lecture 16 ascomycota v - university of...

Lecture 16�

Ascomycota V� - Lichenized fungi �

- Eurotiomycetes �

- Laboulbeniales �

Lutzoni et al., 2004, American Journal of Botany

Sordariomycetes

Lichen-forming

Lichen-forming

Nature 21:937-940. 2001

- Reconstruction of ancestral character-states

uncertain

- Nuclear ribosomal DNA phylogeny

Basidiomycota Archiascomycota

Euascomycota

Hemiascomycota

lichen-forming

Generalities on Lichens

LICHENS = a fungus + a photosymbiont (algae or cyanobacteria) : not a monophyletic group;

LICHENS result from SYMBIOSIS between organisms from different Kingdoms.

- 15-20,000 recognized lichen species vs.a total of ~30,000 Asco species ==> lichen count for ca. > 40% of of all known Ascomycetes ==> one fifth of all known fungi!

- Habitats: primary (eukaryotic) colonizers of harsh / abiotic habitats, including rocks; --- are found in the most extreme environments, e.g., sandstone deserts from hot Namibia to cold Antarctica and up to 7,000 m. high in Mt Everest slopes.

Food for thoughts:

Heckman et al., Science (2001) : speculate lichens as early colonizers of terrestrial habitats 1.5 byo

Kendrick’s textbook (2000) statement p.124: “it has been suggested that if [early] life were found in another planet, it might well be lichen-like… I consider it unlikely, because the existence of lichens depend on the previous existence of … a fungus and an algae… [on other planets] we should look for Archaebacteria…”


The wedding partners:

--- the fungus = an Ascomycota (very rarely a Basidio:e.g., Multiclavulina); -------- more than one fungus can be associated to the same lichen colony.

--- either an algae ------- Trebouxia, in 80% of lichens: unicellular algae, which has never been found free-living, ------- Trentepohlia (a filamentous, also free-living algae). ------- ….

--- or a filamentous cyanobacterium, often Nostoc.

These three genera are the photobiont partner in > 90% of lichens

Nostoc

Arrows show heterocysts, which are specialized cells that fix atmospheric nitrogen.

Trebouxia

(pics from Kendrick)



http://www.bioimages.org.uk/HTML/R133811.HTM

Not necessarily lichenized (=captured by a fungus): Trentepohlia, a free living algae mostly found on light-exposedbark and rock.

Lichen thalli have five kinds of macromorphology (See Kendrick, Chapt. 7)

(1) crustose -- so closely applied to the substrate that to collect them you often have to take some of the rock or bark they are growing on as well (2) foliose -- having leafy or tongue-like lobes which are not so closely applied to the substrate; (3) fruticose -- with upright or hanging, stalked, shrubby or hair-like thalli (fruticose means bushy, and has nothing to do with fruit); (4) squamulose -- the thallus is made up of small scales (5) leprose -- powdery, essentially made up of soredia-like aggregations, and lacking a cortex.

Mixed macromorphology: E.g., in Cladonia the primary thallus is squamulose but there is also a secondary, upright, reproductive fruticose thallus called a podetium.



http://www.msu.edu/course/bot/423/Plntlist8mosslichen.html

Crustose / foliose

fruticose

3) Asexual (vegetative) reproduction: - soredia: the upper surface of the thallus ruptures, exposing a powdery mass of propagules called soredia, which are small groups of algal cells entangled in fungal hyphae. - isidia: small, finger-like or branched structures called isidia, which grow up from the thallus, then break off.

4) Sexual reproduction: ascus ---> ascospores

5) Lichens produce a wide array of unique secondary metabolites that have been used for systematics (chemotaxonomy);

- many lichens have antibiotic properties and have been used in traditional medicine around the world.

- extremely slow growth rate; best measured from old gravestones!

