Ascomycota part 1
What type of ascoma are in fungus that has evolved other dispersal strategies (animals or insects)
cleistothecial ascoma
What type of ascoma has no opening for ascospores to exit and ascoma breaks down at maturity?
cleistothecial ascoma
What type of ascoma have developed as so airborne dispersal not effective in preferred habitat (e.g., below bark, underground)?
cleistothecial ascoma
What type of asoma have spherical shape asci and no longer shoot their spores?
cleistothecial ascoma
What shape is the stoma in ascomycetes?
curved or cup-shaped
What does stroma mean?
cushionlike plate of solid mycelium
What life stratagy is shared by both Ascomycetes and basidiomycetes?
dikaryon
What does trichogyne mean?
formed by antheridium Each gametangium is multinucelate and transfer of the nuclei from the antheridium to the ascogonium is made possible by the formation of a trichogyne, a tubular structure originating from the ascogonium that fuses with the antheridium. a hairlike projection of the female reproductive organs of certain algae, fungi, and lichens, which receives the male gametes before fertilization takes place
What provides nutrition and structural support to the Ascogenous dikaryotic hyphae?
haploid mycelium provides
What does paraphyses mean?
haploid sterile cells
What is a ostiole in an ascoma?
hymenium with small opening, the small opening is the ostiole.
How is nuclei exchanged in Ascomycota?
vegetative hyphae to undergo anastomosis and exchange nuclei
When ascomcetes asci discharge what is the dispersal method?
wind dispersal
Where does Ascogenous dikaryotic hyphae proliferate?
within the developing ascoma
Does the ascoma include both dikaryotic and haploid mycelium?
yes
What is a general characteristic about Ascomycota that is different than zygomycetes? 3 points
1) Can exploit wider range (drier) conditions than zygomycetes 2) Hyphal width (about 5 µm) more narrow than zygomycetes 3) Utilize more complex sources of carbon (cellulose) vs. zygomycetes (sugars, starch)
In Ascomycota, how does dikaryosis take place?
1) Hyphae fuse (haploid, n) and nuclei pair up but do not fuse 2) Plasmogamy but no karyogamy 3) Nuclei divide synchronously with cell division as hyphae grow 4) Forms a number of dikaryotic hyphae (diploid, n + n)
What is the evolutionary advantage of dikaryon formation?
1) Maximizes the potential for genetic recombination
Both ascospore and basidiospore development are similar until the last stages, how are they different in the last stage?
8 ascospores 4 basidiospores
Where does the asci form out of?
Asci will form at the tip of dikaryotic hyphae
What sizes can Ascoma fruiting bodies be?
Ascoma fruiting bodies can be microscopic to macroscopic
What type of ascus at maturity, the thin outer wall splits, and the thick inner wall absorbs water and expands upward, carrying the ascospores with it?
Bitunicate asci
What type of ascus has a double wall. A thin, in extensible outer wall covers a thick, elastic inner wall?
Bitunicate asci
What type of ascus has this 'Jack-in-a-box' design allows the ascus to stretch up into the neck of the ascoma to expel its spores?
Bitunicate asci
What type of ascus is very different from the unitunicate?
Bitunicate asci
What does Ascomycota have at regular intervals in the hyphae?
Cross walls (septa) present at regular intervals in hyphae
What forms the hymenium of the ascoma?
Dikaryotic hyphae
What morphic feature in the phylum Ascomycota is diagnostic?
Meiosporangia are diagnostic
How are nuclei transfered to form a ascogenous dikaryotic hyphae?
Nuclei are transferred by fusion of the trichogyne with the ascogonium and ascogenous dikaryotic hyphae arise from this cell
What does the sexual stage of ascomycetes start with?
Sexual stage begins with anastomosis of compatible haploid mycelia to form a dikaryon
What ecosystems are Ascomycota found?
Show diverse ecological strategies, most terrestrial, some aquatic
What are the 4 types and development of ascus?
Unitunicate-operculate asci Unitunicate-inoperculate asci Prototunicate asci Bitunicate asci
What type of ascoma has the entire fertile layer (hymenium) is exposed and stroma is curved or cup-shaped?
apothecial ascoma
Are ascospores motile?
no
Are there motile cells and does the cell walls contain chitin in phylum Ascomycota?
no motile cells yes the cell walls contain chitin
What do Ascomycota have in the septa to permit cytoplasmic continuity?
pores
What is an ascoma?
the fruiting body of an ascomycete phylum fungus
What type of ascus has the feature of a single wall and no operculum?
unitunicate-inoperculate
How many species are there in phylum Ascomycota?
30,000+ species, about 75% of all known fungi
What are the 4 types of ascoma (fruiting body)?
Apothecial Perithecial Pseudothecial Cleistothecial
What is the difference in developmental steps between Ascus versus basidium?
Ascomycete has an extra step after meiosis, one mitotic division, to create 8 haploid spores Ascomycete: - dikaryon - karyogamy - meiosis - one mitotic division to form eight haploid spores Basidiomycete: - dikaryon - karyogamy - meiosis - four haploid spores
How does Ascomycetes primarily exist?
Ascomycetes exist primarily as the asexual or anamorph phase
What is dikaryon primarily associated with the development of?
