Ascomycetes. / The Sac Fungi

Course Code: MBIO 209
Course Title: Micrology
Assignment 1, 2

1. P R I M E A S I A U N I V E R S I T Y
a mission with a vision
Assignment : 1,2.

Submitted to
Name: Aneeka Nawar fatema
Designation: Lecturer
Department: Microbiology
Institute: Primeasia University


Submitted by
Name: Md Azizul Haque
Student ID: 193016031
Course Code: MBIO 209
Course Title:
Department: Microbiology


Date of Submission: January 10, 2021


Mycology

2. Assignment : 01
Ascomycetes
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the
subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is
the largest phylum of Fungi, with over 64,000 species.
Characteristics of ascomycetes
• Ascomycota are morphologically diverse. The group includes organisms from unicellular
yeasts to complex cup fungi.
• 98% of lichens have an Ascomycota as the fungal part of the lichen.
• There are 2000 identified genera and 30,000 species of Ascomycota.
• The unifying characteristic among these diverse groups is the presence of a reproductive
structure known as the ascus, though in some cases it has a reduced role in the life cycle.
• Many ascomycetes are of commercial importance. Some play a beneficial role, such as the
yeasts used in baking, brewing, and wine fermentation, plus truffles and morels, which are
held as gourmet delicacies.
• Many of them cause tree diseases, such as Dutch elm disease and apple blights.
• Some of the plant pathogenic ascomycetes are apple scab, rice blast, the ergot fungi, black
knot, and the powdery mildews.
• The yeasts are used to produce alcoholic beverages and breads. The mold Penicillium is used
to produce the antibiotic penicillin.
• Almost half of all members of the phylum Ascomycota form symbiotic associations with
algae to form lichens.
• Others, such as morels (a highly prized edible fungi), form
important mycorrhizal relationships with plants, thereby providing enhanced water and
nutrient uptake and, in some cases, protection from insects.
• Almost all ascomycetes are terrestrial or parasitic. However, a few have adapted to marine or
freshwater environments.
• The cell walls of the hyphae are variably composed of chitin and β-glucans, just as in
Basidiomycota. However, these fibers are set in a matrix of glycoprotein containing the
sugars galactose and mannose.
• The mycelium of ascomycetes is usually made up of septate hyphae. However, there is not
necessarily any fixed number of nuclei in each of the divisions.
• The septal walls have septal pores which provide cytoplasmic continuity throughout the
individual hyphae. Under appropriate conditions, nuclei may also migrate between septal
compartments through the septal pores.
• A unique character of the Ascomycota (but not present in all ascomycetes) is the presence
of Woronin bodies on each side of the septa separating the hyphal segments which control
the septal pores. If an adjoining hypha is ruptured, the Woronin bodies block the pores to
prevent loss of cytoplasm into the ruptured compartment. The Woronin bodies are spherical,
hexagonal, or rectangular membrane bound structures with a crystalline protein matrix.

3. Types of reproduction
There are two major forms of reproduction: sexual and asexual.
Sexual reproduction
Sexual reproduction requires two parents. Each parent contributes a gamete - a sex cell that has
half of the normal DNA of a regular body cell. In males, the gametes are sperm and in females,
the gametes are eggs.
When these two gamete combine during fertilization, the result is a zygote, which then continues
to develop into an embryo.
Asexual reproduction
Asexual reproduction requires only one parent.
There are many types of asexual reproduction. Four major types are:
1) Binary fission: Single parent cell doubles its DNA, then divides into two cells. Usually
occurs in bacteria.

4. Figure: Prokaryotic cell undergoing the process of binary fission.
2) Budding: Small growth on surface of parent breaks off, resulting in the formation of two
individuals. Occurs in yeast and some animals (like the hydra below).


figure: Hydra reproduce asexually through budding.
3) Fragmentation: Organisms break into two or more fragments that develop into a new
individual. Occurs in many plants, as well as some animals (like coral, sponges, and starfish).

Figure: This starfish has lost its arm. The fragment is growing into a new individual, while the
parent regrows its lost arm.

5. 4) Parthenogenesis: An embryo develops from an unfertilized cell. Occurs in invertebrates, as
well as in some fish, amphibians, and reptiles.

Figure: Baby Komodo dragon produced through parthenogenesis.

