1. Phylum - Ascomycota
Kingdom - Fungi

2. Higher fungi Two phyla – Ascomycota and Basidiomycota
Thallus in both consists of sepatate hyphae that form extensive mycelia
Septa have pores that allow migration of cytoplasm, organelles and nuclei (specialized septa in Basidiomycota)
Compartments contain multiple nuclei

3. Higher fungi
Vegetative hyphae can fuse with one another = anastomosis (does not occur in lower fungi)
Asexual reproduction by conidia on conidiophores

4. Higher fungi
In sexual cycle, plasmogamy is separated from karyogamy – produces dikaryotic phase
Sexual reproduction produces spores after meiosis – ascospores or basidiospores (1n)

5. Ascomycota General characterisitics
Generally have a similar sexual life cycle
All produce an ascus (sac-like structure) that contains haploid (1n) ascospores after meiosis
Includes ~75% of the described fungi – 30,000 spp.+ 20,000 anamorphs

6. Ascomycota
Sexual life cycle is basically similar – haploid-dikaryotic life cycle
Vegetative phase is haploid mycelium that may reproduce asexually by formation of conidia
Plasmogamy is separated from karyogamy in time so that a dikaryotic phase is produced – the ascogenous hyphae represent the dikaryotic hyphae

7. Gametangia
Male gametangia may be an antheridium or conidium-like structure – spermatium
Female gametangium = ascogonium, may have a long projection, the trichogyne

8. Gametangia

9. Plasmogamy
Male element fuses with trichogyne of the ascogonium, nuclei migrate into the ascogonium to begin the dikaryotic condition
After plasmogamy, two hyphal systems begin to grow
Sterile haploid hyphae envelope the ascogonium to form the multicellular ascoma (fruiting body)
Dikaryotic ascogenous hyphae grow from ascogonium – will give rise to the asci

10. Ascogenous hyphae
Male and female nuclei divide conjugately to maintain the dikaryotic condition
Many ascogenous hyphae produced inside the developing ascoma
Tips of ascogenous hyphae form croziers (hooks) before developing into an ascus

11. Developing ascoma Ascoma contains two types of hyphae
Ascogenous hyphae – dikaryotic, form asci through crozier formation
Sterile hyphae – haploid, form bulk of ascoma

12. Crozier and ascus formation
During ascus formation, karyogamy occurs to form diploid nucleus followed by meiosis to form 4 haploid nuclei
Mitosis
Meiosis
Karyogamy

13. Ascus formation Most asci are cylindrical, but may be globose
8 ascospores/ascus is a common number but this may vary
In most, ascogenous hyphae continue to proliferate, forming more croziers and more asci

14. Types of asci Great deal of variation in asci and ascospores
Three basic types of asci
Prototunicate asci – thin, delicate wall that deliqueses to release ascospores

15. Types of asci
Unitunicate asci – ascus wall layers adhere closely to one another, ascospores released through a pore, a slit or an operculum (hinged cap)
Operculate asci
Inoperculate asci

16. Types of asci
Bitunicate asci – two wall layers that separate with the inner wall expanding, ascospores released through a pore

17. Fruiting bodies - ascomata
In most, the ascogenous hyphae are produced only in the ascoma (pl. ascomata
Ascomata consist of two types of hyphae – dikaryotic ascogenous hyphae that form the asci and haploid sterile hyphae that form the bulk of the ascoma
Four major types of ascomata

18. Cleistothecium
The cleistothecium remain closed until broken by internal forces, the asci are produced randomly within the ascoma

19. Perithecium
Begins as a closed structure but produces a pore at maturity through which the ascospores can escape
Asci produced in a definite layer - hymenium

20. Apothecium
Ascoma is open when asci mature, asci are produced in an hymenium

21. Ascostroma
Asci are produced in a cavity (locule) within a mass of sterile tissue = stroma
No ascoma wall as stroma did not originate from ascogonium

22. Ascomycota classification
Currently in a state of flux
Most current treatments do not divide into classes, but rather orders
43 (35) orders have been proposed in the Ascomycota, some of these only occur in lichens

23. Ascomycota classification
We will examine these fungi as:
Cleistothecial Ascomycota
Perithecial Ascomycota
Apothecial Ascomycota
Pseudothecial Ascomycota
Non ascomatal Ascomycota - yeasts
Will discuss representatives within each of these groups to get an introduction to the Ascomycota

