ASCOMYCETES (CONT.) PYRENOMYCETES I

Presentation on theme: "ASCOMYCETES (CONT.) PYRENOMYCETES I"— Presentation transcript:

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

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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

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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