Associated primarily with ascoma development
What does ascogenous mean?
The hyphae, in fungi of the Ascomycota, that grow from the ascogonium after it has fused with the antheridium.
What is dikaryon?
Compatible cell-types can fuse cytoplasms (plasmogamy). When this occurs, the two nuclei of two cells pair off and cohabit without fusing (karyogamy). This can be maintained for all the cells of the hyphae by synchronously dividing so that pairs are passed to newer cells. In the Ascomycota this attribute is most often found in the ascogenous hyphae and ascocarp while the bulk of the mycelia remains monokaryotic.
What are the vectors that may also disperse ascospores?
Dispersed by animal/insect vectors
How is the dikaryon phase different in Ascomycetes than in Basidiomycetes?
Limited dikaryon phase in Ascomycetes Extended dikaryon phase observed in Basidiomycetes
What is the dikaryon phase?
The presence of paired nuclei following hyphal anastomosis and prior to nuclear fusion cells of two different hyphae fuse and the nuclei of each remain distinct within the new hypha
What does ascogonium mean?
The spiral female organ of an ascomycetous fungus from which asci are produced
During the teleomorph phase where can unique feature of Ascomycetes be found?
Unique features of Ascomycetes can be found in the teleomorph with sexual spore (ascospore, or meiospore) development in the ascus
What is an ascus?
a sac, typically cylindrical in shape, in which the spores of ascomycete fungi develop
What does hymenium mean?
a surface consisting mainly of spore-bearing structures
What is the Anamorph?
an asexual reproductive stage
What type of ascoma may include paraphyses?
apothecial ascoma
What type of ascoma will many asci discharge simultaneously and are wind dispersed?
apothecial ascoma
What does dikaryotic hyphae that form the hymenium of the ascoma develop into after meiosis?
asci
How are asci discharged from a Perithecial ascoma?
asci are enclosed hymenium with small opening (ostiole) that may permit the discharge of one ascus or a few asci at once. Ascospores caught in droplet of stickly liquid that will ooze out of the ostiole at maturity
What is the Defining feature of Ascomycota where nuclear fusion and meiosis take place?
ascus
What is a unitunicate-operculate asci?
ascus has a "lid", the Operculum, which breaks open when the spores are mature and allows the spores to escape.
Does ascomycetes have active or passive release mechanism?
both Spores air dispersed by insect and animal vectors
What does Crozier mean?
is an anatomical feature of many fungi in the phylum Ascomycota that form at the base of asci and look like hook-topped shepherd's staff During the ascus initial formation the crozier helps to maintain a dikaryotic state in the ascus initial and its side branch that will continue the spreading growth of the ascogenous hyphae in Ascomycota fruitbodies.
What is karyogamy?
is the final step in the process of fusing together two haploid eukaryotic cells
What does anastomosis mean?
is the fusion between branches of the same or different hyphae
What are ascus?
is the sexual spore-bearing cell produced in ascomycete fungi
What is the asci?
is the sexual spore-bearing cell produced in ascomycete fungi
What is penultimate apical cell of the hyphal tip
is the top part of the crozier
Where does karyogamy and meiosis occur in ascomycetes?
karyogamy and meiosis occurs in the penultimate apical cell of the hyphal tip (Crozier)
In ascomycetes what is followed by meiosis to create 8 ascospores?
one mitotic division
What type of ascoma has a unitunicate-inoperculate asci
perithecial ascoma
What type of ascus are found in several distinct orders and likely represents a secondary condition?
prototunicate asci
What type of ascus are more or less spherical, found in cleistothecial (occasionally perithecial) ascoma?
prototunicate asci
What type of ascus has a wall that may dissolve at maturity and releases the ascospores, which can then ooze out of the ascoma, or ascospores remain inside until the ascoma is disturbed?
prototunicate asci
What type of ascus has no active spore-shooting mechanism?
prototunicate asci
What type of ascus likely evolved several times from unitunicate asci (e.g., truffles, Family Tuberaceae)?
prototunicate asci
What type of ascoma has an Enclosed hymenium, contains bitunicate asci, and the Ostiole and ascoma are located within stroma and inside locules?
pseudothecial ascoma
Is teleomorph in Ascomycetes a rare event and why is teleomorph important?
rare event a chance to generate variability
What does Meiosporangia mean?
sexual structures containing the sexually derived spores
What is the teleomorph stage of life?
the sexual reproductive stage (morph), typically a fruiting body
What is the Holomorph?
the whole fungus, including anamorphs and teleomorph
What type of ascus has the feature of a special elastic ring mechanism built into the tip. With internal positive pressure, the ring stretches momentarily to let individual spores shoot through?
unitunicate-inoperculate
What type of ascus has the feature where the asci are found in perithecial and in some apothecial ascomata?
unitunicate-inoperculate
What type of ascus has the feature at maturity the lid opens and the spores are ejected by positive pressure inside ascus, resulting in dispersal by wind?
unitunicate-operculate
What type of ascus has the feature of a single wall and a lid or operculum?
unitunicate-operculate
What type of ascus has the feature where asci are found only in apothecial ascoma?
unitunicate-operculate
