Mycology - Phylum Ascomycota
ecological important of truffles?
(ecto)mycorrhizal with forest trees in the western US
describe the ascocarps of Eurotiomycetes and their characteristics?
- Have prototunicate asci and disperse them passively; - Produce a cleistothecium (or perithecium); - Produce small unicellular ascospores. -This group includes a number of important saprotrophs and parasites.
important characteristics of Sardariomycetes?
- Produce a perithecium or rarely a cleistothecium - Mostly produce cylindrical unitunicate asci which forcibly discharge their ascospores
major characteristics of Dothidiomycetes?
- Produce a pseudothecium; - Have bitunicate asci - Are mostly plant associated (saprotrophs or parasites). - It includes a few lichenized fungi, but not very many
general characteristics of the Ascomycota?
-Ascus produced during sexual reproduction -Asci produced on or within an ascocarp (which may not always be present) -Dikaryon or dikaryotic phase inserted between plasmogamy and karyogamy -Unicellular or filamentous forms - Filamentous forms produce hyphae with simple septae with Woronin bodies -Asexual reproduction by conidiophores and conidia
what are the four major types of ascocarps?
-Cleistothecium -Perithecium -Apothecium -Ascostromata or pseudothecium
how is a lichen produced?
-Fungal hyphae come in contact with the cells of the photobiont. The fungus recognizes the alga as a potential partner in forming a lichen by the lectins in the cell wall of the alga. -The fungal hyphae establish contact with the algal cell, often via haustoria which penetrate the algal cell wall, but not the membrane. Other hyphae just make contact with the surface of the algal cell. -The walls of the photobiont are altered so that they become more permeable to carbohydrates. Products of photosynthesis then "leak out" and can be used by the fungus. -The fungus supplies water, provide some shade from damaging wavelengths of light, and inorganic nutrients. The fungi produce lichen acids which, in part, allow the algae to tolerate much greater degrees of dessication
describe monometylhydrazine/gyromitrin poisoning?
-Gyromitrin is a amino acid derived secondary metabolite that gives rise to monomethylhydrazine (MMH), a hemolytic toxin -MMH is also a gastrointestinal irritant and damages the liver
examples of convergent evolution among the Pezzizomycotina?
-Prototunicate asci that break open passively and release the ascospores -Completely enclosed fruiting bodies (cleistothecia). -Bitunicate asci -Apothecia
general mushroom poisoning treatments?
-Reduction of absorption, steps to get rid of as much undigested material as possible -Enhancement of excretion by forced diuresis -General supportive measures including maintenance of respiration, blood pressure with IV fluids or vasopressors, blood sugar and electrolyte balance, close monitoring of hepatic and renal parameters, administration of antispasmodics, analgesics or opiates for pain, and possibly sedatives
important characteristics of Taphrinomycotina?
-Saprophytes or parasites. -Include fungi which do not produce an ascocarp (except for Neolecta). -May be filamentous or yeast-like
what is an ascus?
-a cell which is the site of karyogamy and the site of meiosis during the life cycle -a sac-like cell which contains ascospores
what is a lichen?
-a composite organism that emerges from algae or cyanobacteria living among filaments of a fungus in a mutually beneficial (symbiotic) relationship -has two parts a mycobiont which is the fungal component and a photobiont which is the autotrophic, algal component -are autotrophic (photosynthetic) and ecologically very important.
describe the diversity of the photobionts/algae that participate in lichen symbiosis?
-cyanobacteria, which is prokaryotic (aka blue green algae): Nostoc is the most common, is also nitrogen fixing, and Gloeocapsa and Chroococcidiopsis -chlorophyta, which is eukaryotic (aka green algae)
describe asexual reproduction in the Ascomycota?
-fission -budding (via blastopores) -fragmentation -produce conidia (asexual spores) -many have lost ability to sexually reproduce (Form Division Deuteromycota)
describe sexual reproduction in the Ascomycota?
-have male and female gametangia in their haploid stage -plasmogamy occurs, producing a binucleate dikaryon -several dikaryotic cells (called ascogonius hyphae) are produced and undergoe karyogamy which forms a diploid ascus -undergoes meiosis to form four haploid cells which then undergo mitosis to form eight ascospores
describe the algal/fungal relationship in lichens?
-limited or controlled parasitism -In many cases, the fungus produces haustoria that penetrate the algal cell and in some cases slowly destroys (kills) the algal cell. Unaffected algal cells remain in the lichen to supply the fungus with new cells) -However, the death and disintegration of the algal cells may actually reflect their normal life history and death due to age
important characteristics of Saccharomycotina?
