Title: Phylum Ascomycota Orders Erysiphales
1Phylum AscomycotaOrders Erysiphales
Laboulbeniales
- General Mycology
- Pl P 421/521
- Lecture 7
2(No Transcript)
3Blackwell et al. 2006. Mycologia 98 834
4Blackwell et al. 2006. Mycologia 98 834
5Erysiphales
- Common name Powdery Mildews
- Biotrophs of vascular plants
- Biotroph an obligate parasite growing on
another living organism - 21 genera, 437 species infecting gt 40,000 species
of plants (mostly dicots) - Most species are host specific, a few are
omnivorous, infecting hundreds of host species
6Powdery Mildew Symptoms
Photo by Claudia Nitschwitz
7Characteristics
- Mycelium is mostly superficial
- Anchored to host epidermis by appressoria
- Nutrients obtained via haustoria
- Haustoria are intracellular structures
- Overwinter as mycelium in infected buds or as
ascomata - Asexual reproduction via conidia
- Sexual reproduction via ascospores formed in
cleistothecia
8From APSnet.org
9fungus
10Asexual reproduction
- Erect, hyaline conidiophores are usually formed
on superficial mycelium - One-celled, hyaline thin-walled conidia are
produced holoblastically in basipetal chains - One colony can produce gt 30,000 conidia
11Conidia
- Wind-dispersed
- Germination can occur at low relative humidity
- Germination involves germ tube, appressorium and
penetration peg formation - Apex of penetration peg enlarges to form
haustorium
12(No Transcript)
13Microsphaera alni anamorph on Vaccinium
14Sexual reproduction
- Cleistothecia formed on superficial mycelium in
late summer/early fall - Asci
- Formed in basal layer
- Globose to pyriform
- Discharge by rupture of ascus tip
15Asci/Ascospores
- One to numerous asci/cleistothecium
- Ascospores hyaline, one-celled, ovoid
- 1-8 ascospores/ascus
- Number of asci/cleistothecium is important
character in identification
16From APSnet.org
17Identification
- Anamorph type
- Number of asci/ascocarp
- Cleistothecial appendages
- Mycelioid
- Rigid
- Spear-like with inflated base
- With curled tips
- With dichotomously branched tips
18Microsphaera alni cleistothecia
19Sawadaea bicornis cleistothecia
20Sawadaea bicornis cleistothecial appendages
21Blumeria
- B. graminis--only powdery mildew on grasses
- Mycelial setae
- Digitate haustoria
- Several asci/ascocarp
- Inflated base on conidiophore
22Mycelioid Appendages
- Several asci/ascocarp
- Eryisiphe (100 spp)
- Oidium anamorph
- Leveillula (8 spp.)
- Internal mycelium
- Oidiopsis anamorph (emerges through stomate)
- One ascus/ascocarp
- Sphaerotheca (50 spp.)
- Appendages with curled tips
- Oidium anamorph with fibrosin bodies
23Dichotomously branched appendage tips
- One ascus/ascocarp
- Podosphaera (12 spp.)
- Oidium anamorph with fibrosin bodies
- Several asci/ascocarp
- Microsphaera (125 spp.)
- Oidium anamorph
- Sawadaea (6 spp.)
- Curved tips on appendages
- Oidium anamorph with fibrosin bodies
24Spear-like appendages--Phyllactinia
- 24 species
- Appendages lift ascocarp off leaf surface
- Brush cells on top of ascocarp
- Ovulariopsis and Streptopodium anamorphs
25Appendages with curled tips
- Uncinula (81 spp)
- Oidium anamorph
- Several asci/ascocarp
- Uncinuliella
- Differs by bristle-like appendages on top of
ascocarp
26Molecular data vs. morphology
- Phylogeny analyses of powdery mildews based on
rDNA sequence data shows lineages corresponding
to anamorph type rather than teleomorph
morphology (Saenz Taylor 1999, Can. J. Botany
77150-168 Mori et al 2000, Mycologia 9274-93)
27Saenz Taylor 1999
28Class Laboulbeniomycetes
- Orders Laboulbeniales and Pyxidiophorales
- 5 families, 140 genera, gt 1800 species
- Members of 4/5 families lack hyphae, reduced to
thallus attached to host - Parasitize arthropods
29Laboulbeniomycetes
- Most species are highly host specific, found on
only one arthropod species - Roland Thaxter (1858-1932) at Farlow Herbarium,
Harvard was one of the leading experts on this
group - Published a series of monographs on
Laboulbeniales (1896-1931)
30Roland Thaxters "Contributions towards a
monograph of the Laboulbeniaceae"
31(No Transcript)
32Laboul images by Alex Weir
33Hosts of Laboulbeniales (From Meredith
Blackwell)
Blattoidea (cockroaches and allies) Coleoptera (beetles) Dermaptera (earwigs) Diptera (true flies) Heteroptera (bugs) Hymenoptera Formicidae (ants) Isoptera (termites) Mallophaga (bird lice) Orthoptera (crickets and allies) Thysanoptera (thrips) Acarina (mites) Diplopoda (millipedes)
Most species of. Laboulbeniales have been
reported from beetles and flies in temperate
regions, but recent studies in the tropics
indicate that diversity in these regions may be
much greater than in temperate areas, primarily
because diversity of hosts, especially beetles,
is much higher.
34Pyxidiophorales
- 2 genera, 16 species
- Specialized for dispersal by arthropods (bark
dung beetles, phoretic mites) - Perithecia with ascospores that undergo extreme
morphological changes during maturation
35Blackwell et al. 1986. Hyperphoretic dispersal
of a Pyxidiophora anamorph. Science 232 993-995
36Pyxidiophora perithecia
Development of anamorph
Photos by M. Blackwell
37Presumptive anamorph (above)
From Kirschner (2003). Mycological Progress 2
209-218.