6. Refferance:-
1. Cavalier-Smith, T. (1998). "A revised six-kingdom system of Life". Biological Reviews of
the Cambridge Philosophical Society. 73 (3): 203–266. doi:10.1111/j.1469-
185X.1998.tb00030.x. PMID 9809012.
2. ^ Kirk et al., p. 55.
3. ^ Lutzoni F; et al. (2004). "Assembling the fungal tree of life: progress, classification, and
evolution of subcellular traits". American Journal of Botany. 91 (10): 1446–
80. doi:10.3732/ajb.91.10.1446. PMID 21652303.
4. ^ James TY; et al. (2006). "Reconstructing the early evolution of Fungi using a six-gene
phylogeny". Nature. 443 (7113): 818–
22. Bibcode:2006Natur.443..818J. doi:10.1038/nature05110. PMID 17051209. S2CID 4
302864.
5. ^ McCoy, Peter (2016). Radical Mycology. Chthaeus Press. ISBN 9780986399602.
6. ^ "Caterpillar Fungus". Archived from the original on 2007-03-12.
7. ^ Alexopoulos, Mims & Blackwell 1996, p. 233
8. ^ Alexopoulos, Mims & Blackwell 1996, pp. 218–222
9. ^ Krajicek BJ, Thomas CF Jr, Limper AH (2009). "Pneumocystis pneumonia: current
concepts in pathogenesis, diagnosis, and treatment". Clinics in Chest Medicine. 30 (2):
265–89. doi:10.1016/j.ccm.2009.02.005. PMID 19375633.
10. ^ James RR, Skinner JS (2005). "PCR diagnostic methods for Ascosphaera infections in
bees". Journal of Invertebrate Pathology. 90 (2): 98–
103. doi:10.1016/j.jip.2005.08.004. PMID 16214164.
11. ^ Hendey, N. I. (1964). "Some observations on Cladosporium resinae as a fuel
contaminant and its possible role in the corrosion of aluminium alloy fuel
tanks". Transactions of the British Mycological Society. 47 (7): 467–
475. doi:10.1016/s0007-1536(64)80024-3.
12. ^ Laybourn-Parry J., J (2009). "Microbiology. No place too cold". Science. 324 (5934):
1521–
22. Bibcode:2009Sci...324.1521L. doi:10.1126/science.1173645. PMID 19541982. S2CI
D 33598792.
13. ^ Mello A, Murat, Bonfante P (2006). "Truffles: much more than a prized and local
fungal delicacy". FEMS Microbiology Letters. 260 (1): 1–8. doi:10.1111/j.1574-
6968.2006.00252.x. PMID 16790011.
14. ^ See the Conidium article for full details.
15. ^ Deacon 2005, pp. 164–6
16. ^ Deacon 2005, pp. 167–8
17. ^ Jump up to:
a

b
Wallen RM, Perlin MH (2018). "An Overview of the Function and
Maintenance of Sexual Reproduction in Dikaryotic Fungi". Front Microbiol. 9:
503. doi:10.3389/fmicb.2018.00503. PMC 5871698. PMID 29619017.
18. ^ Carlile, Michael J. (2005). "Two influential mycologists: Helen Gwynne-Vaughan
(1879-1967) and Lilian Hawker (1908-1991)". Mycologist. 19 (3): 129–
131. doi:10.1017/s0269915x05003058.

7. Assignment : 02
Ascomycota - The Sac Fungi
The majority of known fungi belong to the Phylum Ascomycota, which is characterized by the
formation of an ascus (plural, asci), a sac-like structure that contains haploid ascospores. Many
ascomycetes are of commercial importance. Some play a beneficial role, such as the yeasts used
in baking, brewing, and wine fermentation, plus truffles and morels, which are held as gourmet
delicacies. Aspergillus oryzae is used in the fermentation of rice to produce sake. Other
ascomycetes parasitize plants and animals, including humans. For example, fungal pneumonia
poses a significant threat to AIDS patients who have a compromised immune system.
Ascomycetes not only infest and destroy crops directly, they also produce poisonous secondary
metabolites that make crops unfit for consumption. Filamentous ascomycetes produce hyphae
divided by perforated septa, allowing streaming of cytoplasm from one cell to the other. Conidia
and asci, which are used respectively for asexual and sexual reproductions, are usually separated
from the vegetative hyphae by blocked (non-perforated) septa.
Asexual reproduction is frequent and involves the production of conidiophores that release
haploid conidiospores. Sexual reproduction starts with the development of special hyphae from
either one of two types of mating strains. The “male” strain produces an antheridium (plural:
antheridia) and the “female” strain develops an ascogonium (plural: ascogonia). At fertilization,
the antheridium and the ascogonium combine in plasmogamy without nuclear fusion. Special
ascogenous hyphae arise, in which pairs of nuclei migrate: one from the “male” strain and one
from the “female” strain. In each ascus, two or more haploid ascospores fuse their nuclei in
karyogamy. During sexual reproduction, thousands of asci fill a fruiting body called the
ascocarp. The diploid nucleus gives rise to haploid nuclei by meiosis. The ascospores are then
released, germinate, and form hyphae that are disseminated in the environment and start new
mycelia.