-most are the ascomycetous yeasts. -a few filamentous forms and a few that are dimorphic -most reproduce asexually by budding (blastic spore development) and asexual forms are placed in the Form-Class Blastomycetes -includes the Baker's/Brewer's Yeast
what does the fungi/mycobiont get in lichen symbiosis?
-organic nutrition (sugars, sugar alcohols, and maybe nitrogen compounds if photobiont is nitrogen fixing)
what is bitunicate?
-possessing two wallsan exotunica and an endotunica. The endotunica expands two twice or more its original length pushing through the exotunica - Sometimes called the Jack-in-the- box ascus
what is an ascospore?
-produced by meiosis andpossibly by subsequent mitosis and are generally haploid and monokaryotic -there are normally 4 or 8 ascospores per ascus
what does the algae/photobiont get in lichen symbiosis?
-protection from high light intensities -mineral nutrition -protection from dessication
describe the photobiont?
-the autotrophic component of a lichen -are relatively simple unicellular or colonial autotrophs traditionally called algae -about 100 species of algae are known to participate in lichen symbiosis -
describe the mycobiont?
-the fungal component of a lichen -most lichen forming fungi do not grow well in the absence of a photobiont and are found only very rarely as free living organisms -one mycobiont may be able to form lichens with several different photobionts
describe crozier formation?
-the tip of the ascogonius hyphae elongates and bends over to form a hook (CROZIER). -the two compatible nuclei in the apical compartment then undergo mitosis simultaneously. -two septae develop in such a way that the crozier becomes divided into THREE COMPARTMENTS - the tip and basal compartments are uninucleate; the middle compartment is binucleate and is called the ASCUS MOTHER CELL (since it is destined to become an ascus).
describe general rules for eating wild mushrooms?
-you should only eat a mushroom if you are absolutely confident of the identification you should always begin by eating a very small amount of the fungus the first time and save some uncooked mushrooms in the refrigerator. -there are no simple rules to learn to tell if some unknown fungus is edible, poisonous or not. -Never eat raw mushrooms. -for most species of mushrooms, we do not know whether they are edible or not. -avoid little brown mushrooms (LBMs) there are lots of them andthey are difficult for beginners and professionals to identify and some of them are also poisonous.
which phyla of fungi participate in lichen symbiosis?
Asco and Basidiomycota
describe conidiogenesis?
Blastic conidiogenesis, where the spore is already evident before it separates from the conidiogenic hypha which is giving rise to it, Thallic conidiogenesis, where first a cross-wall appears and thus the created cell develops into a spore
what is a hymenium?
a layer of fertile tissue
what is prototunicate?
a single, thin, delicate wall encloses the ascospores and at maturity it ruptures to release the spores, the ancestral type
describe the process of budding in yeasts?
a small bud is formed on the parent cell. The nucleus of the parent cell splits into a daughter nucleus and migrates into the daughter cell. The bud continues to grow until it separates from the parent cell, forming a new cell and leaving scar tissue
what is a conidium?
a spore produced asexually by various fungi at the tip of a specialized hypha
economic importance of truffles?
about $500 per lb
ecological niche of Cordyceps?
an endoparasite on insects and arthropods
describe the specialization of Eurotiomycetes that allows them to be animal parasites
are dermatophytes, so they require keratin for growth
plant diseases caused by Taphrina?
causes Peach Leaf Curl
ecological niche of Claviceps?
infects rye, wheat, and barley
what is an ascocarp?
multicellular structure that bears the asci
what is unitunicate?
possessing two walls an exotunica and an endotunica, but the wall layers stick together throughout and the spores are released by a operculum (cap), a pore, or a slit in the tip of the ascus
what are phialides?
specialized and differentiated conidiogenous cells and are found in some taxa. Often flask or bottle shaped Sometimes the neck is surrounded by a collar
what is a conidiophore?
specialized stalks on which conidia are formed
what are paraphyses?
sterile hairs that form among the asci and are free at the tip
what is stroma?
the dense structural tissue that produces fruiting bodies; made of non-vegetative (asexual) hyphae
describe apothecium?
type of ascocarp that is cup shaped to highly modified shaped, asci in a hymenium
describe perithecium?
type of ascocarp that is flask shaped with the asci organized into a hymenium and open to the outside by way of an ostiole
describe cleistothecium?
type of ascocarp where hyphae completely enclose the asci in a spherical body, this is considered to be the ancestral type
describe Ascostromata/pseudothecium?
type of ascocarp, (limited to the Loculoascomycetidae) a stroma develops and then cavities (locules) are digested into it, and the asci develop within the locules
