPHAERIALES

42. Nais glitra ascus

43. Nais glitra ascospores