24. Cleistothecial Ascomycota
Cleistothecia are the simplest type of ascoma
Surrounded by relatively simple tissue (loose hyphae), do not have an opening, are broken open
Asci are scattered
Asci are prototunicate, globose to pear shaped

25. Cleistothecial Ascomycota
Include species that grow as saprotrophs on keratin (protein in hair, nails)
Contains the teleomorphs of human pathogens
Dermatophytes – cause superficial skin infections such as atheletes foot
Anamorphs are Trichophyton and Microsporium
Also contains fungi that cause deep or systemic infections of humans
Ajellomyces, the teleomorph of Histoplasma capsulatum which causes histoplasmosis
Blastomyces which causes blastomycosis

26. Aspergillus & Penicillium
The anamorphic stages (Aspergillus and Penicillium) – better known than the teleomorphs
Asci are spherical to club shaped, ascus wall dissolves at maturity leaving ascospores free inside the cleistothecium
Most are saprotrophs
Widespread in soil, litter
Opportunistic human & animal pathogens – aspergilloses, penicilloses

27. Aspergillus & Penicillium
Important industrial organisms, used in making –
Chemicals – citric, gluconic & other organic acids
Antibiotics – penicillin, griseofulvin
Production of miso and soy sauce, sake
Cheese production – blue cheese and camembert
Also important in food spoilage
Citrus fruits
Grains & peanuts – produce mycotoxins

28. Aspergillus Anamorphic genus – close to 100 species
11 different teleomorphic genera produce Aspergillus conidia and conidiophores, including Eurotium, Emericella
Common fungi found in air, soil, water
Grow on a variety of substrates, in humid climates found growing on clothing, shoes, etc.
Important as contaminants of stored grain, species produce aflatoxin

29. Aspergillus Produce characteristic conidiophore
Conidia produced by phialides – flask shaped conidiogenous cells
Have a characterisitic foot cell

30. Penicillium
Over 95 species connected to 3 teleomorphic genera – Talaromyces, Eupenicillium, Carpentales
Very common in soil, conidia found in air, water, soil
Food spoilage – on citrus fruits, jelly, cheeses
Produce penicillin and other chemicals industrially
P. roqfertii, P. camembertii used to make cheeses

31. Penicillium Asexual conidiophore – not swollen at tip, no foot cell
Phialides arranged in a brushlike manner

32. Powdery mildews
Ascomata do not form opening so can be termed cleistothecia, but are more like perithecia without an opening
Asci occur in an irregular layer, not scattered
Asci are unitunicate, forcibly discharge ascospores through a slit
Produce colorless hyphae on surface of plant host
Produce haustoria that penetrate epidermal cells of host

33. Asexual reproduction
Hyphae produce chains of conidia during growing season (spring and summer) on surface of plant leaf – giving the powdery, white appearance

34. Sexual reproduction
Late in growing season, as plants begin to senesce, ascomata are produced – thought to overwinter as ascomata
Ascomata are closed, have characteristic appendages extending from them
Asci are globose to ovoid, generally one to a few asci/ascoma

35. Ascoma
Appendages

36. Perithecial Ascomycota
Ascoma is a perithecium
Has an opening through which ascospores leave the ascoma = ostiole
Asci produced in a layer = hymenium
Asci are unitunicate and inoperculate
Asci typically have a pore or slit at the thickened tip

37. Perithecial Ascomycota
A large and diverse group of fungi –(have already discussed the powdery mildews which are sometimes included here
Include species which are
Saprotrophs – wood, dung, soil, plant litter
Parasites – plant, animal (arthropod) diseases
Endophytes
Some produce mycotoxins

38. Perithecia Typically flask shaped structures
Pore with opening = ostiole
Perithecial wall composed of pseudoparenchyma tissue
Centrum is the central part where asci develop

39. Perithecia
Perithecial wall composed of fungal tissue called pseudoparenchyma – thin cell walls, looks like plant parenchyma tissue
Centrum – the asci and sterile structures that fill the cavity within the perithecial wall
Sterile structures:
Paraphyses – basally produced in hymenium
Pseudoparaphyses – originate from top of the perithecium, grow into hymenium
Periphyses – extending into the ostiole