Figure:- Release of ascospores: The bright field light micrograph shows ascospores being
released from asci in the fungus Talaromyces flavus var. flavus.

8. Life Cycle Of Ascomycete

Figure: The lifecycle of an ascomycete is characterized by the production of asci during the
sexual phase. The haploid phase is the predominant phase of the life cycle.
Ascomycete plant pathogens
Unlike human and animal pathogens, widely distributed throughout the Ascomycota numerous
genera and species that cause plant disease both host-specific and opportunistic parasites
Association between plants and fungi is ancient, parasitism has evolved and been lost repeatedly
in fungal lineages Plant pathogens classified according to the types of disease they cause, plant
organs or tissues affected root, shoot, foliage disease, dieback seed rots, seedling diseases
(“damping off”) fruit rots, storage rots canker diseases of woody hosts
Pathogenicity: the ability to cause disease Disease: A deviation from normal physiological
function The ability of fungi to cause disease is usually a direct result of parasitism Parasite: an
organism that obtains its nutrition from another organism Biotrophic parasites do not
immediately kill their hosts, have a prolonged association with living host tissue. Necrotrophic
parasites kill host tissue in advance of occupation. Often involves phytotoxins.
Some pathogens produce toxins that facilitate infection host selective toxins are highly specific,
affect only a single host species, and often a specific genotype
•host selective toxins interact with specific host gene product
•nonselective toxins are general phytotoxins Some pathogens produce chemical analogs of plant
growth regulators, cause galls and abnormal growth Gibberellin was discovered from bakanae

9. disease of rice, caused by Gibberella fujikoroi “green islands” cytokinins prevent host tissue
from sensescence

Gibberellin plant growth regulators were discovered from Gibberella fujikoroi, which causes bakanae
(ʻfoolish seedlingʼ) disease of rice.
Human disease interactions
• Aspergillus fumigatus, the most common cause of fungal infection in the lungs of immune compromised
patients often resulting in death. Also the most frequent cause of Allergic bronchopulmonary aspergillosis,
which often occurs in patients with Cystic fibrosis as well as Asthma.
• Candida albicans, a yeast that attacks the mucous membranes, can cause an infection of the mouth or
vagina called thrush or candidiasis, and is also blamed for "yeast allergies".
• Fungi like Epidermophyton cause skin infections but are not very dangerous for people with healthy
immune systems. However, if the immune system is damaged they can be life-threatening; for
instance, Pneumocystis jirovecii is responsible for severe lung infections that occur in AIDS patients.
• Ergot (Claviceps purpurea) is a direct menace to humans when it attacks wheat or rye and produces highly
poisonous alkaloids, causing ergotism if consumed. Symptoms include hallucinations, stomach cramps,
and a burning sensation in the limbs ("Saint Anthony's Fire").
• Aspergillus flavus, which grows on peanuts and other hosts, generates aflatoxin, which damages the liver
and is highly carcinogenic.
• Histoplasma capsulatum causes histoplasmosis, which affects immunocompromised patients.
• Blastomyces dermatitidis is the causal agent of blastomycosis, an invasive and often serious fungal
infection found occasionally in humans and other animals in regions where the fungus is endemic.
• Paracoccidioides brasiliensis and Paracoccidioides lutzii are the causal agents
of paracoccidioidomycosis.
• Coccidioides immitis and Coccidioides posadasii are the causative agent of coccidioidomycosis (valley
fever).
• Talaromyces marneffei, formerly called Penicillium marneffei causes talaromycosis
Beneficial effects for humans
On the other hand, ascus fungi have brought some important benefits to humanity.
• The most famous case may be that of the mould Penicillium chrysogenum
(formerly Penicillium notatum), which, probably to attack competing bacteria, produces an

10. antibiotic that, under the name of penicillin, triggered a revolution in the treatment of
bacterial infectious diseases in the 20th century.
• The medical importance of Tolypocladium niveum as an immunosuppressor can hardly be
exaggerated. It excretes Ciclosporin, which, as well as being given during Organ
transplantation to prevent rejection, is also prescribed for auto-immune diseases such
as multiple sclerosis, although there is some doubt over the long-term side-effects of the
treatment.

