kingdom fungii. protozoans (heterotrophic protists) division myxomycota (acellular or plasmodial...

Kingdom Fungii

Protozoans(heterotrophic protists)

• Division Myxomycota (acellular or plasmodial slime molds)

• Division Acrasiomycota (cellular slime molds)

• Division Oomycota (water molds or egg fungi)

Myxogastrida (plasmodial slime molds) (formerly Myxomycota latter is

supplement)(a)Feeding stage consists of a motile,

multinucleated, amoeboid mass called a plasmodium

(b)"If the habitat of a slime mold begins to dry up or there is no food left, the plasmodium ceases growth and differentiates into a stage of the life

cycle that functions in sexual reproduction."

Plasmodial slime molds, like Physarum shown here, are basically enormous single cells with thousands of nuclei. They are formed when individual flagellated cells swarm together and fuse. The result is one large bag of cytoplasm with many diploid nuclei.

Dictyostelida (cellular slime molds) (formerly Acrasiomycota latter is supplement)

(a)Unlike the plasmodial slime molds, the cellular slime molds exist as free-living individual cells that come together to form a multicelled slug

(rather than forming a multinucleated plasmodium via multiple rounds of mitosis not followed by cytokinesis as do the plasmodial

slime molds)(b) Individual cells resemble amoebas

(c)"The feeding stage of the life cycle consists of solitary cells that function individually. When

there is no more food, the cells form an aggregate that functions as a unit. Although the mass of cells resembles a plasmodial slime mold, the

important distinction is that the cells of a cellular slime mold maintain their identity and remain

separated by their membranes."

Oomycota (water molds)

(a) The Oomycota or water molds superficially resemble fungi, but differ from true fungi in a number of ways including

• (i) Water molds have cellulose (not chitin) cell walls

• (ii) Water molds are flagellated at certain points in their life cycle

• (iii) Water molds are diploid throughout most of their life cycle

"Oomycota" means "egg fungi," and refers to the large round oogonia, or structures containing the female gametes, as shown in this picture of the common "water mold" Saprolegnia. Oomycetes are oogamous, producing large non-motile gametes called eggs, and smaller gametes called sperm

Fungii

• Ancient Greeks and Egyptians used fungii to make wine

• Myan Indian tribes of Mexico, hallucinogenic mushrooms in religious ceremonies

• World War I, puff balls were used to cover wounds

• Pathogens to humans, plants and other organisms

• Environmental recyclers

Decomposers

• Heterotrophic

• Saprophytic

• Excrete enzymes onto nutrient source

• Absorb material

Fungal Structure

• Eukaryotic, multicelllular

• Filaments (hyphae), connected end to enc

• Diffuse connection of cells, body of a fungii is termed mycellium

• Reproductive hyphae for the sporocap (cap of the mushroom)

Fungal Cells

• In addition to being filamentous, fungus may be coenocytic, no distinction between individual cells.

• Long filaments with a cytoplasm lining and a large vacuole in the center. (zygomycetes)

• Others are septate,filaments are separated by cross walls called septa (ascomycetes and basidiomycetes)

Fungal Cells

Coenocytic

Septate

Hyphae grow at their tips and branch to form a mass of interwoven strands that is called mycelium.

Fungal Mycelium

PloidyFungi typically possess haploid nuclei,

except just prior to meiosisOnly following nuclear fusion (

karyogamy) are fungi diploid, and mitosis in fungi does not occur in the diploid

stateHowever, many fungi routinely achieve a

diploid-like state following cytoplasmic fusion (plasmogamy) that is called a

dikaryon state or stage; note that dikaryon is not synonymous with diploid since nuclei remain haploid even if found

in same cytoplasm

PlasmogamyThough fungi nuclei are typically haploid, that doesn't stop haploid

nuclei from different fungal parents (e.g., mom and dad equivalents) from being present in the same cytoplasmThe process by which the cytoplasms

of two parental fungi fuse is called plasmogamy

Note that plasmogamy may be followed by nuclei fusing, though this

does not necessarily occur immediately, and for some fungi the

time until nuclear fusion occurs can be greatly extended (days, months, years)

Dikaryon state or stageThe post-plasmogamy condition in which two different haploid nuclei occupy the same cytoplasm is a

dikaryon state or stageBeing a dikaryon, since cytoplasms are shared, provides the masking of deleterious alleles of diploidy without

the possession of diploid nuclei

KaryogamyThe fusion of haploid nuclei found in

dikaryonic fungal cells is called karyogamy

Karyogamy is necessary for the occurrence of meiosis (since haploid

nuclei cannot undergo meiosis)Note that meiotic products are both haploid and therefore are no longer

dikaryonic

Sexual ReproductionSexual reproduction (note: order of terms is relevant):

mitosisHyphae (ploidy = n)

mitosisMycelium (ploidy = n)

Plasmogamy (a process) (= fusion of cytoplasm)Dikaryotic stage (ploidy = n + n) (occurs within zygosporangia

for Zygomycete, ascogonia for Ascomycete, or hyphae for Basidiomycete)

mitosisKaryogamy (a process) (= fusion of haploid nuclei)

Diploidy (ploidy = 2n) (occurs within zygosporangia for Zygomycete, ascocarps for Ascomycete, or basidiocarps for

Basidiomycete)Meiosis (a process)

