Loculoascomycetes

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Loculoascomycetes

• General Mycology 421/521
• Lecture 9

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Loculoascomycetes

• Functionally bitunicate asci (fissitunicate,
  Jack-in-the-Box type)
• Extensible inner wall endotunica
• Inextensible outer wall exotunica
• Ascospores generally septate
• Anamorph conidia often similar in septation
• Unwalled locules in ascostroma (ascolocular)asco
  ma is initiated by formation of locule within
  stroma before formation of dikaryon

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Elsinoe
Pleospora
Dothidea
Images from http//www.tolweb.org/onlinecontributo
rs/app?pageImageGalleryserviceexternalspl2905
1sp0
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Bitunicate (fissitunicate) ascus
Apical chamber
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Endotunica
Exotunica
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Ascostromatal types
Hysteriothecium
Pseudothecium
Thyrothecium
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From Blackwell et al. 2006. Mycologia 98 834
Loculoascomycetes Dothideomycetes
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From Schoch et al. 2006. Mycologia 98 1043
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Importance

• Endophytes
• Animal Pathogens
• Plant Pathogens
• Cochliobolus heterostrophus Southern Corn Leaf
  Blight
• Venturia inaequalis Apple Scab
• Toxins (secondary metabolites)host specific
• T-toxins (Bipolaris maydis)
• Alternaria toxins

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Orders

• Pleosporales
• Hysteriales
• Botryosphaeriales
• Capnodiales
• Dothideales
• Myriangiales

paraphysate Dothideomycetes
Lack paraphyses or pseudoparaphysesaparaphysate
Dothideomycetes
Tree of Life Page for Dothideomycetes
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Order Pleosporales

• Relatively large asci
• Septate pseudoparaphyses
• Well known taxa
• Cochliobolus heterostrophus (southern corn leaf
  blight)
• Leptosphaeria maculans (black leg of rape seed)
• Phaeosphaeria nodorum (stagonospora blotch of
  cereals)
• Important anamorphs include Alternaria,
  Stemphylium, Drechslera, Ascochyta, Phoma,
  Pyrenochaeta

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Pleospora
From Hanlin, 1990
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Stemphylium anamorph
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Pyrenophora
From Hanlin, 1990
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Drechsleraconidia cylindrical, germinating from
any cell Pyrenophora teleomorphs
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Exserohilumconidia fusiform-cylindrical to
obclavate with protuberant hilum germination
bipolar. Setosphaeria teleomorphs.
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Bipolarisconidia fusoid, hilum not protuberant
germination bipolar. Cochliobolus teleomorphs.
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Curvularia photo by G. Barron
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Helminthosporium

• Once used for species now placed in Bipolaris,
  Drechslera, and Exserohilum
• Restricted to species with obclavate conidia
  formed on straight conidiophores
• Occurring on non-grass hosts

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Alternaria
Beaked dictyospores formed in acropetal chains
Lewia teleomorph
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Sporormiella spp., common on dung. Ascospores
segmented, each segment with a germ slit
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(No Transcript)
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Venturia

• Globose pseudothecia formed in overwintered
  leaves
• Unequally two-celled ascospores
• Spilocaea anamorph with annellidic conidiogenous
  cells

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Spilocea anamorph
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Apple scab from APSnet, photo by J. Hartman
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Order Botryosphaeriales

• Includes Botryosphaeria and Guignardiaone-celled,
  hyaline to pale brown ascospores
• Anamorphs pycnidial, phialidic
• Diebacks, cankers, witches brooms and leaf
  blights

http//www.crem.fct.unl.pt/botryosphaeria_site/
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Orders of aparaphysate Dothideomycetes

• Capnodiales
• Dothideales
• Myriangiales

Lack paraphyses or pseudoparaphysesaparaphysate
Tree of Life Page for Dothideomycetes
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Order Capnodiales

• Used in the traditional sense for sooty molds
  (leaf epiphytes associated with honeydew of
  insects)
• Now includes families
• Capnodiaceaesooty molds
• DavidiellaceaeCladosporium anamorphs
• Mycosphaerellaceae--Mycosphaerella
• Piedraiaceae

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Family Capnodiaceae

• Sooty Moldsform dense, dark, tangled mixtures
  of hyphae on plant stems and leaves
• Often associated with honeydew exudates of
  insects
• Produce superficial ascocarps on well-developed
  subiculum

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Sooty Molds
From USDA Forest Service North Central Research
Station
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Scorias
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Family Mycosphaerellaceae

• Mycosphaerella sensu lato (now in 4 different
  genera)
• Over 3000 species
• gt 30 different anamorphs recognized
  (Cercospora-like)
• Small pseudothecia lacking pseudoparaphyses
• Many important plant pathogens
• Reference Crous et al. 2007. Studies in
  Mycology 581-32.

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Family Davidiellaceae

• Cladosporium anamorphs have protuberant,
  thickened, darkened scars
• Teleomorph Davidiella, similar to Mycosphaerella

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Family Piedraiaceae
http//www.doctorfungus.org
Piedraia hortaecauses black piedra a
specialized parasite on hair of primates in moist
tropical areas
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Order Dothideales

• Dothidea and allied genera
• Small ascomata and relatively few asci
• Biotrophs, necrotrophs and saprobes on plant
  tissue
• Black yeast anamorphs, including Aureobasidium,
  Hormonema

Dothidea ascus by Sabine Huhndorf from TOL site
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Aureobasidium pullulans (Sydowia polyspora)

• Holoblastic development multiple conidia form
  from same cell
• Conidiogenous
  cells usually not
  
  differentiated

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Order Myriangiales

• Globose asci produced singly in locules
• Ascostroma with indeterminate growth
• Representatives
• Myriangiumassociated with plants, resins or
  scale insects on plants tropical to subtropical
• Elsinoëparasites on plant leaves and stems
  tropical to subtropical

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Myriangium Elsinoë
From Hanlin, 1990
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From Schoch et al. 2006. Mycologia 98 1043