Stilton cheese veined with Penicillium roqueforti
• Some ascomycete fungi can be altered relatively easily through genetic
engineering procedures. They can then produce useful proteins such as insulin, human
growth hormone, or TPa, which is employed to dissolve blood clots.
• Several species are common model organisms in biology, including Saccharomyces
cerevisiae, Schizosaccharomyces pombe, and Neurospora crassa. The genomes of a number
of ascomycete fungi have been fully sequenced.
• Baker's Yeast is used to make bread, beer and wine, during which process sugars such
as glucose or sucrose are fermented to make ethanol and carbon dioxide. Bakers use the
yeast for carbon dioxide production, causing the bread to rise, with the ethanol boiling off
during cooking. Most vintners use it for ethanol production, with the carbon dioxide being
released into the atmosphere during fermentation. Brewers and traditional producers
of sparkling wine use both, with a primary fermentation for the alcohol and a secondary one
to produce the carbon dioxide bubbles that provide the drinks with "sparkling" texture in the
case of wine and the desirable foam in the case of beer.
• Enzymes of Penicillium camemberti play a role in the manufacture of the
cheeses Camembert and Brie, while those of Penicillium roqueforti do the same
for Gorgonzola, Roquefort and Stilton.
• In Asia, Aspergillus oryzaeis added to a pulp of soaked soya beans to make soy sauce, and is
used to break down starch in rice and other grains into simple sugars for fermentation into
East Asian alcoholic beverages such as huangjiu and sake.
• Finally, some members of the Ascomycota are choice edibles; morels,truffles(Tuber spp.),
and lobster mushroom (Hypomyces lactifluorum) are some of the most sought-after fungal
delicacies.

11. References
Adl, S., A. Simpson, M. Farmer, R. Andersen, O. Anderson, J. Barta, J. et al. 2005. The new
higher level classification of eukaryotes with emphasis on the taxonomy of protists. Journal of
Eukaryotic Microbiology, 52(5), 399-451. DOI:10.1111/j.1550-7408.2005.00053.x.
Alexopoulos, C.J., C.W. Mims, and M. Blackwell. 1996.Introductory Mycology. Fourth Edition.
John Wiley & Sons Inc., New York.
Barron, G.L. 1977.The Nematode-Destroying Fungi.Canadian Biological Publications, Guelph,
ON.
Berger, L., R. Speare, P. Daszak, D.E. Green, A.A. Cunningham, C.L. Goggin, R. Slocombe,
M.A. Ragan, A.D. Hyatt, K.R. McDonald, H.B. Hines, K.R. Lips, G. Marantelli, and H. Parkes.
1998. Chytridiomycosis causes amphibian mortality associated with population declines in the
rain forests of Australia and Central America. Proceedings of the National Academy of Sciences
USA 95:9031-9036.
Blackwell, M.2011. The Fungi: 1, 2, 3…5.1 million species?American Journal of Botany
98:426-438.
Blackwell, M., D.S. Hibbett, J.W. Taylor, and J.W. Spatafora. 2006. Research Coordination
Networks: a phylogeny for kingdom Fungi (Deep Hypha).Mycologia 98:829-837.
Blackwell, M., R. Vilgalys, T.Y. James, and J.W. Taylor. 2012. Fungi. Eumycota: mushrooms,
sac fungi, yeast, molds, rusts, smuts, etc. Version 30 January
2012. http://tolweb.org/Fungi/2377/2012.01.30 in The Tree of Life Web
Project, http://tolweb.org/
Blehert, D.S., A.C. Hicks, M. Behr, C.U. Meteyer, B.M. Berlowski-Zier, E.L. Buckles, J.T.H.
Coleman, S.R. Darling, A. Gargas, R. Niver, J.C. Okoniewski, R.J. Rudd, and W.B. Stone. 2009.
Bat white-nose syndrome: An emerging fungal pathogen? Science 323:227.
Boerjan, W., J. Ralph, and M. Baucher. 2003.Lignin biosynthesis.Annual Review of Plant
Biology 54:519-546.
Bromenshenk, J.J., C.B. Henderson, C.H. Wick, M.F. Stanford, A.W. Zulich, et al. 2010.
Iridovirus and Microsporidian linked to Honey Bee Colony Decline. PLoS ONE 5(10): e13181.
DOI:10.1371/journal.pone.0013181.
Callan, B.E. and L.M. Carris 2004. Fungi on living plant substrata, including fruits. Chap. 7 in:
G.M. Mueller, G.F. Bills, and M.S. Foster, eds. Biodiversity of Fungi. Inventory and Monitoring
Methods. Elsevier Academic Press, San Diego, CA.
Deacon, J. 2006. Fungal Biology. Fourth Edition. Blackwell Publishing, Malden, MA.
Dugan, F.M. 2008.Fungi in the Ancient World.How Mushrooms, Mildews, Molds, and Yeast
Shaped the Early Civilizations of Europe, the Mediterranean, and the Near East.APS Press, St.
Paul, MN.
Duplessis, S. et al. (49 additional authors). 2011.Obligate biotrophy features unraveled by the
genomic analysis of rust fungi.Proceedings of the National Academy of Sciences U.S.A.
108:9166-9171.