Spore-producing structures (ploidy = n) (= sporangium for Zygomycete, asci for Ascomycete, or basidia for

Basidiomycete)Spores (ploidy = n) (= spores for Zygomycete, ascospores

for Ascomycete, or basidiospores for Basciomycete)Germination (a process)

mitosisHyphae (ploidy = n)

mitosisMycelium (ploidy = n)

Asexual reproduction (note: order of terms is relevant):

mitosisHyphae (ploidy = n)

mitosisMycelium (ploidy = n)

mitosisSpore-producing structures (ploidy = n)

mitosisSpores (ploidy = n) (= conidia for sac

fungi)Germination (a process)

mitosisHyphae (ploidy = n)

mitosisMycelium (ploidy = n)

Placement into a division is based on the way in which the fungus reproduces sexually. The shape and internal structure of the sporangia, which produce the spores, are the most useful character for identifying these various major

groups. There are also two conventional groups which are not recognized as formal

taxonomic groups (ie. they are polyphyletic

Club Fungi (Basidiomycota)

latticed stinkhorn

Species in this phylum produce spores on a club-like structure called the basidium

Produce spores on exposed surfaces -- releasing the spores gradually through structures such as pores or gills.

Division Basidiomycota (club fungi, mushrooms)

Members of Division Basidiomycota are also called the club fungi and include the

mushroomsMushrooms are fruiting bodies of

underground myceliaClub fungi spend most of their life cycle in

the dikaryotic state

Basiodospores (mushroom gill)

Basidiospores

Sac Fungi (Ascomycota)

Sac fungi produce spores inside cases (asci) which may open at one end.

White Morel (Morchella deliciosa, left), however, is often found in urban locations growing among leaves or other discarded stuff.

Another prominent group of Ascomycota is the Cup Fungi

The mushrooms of these fungi look like little cups or sacs and often do not have a stalk at all. An exception to this is the brightly colored Stalked Orange Peel Fungus (Aleuria rhenana).

In hyphal Ascomycota, the youngest, terminal hyphal segments develop into 8-spored asci.

Ascomycota are either single-celled (yeasts) or filamentous (hyphal) or both (dimorphic). Yeasts grow by budding or fission and hyphae grow apically and branch laterally. Most yeasts and filamentous Ascomycota are haploid, but some species, Saccharomyces cerevisiae for example, can also be diploid. Mitospores may simply reproduce the parent, or may also act as gametes to fertilize a compatible partner.

Conidia

Conjugation Fungi (Zygomycota)

The best known of this phylum of around 600 species is black bread mold, such as Rhizopus stolonifer.

Division Zygomycota (zygote fungi) These are the zygote

fungiIn their sexual cycle

these fungi form gametangia that are multinucleated cells

walled off from parental cells by septa

Gametangia from two different parental fungi

fuse (undergo plasmogamy) to form

dikaryonic zygosporangia that are capable of

toughening to form a dormant stage

Zygosporangia give rise to sporangia following germination, karyogamy, and meiosis

Imperfect Fungi (Deuteromycota)

Around 25,000 additional fungus species are grouped in this phylum -- these species are the "left-overs" that don't fit well into any of the other groups. Members include Trichophyton (Athlete's foot), Penicillium (Penicillin), and Candida albicans ("Yeast" infections).

Imperfect fungi Imperfect fungi fail to

reproduce sexually, consequently fail to produce the sexual structures by which

other fungi are classified (at least traditionally), so are not well

phylogenetically classified, at least using classical methods

Hyphae

Lichens

LichensLichens are a polyphyletic grouping of fungi that

possess algae (eukaryotic or blue-green) symbionts

"The fungus usually gives the lichen its overall shape and structure, and tissues formed by

hyphae account for most of the lichen's mass… The alga always provides the fungus with food. Cyanobacteria in lichens fix nitrogen and provide organic nitrogen. The fungus provides the alga

with a suitable physical environment for growth. Lichens absorb most of the minerals they need either from air or in the form of dust… Fungal

pigment shades the algae from intense sunlight. Some fungal compounds are toxic and prevent

lichens from being eaten by consumers."

Crustose Lichens

Crustose lichens are flaky or crust-like. They can be found covering rocks, soil, bark, etc. -- often forming brilliantly colored streaks. The yellow ones pictured here on a granite stone in the Rocky mountains, are probably Common Yolk Lichens (Acarospora spp.); the red, Caloplaca spp.; and green, Lecanora spp.. The little buttons to the left are a magnification of the red streaks above.

Foliose Lichens

Foliose (leaf-like) lichens can be papery thin or, in more advanced forms, netted branch-like. Branched foliose lichens have a distinct top and bottom surface, thus differentiating them from most fruticose lichens. This can be seen clearly in the Pseudocyphellaria anthraspis photo, above left; the Hypogymnia imshaugii on the right has a puffed body with a black undersurface.

Fruticose Lichens

                                                 Fruticose lichens are the

most highly developed lichens. Their branches are much closer in form to "true" branches although, unlike most plants, the lichen branch has no specialized vascular system for transporting fluids. The British Soldier Lichen (Cladonia macilenta), left, is one of the showiest fruiting lichens: even though the mushrooms are quite tiny, their bright color and distinctive form makes them stand out in their forest habitat.

Old Man's Beard