- extreme longevity; some lichen colonies are thought to be > 4,000 year old

- extreme sensibility to air pollution mostly acid rain and carbon dioxide; many cities are virtually lichen-free! Can be used for biocontrol of air-quality. See for instance: http://www.ac.wwu.edu/~fredr/Lichen_table.htm


Two small groups of lichens in the Sordariomycetes clade

- Lichinomycetes - Arthoniomycetidae (= Arthoniomycetes) �

Lutzoni et al., 2004, American Journal of Botany

Sordariomycetes

Lichen-forming

Lichen-forming

Sordariomycetes clade:Lichinomycetes

- derived from Dothideomycetidae - mostly crustose; bitunicate ascus - photobiont = generally cyanobacteria - Examples:

Peltula tortuosa

http://www.uni-kl.de/FB-Biologie/Botanik/sys_tax_flechten.htm

Anema nummularium

Sordariomycetes clade: Arthoniomycetidae

- photobiont = Trebouxia - mostly crustose; elongate apothecia with bitunicate ascus - Examples:

Arthonia glaucomaria Roccella fusiformis

http://www.bildungsservice.at/faecher/geo/Flechten%20und%20lichenicole %20Pilze/flechten_und_lichenicole_pilze2.htm http://www.alm-neu.de/Jersey/thumbnails/3/Roccella%20fuciformis.htm

Lecanoroycetidae, Acarosporoycetidae, and Ostropomycetidae � (three predominantly lichen-forming clades = “Lecanoromycetes”)

- includes the vast majority of lichens - sexual stage of the fungus = mostly Inoperculate Discomycetes (but also some perithecium)

- many conflicts between traditional and molecular classification

Visit www.lichen.com/ (consider this website to be a mandatory reading)

Some interesting or common Lecanoromycetes

Letharia vulpina (the “Wolf Moss”)

- grows mostly on old or dead trees in dry, low temperature ‘old growth’ coniferous forests; also on old wooden fenceposts. - known only from North America and Europe. - highly sensitive to human disturbance, especially the eradication of old growth forests. ----- It is now reportedly extinct in Finland!.

- Toxic; widely used in both Native American and early European civilizations: ---- Scandinavians used to mix with meat to kill wolves, hence its common name, the “Wolf Moss”. ---- The Achomawi in Northern California used it to make poison arrowheads. ---- Water extracts also used as a medicine for internal problems and in stronger solution to wash external sores and wounds. ---- Also employed as a yellow dye for staining baskets and fibers.

http://bio.research.ucsc.edu/people/goff/letharia.htm


Letharia vulpina (the “Wolf Moss”)

http://bio.research.ucsc.edu/people/goff/letharia.htm


- a "vagrant" lichen, not attached to any substrate and blown around by wind;

- source of dye for Navajo weavers.

Xanthoparmelia chlorochroa

http://www.lichen.com/


- long use in traditional Chinese and European medicine, also by natives in the Pacific Islands and New Zealand. - contain usnic acid; recently used as antibiotic in salves and deodorants; also used in contemporary homeopathic medicine.

Usnea species

http://www.perspective.com/nature/fungi/


Cladonia species Peltigera species

Eurotiomycetes Two clades:

- Chaetothyriomycetidae ----- Capronia, Verrucaria, Pyrenula, Dermatocarpon, Chaetothyriales

- Eurotiomycetidae - ascomata = cleistothecium (sometimes lacking) - asci --- scattered within the cleistothecium (i.e. not forming an hymenium) --- thin walled, often ellipsoid, inoperculate, evanescent --- many conidial forms (anamorphs) known

Major Orders: Ascosphaerales, Eurotiales and Onygenales

Eurotiomycetes

Ascosphaerales

Genus Ascosphaera - associated with bees: --- feed on pollen and nectar(saprobic); --- some species pathogens on larvae. - ascospores become united in cysts

From Alexopoulos

Eurotiomycetes

Ascosphaerales

Genus Eremascus - lacks ascomata (secondary loss?), otherwise typically ascomycota (no yeast phase known as in Archaeascomycota or Hemiascomycota)

- basically, multiple, independent formation of asci from the mycelial mat,

- saprophytic

From Alexopoulos

Eurotiomycetes Eurotiales

- Many genera known as teleomorph of Penicillium and Aspergillus spp., and other phialidic anamorphs. (Note that neither Penicillium or Aspergillus are monophyletic…) - Major genera: Talaromyces, Eupenicillium, Eurotium, Emericella

Talaromyces anamorphs: Penicillium, Paecilomyces...

