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Title: Filamentous Ascomycota: Pyrenomycetes (Part 1)


1
Filamentous Ascomycota Pyrenomycetes (Part 1)
  • General Mycology Pl P 421/521
  • Lecture 8

2
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3
From Blackwell et al. 2006. Mycologia 98 834
Pyrenomycetes Sordariomycetes
4
Sordariomycetes (Pyrenomycetes)
  • Subclasses Hypocreomycetidae, Xylariomycetidae
    and Sordariomycetidae include 16 orders
  • gt 600 genera, 3,000 species
  • Mostly unitunicate asci formed in hymenium and
    perithecial ascocarps (Pyrenomycetes sensu
    Luttrell 1951)
  • Asci forcibly discharge ascospores through ascus
    tip apparatus in most taxa
  • Asci evanescent (prototunicate) with passive
    discharge of ascospores in a few taxa
  • Diverse and often complex anamorphs

5
From Zhang et al. 2006. An overview of the
systematics of the Sordariomycetes based on a
four-gene phylogeny. Mycologia 98 1076-1087.
6
Order Hypocreales
  • Soft textured, usually pale to brightly colored
    perithecia
  • Unitunicate asci with thickened apices develop
    among apical periphyses
  • Often with pale to brightly colored, fleshy
    stromata

7
Hypocreales anamorphs
  • Wet conidia produced from phialidic conidiogenous
    cells
  • One-celled conidia
  • Acremoniumsimple conidiophores
  • Verticillium, Trichodermabranched conidiophores
  • Gliocladiumcomplex conidiophores
  • Stachybotryswhorl of phialides at conidiophore
    apex
  • Volutella, Tuberculariaconidiomata (sporodochia)
  • Septate conidia
  • Fusarium, Cylindrocarpon, Cylindrocladium

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10
Stachybotrys
Enteroblastic/phialidic development,
macronematous conidiophores, dark amerospores in
wet masses
11
Family Hypocreaceae
  • Hypocrea (anamorph Trichoderma)
  • Trichoderma is an important biological control
    agent
  • Hypomyces (diverse anamorphs)
  • Many species as parasites of mushrooms

12
Hypomyces lactiflorum
  • Parasitizes mushrooms early in their development
  • Russula brevipes is most common host
  • Lobster Mushroom
  • Produces bright orange perithecia embedded in
    subiculum
  • Ascospores two-celled
  • Anamorph Sepedonium

From Hanlin, 1990
13
Hypomyces lactiflorum Lobster Mushroom
14
Non-parasitized Russula brevipes, the host for H.
lactiflorum
15
Family Nectriaceae
  • Species previously placed in Nectria with large,
    nonstromatic perithecia now in Nectriaceae and
    Bionectriaceae (not covered)
  • Perithecia are orange to red, KOH
  • Most species have two-celled ascospores
  • Includes the teleomorphs of Fusarium,
    Cylindrocarpon, Cylindrocladium, Tubercularia

16
Nectria cinnabarina
  • Common parasite on dead branches
  • Orange perithecia formed on cushion-shaped
    stromata that previously formed Tubercularia
    anamorph

From Hanlin, 1990
17
Nectria cinnabarina from http//www.grzyby.pl/gatu
nki/Nectria_cinnabarina.htm
18
Cosmospora photo by B. Callan
19
Family Clavicipitaceae
  • Characterized by threadlike ascospores and
    perithecia embedded in stromata
  • Produce a wide range of secondary metabolites
  • Parasitic on plants and animals
  • Balansia, Claviceps and Epichloë are plant
    parasites
  • Cordyceps parasitizes insect larvae and hypogeous
    fungal fruiting bodies
  • Anamorphic genera Beauveria, Hirsutella,
    Metarhizium and Tolypocladium parasitize insects

20
Claviceps purpurea from Hanlin, 1990
21
Claviceps purpurea stromata and sclerotium
(left), and perithecia (above)
22
Claviceps purpurea lifecycle
  • Sclerotia fall to ground in fall and overwinter
  • Sclerotia germinate in spring to produce stromata
    with perithecia
  • Thread-like ascospores are wind-disseminated
  • Ascospores that land on susceptible flower
    germinate and grow into the ovary
  • Sphacelia anamorph develops in honey dew formed
    on infected florets
  • Conidia are dispersed to uninfected flowers by
    rain or insects

23
Claviceps purpurea
  • Causes ergot of rye and other grasses
  • Sclerotia formed in grass ovary composed of
    pseudoparenchymatous fungal tissue
  • May contain high levels of 3 types of alkaloids
  • Secoergolenes
  • Ergolines
  • Lysergic acid derivatives

24
Ergotism
  • Ergotism is a disease in animals (including
    humans)
  • Vascular constriction that may lead to gangrene
  • Hallucinations
  • Ergotism involved in/responsible for
  • St. Anthonys Fire (Middle Ages)
  • Salem Witch Trials (1692)
  • Modern outbreaks in France, Ethiopia, India

25
Balansia and Epichloë
  • Grass and sedge endophytes
  • Endophytes are fungi that cause symptomless
    infections in plant hosts
  • Anamorph Neotyphodium grows intercellularly in
    plant host
  • Seed transmitted (vertical transmission) if
    flowers are produced by infected plants
  • Horizontally transmitted in species inhibiting
    flower production
  • Beneficial to plant
  • Secondary metabolites (alkaloids) produced by
    endophyte protects plants from herbivores
    (Ryegrass Staggers)
  • May confer drought resistance to infected plants

