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ASCOMYCETES (CONT.) PYRENOMYCETES I

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Primarily saproprobic on plant or animal remains, dung. Ascomata rarely in a stroma ... Found on dung (fimicolous) Color mutations in ascospores used as markers ... – PowerPoint PPT presentation

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Title: ASCOMYCETES (CONT.) PYRENOMYCETES I


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
Xylariastroma
15
Xylariaasci
16
Xylariaasci
17
XYLARIALES
  • Remember
  • Xylaria polymorpha dead mans 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
22
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23
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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

34
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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
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