Eurotium anamorphs: Aspergillus,...

Eupenicillium anamorphs: Penicillium,...

http://www.univ-brest.fr/esmisab/sitesc/ Myco/fiches/Eochra.htm

Pics from Malloch’s web site

Penicillium

Talaromyces

From Alexopoulos

Emericella nidulans

A. Colony on Oatmeal agar, 14 days at 25°C. B. Macrograph of the conidial heads and ascoma. C-D. Hülle cells: C. 700x; D. 1200x. E. Conidiophore and conidia 1700x. F. Ascospores 1600x.

Note the Aspergillus anamorph

Eurotiales: Emericella

http://www.iums.org/ICPAEmenid.htm

Eurotiomycetes

- High diversity in cleistothecium types.

- species with the ability to degrade keratin (a major component of skin, hairs, nails, horns, feathers etc…) are all found in this order ===> associations with animals (saprobic or pathogens); pathogenic forms generally the anamorph (sometimes yeast-like), which may have an optimal growth temperature at 37C !

Some important genera of human / animals pathogens: - Ajellomyces, Coccidioides, Arthroderma

Arthroderma species Conidial anamorphs Microsporum, Trichophyton - saprobic in soil, “ringworm” on skin

Onygenales

Eurotiomycetes

Onygenales

Eurotiomycetes

- High diversity in cleistothecium types - Taxonomic diversity

From Alexopoulos

Ajellomyces capsulatum Yeast anamorph = Histoplasma capsulatum - lung infection; in immunodepressed people the disease can spread to other body parts including bones

Onygenales

Eurotiomycetes

<===>

More info from http://botit.botany.wisc.edu/toms_fungi/jan2000.html

cleistothecium

Ajellomyces dermatitidis Yeast anamorph Blastomyces dermatitidis (mutinucleate, generally 2-5 nuclei) - skin disease& lesion in humans, dogs, cats etc.; widespread in Africa

Onygenales

Eurotiomycetes

Blastomyces dermatitidis

Ajellomyces dermatitidis: simple cleistothecium

<===>


An anamorph Coccidioides immitis: teleomorph not known - systemic human pathogen; also grow in soil - generally starts from lung infection; can transfer to other body parts; allergic reactions (e.g. reddening of skin) - dimorphism mycelium <==> asexual endospores (better adapted for circulation in the blood)

Onygenales

Eurotiomycetes


<===>

- All the ca 1700 described morphospecies are invariably found attached to the exoskeleton of insects, or occasionally, millipedes and mites. - Poorly studied group; evolutionary relationships to other Ascomycota still unclear;. - apparently, don't produce anamorphs; - extreme species and site-specificity: many species are only found in one part of their insect host, for example, on a particular limb, or restricted to either males or females.

Fig. on the right: Development of Stigmatomyces baerii on houseflies:

An ascospore (A) becomes attached to the animal, germinates, and sends a foot into the exoskeleton to absorb nutrients. Although haustoria may penetrate as far as the epidermal cells, there is never any real invasion of host tissues. The ascospore develops a median septum, and the upper cell becomes differentiated into a male organ, with several phialide-like cells (B) that produce spermatia. The lower cell then develops an ascogonium with a trichogyne, which is fertilized by the spermatia (C). Several asci then develop from the ascogonium, and eventually deliquesce. The mature ascoma is spine-like, projecting from the exterior of the host, and can be seen with a hand-lens (D). Other genera exhibit the same basic features (Hesperomyces - E and Corethromyces - F).

Laboulbeniales / Laboulbeniomycetes

From Kendrick

lecture 16 ascomycota v - university of...

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