40. Perithecium
Ostiole
Periphysis
Wall
Classification is based in large part on development of centrum, development of paraphyses or pseudoparaphyses
Stroma
Paraphysis
Ascus
Ascospore

41. Perithecia
Perithecia may be produced individually or they may be produced within a mass of tissue = stroma (always produce a separate perithecial wall)

42. Stroma (stromata) Compact tissue that forms a flat plate or a mass
Hyphae may be inflated, intertwined, have lost identity to form a tissue that looks like parenchyma tissue of plants – called pseudoparenchyma
May be hard and woody or soft and fleshy

43. Perithecial Ascomycota
Saprotrophic fungi on dung, wood, in soil & decaying leaves
Includes Neurospora – important in study of genetics
Asci are club shaped to cylindrical, most produce 8 ascospores
Asci may breakdown and release ascospores or persist & forcibly discharge ascospores

44. Chaetomium Common saprotrophs in soil and dung, highly cellulolytic
Perithecia have distinctive filaments (straight or spiral )extending from upper part of perithecium
Asci are club shaped and wall deliqueses leaving ascospores embedded in jelly like substance that oozes out of the ostiole

45. Chaetomium
Ascospores are lemon shaped

46. Neurospora crassa
Red (pink) bread mold – grows on dough in bakeries, forms lots of conidia, bad contaminant
Widely used in genetic studies, one gene – one enzyme concept developed in Neurospora
Most species are heterothallic – two mating types – A & a

47. Sordaria perithecia & asci

48. Ascospore discharge
In many Ascomycota, asci develop high turgor pressure and actively discharge ascospores individually or as a group from ascus
In some, particularly coprophilous forms, the asci or ascomata may be phototrophic so that ascospores are discharged toward the light

49. Ascospore discharge
In Sordaria, Neurospora and other members of this group, asci stretch through ostiole and actively discharge ascospores

50. Xylaria
Produce dark colored, brittle solitary perithecia or perithecia may be produced in a stroma
Stromata are hard and woody, generally dark colored
In development of centrum, paraphyses grow from base and sides to expand the perithecium that allows the asci space – paraphyses may persist or disappear

51. Xylaria
Forms a dark colored, woody stroma, ca 10 cm long and 1-2 cm in diam
Extends up from ground, grows on wood
Commonly called “dead man’ s fingers”

52. Nectria
Produce brightly colored stromata that are generally soft and fleshy with embedded perithecia
Includes both plant and fungal parasites

53. Claviceps purpurea
Ascospores produced in spring – infect the ovaries of rye flowers
Hyphae grow and replace ovary tissue, forming a hyphal mat that produces small conidiophores and conidia, secretes a nectar like substance that attracts insects for dispersal to other plants
Mycelial mat differentiates – becomes hardened and forms pseudoparenchyma – eventually becoming a sclerotium

54. Claviceps purpurea
Sclerotium – firm mass of fungal tissue, resistant to environmental extremes, can remain dormant
Falls to ground & overwinters as a sclerotium

55. Claviceps purpurea
In spring, sclerotia germinate to produce stalked stromata within which perithecia are produced

56. Claviceps life cycle

57. Ergotism
If sclerotia are harvested with grain and ground into flour, they contain a number of alkaloids that are poisonous to humans and animals – cause ergotism
Latest epidemic in 1951 in France resulted in several deaths and many sick and crippled people – also called St. Anthony’s fire
Symptoms – vomiting, intense cold or hot sensations, lesions on hands and feet, diarrhea, convulsions, gangrenous condition in limbs that may lead to loss, causes constriction of arteries and contraction of smooth muscle

58. Ergotism In 1951, some people suffered from hallucinations
Concluded that these were similar to LSD (lysergic acid diethylamide)
LSD not produced by Claviceps, but thought that other fungi converted some of the alkaloids produced to LSD

59. Ergotism
Ergotism thought to have caused symptoms that lead to the Salem witch trials
Ergot alkaloids in the proper dose have been used in medicine
Stimulate labor – sclerotia carried by midwives
Treatment of migraines
Alkaloids only produced by sclerotium, not by mycelium – until recently had to infect fields of rye to obtain sclerotia, recent methods have produced alkaloids in culture