26
Epichloe typhina
27
Cordyceps
  • Infects insect larvae (e.g., caterpillars) or
    underground fungal fruiting bodies
  • Club-like stromata emerge from host, perithecia
    embedded in apical region
  • Threadlike ascospores break apart while in ascus
  • Cordyceps militaris has medicinal properties and
    has a long history of use in Asia

28
Cordyceps
29
Order Xylariales
  • Dark, leathery, woody or carbonaceous perithecia
    usually embedded in well-developed stromata
  • Ascus tips have ring that turns blue in Melzers
    reagent (amyloid reaction)
  • Anamorphs usually holoblastic
  • Wood decompers, endophytes, plant pathogens
  • Two families
  • Xylariaceae
  • Diatrypaceae

30
From Hanlin 1990)
31
Hypoxylon spp. from Home of the
Xylariaceae http//mycology.sinica.edu.tw/Xylariac
eae/
32
Xylaria hypoxylon from www.mykoweb.com/CAF/species
/Xylaria_hypoxylon.html
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Order Microascales
  • Family Ceratocystidiaceae
  • Ceratocystis (Chalara anamorphs)
  • Perithecia with long necks, ascospores passively
    discharged
  • Cyclohexamide sensitive, lacks cellulose and
    rhamnose in walls
  • Ascospores dispersed by bark beetles
  • May cause wilt diseases, blue stain

35
Chalara anamorph
From Nag Raj and Kendrick, 1975
From Hanlin, 1990
36
Blue stain in pine http//forestpathology.coafes.
umn.edu/biocontrol.htm
37
Family Glomerellaceae
  • Monotypic family characterized by black,
    nonstromatic perithecia, abundant paraphyses and
    asci with a J- apical ring
  • Glomerella
  • Glomerella cingulata (anamorph Colletotrichum
    gloeosporioides) causes anthracnose type
    diseases in gt 100 species of plants
  • Anamorphs characterized by acervuli with
    prominent setae, production of appressoria upon
    conidial germination

38
Hanlin, 1990
39
Colletotrichum coccoides
40
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Order Ophiostomatales
  • Ophiostoma differs from Ceratocystis
  • Cyclohexamide insensitive
  • Cellulose and rhamnose in cell walls
  • Nonphialidic anamorphs (Sporothrix and
    Leptographium)
  • Ophiostoma ulmi, causal agent of Dutch Elm
    Disease, killed many of the North American elm
    trees in 1920s
  • Second pandemic of elm disease that occurred
    later was caused by N. novo-ulmi, a more
    aggressive pathogen due to formation of toxin
    (see Brasier Buck, 2001 Brasier Kirk, 2001)

42
Ophiostoma and Leptographium
From D. Malloch www.botany.utoronto.ca
From Hanlin, 1990
43
Perithecial necks and ascospores
Beetle galleries
44
Order Diaporthales
  • Black perithecia in stromata composed of host
    fungal tissues, asci float free at maturity, most
    with refractive ascus tip
  • Important genera
  • Diaporthe (Phomopsis anamorphs)
  • Phomopsis characterized by ?- and ?-conidia
  • Cryphonectria parasitica (Chestnut blight)
  • Gaeumannomyces graminis var. tritici (Take-all
    disease of wheat)

45
Diaporthe and Phomopsis
46
Soybeans infected by Phomopsis http//www.ent.iast
ate.edu/imagegal/plantpath/soybean/phomopsis/phomp
sisseeddamxb.html
Phomopsis Cane Spot on Grapes
Phomopsis on alfalfa stem (USDA ARS Systematic
Mycology Lab)
http//winegrapes.tamu.edu/grow/diseases/photos/ph
omopsis1.jpg
47
Cryphonectria parasitica
  • Chestnut blight pathogen introduced to North
    America in 1904, by 1940 had destroyed all the
    chestnut trees in the eastern US

48
Chestnut blight - virulent canker
49
Cryphonectria parasitica
50
Family Magnaporthaceae
  • Magnaporthe grisea, anamorph Pyricularia grisea
    causes Rice Blast

From Valent (2004). Nature 431 516-517
51
Magnaporthe and Pyricularia
From Hanlin, 1990
From Carmichael et al., 1980
52
Order Sordariales
  • Mostly wood or dung inhabiting taxa
  • Asci with thin, refractive apical ring, one or
    two-celled ascospores, often with appendages or
    sheaths
  • Phialophora-like anamorphs (phialidic) when known
  • Taxa to be covered
  • Chaetomium, Gelasinospora, Neurospora, Sordaria

53
Neurospora
  • Asci with refractive apical ring
  • Ascospores one-celled, darkly pigmented, apical
    germ pore
  • Grow rapidly in culture, sporulate abundantly
  • Chrysonilia (Monilia) anamorph
  • common on burnt substrates
  • N. sitophila is the red bread mold
  • G. W. Beadle and E. L. Tatum used mutated strain
    of Neurospora to demonstrate that enzymes are
    controlled by genes

54
Chrysonilia anamorph http//www.botany.utoronto.ca
/Research Labs/MallochLab/Malloch/Moulds/Contents.
html
Hanlin, 1990
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Neurospora tetraspora
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Sordaria and Gelasinospora
Hanlin, 1990
59
Chaetomium
  • Asci deliquesce at maturity
  • Ascospores one-celled, with germ pore(s)
  • Conspicuous hairs on ascomata
  • Cellulolytic, occur on paper and cotton

Hanlin 1990
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