60. Cordyceps
Parasite of insects and fungi forms stromata from host

61. Apothecial Ascomycota
Unitunicate asci
Operculate & inoperculate asci
Asci present in a hymenium
Ascoma is open & hymenium exposed when asci mature

62. Apothecia Range in size from microscopic to morels
Many called cup fungi since apothecium forms a cup, others may be flat, disk shaped or stalked
Truffles produce a modified apothecium

63. Apothecia Most are produced above ground = epigean
Some are produced below ground = hypogean
Asci are typically club shaped or cylindrical
Most actively discharge ascospores distances from 2-30 cm
Simultaneous discharge of many asci causes wind currents that may carry ascospores farther – puffing
Puffing caused by changes in humidity, wind,etc

64. Puffing

65. Apothecial development in Ascobolus

66. Apothecia in Pezizales
Cup-shaped apothecia
Stalked
Sessile

67. Morels and relatives
Morchella
Modified apothecia

68. Morels
False morels - Verpa

69. False morels
Gyromitra
Helvella

70. Truffles Truffles produce hypogeous ascomata
Ascomata are highly modified
Hymenium has great deal of infolding
Ascospores not forcibly ejected

71. Truffles Ascomata broken open by animals or by weathering
Some species emit strong odor so that small animals, insects can detect them underground, dig up and eat them, dispersing spores
Geopora, Tuber

72. Truffles Ascomata of Tuber thought to be the best fungi to consume
Are mycorrhizal with certain trees (oaks, hazelnuts)
Use trained pigs and dogs to find them

73. Pseudothecial Ascomycota
Ascoma produced by these fungi is an ascostroma – asci are produced in cavities (locules) in a stroma, no separate wall around ascoma, only stroma
In some, superficially look like perithecia

74. Asci
Most produce bitunicate asci
Two layers that separate when mature

75. Ascomycota - yeasts
Produce naked asci, never produce ascomata or ascogenous hyphae
Include single cell and filamentous yeasts
Cell wall polysaccharides include mannans, -glucans plus small amount of chitin
DNA sequences indicate that these yeasts are a monophyletic group sister to the filamentous Ascomycota

76. Yeasts
Many species associated with flowers, fruits where high concentrations of sugar are present
Many are facultative anaerobes – aerobic respiration or ethanol fermentation
Widely used in brewing (beer, wine) and baking industries
Some used as human & animal food, source of vitamins
Also include some human pathogens – Candida albicans – normal flora

77. Yeasts
Thallus is typically unicellular, in some species there may be a limited mycelium (filamentous yeasts)
Asexual reproduction – cell division in unicellular forms
Commonly occurs as budding – unequal cell division where a daughter cell grows larger until it separates from mother cell

78. Budding

79. Sexual reproduction
Haploid-diploid life cycle as in Saccharomyces cerevisiae (baker’s and brewer’s yeast)

80. Taphrinales Pathogens of plants
Cause peach leaf curl, witches broom, shriveled pocket of plum and others

81. Taphrinales
Produce dikaryotic hyphae in the host tissue that give rise to naked asci (no ascoma)
Asci split across the top to release ascospores (not typical of other Ascomycota)

82. Ascomycota - review Large phylum – ca 30,000 spp.
Most form septate hyphae, some have unicellular thallus
Sexual life cycle – produce ascus with haploid ascospores after meiosis
Vegetative thallus is haploid
Dikaryotic stage is extended – ascogenous hyphae

83. Ascomycota - review
Most produce multicellular fruting body – the ascoma in which the asci and ascospores are formed
An ascoma contains two types of hyphae
Haploid hyphae that form the wall and sterile structures (paraphyses)
Dikaryotic ascogenous hyphae in which karyogamy and meiosis occur
Characterisitics of asci and ascoma important in classification

84. Ascomycota - review
Asexual reproduction – production of conidia on conidiophores
Represents the anamorphic stage
Many of the Deuteromycota thought to be anamorphs of Ascomycota

85. Ascomycota - review Phylogeny
Previous hypotheses that the Ascomycota evolved from red algae (similarities in morphology of sexual structures) and Mucorales
Evidence from DNA sequences suggests that Ascomycota and Basidiomycota are sister groups but to date no indication of ancestors